Grid Stability Evaluation. · 2012. 12. 3. · Southern Company Services, Inc., Southwestern Power Administration, and Tennessee Valley Authority. The bulk power transmission and

Attachment 12

GNRO-2010/00056

Grid Stability Evaluation

Attachment 12 to GNRO-2010/00056 Page 1 of 6

Grid Stability Evaluation Introduction This attachment describes the results of studies that were performed to evaluate the effects of the Grand Gulf Nuclear Station (GGNS) Extended Power Uprate (EPU) on grid reliability and stability. The evaluation is based on:

Generation Interconnection Facilities Study PID-226, Revision 5 performed in accordance with the Federal Energy Regulatory Commission (FERC) Large Generator Interconnection Agreement (LGIA),

System Impact Study (OASIS Request Number: 1598291, ICTT-2008-180), Revision 0, Transmission Service Request Facilities Study (OASIS1598291, ICTT-2008-180),

Revision 1, and Offsite Power Supply Analysis for GGNS

According to the FERC LGIA, a generator interconnection customer is required to be capable of supplying at least 0.33 Mega-Volt Ampere Reactive (MVAR) for each MW of power injected into the grid, in order to meet the specified 0.95 leading power factor requirement at the point of interconnect. When GGNS is at maximum power (i.e., 1503.5 MWe gross generation and 547.25 MVAR), the power factor at the generator terminals is 0.940. Accounting for MW and MVAR losses in the 20.9 / 500kV step-up transformer and unit auxiliary power requirements, the power reaching the point of interconnect is 1443 MWe and 260 MVAR, which corresponds to a 0.979 power factor. To meet the LGIA power factor design criteria, approximately 216 MVAR of additional reactive power capability is required. Due to the large amount of total reactive power capability needed following the GGNS EPU, it is more advantageous in terms of system reliability for capacitor banks to be distributed appropriately at designated load centers throughout the system, as confirmed by the studies. The PID-226 Interconnection Study demonstrated that the power uprate will not adversely impact bulk power transmission system steady-state power flow (thermal ratings and voltage), stability, short circuit duty or power transfer levels. Grid events analyzed included loss of the largest generator, loss of GGNS, and loss of the most critical transmission line due to fault with the unit operating at full power uprate capacity. Pre-event line outages were also considered. Stability simulations were transiently stable and exhibited positive damping with the power uprate. GGNS offsite steady state and transient voltages resulting from critical transmission line faults or loss of GGNS generation are adequate to operate loads required for safe shutdown and will preclude the inadvertent separation from the offsite supply. Reactive power will be maintained within acceptable limits analyzed in the grid studies. As stated above, this will be accomplished by the addition of 216 MVAR capacitor banks, utilizing the existing generator-exciter control system and governed by operational procedures. Offsite Electrical System General Description Entergy Mississippi Inc. as a member of Entergy Electric System (EES) power grid system supplies off-site AC power to support GGNS plant operations. The grid system of EES consists of interconnected hydro-plants, fossil fuel plants, and nuclear plants supplying electric energy over a 500/230/161/115 kV transmission system.


Other members of the system are Entergy Arkansas, Inc. (EAI), Entergy Gulf States Louisiana, L.L.C. (EGSL), Entergy Louisiana, LLC (ELL), Entergy Mississippi, Inc. (EMI), Entergy New Orleans Inc. (ENOI) and Entergy Texas, Inc. (ETI). The EES is interconnected with Ameren Transmission, Associated Electric Cooperative, Inc., Constellation Energy Control and Dispatch, Central and Southwest, Cleco Power LLC, Empire District Electric Co. Lafayette Utilities System, Louisiana Energy and Power Authority, Louisiana Generating, LLC, Oklahoma Gas and Electric, South Mississippi Electric Power Association, Southern Company Services, Inc., Southwestern Power Administration, and Tennessee Valley Authority. The bulk power transmission and generation needs of the EES are planned on a system-wide basis. In 1965 the basic 500 kV system now in operation was designed and put into operation. The system has proven to be highly reliable. EES interconnects with Tennessee Valley Authority to the north at West Memphis, Arkansas and to the east at West Point, Mississippi. It interconnects to the southwest with Entergy Gulf States Inc. at Willow Glen, Louisiana, and to the west with Oklahoma Gas and Electric at Fort Smith, Arkansas. Agreements with each of these utilities provide a reliable and widely dispersed source of power when connected at 500 kV over such relatively short distances. These interconnections serve to enhance the reliability of the 500 kV bulk power system of the EES. Other system connections exist at 345 kV, 230 kV, 161 kV, and 115 kV voltages. Direct generation connections to the 500 kV transmission system include Arkansas Nuclear One, Grand Gulf Nuclear Unit 1, Baxter Wilson, and Little Gypsy. Other 500 kV connections in the Entergy System, made through step-up transformers, include West Memphis, Mabelvale, El Dorado, Baxter Wilson, Ray Braswell, Franklin, Fancy Point, and Waterford. These diverse power inputs provide a highly reliable source of power for the grid that supplies off-site power to GGNS. Off site power is also provided to GGNS via a 115 kV system which consists of an overhead 115 kV line from the Port Gibson Substation terminated near the plant site to an underground 115 kV cable that connects this source to the site. The115 kV power source is completely independent from the 500 kV lines for offsite power and is on a completely different overhead line right-of-way from the 500 kV lines, in its routing to the Port Gibson Substation. GGNS is connected to the transmission grid at an on-site 500 kV switchyard through a 20.9 / 500kV main step-up transformer. Power is transmitted off-site through two 500 kV overhead lines: one terminating at the Baxter Wilson Substation and the other at the Franklin Substation. The primary transmission owner is Entergy Mississippi, Inc. None of the 500 kV lines to the GGNS 500 kV switchyard share a common tower or common right-of-way. The lines diverge as they leave GGNS switchyard. The lines are widely dispersed to minimize the probability of multiple concurrent line damages due to tornadoes. The nominal voltage of the 500 kV grid is 510 kV. The maximum and minimum anticipated voltages of the 500 kV grid at GGNS are 525 kV and 491 kV, respectively. The recorded voltages in the past years indicate no voltage excursions outside these limits. The 500 kV and 115 kV lines are designed and built to meet the National Electrical Safety Code.


Design Basis The GGNS onsite and off-site electric power systems meet the requirements of 10 CFR 50, Appendix A General Design Criteria (GDC) 17, Electric Power Systems and GDC 18, Inspection and Testing of Electric Power Systems. The off-site power system is designed and constructed with sufficient capacity and capability from the transmission network to support plant operations and assure that the specified acceptable fuel design limits and conditions are not exceeded as a result of anticipated operational occurrences. The design and construction also assures containment integrity, core cooling, and other vital functions are maintained in the event of postulated accidents. Compliance with the GDC and the off-site power system are described in GGNS Updated Final Safety Analysis Report (UFSAR) Sections 3.1.2.2.8, 3.1.2.2.9 and 8.2. Evaluation Assumptions and Methodology The studies assumed the following:

To accommodate seasonal swings in MWe output, the grid stability analysis was evaluated assuming a maximum gross generation of 1503.5 MWe.

A new generator which is rated at 1600 MVA as compared to a 1525 MVA rating for the existing generator.

The 2012 summer peak system conditions. Prior-queued generation projects in the system that could have an impact on the GGNS

generation increase. To demonstrate conformance of the GGNS EPU to applicable national and regional reliability council criteria, the stability analysis was performed using Siemens-PTIs PSS/ETM dynamics program V30.3.2 for both pre-uprate and post-uprate conditions. Three-phase line faults with normal clearing and delayed clearing and single-phase line faults were simulated for the specified duration and synchronous machine rotor angle and wind turbine generator speeds were monitored to check whether synchronism is maintained following fault removal. Since PSS/E inherently models the positive sequence fault impedance, the sum of the negative and zero sequence Thevenin impedances were added and entered as the fault impedance at the faulted bus. In addition to criteria for the stability of the machines, evaluation criteria for the transient voltage dip are also applicable, as follows:

3-phase fault or single-line-to-ground (SLG) fault with normal clearing resulting in the loss of a single component (generator, transmission circuit or transformer) or a loss of a single component without fault:

- Not to exceed 20% for more than 20 cycles at any bus

- Not to exceed 25% at any load bus

- Not to exceed 30% at any non-load bus


3-phase faults with normal clearing resulting in the loss of two or more components

(generator, transmission circuit or transformer), and SLG fault with delayed clearing resulting in the loss of one or more components:

- Not to exceed 20% for more than 40 cycles at any bus

- Not to exceed 30% at any bus The duration of the transient voltage dip excludes the duration of the fault. The transient voltage dip criteria were not applied to three-phase faults followed by stuck breaker conditions unless the determined impact was extremely widespread. The voltages at all local buses (above 115 kV) were monitored during each of the fault cases as appropriate. As there are no specific voltage dip criteria for three-phase stuck breaker faults, the results of these faults were compared with the most stringent voltage dip criteria of “not to exceed 20 % for more than 20 cycles.” Transient Stability Analysis Stability simulations were run to examine the transient behavior of the impact of the proposed uprate on the Entergy system. The fault clearing times used for the simulations are given in the following table:

Contingency at kV level Normal Clearing Delayed Clearing

500 5 cycles 5 + 9 cycles The breaker failure scenario was simulated with the following sequence of events:

1) At the normal clearing time for the primary breakers, the faulted line is tripped at the far end from the fault by normal breaker opening.

2) The fault remains in place for three-phase stuck-breaker faults. The fault admittance is changed to Thevenin equivalent admittance of single phase faults.

3) The fault is then cleared by back-up clearing. If the system was found to be unstable, then the fault was repeated without the proposed uprate.

All line trips are assumed to be permanent (i.e., no high speed re-closure). Fifteen (15) three phase normally cleared and twenty seven (27) three-phase stuck breaker converted into single-line-to-ground fault (following Independent Pole Operation of breakers) were simulated. For all cases analyzed, the initial disturbance was applied at t = 0.1 seconds. The breaker clearing was applied at the appropriate time following this fault inception. The system was found to be stable following all simulated faults.


Critical Clearing Time Analysis An evaluation of the critical clearing times (CCT) was performed for faults on lines and transformers in the GGNS 500 kV substations (i.e., Baxter Wilson and Franklin) at 2012 summer peak system conditions. CCT is defined as the longest fault clearing time for which stability is maintained. CCT was calculated for a three-phase stuck-breaker fault on each branch connected to GGNS 500 kV substations. Independent pole operation (IPO) was assumed for breakers in both switchyards, with breaker failure occurring on only a single phase. This results in a three-phase fault becoming a single-phase fault at the normal clearing time. The single phase fault is then cleared by backup protection. The Normal Clearing Time was kept equal to the normal value (5 cycles on 500 kV and 6 cycles on 230 kV) and the backup clearing time was varied to find the CCT. The lowest critical clearing time 20 cycles (=5 + 15 cycles) is still larger than Entergy’s standard clearing time of 14 cycles (= 5 + 9 cycles) for 500 kV breakers. All machines in the Entergy system were monitored for stability. Based on the results of the CCT analysis, the proposed uprate does not adversely impact the critical clearing at either GGNS 500kV substations. Transient Voltage Recovery The voltages at all buses in the Entergy system above 115kV were monitored during each of the fault cases as appropriate. No voltage criteria violation was observed following a normal cleared three-phase fault. As there are no specific voltage dip criteria for three-phase fault converted into single-phase stuck breaker faults, the results of these faults were compared with the most stringent voltage dip criteria: “not to exceed 20% for more than 20 cycles.” After comparison against the voltage criteria, no voltage criteria violation was observed with the proposed uprate of GGNS. Conclusion With the addition of 216 MVAR capacitor banks, utilization of the existing generator-exciter control system and governance by operational procedures, the interconnection study demonstrated that the system remains stable. No voltage criteria violations were observed following all simulated normally cleared and stuck-breaker faults. The studies demonstrated that with GGNS at full EPU rated output:

Loss of GGNS will result in a stable grid and offsite power remains available to support shutdown.

Loss of the largest generator is bounded by the loss of GGNS.


Loss of the most critical 500kV transmission line due to fault will result in a stable transmission grid and GGNS will retain offsite power.

System faults as described in PID 226 Stability Analysis result in a stable transmission

grid and have no impact to GGNS offsite power. In summary the proposed increase in power associated with the GGNS EPU does not adversely impact the stability of the Entergy transmission grid in the local area.

Attachment 13

GNRO-2010/00056

Extended Power Uprate Risk Analysis

IDENTIFICATION OF RISK

IMPLICATIONS DUE TO EXTENDED POWER UPRATE AT

GRAND GULF

Prepared for ENTERGY

Prepared by:

Engineering and Research, Inc.an SKF Group Company

Engineering and Research, Inc.an SKF Group Company

MAY 2010


C247090004-9013-07/09/10


IDENTIFICA TION OF RISK IMPLICA TIONS DUE TO

EXTENDED POWER UPRA TE AT GRAND GULF

Prepared by: Date: 5 Ii 4.1 2.010

Reviewed by: Date: 5' /1 41 L.!J , 0

Approved by: Date: ~ /, L/ I .2 010

C247090004-9013-07/09/10

IDENTIFICATION OF RISK IMPLICATIONS DUE TO

EXTENDED POWER UPRATE AT GRAND GULF

Prepared by: Garrett Snedeker Date: 5/14/2010 Reviewed by: Vincent Andersen Date: 5/14/2010 Approved by: Lawrence Lee Date: 5/14/2010


i

EXECUTIVE SUMMARY

The Extended Power Uprate (EPU) project for Grand Gulf has been reviewed to

determine the net impact on the Grand Gulf risk profile. The GGNS EPU is a constant

pressure power uprate (CPPU).

The existing Grand Gulf Probabilistic Risk Assessment (PRA) is based on the current

licensed thermal power (CLTP) level of 3898 MWt. Grand Gulf is currently pursuing a

113% increase (i.e., Extended Power Uprate) of the CLTP to 4408 MWt(1).

The enclosed assessment of the power uprate impacts on risk has been performed

relative to the current PRA. The guidelines from the NRC (Regulatory Guide 1.174) are

followed to assess the change in risk as characterized by core damage frequency

(CDF) and Large Early Release Frequency (LERF).

The methodology consists of an examination of the important elements of the Grand

Gulf Probabilistic Risk Assessment (PRA) to assess the impact of the following EPU

changes on the PRA elements:

• Power level change

• Hardware changes

• Procedural changes

• Operational changes These changes are interpreted in terms of their PRA model effects, which can then be

used to assess whether there are any resulting risk profile changes.

(1) The GGNS original licensed thermal power (OLTP) was 3833 MWt.


ii

Risk impacts due to internal events are assessed using the GGNS Level 1 and Level 2

PRA Models of Record (ggr3.caf and GGLERFR3.caf, respectively). [2, 9] External

events are evaluated using the analyses of the Grand Gulf Individual Plant Examination of

External Events (IPEEE) Submittal [10]. The impacts on shutdown risk contributions are

evaluated on a qualitative basis.

The results of the PRA evaluation are the following:

• Detailed thermal hydraulic analyses of the plant response using the EPU configuration indicate reductions in the operator action “allowable” times for some actions.

• The reduced operator action “allowable” times resulted in increases in the assessed Human Error Probabilities (HEPs) for some actions in the PRA model.

• Only small risk increases were identified for the changes associated with the EPU, those associated with: (1) reduced times available for effective operator actions; and (2) minor changes in some functional success criteria in the PRA (negligible impact on results).

• The risk impact due to the implementation of the Extended Power Uprate is low and acceptable without the requirement for special compensatory measures. The risk impact is in the “very low” category (i.e., Region III) of the Regulatory Guide 1.174 guidelines for CDF and for LERF.

The EPU is estimated to increase the Grand Gulf internal events PRA CDF from the base

value of 2.68E-6/yr (1) to 2.91E-6/yr, an increase of 2.3E-7/yr (8.6%). LERF increases from

the base value of 1.44E-7/yr(1) to 1.48E-07/yr, an increase of 4.3E-9/yr (3%).

(1) The CDF and LERF results documented in this report are per reactor-year, and assume 100% plant

availability. The GGNS average unavailability is approximately 93.1% (based on years 2001-2005). The GGNS CDF and LERF per calendar year (i.e., taking into account actual availability) are 2.50E-6/yr and 1.38E-7/yr, respectively. This information is provided as a background and does not impact the delta CDF and delta LERF results of this analysis.


iii

TABLE OF CONTENTS

Section Page EXECUTIVE SUMMARY.........................................................................................................i 1.0 INTRODUCTION .....................................................................................................1-1 1.1 Background...................................................................................................1-1 1.2 PRA Quality ..................................................................................................1-2 1.3 PRA Definitions and Acronyms....................................................................1-3 1.4 General Assumptions ...................................................................................1-8 2.0 SCOPE.....................................................................................................................2-1 3.0 METHODOLOGY ....................................................................................................3-1 3.1 Analysis Approach........................................................................................3-1 3.2 PRA Elements Assessed .............................................................................3-3 3.3 Inputs (Plant Changes).................................................................................3-4 3.4 Scoping Evaluation.......................................................................................3-6 4.0 PRA CHANGES RELATED TO EPU CHANGES ..................................................4-1 4.1 PRA Elements Potentially Affected by Power Uprate..................................4-1 4.2 Level 1 PRA................................................................................................4-56 4.3 Internal Fires Induced Risk.........................................................................4-59 4.4 Seismic Risk ...............................................................................................4-63 4.5 Other External Events Risk ........................................................................4-64 4.6 Shutdown Risk............................................................................................4-65 4.7 Radionuclide Release (Level 2 PRA).........................................................4-70 5.0 CONCLUSIONS ......................................................................................................5-1 5.1 Level 1 PRA..................................................................................................5-2 5.2 Fire Induced Risk..........................................................................................5-3 5.3 Seismic Risk .................................................................................................5-3 5.4 Other External Hazards................................................................................5-3 5.5 Shutdown Risk............................................................................................5-10 5.6 Level 2 PRA................................................................................................5-10 5.7 Quantitative Bounds on Risk Change........................................................5-11 REFERENCES................................................................................................................... R-1


iv

TABLE OF CONTENTS (cont’d)

APPENDIX A PRA QUANTIFICATION RESULTS APPENDIX B IMPACT OF EPU ON SHUTDOWN OPERATOR ACTION RESPONSE

TIMES APPENDIX C GRAND GULF PRA QUALITY APPENDIX D HEP ASSESSMENTS APPENDIX E GRAND GULF EPU MAAP CALCULATIONS


1-1

Section 1

INTRODUCTION

The Grand Gulf Nuclear Station is currently pursuing an increase in reactor power from the

current licensed thermal power of 3898 MWth to 4408 MWth, an Extended Power Uprate

(EPU) of 113% CLTP(1). The purpose of this report is to:

(1) Identify any significant change in risk associated with the Extended

Power Uprate (EPU) as measured by the Grand Gulf PRA models; (2) Provide the basis for the impacts on the risk model associated with

EPU 1.1 BACKGROUND The Grand Gulf PRA is a state-of-the-technology tool developed consistent with current

PRA methods and approaches. The GGNS model is developed and quantified using the

EPRI R&R Workstation software.

The Grand Gulf PRA is based on realistic assessments of system capability over the 24

hour mission time of the PRA analysis. Therefore, PRA success criteria may be different

than the design basis assumptions used for licensing Grand Gulf. This report examines

the risk profile changes from this realistic perspective to identify changes in the risk profile

on a best estimate basis that may result from postulated accidents, including severe

accidents.

(1) The GGNS original licensed thermal power (OLTP) was 3833 MWt.


1-2

1.2 PRA QUALITY The quality of the GGNS PRA models used in performing the risk assessment for the

GGNS EPU is manifested by the following:

• Sufficient scope and level of detail in PRA

• Active maintenance of the PRA models and inputs

• Comprehensive Critical Reviews

Scope and Level of Detail The GGNS PRA is of sufficient quality and scope for this application. The GGNS PRA

modeling is highly detailed, including a wide variety of initiating events (e.g., transients,

internal floods, LOCAs inside and outside containment, support system failure

initiators), modeled systems, extensive level of detail, operator actions, and common

cause events.

Maintenance of Model, Inputs, Documentation The GGNS PRA model and documentation has been updated to reflect the current plant

configuration and to reflect the accumulation of additional plant operating history and

component failure data. The current GGNS PRA model at the time of this analysis is

Revision 3 of the Grand Gulf Level 1 and Level 2 PRA models (fault trees ggr3.caf and

GGLERFR3.caf, respectively). [2, 9] The Level 1 and Level 2 GGNS PRA analyses

were originally developed and submitted to the NRC in December 1992 as the Grand

Gulf Individual Plant Examination (IPE) Submittal. [1] The NRC subsequently provided

a Safety Evaluation of the IPE in March 1996.

Critical Reviews The GGNS IPE was updated and renamed the GGNS PRA in 1997. The revision

underwent a BWROG PSA Peer Review Certification review.


1-3

Summary In summary, it is found that the Grand Gulf Level 1 and Level 2 PRAs provide the

necessary and sufficient scope and level of detail to allow the calculation of CDF and

LERF changes due to the Extended Power Uprate (EPU). Refer to Appendix C for

further details regarding the quality of the GGNS PRA.

1.3 PRA DEFINITIONS AND ACRONYMS Definitions The following PRA terms are used in this study:

CDF – Core Damage Frequency (CDF) is a risk measure for calculating the frequency of a severe core damage event at a nuclear facility. Core damage is the end state of the Level 1 PRA. A core damage event may be defined in the GGNS PRA by one or more of the following:

- Maximum core temperature greater than 1800°F, - RPV water level at 1/3 core height and decreasing, - Containment failure induced loss of injection.

CDF is calculated in units of events per year. With respect to analyzing MAAP thermal hydraulic runs, very short spikes (e.g., seconds or a couple minutes) above 1800°F are not automatically declared core damage. The case is typically re-run and re-analyzed using a different time step to confirm the highest core temperature and the duration it remains above 1800°F. LERF – Large Early Release Frequency (LERF) is a risk measure for calculating the frequency of an offsite radionuclide release that is HIGH in fission product magnitude and EARLY in release timing. A HIGH magnitude release is defined as a radionuclide release of sufficient magnitude to have the potential to cause early fatalities. An EARLY timing release is defined as the time prior to that where minimal offsite protective measures have been implemented. LERF is calculated in units of events per year.


1-4

Initiating Event – Any event that causes/requires a scram/manual shutdown (e.g., Loss of PCS, MSIV Closure) and requires the initiation of mitigation systems to reach a safe and stable state. An initiating event is modeled in the PRA to represent the primary transient event that can lead to a core damage event given failure of adequate mitigation systems (i.e., adequate with respect to the transient in question).

Internal Events – Those initiating events caused by failures internal to the system boundaries. Examples include Loss of PCS, MSIV Closure, Loss of an AC Bus, Loss of Offsite Power, and internal floods.

External Events – Those initiating events caused by failures external to the

system boundaries. Examples include fires, seismic events, and tornadoes. HEP – Human Error Probability (HEP) is the probabilistic estimate that the

operating crew fails to perform a specific action (either properly or within the necessary time frame) to support accident mitigation. The HEP is calculated using industry methodologies and considers a number of performance shaping factors such as:

- training of the operating crew, - availability of adequate procedures, - time required to perform action - time available to perform action - stress level while performing action

HRA – Human Reliability Analysis (HRA) is the systematic process used to

evaluate operator actions and quantify human error probabilities. MAAP – The Modular Accident Analysis Package (MAAP) is an industry

recognized thermal hydraulic code used to evaluate design basis and beyond design basis accidents. MAAP can be used to evaluate thermal hydraulic profiles within the primary system (e.g., RPV pressure, boil down timing) prior to core damage. MAAP also can be used to evaluate post core damage phenomena such as RPV breach, containment mitigation, and offsite radionuclide release magnitude and timing.

Level 1 PRA – The Level 1 PRA is the evaluation of accident scenarios that

begin with an initiating event and progress to core damage. Core damage is the end state for the Level 1 PRA. The Level 1 PRA focuses on the capability of plant systems to mitigate a core damage event.


1-5

Level 2 PRA – The Level 2 PRA is a continuation of the Level 1 PRA evaluation. The Level 2 PRA begins with the accident scenarios that have progressed to core damage and evaluates the potential for offsite radionuclide releases. Offsite radionuclide release is the end state for the Level 2 PRA. The Level 2 PRA focuses on the capability of plant systems (including containment structures) to prevent a core damage event to result in an offsite release.

RAW – The Risk Achievement Worth (RAW) is the calculated increase in a

risk measure (e.g., CDF or LERF) given that a specific system, component, operator action, etc. is assumed to fail (i.e., failure probability of 1.0). RAW is presented as a ratio of the risk measure given the component is failed divided by the risk measure given the component is assigned its base failure probability.

FV – The Fussell-Vesely (FV) importance is a measure of the contribution of

a specific system, component, operator action, etc. to the overall risk. FV is presented as the percentage of the overall risk to which the component failure contributes. In other words, the FV importance represents the overall decrease in risk if the component is guaranteed to successfully operate as designed (i.e., failure probability of 0.0).

Acronyms The following acronyms are used in this study:

AC Alternating Current ACRS Advisory Committee on Reactor Safeguards ADS Automatic Depressurization System ARI Alternate Rod Insertion ATWS Anticipated Transient Without Scram BIIT Boron Injection Initiation Temperature BOC Break Outside Containment BOP Balance of Plant BWR Boiling Water Reactor CCW Component Cooling Water CDF Core Damage Frequency CLTP Current Licensed Thermal Power CPPU Constant Pressure Power Uprate CRD Control Rod Drive CST Condensate Storage Tank CTS Condensate Transfer System DBA Design Basis Accident


1-6

DC Direct Current DFP Diesel Driven Fire Pump DHR Decay Heat Removal DW Drywell ECCS Emergency Core Cooling System ED Emergency Depressurization EOP Emergency Operating Procedure EPRI Electric Power Research Institute EPU Extended Power Uprate FIVE Fire-Induced Vulnerability Evaluation FV Fussell-Vesely (risk importance measure) FW Feedwater FWLC Feedwater Level Control GE General Electric GGNS Grand Gulf Nuclear Station HCLPF High Confidence Low Probability of Failure HCTL Heat Capacity Temperature Limit HEP Human Error Probability HP High Pressure HPCS High Pressure Core Spray HRA Human Reliability Analysis I&C Instrumentation and Control IORV Inadvertently Opened Relief Valve IPE Individual Plant Evaluation IPEEE Individual Plant Evaluation of External Events ISLOCA Interfacing Systems LOCA LERF Large Early Release Frequency LLOCA Large LOCA LOCA Loss of Coolant Accident LOOP Loss of Offsite Power LP Low Pressure LPCI Low Pressure Coolant Injection LPCS Low Pressure Core Spray MAAP Modular Accident Analysis Program MLOCA Medium LOCA MSCRWL Minimum Steam Cooling RPV Water Level MSIV Main Steam Isolation Valve MSL Main Steam Line MWt Megawatt (thermal) NEI Nuclear Energy Institute NPSH Net Positive Suction Head


1-7

NRC Nuclear Regulatory Commission NSSS Nuclear Steam Supply System OLTP Original Licensed Thermal Power OOS Out Of Service PCS Power Conversion System PRA Probabilistic Risk Assessment (alternative term for PSA) PSA Probabilistic Safety Assessment (alternative term for PRA) PSSA Probabilistic Shutdown Safety Assessment PSW Plant Service Water RAW Risk Achievement Worth (risk importance measure) RCIC Reactor Core Isolation Cooling RHR Residual Heat Removal RPS Reactor Protection System RPT Recirculation Pump Trip RPV Reactor Pressure Vessel RWCU Reactor Water Clean-Up SAMG Severe Accident Management Guidelines SAP Severe Accident Procedures SBO Station Blackout SDC Shutdown Cooling SDV Scram Discharge Volume SLC Standby Liquid Control SLOCA Small LOCA SMA Seismic Margins Analysis SORV Stuck Open Relief Valve SPMU Suppression Pool Makeup SRV Safety Relief Valve SSC Systems, Structures, and Components SSW Standby Service Water SV Safety Valve TAF Top of Active Fuel TBCW Turbine Building Cooling Water VB Vacuum Breaker WW Wetwell


1-8

1.4 GENERAL ASSUMPTIONS The Extended Power Uprate (EPU) risk evaluation includes a limited number of general

assumptions as follows:

• The plant and procedural changes identified by Entergy are assumed to reflect the as-built, as-operated plant after the Extended Power Uprate is fully implemented. The information provided by Entergy (as well as the GGNS EPU GE Task Reports) is used as input to the current Grand Gulf PRA model to evaluate the risk impact of the power uprate.

• This analysis is based on all the inputs provided by Entergy in support of this assessment. For systems where no hardware or procedural changes have been identified, the risk evaluation is performed assuming no impact as a result of the EPU.

• Replacement of components with enhanced like components does not result in any supportable significant increase in the long-term failure probability for the components.

• The PRA success criteria are different than the success criteria used for design basis accident evaluations. The PRA success criteria assume that systems that can realistically perform a mitigation function (e.g., main condenser or containment venting for decay heat removal) are credited in the PRA model. In addition, the PRA success criteria are based on the availability of a discrete number of systems or trains (e.g., number of pumps for RPV makeup).


2-1

Section 2

SCOPE

The scope of this risk assessment for the Extended Power Uprate at Grand Gulf

addresses the following plant risk contributors:

• Level 1 Internal Events At-Power (CDF)

• Level 2 Internal Events At-Power (LERF)

• External Events At-Power - Seismic Events - Internal Fires - Other External Events

• Shutdown Assessment Risk impacts due to internal events are assessed using the GGNS Revision 3 Level 1 and

Level 2 PRA models (fault trees ggr3.caf and GGLERFR3.caf, respectively). [2, 9] Level

2 sequences resulting in the Large-Early release category comprise the LERF risk

measure. External events are evaluated using the analyses of the Grand Gulf Individual

Plant Examination of External Events (IPEEE) Submittal [10]. The impacts on shutdown

risk contributions are evaluated on a qualitative basis.

All commitments resulting from the GGNS IPE and IPEEE Programs have been resolved.

The term “commitments” in this context refers to potential plant or procedural modifications

identified and credited in the IPE and IPEEE submittals.

As discussed in Section 3, all PRA elements are reviewed to ensure that identified EPU

plant, procedural, or training changes that could affect the risk profile are addressed. The

information input to this process consisted of preliminary design, and procedural

information provided by Entergy. The final design, analytical calculations, and procedural

changes had not been completed prior to this risk assessment.


3-1 C247090004-9013-07/09/10

Section 3

METHODOLOGY This section of the report addresses the following:

• Analysis approach used in this risk assessment (Section 3.1)

• Identification of principal elements of the risk assessment that may be affected by the Extended Power Uprate and associated plant changes (Section 3.2)

• Plant changes used as input to the risk evaluation process (Section 3.3)

• Scoping assessment (Section 3.4) 3.1 ANALYSIS APPROACH The approach used to examine risk profile changes is described in the following

subsections.

3.1.1 Identify PRA Elements This task is to identify the key PRA elements to be assessed as part of this analysis for

potential impacts associated with plant changes. The identification of the PRA elements

uses the NEI PRA Peer Review Guidelines [4]. Section 3.2 summarizes the PRA

elements assessed for the Grand Gulf EPU.

3.1.2 Gather Input The input required for this assessment is the identification of any plant hardware

modifications, procedural or operational changes that are to be considered part of the

Extended Power Uprate. This includes changes such as added equipment, procedural

modifications, and instrument setpoint changes.


3-2 C247090004-9013-07/09/10

3.1.3 Scoping Evaluation This task is to perform a scoping evaluation by reviewing the plant input against the key

PRA elements. The purpose is to identify those items that require further quantitative

analysis and to screen out those items that are judged to have negligible or no impact on

plant risk as modeled by the GGNS PRA.

3.1.4 Qualitative Results The result of this task is a summary which dispositions all the risk assessment elements

regarding the effects of the Extended Power Uprate. The disposition consists of three

Qualitative Disposition Categories:

Category A: Potential PRA change due to power uprate. PRA modification

desirable or necessary

Category B: Minor perturbation, negligible impact on PRA, no PRA changes required

Category C: No change Refer to Section 4 for a summary of these impacts as a function of PRA element.

3.1.5 Implement and Quantify Required PRA Changes This task is to identify the specific PRA model changes required to address the EPU,

implement them, and quantify the model. The GGNS PRA elements were investigated

with the aid of additional deterministic calculations performed in support of this analysis

(see Appendix E). Section 4.1 summarizes the review of PRA analysis impacts

associated with the increased power level. These effects and other effects related to plant

or procedural changes are identified and documented in Section 4.


3-3 C247090004-9013-07/09/10

3.2 PRA ELEMENTS ASSESSED The PRA elements to be evaluated and assessed can be derived from a number of

sources. The NEI PRA Peer Review Guidelines [4] provide a convenient division into

“elements” to be examined.

Each of the major risk assessment elements is examined in this evaluation. Most of the

risk assessment elements are anticipated to be unaffected by the Extended Power

Uprate. The risk assessment elements addressed in this evaluation for impact due to the

EPU (refer to Section 4 for impact evaluation) include the following:

• Initiating Events

• Systemic/Functional Success Criteria, e.g.:

- RPV Inventory Makeup

- Heat Load to the Suppression Pool

- Time to Boil down

- Blowdown Loads

- RPV Overpressure Margin

- SRV Actuations

- SRV Capacity for ATWS

• Accident Sequence Modeling

• System Modeling

• Failure Data

• Human Reliability Analysis

• Structural Evaluations

• Quantification

• Containment Response (Level 2)


3-4 C247090004-9013-07/09/10

3.3 INPUTS (PLANT CHANGES) This section summarizes the inputs to the risk evaluation, which include hardware

modifications, setpoint changes, procedural and operational changes associated with the

Extended Power Uprate. Table 3-1 has a complete list of the changes planned for the

Grand Gulf EPU.

3.3.1 Hardware Modifications The hardware modifications associated with the Extended Power Uprate have been

identified by Entergy as input to this assessment. The hardware modifications to be

implemented as part of the power uprate are included in an attachment to the License

Amendment Request.

3.3.2 Procedural Changes Slight adjustments to the GGNS EOPs/SAPs will be made to be consistent with EPU

operating conditions. In almost all respects, the EOPs/SAPs are expected to remain

unchanged because they are symptom-based; however, certain parameter thresholds and

graphs are dependent upon power and decay heat levels and will require slight

modifications. In addition, changes to some Abnormal Operating Procedures (AOPs) are

also expected.

The following EOP/SAP curves are affected:

• Heat Capacity Temperature Limit (HCTL) - The EPU will result in additional heat being added to the SP during certain accident scenarios. The HCTL curve will be revised as a result of the increase in decay heat rejected to the SP. The change is not significant (approximately 1˚F).

• Pressure Suppression Pressure (PSP) - The PSP Curve will be revised as a result of the increase in reactor power and in decay heat loading. The change is not significant (<1 psi).

• Minimum Debris Retention Injection Rate – The Minimum Debris Retention Injection Rate will be revised as a result of the increase in


3-5 C247090004-9013-07/09/10

decay heat loading. The injection flow will increase by approximately 10% of the CLTP flow.

Planned changes to AOPs (termed Off-Normal Event Procedures, ONEPs, at GGNS) are

as follows:

• The ONEPs listed below will be revised to rescale action points associated with reactor power; however, the event mitigation philosophy will not be changed. Affected procedures include: 05 1 02-I-2, Turbine and Generator Trips; 05-1-02-III-5, Automatic Isolations; 05-1-02-V-5, Loss of Feedwater Heating; 05-1-02-V-7, Feedwater System Malfunctions; 05 1 02 V 8, Loss of Condenser Vacuum; and 05 1 02 V 11, Loss of Plant Service Water.

• 05-1-02-III-1, Inadequate Decay Heat Removal has decay heat curves, heat up rates and temperature related data sheets that will be revised to reflect the new EPU values.

• 05-1-02-V-5, Loss of Feedwater Heating has a FW temperature vs. core power curve which determines the actions to be taken in response to the event. This curve will be revised to reflect the new EPU values.

3.3.3 Setpoint Changes Planned changes to setpoints to support EPU are as follows:

• The trip value for MSL High Flow Group 1 Isolation in terms of differential pressure is being revised to reflect the changes associated with the EPU rated thermal power level increase and steam flow increase.

• The trip value for the Turbine First Stage Pressure Scram Bypass Permissive is being revised to reflect the changes associated with the HP turbine modification and the EPU rated thermal power level increase. The absolute thermal power associated with the Turbine First Stage Pressure Scram Bypass Permissive remains unchanged. The specific first stage pressure associated with this power is being changed.

• Trip values for APRMs are being revised to reflect the changes associated with the EPU rated thermal power level increase.

• The Rod Worth Minimizer (RWM) and the Rod Block Monitor (RBM) setpoints remain at the same value in terms of percent. The absolute power values are being changed accordingly.


3-6 C247090004-9013-07/09/10

• The overspeed setpoint on the reactor feedpump turbines is being increased to accommodate the increased speed demand at normal EPU operations.

• The condensate booster pump low suction pressure trip setpoint is being increased due to the increased condensate booster pump flow rates at EPU conditions.

• The pressure control system pressure regulator setting is being lowered to provide for the increased steam line pressure drop at EPU steam flow rates.

Changes to the following setpoints are not anticipated for the EPU:

• RPT/ATWS high dome pressure

• SRV setpoints (refer to Section 4.1.2.6 for impact on stuck open relief valve probability)

3.3.4 Plant Operating Conditions The key plant operational modifications to be made in support of the EPU are:

• Increase in reactor thermal power from 3898 to 4408 MWt

• Feedwater/Condensate flow (and steam flow) rates will increase by approximately 13% over current licensed thermal power

RPV pressure will remain unchanged for the EPU.

3.4 SCOPING EVALUATION The scoping evaluation examines the hardware, procedural, setpoint, and operating

condition changes to assess whether there are PRA impacts that need to be considered in

addition to the increase in power level. These changes are also examined in Section 4

relative to the PRA elements that may be affected. The scoping evaluation conclusions

reached are discussed in the following subsections. Table 3-1 summarizes the list of the

changes planned for the Grand Gulf EPU and their effect on the PRA.


3-7 C247090004-9013-07/09/10

3.4.1 Hardware Changes The hardware changes required to support the EPU (see Section 3.3.1) were reviewed

and determined not to result in new accident types or increased frequency of challenges to

plant response. This assessment is based on review of the plant hardware modifications

and engineering judgment based on knowledge of the PRA models. The majority of the

changes are characterized by either:

• Replacement of components with enhanced like components

• Upgrade of existing components The GGNS PRA program encompasses an effectively exhaustive list of hazards and

accident types (i.e., from simple non-isolation transients to ATWS scenarios to internal

floods, and numerous others). Sabotage and acts of war are outside the scope of the

PRA program. Extensive and unique changes to the plant would have to be implemented

to result in new previously unidentified accidents.

Extensive changes to plant equipment have been shown by operating experience to result

in an increase in system unavailability or failure rate during the initial testing and break-in

period. There may be some short term increase in such events at Grand Gulf but the

frequency and duration of such events can not be projected. Nevertheless, it is expected

that a steady state condition equivalent to (or potentially better than) current plant

performance would result within approximately one year of operation with the new

equipment.

3.4.2 Procedure Changes The impacts on the risk assessment from the EOP/SAP and AOP procedure changes

identified in Section 3.3.2 are summarized below:

• Heat Capacity Temperature Limit (HCTL) - 1˚F change in the HCTL curve. Such a minor change does not significantly impact operator action timing windows or associated human error probabilities in the PRA. For example, MAAP run GGNSEPU9a shows that the HCTL


3-8 C247090004-9013-07/09/10

curve is reached for a transient with loss of containment heat removal in approximately 2.3 hrs. The MAAP runs are performed with the CLTP HCTL curve given that changes to the EOP/SAP curves were not yet finalized by the time the PRA EPU thermal hydraulic calculations were performed, and any changes to the EOP/SAP curves were to be minor. The 2.3 hr time window would change by approximately 1 minute for the HCTL curve change; such a minor time window change would not result in any significant HEP change to operator actions in the GGNS PRA.

• Pressure Suppression Pressure (PSP) - <1 psi change in the PSP curve. Similar to the discussion above for the HCTL curve change, this minor change to the PSP curve will not significantly impact operator action timing windows or HEPs in the PRA. For example, MAAP run GGNSEPU9a shows that the PSP curve is reached for a transient with loss of containment heat removal in approximately 5.6 hrs. This time window would change by <5 minutes for the PSP curve change; such a minor time window change would not result in any significant HEP change to operator actions in the GGNS PRA.

• Minimum Debris Retention Injection Rate – The Minimum Debris Retention Injection Rate will be revised as a result of the increase in decay heat loading. The injection flow will increase by approximately 10% of the CLTP flow. A change of 10% in coolant injection requirements to stay within the MDRIR safe zone for the EPU is a non-significant change with respect to available injection systems and does not change the GGNS Level 2 success criteria or modeling of post core damage accident progression and mitigation.

• The rescaled action points, heatup rates and associated data sheet changes for the ONEPs listed in Section 3.2 have no direct impact on the operator actions or associated error probabilities as modeled in the PRA. These are minor changes. Many of these AOPs relate to BOP related abnormal conditions. This risk assessment includes quantitative sensitivity studies to assess the impact of postulated changes in initiating event frequencies due to changes to the BOP (refer to Section 5.7).

3.4.3 Setpoint Changes The setpoint changes identified in Section 3.3.3 have no direct impact on the PRA models.

The setpoint changes are to maintain operational flexibility and margin and to reflect the

EPU. These setpoint changes are not anticipated to change the long term average of


3-9 C247090004-9013-07/09/10

plant trip frequency; however, postulated changes in plant trip frequency due to these

setpoint changes is addressed in this risk assessment by sensitivity studies (refer to

Section 5.7).

3.4.4 Normal Plant Operational Changes The Feedwater/Condensate flow rates will be increased to support the EPU, but this

operational change is not expected to significantly impact component failure rates or

initiating event frequencies used in the PRA. However, sensitivity cases are performed

(refer to Section 5) that postulate a significant increase in LOCA frequency due to

increased erosion corrosion rates.

An additional Ranney well is being planned which will affect the PSW system. Currently,

the PSW system consists of 8 pumps and 7 of 8 would have to fail to result in

inadequate PSW flow for the PRA mitigation function; the Loss of PSW initiator requires

5 of 8 PSW pumps (6 normally running) to fail to result in a scram or plant shutdown.

The addition of another Ranney well (with two additional PSW pumps) adds redundancy to

the PSW system. However, for the purposes of this analysis, reconstruction of the system

fault trees to address this change is not necessary (and was not performed for this

analysis) given that the impact on the loss of PSW initiator frequency or the PSW system

reliability during the PRA mission time would be negligibly impacted. The addition of two

more PSW pumps to the existing eight pumps would have a negligible impact on the

results of this risk assessment.

There are no other significant systemic configuration changes as part of the EPU as far

as additional trains of key equipment required to operate during plant operation.


3-

10

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Har

dwar

e

(Mec

hani

cal)

Fue

l Poo

l Coo

ling

and

Cle

anup

Hea

t E

xcha

nger

Upg

rade

N

o T

his

mod

ifica

tion

supp

orts

the

incr

ease

in d

ecay

hea

t fro

m

the

spen

t fue

l exp

ecte

d fr

om a

n in

crea

se in

ther

mal

pow

er.

The

fuel

poo

l coo

ling

and

clea

nup

syst

em d

oes

not i

mpa

ct

the

full

pow

er P

RA

mod

el.

See

App

endi

x B

for

the

EP

U

impa

ct o

n th

e sh

utdo

wn

risk

prof

ile.

C

onde

nser

Str

uctu

ral S

uppo

rt U

pgra

de/T

ube

Sta

king

N

o T

his

mod

ifica

tion

supp

orts

the

new

pow

er p

rodu

ctio

n as

pect

of

the

plan

t. T

he c

onde

nser

impa

cts

the

PR

A in

the

area

of

initi

atin

g ev

ent f

requ

ency

(i.e

., lo

ss o

f con

dens

er is

a

cont

ribut

or to

PR

A tr

ansi

ent i

nitia

ting

even

t fre

quen

cies

).

Alth

ough

equ

ipm

ent r

elia

bilit

y ca

n be

pos

tula

ted

theo

retic

ally

to b

ehav

e as

a “

bath

tub”

cur

ve (

i.e.,

the

begi

nnin

g an

d en

d of

life

pha

ses

bein

g as

soci

ated

with

hi

gher

failu

re r

ates

than

the

stea

dy-s

tate

per

iod)

, no

sign

ifica

nt im

pact

on

the

long

-ter

m a

vera

ge o

f the

tran

sien

t in

itiat

ing

even

t fre

quen

cies

, or

the

cond

ense

r re

liabi

lity

durin

g th

e 24

hr

PR

A m

issi

on ti

me

due

to th

e re

plac

emen

t of

the

cond

ense

r tu

be m

odul

es is

exp

ecte

d. H

owev

er,

sens

itivi

ty c

ases

that

incr

ease

the

MS

IV C

losu

re a

nd

Tra

nsie

nt w

ith P

CS

Ava

ilabl

e in

itiat

or fr

eque

ncie

s ar

e qu

antif

ied

in th

is r

isk

asse

ssm

ent t

o ad

dres

s th

e va

rious

ch

ange

s to

the

BO

P s

ide

of th

e pl

ant.(2

)


3-

11

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Har

dwar

e

(Mec

hani

cal)

(con

t’d)

Hig

h P

ress

ure

Tur

bine

Rep

lace

men

t N

o A

lthou

gh e

quip

men

t rel

iabi

lity

can

be p

ostu

late

d th

eore

tical

ly to

beh

ave

as a

“ba

thtu

b” c

urve

(i.e

., th

e be

ginn

ing

and

end

of li

fe p

hase

s be

ing

asso

ciat

ed w

ith

high

er fa

ilure

rat

es th

an th

e st

eady

-sta

te p

erio

d), n

o si

gnifi

cant

impa

ct o

n th

e lo

ng-t

erm

ave

rage

of t

rans

ient

in

itiat

ing

even

t fre

quen

cies

, due

to th

e re

plac

emen

t of t

he

tran

sfor

mer

is e

xpec

ted.

How

eve

r, s

ensi

tivity

cas

es th

at

incr

ease

the

MS

IV C

losu

re a

nd T

rans

ient

with

PC

S

Ava

ilabl

e in

itiat

or fr

eque

ncie

s ar

e qu

antif

ied

in th

is r

isk

asse

ssm

ent t

o ad

dres

s th

e va

rious

cha

nges

to th

e B

OP

sid

e of

the

plan

t.(2)

T

/G M

od –

Gen

erat

or R

otor

R

epla

cem

ent/S

tato

r R

efur

b an

d R

epla

cem

ent

No

Alth

ough

equ

ipm

ent r

elia

bilit

y ca

n be

pos

tula

ted

theo

retic

ally

to b

ehav

e as

a “

bath

tub”

cur

ve (

i.e.,

the

begi

nnin

g an

d en

d of

life

pha

ses

bein

g as

soci

ated

with

hi

gher

failu

re r

ates

than

the

stea

dy-s

tate

per

iod)

, no

sign

ifica

nt im

pact

on

the

long

-ter

m a

vera

ge o

f tra

nsie

nt

initi

atin

g ev

ent f

requ

enci

es, d

ue to

the

repl

acem

ent o

f the

tr

ansf

orm

er is

exp

ecte

d. H

owe

ver,

sen

sitiv

ity c

ases

that

in

crea

se th

e M

SIV

Clo

sure

and

Tra

nsie

nt w

ith P

CS

A

vaila

ble

initi

ator

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us c

hang

es to

the

BO

P s

ide

of th

e pl

ant.(2

)


3-

12

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Har

dwar

e

(Mec

hani

cal)

(con

t’d)

Mai

n T

rans

form

er Is

opha

se B

us D

uct C

oolin

g N

o T

his

mod

ifica

tion

supp

orts

the

new

pow

er p

rodu

ctio

n as

pect

of

the

plan

t. A

s th

e P

RA

mod

els

plan

t ris

k by

ass

essi

ng th

e sa

fe s

hutd

own

proc

ess

follo

win

g pl

ant t

rips,

this

mod

ifica

tion

does

not

dire

ctly

impa

ct th

e P

RA

mod

els.

An

impa

ct to

the

Tra

nsie

nt w

ith P

CS

Ava

ilabl

e in

itiat

ing

even

t fre

quen

cy m

ay

be c

onse

rvat

ivel

y po

stul

ated

, but

no

sign

ifica

nt n

umer

ical

di

ffere

nce

can

be r

easo

nabl

y qu

antif

ied.

How

ever

, se

nsiti

vity

cas

es th

at in

crea

se th

e M

SIV

Clo

sure

and

T

rans

ient

with

PC

S A

vaila

ble

initi

ator

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us

chan

ges

to th

e B

OP

sid

e of

the

plan

t.(2)

F

eedw

ater

Tur

bine

Rot

or R

epla

cem

ent

No

The

FW

turb

ine-

pum

ps im

pact

the

PR

A in

the

area

of

initi

atin

g ev

ent f

requ

ency

(i.e

. FW

pum

p fa

ilure

s/tr

ips

are

cont

ribut

ors

to P

RA

tran

sien

t ini

tiatin

g ev

ent f

requ

enci

es)

and

the

failu

re p

roba

bilit

y of

the

FW

turb

ine-

pum

ps d

urin

g th

e 24

hr

PR

A m

issi

on ti

me.

Alth

ough

equ

ipm

ent r

elia

bilit

y ca

n be

pos

tula

ted

theo

retic

ally

to b

ehav

e as

a “

bath

tub”

cu

rve

(i.e.

, the

beg

inni

ng a

nd e

nd o

f life

pha

ses

bein

g as

soci

ated

with

hig

her

failu

re r

ates

than

the

stea

dy-s

tate

pe

riod)

, no

sign

ifica

nt im

pact

on

the

long

-ter

m a

vera

ge o

f th

e tr

ansi

ent i

nitia

ting

even

t fre

quen

cies

, or

the

FW

turb

ine-

pum

p re

liabi

lity

durin

g th

e 24

hr

PR

A m

issi

on ti

me

due

to

the

FW

turb

ine

roto

r re

plac

emen

t is

expe

cted

. Lo

ss o

f a

sing

le F

W p

ump

coul

d le

ad to

a tu

rbin

e tr

ip, b

ut n

ot a

co

mpl

ete

loss

of F

W.

How

ever

, sen

sitiv

ity c

ases

that

in

crea

se t

he M

SIV

Clo

sure

and

Tra

nsie

nt w

ith P

CS

A

vaila

ble

initi

ator

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us c

hang

es to

the

BO

P s

ide

of th

e pl

ant.(2

)


3-

13

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Har

dwar

e

(Mec

hani

cal)

(con

t’d)

Con

dens

ate

Ful

l Flo

w F

iltra

tion

Add

ition

N

o T

he r

epla

cem

ent o

f dem

iner

aliz

er f

ilter

s w

ith th

ose

of a

sl

ight

ly d

iffer

ent d

esig

n w

ould

not

res

ult i

n an

y qu

antif

iabl

e di

ffere

nce

in th

e tr

ansi

ent i

nitia

ting

even

t fre

quen

cies

or

the

failu

re p

roba

bilit

y of

the

sys

tem

dur

ing

the

24 h

r P

RA

m

issi

on ti

me.

How

ever

, sen

sitiv

ity c

ases

that

incr

ease

the

MS

IV C

losu

re a

nd T

rans

ient

with

PC

S A

vaila

ble

initi

ator

fr

eque

ncie

s ar

e qu

antif

ied

in th

is r

isk

asse

ssm

ent t

o ad

dres

s th

e va

rious

cha

nges

to th

e B

OP

sid

e of

the

plan

t.(2)

A

uxili

ary

Coo

ling

Tow

er E

xpan

sion

N

o T

his

mod

ifica

tion

supp

orts

the

incr

ease

in h

eat r

emov

al

requ

irem

ent f

or th

e E

PU

pow

er le

vel.

Mak

eup

wat

er fo

r th

e co

olin

g to

wer

bas

ins

is s

uppl

ied

by P

SW

. T

he A

uxili

ary

Coo

ling

Tow

er h

as n

o si

gnifi

cant

impa

ct o

n th

e P

RA

; the

P

RA

rel

ies

on th

e S

SW

coo

ling

tow

er a

nd th

e na

tura

l dra

ft co

olin

g to

wer

. T

he A

uxili

ary

Coo

ling

Tow

er a

ugm

ents

the

natu

ral d

raft

cool

ing

tow

er d

urin

g ho

t wea

ther

. T

hese

ch

ange

s to

the

Aux

iliar

y C

oolin

g T

ower

hav

e no

impa

ct o

n ac

cide

nt s

eque

nce

miti

gatio

n an

d no

impa

cts

on tr

ansi

ent

initi

ator

freq

uenc

ies

are

expe

cted

.

U

ltim

ate

Hea

t S

ink

(Ext

end

the

exis

ting

siph

on

in th

e U

nit 2

Bas

in)

No

Thi

s m

odifi

catio

n su

ppor

ts th

e in

crea

se in

hea

t rem

oval

re

quire

men

t for

the

EP

U p

ower

leve

l. T

he c

oolin

g to

wer

ba

sis

is u

sed

as th

e C

W p

ump

suct

ion

sour

ce.

The

se

enha

ncem

ents

to th

e ba

sin

leve

l sup

ply

do n

ot d

irect

ly

impa

ct P

RA

faul

t tre

e m

odel

ing.

No

impa

cts

on tr

ansi

ent

initi

ator

freq

uenc

ies

are

expe

cted

; how

ever

, sen

sitiv

ity

stud

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us c

hang

es to

the

BO

P s

ide

of th

e pl

ant.


3-

14

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Har

dwar

e

(Mec

hani

cal)

(con

t’d)

Sta

ndby

Ser

vice

Wat

er T

ower

Fill

R

epla

cem

ent

No

The

SS

W c

oolin

g to

wer

bas

in is

the

suct

ion

sour

ce fo

r th

e S

SW

pum

ps th

at s

uppl

y R

HR

. T

he P

SA

sys

tem

pro

vide

s m

akeu

p to

the

SS

W c

oolin

g to

wer

bas

in.

Thi

s m

odifi

catio

n ha

s no

dire

ct im

pact

on

the

PR

A fa

ult t

ree

mod

els

or th

e ca

lcul

ated

pla

nt r

isk

prof

ile.

C

ircul

atin

g W

ater

Pum

p U

pgra

des

No

Alth

ough

equ

ipm

ent r

elia

bilit

y ca

n be

pos

tula

ted

theo

retic

ally

to b

ehav

e as

a “

bath

tub

curv

e (i.

e., t

he

begi

nnin

g an

d en

d of

life

pha

ses

bein

g as

soci

ated

with

hi

gher

failu

re r

ates

than

the

stea

dy-s

tate

per

iod)

, no

sign

ifica

nt im

pact

on

the

long

-ter

m a

vera

ge o

f the

tran

sien

t in

itiat

ing

even

t fre

quen

cies

, or

the

CW

sys

tem

rel

iabi

lity

durin

g th

e 24

hr

PR

A m

issi

on ti

me

is e

xpec

ted.

How

ever

, se

nsiti

vity

cas

es th

at in

crea

se th

e M

SIV

Clo

sure

and

T

rans

ient

with

PC

S A

vaila

ble

initi

ator

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us

chan

ges

to th

e B

OP

sid

e of

the

plan

t.(2)

Z

IP S

kid

Val

ve T

rim/S

trai

ner

Mod

ifica

tions

N

o T

he Z

IP s

yste

m h

as n

o di

rect

impa

ct o

n P

RA

initi

atin

g ev

ent

freq

uenc

ies

or a

ccid

ent m

itiga

tion.

M

odify

or

Rep

lace

Con

trol

Val

ve 1

P44

F50

1 (P

SW

flow

con

trol

val

ve to

CC

W h

eat

exch

ange

rs)

No

The

PS

W a

nd C

CW

sys

tem

s im

pact

the

PR

A in

the

area

of

initi

atin

g ev

ent f

requ

enci

es.

Alth

ough

equ

ipm

ent r

elia

bilit

y ca

n be

pos

tula

ted

theo

retic

ally

to b

ehav

e as

a “

bath

tub

curv

e (i.

e., t

he b

egin

ning

and

end

of l

ife p

hase

s be

ing

asso

ciat

ed w

ith h

ighe

r fa

ilure

rat

es th

an th

e st

eady

-sta

te

perio

d), n

o si

gnifi

cant

impa

ct o

n th

e lo

ng-t

erm

ave

rage

of

the

tran

sien

t ini

tiatin

g ev

ent f

requ

enci

es, o

r th

e P

SW

and

C

CW

sys

tem

failu

re p

roba

bilit

ies

durin

g th

e 24

hr

PR

A

mis

sion

tim

e du

e to

the

repl

acem

ent o

f the

con

trol

val

ve is

ex

pect

ed.


3-

15

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Har

dwar

e

(Mec

hani

cal)

(con

t’d)

Fee

dwat

er H

eate

rs N

o. 2

A, 2

B, 2

C, 3

A,

3B,

3C, 4

A, 4

B, a

nd 4

C r

epla

cem

ent,

heat

er r

elie

f va

lve

repl

acem

ent,

and

5A a

nd 5

B lo

op s

eal

drai

ns m

odifi

catio

ns.

No

The

FW

hea

ters

impa

ct th

e P

RA

in th

e ar

ea o

f ini

tiatin

g ev

ent f

requ

ency

(i.e

. FW

/Con

dens

ate

failu

res/

trip

s ar

e co

ntrib

utor

s to

PR

A tr

ansi

ent i

nitia

ting

even

t fre

quen

cies

) an

d th

e fa

ilure

pro

babi

lity

of th

e F

W s

yste

m d

urin

g th

e 24

hr

PR

A m

issi

on ti

me.

The

PR

A d

oes

not m

odel

the

effic

ienc

y of

the

FW

hea

ters

. A

lthou

gh e

quip

men

t rel

iabi

lity

can

be

post

ulat

ed th

eore

tical

ly to

beh

ave

as a

“ba

thtu

b) c

urve

(i.e

., th

e be

ginn

ing

and

end

of li

fe p

hase

s be

ing

asso

ciat

ed w

ith

high

er fa

ilure

rat

es th

an th

e st

eady

-sta

te p

erio

d), n

o si

gnifi

cant

impa

ct o

n th

e lo

ng-t

erm

ave

rage

of t

he tr

ansi

ent

initi

atin

g ev

ent f

requ

enci

es, o

r th

e F

W s

yste

m r

elia

bilit

y du

ring

the

24 h

r P

RA

mis

sion

tim

e is

exp

ecte

d. H

owev

er,

sens

itivi

ty c

ases

that

incr

ease

the

MS

IV C

losu

re a

nd

Tra

nsie

nt w

ith P

CS

Ava

ilabl

e in

itiat

or fr

eque

ncie

s ar

e qu

antif

ied

in th

is r

isk

asse

ssm

ent t

o ad

dres

s th

e va

rious

ch

ange

s to

the

BO

P s

ide

of th

e pl

ant.(2

)

M

ain

Gen

erat

or H

ydro

gen

Coo

ler

Rep

lace

men

t N

o T

hese

mod

ifica

tions

to th

e ge

nera

tor

cool

ing

syst

em a

re to

pr

ovid

e ad

equa

te c

oolin

g to

the

gene

rato

r co

mpo

nent

s du

e to

the

incr

ease

in p

ower

. N

one

of th

ese

item

s ha

s a

quan

tifia

ble

impa

ct o

n th

e re

liabi

lity

of th

e m

ain

gene

rato

r.

How

ever

, sen

sitiv

ity c

ases

that

incr

ease

the

MS

IV C

losu

re

and

Tra

nsie

nt w

ith P

CS

Ava

ilabl

e in

itiat

or fr

eque

ncie

s ar

e qu

antif

ied

in th

is r

isk

asse

ssm

ent t

o ad

dres

s th

e va

rious

ch

ange

s to

the

BO

P s

ide

of th

e pl

ant.(2

)


3-

16

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Har

dwar

e

(Mec

hani

cal)

(con

t’d)

Moi

stur

e S

epar

ator

R

ehea

ter

– R

elie

f V

alve

R

epla

cem

ent

No

The

MS

R p

lays

no

expl

icit

role

in th

e P

RA

. A

n im

pact

to

tran

sien

t ini

tiatin

g ev

ent f

requ

enci

es m

ay b

e co

nser

vativ

ely

post

ulat

ed d

ue to

the

mod

ifica

tions

, but

no

sign

ifica

nt

num

eric

al d

iffer

ence

s ca

n be

rea

sona

bly

quan

tifie

d.

How

ever

, sen

sitiv

ity c

ases

that

incr

ease

the

MS

IV C

losu

re

and

Tra

nsie

nt w

ith P

CS

Ava

ilabl

e in

itiat

or fr

eque

ncie

s ar

e qu

antif

ied

in th

is r

isk

asse

ssm

ent t

o ad

dres

s th

e va

rious

ch

ange

s to

the

BO

P s

ide

of th

e pl

ant.(2

)

C

CW

Hx

tube

cle

anin

g sy

stem

s N

o T

he C

CW

sys

tem

impa

cts

the

PR

A in

the

area

of i

nitia

ting

even

t fre

quen

cies

(i.e

. CC

W h

eat e

xcha

nger

pl

uggi

ng/fa

ilure

s ar

e co

ntrib

utor

s to

PR

A in

itiat

ing

even

t fr

eque

ncie

s).

Alth

ough

equ

ipm

ent r

elia

bilit

y ca

n be

po

stul

ated

theo

retic

ally

to b

ehav

e as

a “

bath

tub”

cur

ve (

i.e.,

the

begi

nnin

g an

d en

d of

life

pha

ses

bein

g as

soci

ated

with

hi

gher

failu

re r

ates

than

the

stea

dy-s

tate

per

iod)

, no

sign

ifica

nt im

pact

on

the

long

-ter

m a

vera

ge o

f the

Los

s of

C

ompo

nent

Coo

ling

Wat

er in

itiat

ing

even

t fre

quen

cy, o

r th

e C

CW

Hea

t Exc

hang

er p

lugg

ing/

failu

re p

roba

bilit

ies

durin

g th

e 24

hr

PR

A m

issi

on ti

me

due

to th

e re

plac

emen

t of t

he

CC

W H

X tu

be c

lean

ing

syst

em is

exp

ecte

d.

E

xtra

ctio

n S

team

Pip

ing

Upg

rade

s fo

r F

AC

N

o P

ipin

g m

odifi

catio

ns d

ue to

the

EP

U im

pact

the

PR

A in

the

area

of L

OC

A in

itiat

ing

even

ts.

The

rel

ativ

ely

low

incr

ease

in

flow

rat

e an

d no

cha

nge

in p

ress

ure

or w

ater

che

mis

try

is

plan

ned

for

the

EP

U; a

s su

ch, n

o si

gnifi

cant

impa

ct o

n th

e LO

CA

freq

uenc

ies

can

be p

ostu

late

d at

this

tim

e. H

owev

er,

a se

nsiti

vity

cas

e is

ana

lyze

d th

at d

oubl

es th

e La

rge

LOC

A

initi

ator

freq

uenc

y.


3-

17

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Har

dwar

e

(Mec

hani

cal)

(con

t’d)

Ran

ney

Wel

l Add

ition

Y

es

An

addi

tiona

l wel

l is

bein

g pl

anne

d fo

r th

e E

PU

. D

etai

ls o

f th

e ad

ditio

n an

d th

e ch

ange

to th

e P

RA

wer

e no

t ava

ilabl

e at

the

time

of th

is r

epor

t. T

he a

dditi

on o

f ano

ther

Ran

ney

wel

l (w

ith tw

o ad

ditio

nal P

SW

pum

ps)

adds

red

unda

ncy

to th

e P

SW

sys

tem

. How

ever

, for

the

purp

oses

of t

his

anal

ysis

, re

cons

truc

tion

of th

e sy

stem

faul

t tre

es to

add

ress

this

cha

nge

is n

ot n

eces

sary

(an

d w

as n

ot p

erfo

rmed

for

this

ana

lysi

s)

give

n th

at th

e im

pact

on

the

loss

of P

SW

initi

ator

freq

uenc

y or

th

e P

SW

sys

tem

rel

iabi

lity

durin

g th

e P

RA

mis

sion

tim

e w

ould

be

neg

ligib

ly im

pact

ed. G

GN

S c

urre

ntly

has

eig

ht (

8) P

SW

pu

mps

and

7 o

f 8 o

f the

pum

ps a

re r

equi

red

in th

e P

RA

to fa

il to

res

ult i

n in

adeq

uate

PS

W fl

ow. T

he a

dditi

on o

f tw

o m

ore

PS

W p

umps

wou

ld h

ave

a ne

glig

ible

impa

ct o

n th

e re

sults

of

this

ris

k as

sess

men

t.

C

onde

nsat

e/F

eedw

ater

Filt

ratio

n B

ypas

s V

alve

A

utom

atic

Act

uatio

n N

o A

loss

of c

onde

nsat

e bo

oste

r pu

mp

requ

ires

that

the

cond

ensa

te fu

ll flo

w fi

lter

bypa

ss v

alve

be

open

ed to

m

aint

ain

net p

ositi

ve s

uctio

n he

ad o

n th

e re

mai

ning

pum

ps.

T

he lo

ss o

f a s

ingl

e pu

mp

is n

ot c

onsi

dere

d an

initi

atin

g ev

ent.

The

failu

re o

f the

pos

sibl

e by

pass

val

ve w

ould

be

subs

umed

in th

e lo

ss o

f fee

dwat

er in

itiat

ing

even

t and

is n

ot

expl

icitl

y m

odel

ed in

the

PR

A.

An

impa

ct to

tran

sien

t in

itiat

ing

even

t fre

quen

cies

may

be

cons

erva

tivel

y po

stul

ated

due

to th

e m

odifi

catio

ns, b

ut n

o si

gnifi

cant

nu

mer

ical

diff

eren

ces

are

expe

cted

. H

owev

er, s

ensi

tivity

ca

ses

that

incr

ease

the

MS

IV C

losu

re a

nd T

rans

ient

with

P

CS

Ava

ilabl

e in

itiat

or fr

eque

ncie

s ar

e qu

antif

ied

in th

is r

isk

asse

ssm

ent t

o ad

dres

s th

e va

rious

cha

nges

to th

e B

OP

sid

e of

the

plan

t.(2)


3-

18

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Enr

iche

d B

oron

SLC

N

o A

n in

crea

se in

the

con

cent

ratio

n of

the

boro

n in

the

SLC

sy

stem

is b

eing

con

side

red

for

the

EP

U.

Cur

rent

ly th

e P

RA

m

odel

s on

e pu

mp

requ

ired

for

succ

ess

of th

e S

LC s

yste

m.

The

FS

AR

sta

tes

“Onl

y on

e of

the

two

stan

dby

liqui

d co

ntro

l pu

mps

is n

eede

d fo

r sy

stem

ope

ratio

n” a

nd th

e A

TW

S w

ork

pack

age

conf

irms

one

of tw

o pu

mps

are

req

uire

d. A

n in

crea

se in

the

conc

entr

atio

n of

the

boro

n w

ill n

ot a

ffect

the

succ

ess

crite

ria o

r th

e op

erat

ion

of th

e S

LC s

yste

m in

the

PR

A.

Har

dwar

e

(Mec

hani

cal)

(con

t’d)

Dry

er R

epla

cem

ent

No

Thi

s m

odifi

catio

n su

ppor

ts th

e ne

w s

team

pro

duct

ion

leve

l du

e to

the

EP

U.

The

Ste

am D

ryer

is n

ot e

xplic

itly

incl

uded

in

the

PR

A (

moi

stur

e ca

rryo

ver

to th

e m

ain

turb

ine

is n

ot a

n is

sue

for

the

PR

A).

How

ever

, sen

sitiv

ity c

ases

that

incr

ease

th

e M

SIV

clo

sure

and

Tra

nsie

nt w

ith P

CS

Ava

ilabl

e in

itiat

or

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us c

hang

es to

the

BO

P s

ide

of th

e pl

ant.(2

)

F

eedw

ater

Con

trol

s N

o T

he E

PU

mod

ifica

tions

to th

e fe

edw

ater

con

trol

s ar

e to

in

crea

se th

e flo

w o

f fee

dwat

er to

the

reac

tor

durin

g no

rmal

op

erat

ion.

No

chan

ge in

the

type

or

basi

c m

ode

of

oper

atio

n is

pla

nned

(no

t a c

hang

e to

dig

ital f

eedw

ater

co

ntro

l). A

n im

pact

to tr

ansi

ent i

nitia

ting

even

t fre

quen

cies

m

ay b

e co

nser

vativ

ely

post

ulat

ed d

ue to

the

mod

ifica

tions

, bu

t no

sign

ifica

nt n

umer

ical

diff

eren

ces

are

expe

cted

. H

owev

er, s

ensi

tivity

cas

es th

at in

crea

se th

e M

SIV

Clo

sure

an

d T

rans

ient

with

PC

S A

vaila

ble

initi

ator

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us

chan

ges

to th

e B

OP

sid

e of

the

plan

t.(2)


3-

19

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Har

dwar

e

(Ele

ctric

al/ I

&C

) (c

ont’d

)

Mai

n T

rans

form

er R

epla

cem

ent

No

Alth

ough

equ

ipm

ent r

elia

bilit

y ca

n be

pos

tula

ted

theo

retic

ally

to b

ehav

e as

a “

bath

tub”

cur

ve (

i.e.,

the

begi

nnin

g an

d en

d of

life

pha

ses

bein

g as

soci

ated

with

hi

gher

failu

re r

ates

than

the

stea

dy-s

tate

per

iod)

, no

sign

ifica

nt im

pact

on

the

long

-ter

m a

vera

ge o

f tra

nsie

nt

initi

atin

g ev

ent f

requ

enci

es, o

r tr

ansf

orm

er fa

ilure

dur

ing

the

24 h

r P

RA

mis

sion

tim

e du

e to

the

repl

acem

ent o

f the

tr

ansf

orm

er is

exp

ecte

d. H

owe

ver,

sen

sitiv

ity c

ases

that

in

crea

se th

e M

SIV

Clo

sure

and

Tra

nsie

nt w

ith P

CS

A

vaila

ble

initi

ator

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us c

hang

es to

the

BO

P s

ide

of th

e pl

ant.(2

)

Cap

acito

r B

ank

/ “S

witc

habl

e R

eact

or”

Inst

alla

tion

No

The

cap

acito

r ba

nks

fall

in th

e tr

ansm

issi

on s

cope

of w

ork.

U

pgra

des

to th

e tr

ansm

issi

on s

yste

m w

ill n

ot d

irect

ly a

ffect

th

e P

RA

.

Inst

rum

enta

tion

Rep

lace

men

t N

o T

he m

odifi

catio

n to

the

inst

rum

enta

tion

due

to th

e E

PU

is

assu

med

to n

ot d

irect

ly a

ffect

the

PR

A.

How

ever

, sen

sitiv

ity

case

s th

at in

crea

se th

e M

SIV

Clo

sure

and

Tra

nsie

nt w

ith

PC

S A

vaila

ble

initi

ator

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us c

hang

es to

the

BO

P s

ide

of th

e pl

ant.(2

)


3-

20

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Upg

rade

of

P

ower

R

ange

N

eutr

on

Mon

itors

(A

dded

by

prev

ious

sub

mitt

al)

No

Neu

tron

mon

itorin

g co

uld

play

two

role

s in

PR

A m

odel

ing:

• O

verly

sen

sitiv

e eq

uipm

ent c

ould

lead

to in

crea

sed

turb

ine

trip

s

• P

oor

equi

pmen

t cou

ld le

ad to

incr

ease

d el

ectr

ical

sc

ram

failu

re p

roba

bilit

y

An

impa

ct to

tran

sien

t ini

tiatin

g ev

ent f

requ

enci

es m

ay b

e co

nser

vativ

ely

post

ulat

ed d

ue to

the

new

equ

ipm

ent,

but n

o si

gnifi

cant

num

eric

al d

iffer

ence

is e

xpec

ted.

How

ever

, se

nsiti

vity

cas

es th

at in

crea

se th

e M

SIV

Clo

sure

and

T

rans

ient

with

PC

S A

vaila

ble

initi

ator

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us

chan

ges.

(2)

A s

igni

fican

t im

pact

to th

e el

ectr

ical

scr

am fa

ilure

pro

babi

lity

due

to th

e N

ucle

ar In

stru

men

tatio

n ch

ange

s is

not

exp

ecte

d.

In a

dditi

on, e

lect

rical

scr

am fa

ilure

is n

ot a

dom

inan

t co

ntrib

utor

to A

TW

S c

ore

dam

age

freq

uenc

y (i.

e.,

“ele

ctric

al”

scra

m fa

ilure

s ca

n be

miti

gate

d by

AR

I, un

like

mec

hani

cal s

cram

failu

res)

.

Har

dwar

e

(Ele

ctric

al/ I

&C

) (c

ont’d

)

BO

P V

ibra

tion

Mon

itorin

g N

o T

his

mod

ifica

tion

supp

orts

the

new

pow

er p

rodu

ctio

n as

pect

of

the

plan

t. T

he P

RA

doe

s no

t exp

licitl

y m

odel

the

vibr

atio

n m

onito

ring

syst

em o

f the

pla

nt.

How

ever

, sen

sitiv

ity c

ases

th

at in

crea

se th

e M

SIV

Clo

sure

and

Tra

nsie

nt w

ith P

CS

A

vaila

ble

initi

ator

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us c

hang

es to

the

BO

P s

ide

of th

e pl

ant.(2

)


3-

21

Tab

le 3

-1

PLA

NT

CH

AN

GE

S P

LA

NN

ED

DU

E T

O E

PU

Cat

egor

y D

escr

iptio

n of

Pla

nt C

hang

e(3

) P

RA

C

hang

e?(1

) D

iscu

ssio

n

Pro

cedu

res

Var

ious

pot

entia

l im

pact

s to

EO

Ps/

SA

Ps

and

AO

Ps

No

Cha

nges

to th

e E

OP

s/S

AP

s an

d A

OP

s as

a r

esul

t of t

he

EP

U a

re m

inor

to m

aint

ain

ma

rgin

s an

d to

ref

lect

the

EP

U

(e.g

., 1

°F c

hang

e in

HC

TL

curv

e). S

uch

min

or c

hang

es d

o no

t sig

nific

antly

influ

ence

the

risk

prof

ile.

Set

poin

ts

Var

ious

pot

entia

l set

poin

t cha

nges

(F

W/C

onde

nsat

e P

ump

Trip

Mar

gin;

Bre

aker

P

rote

ctiv

e R

elay

Set

poin

t Rec

alib

ratio

n)

No

Pot

entia

l set

poin

t cha

nges

mad

e fo

r th

e E

PU

are

to

mai

ntai

n op

erat

iona

l fle

xibi

lity

and

mar

gin

and

will

not

res

ult

in a

ny q

uant

ifiab

le im

pact

to th

e P

RA

. A

n im

pact

to th

e tr

ansi

ent i

nitia

ting

even

t fre

quen

cies

may

be

cons

erva

tivel

y po

stul

ated

due

to th

ese

cont

rol m

odifi

catio

ns, b

ut n

o si

gnifi

cant

num

eric

al d

iffer

ence

s ar

e ex

pect

ed.

Fee

dwat

er/C

onde

nsat

e flo

w r

ates

to in

crea

se

by 1

3% o

ver

pres

ent v

alue

s (1

5% o

ver

OLT

P)

to s

uppo

rt u

prat

e

No

Alth

ough

FW

/Con

d. fl

ow w

ill in

crea

se, n

o si

gnifi

cant

nu

mer

ical

diff

eren

ce in

the

PR

A tr

ansi

ent i

nitia

ting

even

t fr

eque

ncie

s or

the

failu

re p

roba

bilit

y of

FW

/Con

dens

ate

durin

g th

e 24

hr

PR

A m

issi

on ti

me

are

expe

cted

. In

addi

tion,

se

nsiti

vity

cas

es th

at in

crea

se th

e M

SIV

Clo

sure

and

T

rans

ient

with

PC

S A

vaila

ble

initi

ator

freq

uenc

ies

are

quan

tifie

d in

this

ris

k as

sess

men

t to

addr

ess

the

vario

us

chan

ges

to th

e B

OP

sid

e of

the

plan

t.(2)

Ope

ratio

nal

Incr

ease

d th

erm

al p

ower

ope

ratio

n of

13%

ov

er p

rese

nt v

alue

s (1

5% o

ver

OLT

P)

Yes

T

he p

ropo

sed

EP

U w

ould

incr

ease

the

curr

ent t

herm

al

pow

er fr

om 3

898

MW

t to

4408

MW

t. T

his

incr

ease

in p

ower

w

ill a

ffect

the

time

to b

oil,

allo

wab

le o

pera

tor

actio

n tim

es,

etc.

Thi

s is

incl

uded

in th

e P

RA

mod

el.


3-22

Notes to Table 3-1:

(1) Extensive changes to plant equipment have been shown by operating experience to result in an increase in system unavailability or failure rate during the initial testing and break-in period. It can be expected that there will be some short term increase in such events at Grand Gulf. The frequency and duration of such events can not be projected. Nevertheless, it is expected that a steady state condition equivalent to or better than current plant performance would result within approximately one year of operation with the new equipment. Therefore, this short term break-in period is not explicitly quantified as part of the steady state plant risk profile.

(2) Refer to Section 5.7 of this report for the transient initiator frequency sensitivity studies.

(3) Refer to the main LAR document for a discussion of the proposed plant changes for the EPU.


4-1

Section 4

PRA CHANGES RELATED TO EPU CHANGES Section 3 has examined the plant changes (hardware, procedural, setpoint, and

operational) that are part of the Extended Power Uprate (EPU). Section 4 examines these

changes to identify GGNS PRA modeling changes necessary to quantify the risk impact of

the EPU. This section discusses the following:

• Individual PRA elements potentially affected by EPU (4.1)

• Level 1 PRA (4.2)

• Internal Fires Induced Risk (4.3)

• Seismic Risk (4.4)

• Other External Hazards Risk (4.5)

• Shutdown Risk (4.6)

• Radionuclide Release (Level 2 PRA) (4.7) 4.1 PRA ELEMENTS POTENTIALLY AFFECTED BY POWER UPRATE A review of the PRA elements has been performed to identify potential effects associated

with the Extended Power Uprate. The result of this task is a summary which dispositions

all PRA elements regarding the effects of the Extended Power Uprate. The disposition

consists of three Qualitative Disposition Categories.

Category A: Potential PRA change due to power uprate. PRA modification

desirable or necessary Category B: Minor perturbation, negligible impact on PRA, no PRA

changes required Category C: No change Table 4.1-1 summarizes the results from this review. Based on Table 4.1-1, only a

small number of the PRA elements are found to be potentially influenced by the power

uprate.


4-2

The following PRA elements are discussed in Table 4.1-1 to summarize whether they may

be affected by the Extended Power Uprate and the associated changes.


• Systemic/Functional Success Criteria, e.g.:

- RPV Inventory Makeup

- Heat Load to the Suppression Pool

- Time to Boil down

- Blowdown Loads

- RPV Overpressure Margin

- SRV Actuations

- SRV Capacity for ATWS

• Accident Sequence Modeling

• System Modeling

• Failure Data


• Structural Evaluations

• Quantification

• Containment Response (Level 2)

4.1.1 Initiating Events The evaluation has examined whether there may be increases in the frequency of the

initiating events or whether there may be new types of initiating events introduced into the

risk profile.

The GGNS PRA program encompasses an effectively exhaustive list of hazards and

accident types (i.e., from simple non-isolation transients to ATWS scenarios to internal

fires to hurricanes to toxic releases to draindown events during refueling activities, and

numerous others). Extensive and unique changes to the plant would have to be


4-3

implemented to result in new previously unidentified accidents; this is not the case for the

GGNS EPU.

The GGNS PRA initiating events can be categorized into the following:

• Transients

• LOOP

• LOCAs

• Support System Failures

• Internal Floods

• External Events

Transients The evaluation of the plant and procedural changes does not result in any new transient

initiators, nor is there anticipated any direct significant impact on transient initiator

frequencies due to the EPU. The data that were used to develop the current transient

initiators includes both generic and plant specific data which remains applicable to this

analysis. Changes due to the EPU mainly involve upgrading with similar equipment with

higher capabilities. These changes do not impact the equipment failure rates used in the

PRA (refer to discussions in Section 4.1.5).

However, sensitivity quantifications are performed that increase the MSIV Closure and

Transient with PCS Available initiator frequencies to bound the various changes to the

BOP side of the plant (e.g., main turbine modifications).

LOOP No change in the Loss of Offsite Power initiating event frequency is expected. Currently

GGNS has certain operating configurations/conditions that require power reductions to

maintain grid stability or to respond to grid voltage changes. The same or similar

conditions and operations will exist for the EPU, and are not expected to have any grid


4-4

related impact on the LOOP initiating event frequency. The EPU stability analysis did not

find significant impacts on grid stability due to the GGNS power uprate.

LOCAs No significant changes to RPV operating pressure, inspection frequencies, or primary

water chemistry are planned in support of the EPU; as such, no significant impact on

LOCA frequencies due to the EPU can be postulated. However, a sensitivity case is

analyzed that doubles the Large LOCA initiator frequency.

Support System Initiators An additional Ranney well is being planned for the PSW system. This will increase the

number of pumps from eight to ten lowering the probability of PSW system failure. No

changes were made to the PSW system model (this is conservative, but a negligible

impact on the results).

No other significant changes to support systems, outside of replacement of certain

components, are planned as part of the EPU; as such, no significant impact on support

system initiating event frequencies due to the EPU are postulated.

Internal Flood Initiators No changes to pipe inspection scopes or frequencies are planned in support of the EPU;

as such, no significant impact on internal flooding initiator frequencies due to the EPU is

postulated. An increase in the flow rate of the Feedwater, Condensate, and Main Steam

due to the EPU and potential increases in Flow Accelerated Corrosion (FAC) would not

increase the piping failure rates used in the PRA. Plant monitoring programs remain in

place. Postulating an increase in the piping failure rates would not significantly impact the

risk results and conclusions of this risk assessment given the small risk contribution of

flooding scenarios to the risk profile (i.e., ~0.1% of CDF).


4-5

External Event Initiators The frequency of external event initiators (e.g., seismic events, extreme winds, fires) is not

linked to reactor power or operation; as such, no impact on external event initiator

frequencies due to the EPU can be postulated.

4.1.2 Success Criteria The success criteria for the Grand Gulf PRA are based on realistic evaluations of system

capability over the 24 hour mission time of the PRA analysis. These success criteria

therefore may be different than the design basis assumptions used for licensing Grand

Gulf. This report examines the risk profile changes caused by EPU from a realistic

perspective to identify changes in the risk profile that may result from severe accidents on

a best estimate basis. The following subsections discuss different aspects of the success

criteria as used in the PRA. Appendix E provides the deterministic calculations performed

to support assessment of the impacts on success criteria and sequence timing.

4.1.2.1 Timing Shorter times to boil down are likely on an absolute basis due to the increased power

levels. The reduction in timings can impact the human error probability calculations,

especially for short-term operator actions. See HRA discussion in Section 4.1.6.

4.1.2.2 RPV Inventory Makeup Requirements The PRA success criteria for RPV makeup remains the same for the post-uprate

configuration. Both high pressure (e.g., FW, HPCS, and RCIC) and low pressure

(e.g., LPCI, LPCS, and condensate) injection systems have more than adequate flow

margin for the post-uprate configuration.

4.1.2.3 Heat Load to the Pool Energy to be absorbed by the pool during an isolation event or RPV depressurization

increases for the EPU case relative to the CLTP. For non-ATWS scenarios, the RHR heat


4-6

exchangers, the main condenser, and the containment vent all have capacities that

exceed the increase in heat load due to extended power uprating. The heat removal

capability margins are sufficiently large such that the changes in power level associated

with EPU do not affect the success criteria for these systems.

A GGNS “successful vent initiation” MAAP run was performed in support of this risk

assessment (GGNSEPU9b) and shows that once the containment vent is opened, per the

EOPs, containment pressure decreases immediately and rapidly. This is true for both the

CLTP and EPU condition.

No changes to the above DHR systems to augment their capabilities for the EPU

configuration are planned.

4.1.2.4 Blowdown Loads Dynamic loads would increase slightly because of the increased stored thermal energy.

This change would not quantitatively influence the PRA results. The containment

analyses for LOCA under EPU conditions indicate that dynamic loads on containment

remain acceptable.

4.1.2.5 RPV Overpressure Margin The RPV dome operating pressure will not be increased as a result of the power uprate.

However, the RPV pressure following a failure to scram is expected to increase slightly.

The current GGNS CLTP PRA requires one (1) SRV to open for initial pressure control

during a transient. Based on MAAP runs performed for this EPU risk assessment, this

success criterion remains unchanged for the EPU. GGNS EPU MAAP runs GGNSEPU1a

and GGNSEPU1b show that one SRV is required for initial RPV overpressure protection

during an isolation transient for the EPU configuration to maintain RPV pressure below the

ASME service Level C RPV pressure of 1500 psig.


4-7

The current GGNS PRA does not require any SRVs for initial RPV overpressure control for

LOCA initiators. This success criterion also remains unchanged for the EPU.

The CLTP PRA uses a success criterion of 13 of 20 SRVs required for RPV initial

overpressure protection during an ATWS scenario. Based on EPU ATWS analysis (GGNS

EPU Task Report 902, Draft), 15 of 20 SRVs are required for the uprated condition for

RPV initial overpressure protection during an ATWS scenario.

4.1.2.6 SRV Actuations Given the power increase of the EPU, one may postulate that the probability of a stuck

open relief valve given a transient initiator would increase due to an increase in the

number of SRV cycles.

The stuck open relief valve probability following a plant trip and SRV challenge used in

the GGNS PRA is 1.13E-2 for one stuck open relief valve (basic event P1) and 1.52E-3

for two or more stuck open relief valves (basic event P2). The GGNS PRA base stuck

open relief valve probabilities may be modified using different approaches to consider

the effect of a postulated increase in valve cycles. The following three approaches are

considered:

1. The upper bound approach would be to increase the stuck open relief valve probability by a factor equal to the increase in reactor power (i.e., a factor of 1.13 in the case of the GGNS 113% CLTP EPU). This approach assumes that the stuck open relief valve probability is linearly related to the number of SRV cycles, and that the number of cycles is linearly related to the reactor power increase.

2. A less conservative approach to the upper bound approach would be to

assume that the stuck open relief valve probability is linearly related to the number of SRV cycles, BUT the number of cycles is not necessarily directly related to the reactor power increase. In this case the postulated increase in SRV cycles due to the EPU would be determined by thermal hydraulic calculations (e.g., MAAP runs).


4-8

3. The lower bound approach would be to assume that the stuck open relief valve probability is dominated by the initial cycle and that subsequent cycles have a much lower failure rate. In this approach the base stuck open relief valve probability could be assumed to be insignificantly changed by a postulated increase in the number of SRV cycles.

Approach #1 is used here to modify the GGNS PRA stuck open relief valve probability.

Therefore, the GGNS PRA base for one stuck open relief valve probability given a

transient initiator is increased 13% to 1.28E-2 to represent the EPU configuration, and

the probability for two or more stuck open relief valves is likewise increased 13% to

1.72E-3.

4.1.2.7 RPV Emergency Depressurization The CLTP GGNS PRA requires three (3) SRVs for RPV emergency depressurization in

transient scenarios. MAAP cases performed in support of this EPU risk assessment (e.g.,

GGNSEPU1a) show that this success criterion remains unchanged by the EPU.

The CLTP GGNS PRA also assumes that three (3) SRVs are required in those instances

when alternative low pressure injection system alignments of FPS or SSW are used. This

success criterion is also assessed as appropriate for the EPU.

4.1.2.8 Success Criteria Summary The Level 1 and Level 2 GGNS PRAs have developed success criteria for the key safety

functions. Tables 4.1-2 through 10 summarize these safety functions and the minimum

success criteria under the current power configuration and that required under the

Extended Power Uprate configuration. Success criteria are summarized for the following:

• General Transients (Table 4.1-2)

• IORV, Transient w/SORV (Table 4.1-3)

• Small LOCA (Table 4.1-4)

• Medium LOCA (Table 4.1-5)


4-9

• Large LOCA (Table 4.1-6)

• ATWS Events (Table 4.1-7)

• Internal Floods (Table 4.1-8)

• ISLOCA, Breaks Outside Containment (Table 4.1-9)

• Level 2 (Table 4.1-10)

The PRA success criteria are affected by the increased boil off rate, the increased heat

load to the suppression pool, and the increase in containment pressure and temperatures.

Based on the previous discussions, only one success criteria impact due to the EPU

was identified for the Level 1 PRA:

15 of 20 SRVs are required for the EPU condition for RPV initial overpressure protection during an ATWS scenario (as opposed to 13 of 20 for the CLTP condition).

This Level 1 PRA success criteria change is addressed in the GGNS EPU risk

assessment.

No changes in success criteria have been identified with regard to the Level 2

containment evaluation. The slight changes in accident progression timing and decay

heat load have negligible impacts on Level 2 PRA safety functions, such as containment

isolation, ex-vessel debris coolability, and challenges to the ultimate containment

strength.

4.1.3 Accident Sequence Modeling The EPU does not change the plant configuration and operation in a manner such that

new accident sequences or changes to existing accident scenario progressions result. A

slight exception is the reduction in available accident progression timing for some

scenarios and the associated impact on operator action HEPs (this aspect is addressed in

the Human Reliability Analysis section).


4-10

This assessment for GGNS is consistent with GE’s generic conclusions on this issue [14]:

“The basic BWR configuration, operation and response is unchanged by power uprate. Generic analyses have shown that the same transients are limiting. … Plant-specific analyses demonstrate that the accident progression is basically unchanged by the uprate.”

4.1.4 System Modeling The GGNS plant changes associated with the EPU do not result in the need to change

any system fault trees to address changes in standby or operational configurations, or the

addition of new equipment (refer to failure data discussion below regarding replacement of

components with upgraded components).

An additional Ranney well is being planned which will affect the PSW system. Currently,

the PSW system consists of 8 pumps and 7 of 8 would have to fail to result in

inadequate PSW flow for the PRA mitigation function; the Loss of PSW initiator requires

5 of 8 PSW pumps (6 normally running) to fail to result in a scram or plant shutdown.

The addition of another Ranney well (with two additional PSW pumps) adds redundancy to

the PSW system. However, for the purposes of this analysis, reconstruction of the system

fault trees to address this change is not necessary (and was not performed for this

analysis) given that the impact on the loss of PSW initiator frequency or the PSW system

reliability during the PRA mission time would be negligibly impacted. The addition of two

more PSW pumps to the existing eight pumps would have a negligible impact on the

results of this risk assessment.

4.1.5 Failure Rate Data The majority of the hardware changes in support of the EPU may be characterized as

either:

• Replacement of components with enhanced like components

• Upgrade of existing components


4-11

Although equipment reliability as reflected in failure rates can be theoretically postulated to

behave as a “bathtub” curve (i.e., the beginning and end of life phases being associated

with higher failure rates than the steady-state period), no significant impact on the long-

term average of initiating event frequencies, or equipment reliability during the 24 hr. PRA

mission time due to the replacement/modification of plant components is anticipated, nor is

such a quantification supportable at this time. If any degradation were to occur as a result

of EPU implementation, existing plant monitoring programs would address any such

issues. This assessment is consistent with GE’s generic conclusions on this issue [15]:

“..CPPU is not expected to have a major effect on component or system reliability, as long as equipment operating limits, conditions, and/or ratings are not exceeded.”

No planned operational modifications as part of the GGNS EPU include operating

equipment beyond design ratings. However, sensitivity cases that increase transient

initiating event frequencies are quantified in this EPU risk analysis to bound the various

changes to the BOP side of the plant (refer to Section 5.7 of this report).

Minor variations in system or component design response times that may be postulated or

planned due to the EPU are minor and would not impact the PRA risk profile.

4.1.6 Human Reliability Analysis The Grand Gulf risk profile, like other plants, is dependent on the operating crew actions

for successful accident mitigation. The success of these actions is in turn dependent on a

number of performance shaping factors. The performance shaping factor that is

principally influenced by the power uprate is the time available within which to detect,

diagnose, and perform required actions. The higher power level results in reduced times

available for some actions. To quantify the potential impact of this performance shaping

factor, deterministic thermal hydraulic calculations using the MAAP computer code are


4-12

used. Refer to Appendix E for a summary of MAAP cases performed to support the Grand

Gulf power uprate.

Discussion of Impact on Human Error Probabilities The increased power level reduces the time available for some operator actions by

small increments. The reduction in the available time is generally small compared with

the total time available to detect, diagnose, and perform the actions.

Table 4.1-11 summarizes the assessment of the operator actions explicitly reviewed in

support of this analysis (both Level 1 and Level 2 PRA operator actions considered).

The operator actions identified for explicit review were selected based on the following

criteria:

1. FV (with respect to CDF) importance measure ≥ 5E-3

2. RAW (with respect to CDF) importance measure ≥2.0

3. FV (with respect to LERF) importance measure ≥ 5E-3

4. RAW (with respect to LERF) importance measure ≥ 2.0

5. Time critical (≤ 30 min. available) action

These criteria have been used in past EPU risk assessments. If any of the above criteria

are met for an operator action the action is maintained for explicit consideration in the EPU

risk assessment. Potential HEP changes for operator actions screened out from explicit

assessment in this EPU risk assessment will not have a significant impact on the

quantitative results.

The non-significant HEPs if adjusted would be expected to impact the risk profile by a

fraction of a percent.

Sixty-two operator actions were identified for explicit consideration regarding potential

timing impacts due to the EPU. MAAP calculations for the GGNS CLTP and EPU

configurations were performed to determine changes in allowable operator action


4-13

timings. The human error probabilities (HEPs) were then re-calculated using the same

human reliability analysis (HRA) methods used in the GGNS PRA. [26]

The GGNS PRA Human Reliability Analysis (ECH Calculation PRA-GG-01-001503)

utilizes two methods to calculate the HEP probabilities, the HCR/ORE correlation and

the Caused-Based approach. The method used is determined by choosing the highest

probability from the two methods. The Cause-Based method is not affected by the

allowable operator action time; therefore, any HEPs calculated using the Cause-Based

method will not be changed for the EPU.

Refer to Appendix D for a summary of the operator action screening performed for this risk

assessment.

As can be seen in Table 4.1-11, the changes in timing are estimated to result in

changes to some HEPs. The changes in allowable operator action timings are not always

directly linear with respect to the EPU power increase (i.e., a 13% power uprate does not

always correspond to a 13% reduction in operator action timings):

• Allowable time windows for some actions are not impacted by the power uprate (e.g., timings based on battery life, timings based on internal flood rates, etc.)

• Allowable time windows for LOCAs may be driven more by the inventory loss than the decay heat.

• Allowable time windows for actions related directly to RCS boil off time during non-LOCA events are also not necessarily linear with respect to the power uprate percentage. It is not uncommon that some actions have reductions many percentage points more than the uprate percentage. This is due to various factors, such as higher initial fuel temperature for the EPU providing more initial sensible heat to the RCS water in the early time frame after a plant trip than the CLTP condition, or more integrated fluid release out SRVs in the early time frame compared to the CLTP condition.

• Some operator action time windows are dominated by a portion of the window not impacted by decay heat (e.g., RCIC operating for 6 hours then fails due to battery depletion, remainder of window to core damage impacted by decay heat)


4-14

Section 5 summarizes the increase in the CDF and LERF associated with these HEP

changes (in addition to other model changes).

The risk importance measures of these actions change slightly for the EPU but do not

result in changing their relative significance to the GGNS risk profile. Using the FVCDF

≥ 5E-3 and RAWCDF ≥ 2.0 as the criteria for risk significance of the operator actions,

three post-initiator operator action HEP moved up past this risk significance test

threshold for the EPU results.

The following HEPs moved past the test threshold:

• E12-FO-HECS-N: This action is based on long time periods (i.e., >5 hr.) Changes in allowable time will not significantly affect this HEP.

• NRC-OSP-DLXO: This HEP is an AC power recovery based on long time window. Changes in allowable time will not significantly affect this HEP.

• NRC-DGCF4&FW: This HEP is a recovery action based on restoring diesel common cause failures within four hours and failure to start Fire Water. The probability is based on the diesel common cause recovery within 4 hours (which would be unchanged by the EPU) and the probability for aligning fire water (Event P64-FO-HE-G which increased from 0.57 to 0.67). The increase in probability would not significantly affect the EPU results (i.e., the EPU CDF and LERF would change by <0.1%).

There are no new credited operator actions required as a result of EPU. Changes to

control room instruments and controls for the EPU are minimal (rescaled indicators and

meters). There are no changes to these systems/controls that will affect operator ability

to interpret, read or respond to the information provided by the updated

systems/controls. As such, the only impacts to the PRA human reliability analysis are

changes in available operator timings (for the existing actions in the PRA) due to the

decay heat increase, as previously discussed.


4-15

4.1.7 Structural Evaluations This assessment did not identify issues associated with postulated impacts from the

EPU on the PRA modeling of structural (e.g., piping, vessel, containment) capacities.

This is consistent with GE’s generic conclusions [14]:

“The RPV is analyzed for power uprate conditions. Transients, accident conditions, increased fluence, and past operating history are considered to recertify the vessel. Plant specific analyses at power uprate conditions demonstrates that containment integrity will be maintained.…no significant effect on LOCA probability. Increase in flow rates is addressed by compliance with Generic Letter 89-08, Erosion/Corrosion in Piping…”

4.1.8 Quantification No changes in the GGNS PRA quantification process (e.g., truncation limit, etc.) due to

the EPU have been identified (nor were any anticipated). Small changes in the

quantification results (accident sequence frequencies) were realized as a result of HEP

and modeling changes were made to reflect the EPU.

4.1.9 Level 2 PRA Analysis Given the minor change in Level 1 CDF results, minor changes in the Level 2 release

frequencies can be anticipated. Such changes are directly attributable to the changes in

the Level 1 PRA. (Refer to Section 4.7 for additional discussion). The accident sequence

modeling in the Level 2 PRA is not impacted by the EPU.

No modeling or success criteria changes are required in the post core damage Level 2

sequences due to the EPU. The Level 2 functions are either conservatively based or are

driven by accident phenomena. Refer to Table 4.1-10.


4-16

Fission product inventory in the reactor core is higher as a result of the increase in power

due to the EPU. The increase in fission product inventory results in an increase in the total

radioactivity available for release given a severe accident. However, this does not impact

the definition or quantification of the LERF risk measure used in Regulatory Guide 1.174,

and as the basis for this risk assessment. The GGNS Level 2 PRA categorizes releases

as LERF based on accident sequence characteristics (e.g., containment bypassed,

unscrubbed release, etc.). The EPU will not impact the release sequence categorization

process.


4-17

Table 4.1-1

REVIEW OF PRA ELEMENTS FOR POTENTIAL RISK MODEL EFFECTS

PRA Elements

Disposition Category(1)

Basis

Initiating Events B No new initiators or increased frequencies of existing initiators are anticipated to result from the GGNS EPU. However, quantitative sensitivity cases that increase transient and LOCA frequencies are performed as part of this analysis.

Success Criteria

B

A number of potential effects that could alter success criteria. These are discussed in the text. They include the following:

• Time to boil down • Heat Load to the Pool • Blowdown Loads • RPV Overpressure Margin (number of

SRVs/SVs required) • RPV Emergency Depressurization (number

of SRVs required, no change due to EPU)

Accident Sequences (Structure, Progression)

C

No changes in the accident sequence structure result from the increase in power rating.

The accident progression is slightly modified in timing. These changes are incorporated in the Human Reliability Analysis (HRA).

System Analysis B No new system failure modes or significant changes in system failure probabilities due to the EPU.

Data C No change to component failure probabilities.

Human Reliability Analysis

A The change in initial power level results in decreases in the time available for operator actions. See discussion of operator actions in Section 4.1.6.


4-18

Table 4.1-1 (Continued)

REVIEW OF PRA ELEMENTS FOR POTENTIAL RISK MODEL EFFECTS

PRA Elements

Disposition Category

Basis

Structural C No changes in the structural analyses are identified that would adversely impact the PRA models.

Quantification

B No changes in PRA quantification process (e.g., truncation limit, flag settings, etc.) due to EPU. However, a small number of changes are identified in the accident sequence quantification results. Individual basic event quantification effects are addressed under HRA.

Level 2

B Slight changes in accident progression timing result from the increased decay heat. However, the slight changes are negligible compared with the overall timing of the core melt accident progression. The Level 2 PRA accident sequence release categorization process is not impacted by the EPU.

(1)See section 3.1.4 for an explanation of the disposition categories.


4-19

Table 4.1-2

KEY SAFETY FUNCTIONS AND MINIMUM SYSTEM REQUIREMENTS FOR SUCCESS (LEVEL 1) INITIATING EVENT: GENERAL TRANSIENTS

Minimum Systems Required

Safety Function Current PRA Power

(CLTP) EPU Power(6) (113% CLTP)

Reactivity Control All control rods inserted (RPS electrical and mechanical

success)

Same (by definition)

Primary System Pressure Control (Overpressure)

PSC Or

1 of 20 SRVs(7)

Same(7), (8)

Primary System Pressure Control (SRVs reclose)

All SVs/SRVs must reclose Same (by definition)

High Pressure Injection 1 FW (1) or

HPCS or

RCIC or

CRD (3)

Same(9)

RPV Emergency Depressurization

3 of 8 SRVs

Same(10)

Low Pressure Injection LPCS

or 1 of 3 LPCI

Same(11)

Alternate Injection Condensate(2)

Or SSW Crosstie(4)

Or Firewater(4)

Same(11), (12)

Containment Heat Removal Main Condenser

or 1 of 2 RHR(14)

(SPC, SDC, or CS) or

Containment Venting(5)

Same(5), (13)


4-20

Notes To Table 4.1-2: (1) One FW pump injecting, with one condensate pump providing suction, is a success for high pressure

injection for a transient. FW/CD operation requires the PCS be operable (i.e., MSIVs open, TBVs open, condenser vacuum maintained, and FW/CD).

(2) One condensate pump injecting is a success for low pressure injection for a transient. Hotwell

makeup is required for condensate use for alternate injection. (3) Operation of both CRD (i.e. maximized flow) pumps is only successful when the vessel is at high

pressure and only after coolant makeup has been provided by some other source for approximately five hours.

CRD in the enhanced flow mode (two pumps) is assumed to fail following a reactor depressurization. The CRD system pumps water from the Condensate Storage Tank in the enhanced mode at approximately 200 gpm with the reactor at high pressure. With reactor depressurization, the pumps go to runout conditions and cavitate on low NPSH.

(4) The fire protection water system alternate alignment requires three SRVs to depressurize the reactor and one fire pump operating. The fire protection system is only considered successful in long term accident sequences when coolant makeup has been established for a period of time.

The SSW Crosstie provides injection to the RPV via the RHR system. Manual action for the

alignment is required as well as depressurization of the RPV with 3 SRVs. (5) By design and EOPs, emergency containment venting is a success in the PRA for the containment

heat removal function. This is true for both the CLTP and EPU condition (see MAAP run GGNSEPU9b).

(6) The success criteria applied for the power uprate configuration are based on MAAP calculations, GE

calculations, or engineering judgment using conservative margins.

(7) Grand Gulf currently requires only 1 SRV for pressure control during a transient. The PRA does not model this due to the low probability of 20 of 20 SRVs failing to open.

GGNS MAAP runs GGNSEPU1a and GGNSEPU1b show that one SRV is required for initial RPV overpressure protection during an isolation transient as well as a LOFW transient for the EPU configuration.

(8) By plant design the GGNS turbine bypass is sufficient for RPV overpressure protection during a

transient with the condenser heat removal path available. (9) FW/Condensate, HPCS, and RCIC, by design, have more than enough capacity to provide coolant

makeup at the EPU condition for a transient initiator. (10) MAAP run GGNSEPU1a shows that 3 SRVs are sufficient for RPV Emergency Depressurization for

the EPU configuration for a transient initiator. The EPU risk assessment reasonably assumes the 3 SRV success criterion for use of the alternate low flow LP injection sources in the CLTP PRA remains appropriate for the EPU.

(11) LPCI, Core Spray, and Condensate, by design, have more than enough capacity to provide coolant

makeup at the EPU condition. (Also refer to MAAP run GGNSEPU1a) for a transient initiator.


4-21

(12) Engineering judgment. (13) By plant design, the main condenser, RHR system, and emergency containment vent remain

successful for the EPU condition. Also refer to GGNSEPU12 MAAP run that shows that 1 loop of SPC is effective for 24 hrs. The PRA credits RHR suppression pool cooling, shutdown cooling, and containment spray modes.

(14) 1 RHR pump, 1 RHR heat exchanger and 1 SSW pump are required for success.


4-22

Table 4.1-3

KEY SAFETY FUNCTIONS AND MINIMUM SYSTEM REQUIREMENTS FOR SUCCESS (LEVEL 1) INITIATING EVENT: IORV or TRANSIENT w/SORV





success)



n/a (addressed by SORV)

Same


n/a (SRV stuck-open)


High Pressure Injection 1 FW pump(1) or

HPCS or

RCIC

Same(9)

RPV Emergency Depressurization 3 of 8 SRVs

(SRVs reclose)

Same(7)

Low Pressure Injection 1 LPCI pump

or LPCS

Same(8)

Alternate Injection Condensate (2)

Or SSW Crosstie

Or Firewater(3)

(Late Injection)

Same(8), (10)

Containment Heat Removal

Main Condenser or

1 of 2 RHR(4) (SPC or CS)

or Containment Venting(5)

Same(5), (11)


4-23


injection for a transient. FW/CD operation requires the PCS be operable (i.e., MSIVs open, TBVs open, condenser vacuum maintained, and FW/CD).





(4) 1 RHR pump, 1 RHR heat exchanger and 1 SSW pump are required for success. (5) By design and EOPs, emergency containment venting is a success in the PRA for the containment



calculations, or engineering judgment using conservative margins. (7) MAAP run GGNSEPU1a shows that 3 SRVs are sufficient for RPV Emergency Depressurization for

the EPU configuration for a transient initiator. The EPU risk assessment reasonably assumes the 3 SRV success criterion for use of the alternate low flow LP injection sources in the CLTP PRA remains appropriate for the EPU.

(8) LPCI, LPCS, and Condensate, by design, have more than enough capacity to provide coolant

makeup at the EPU condition for an SORV scenario. Refer to GGNS EPU MAAP run GGNSEPU7b which shows one LPCI train is sufficient for a LLOCA; this bounds the SORV case.

(9) FW/Condensate, HPCS, and RCIC, by design, have more than enough capacity to provide coolant

makeup at the EPU condition for a transient initiator. (10) Engineering judgment.

(11) By plant design, the main condenser, RHR system, and emergency containment vent options

remain successful for the EPU condition. Also refer to GGNSEPU12 MAAP run that shows that 1 loop of SPC is effective for 24 hrs. The PRA credits RHR suppression pool cooling and containment spray modes.


4-24

Table 4.1-4

KEY SAFETY FUNCTIONS AND MINIMUM SYSTEM REQUIREMENTS FOR SUCCESS (LEVEL 1) INITIATING EVENT: SMALL LOCA





success)



Not required Same

Vapor Suppression Not required Same

High Pressure Injection 1 FW(1)

or HPCS

Or RCIC

Same(3)


3 of 8 SRVs

Same(7)

Low Pressure Injection

(1 of 3 LPCI or

LPCS) And

1 of 2 SPMU

Same(4)

Alternate Injection

SSW Crosstie or

Condensate(2)

Same(4), (7)

Containment Heat Removal Main Condenser

or 1 of 2 RHR

(SPC or CS) or

Containment Venting

Same(6)


4-25


injection for a SLOCA scenario. FW/CD operation requires the PCS be operable (i.e., MSIVs open, TBVs open, condenser vacuum maintained, and FW/CD).

(2) One condensate pump injecting is a success for low pressure injection for a SLOCA. Hotwell makeup

is required for condensate use for alternate injection. (3) FW/Condensate and HPCS have more than enough capacity to provide coolant makeup at the

EPU condition for a SLOCA scenario. Refer to GGNS EPU MAAP run GGNSEPU7a which shows that HPCS can function as the only injection source for a LLOCA for the EPU condition throughout the PRA 24 hour mission time; this bounds the SLOCA case.

(4) LPCI, Core Spray, and Condensate have more than enough capacity to provide coolant makeup at the EPU condition for a small LOCA. Refer to GGNS EPU MAAP run GGNSEPU7b which shows the one LPCI train is sufficient for a LLOCA; this bounds the SLOCA case.

(5) The success criteria applied for the power uprate configuration are based on MAAP calculations,

GE calculations, or engineering judgment using conservative margins. (6) By plant design, the main condenser, RHR system, and emergency containment vent options

remain successful for the EPU condition. Also, refer to GGNSEPU12 MAAP run that shows that 1 loop of SPC is effective for 24 hrs. The PRA credits RHR suppression pool cooling, shutdown cooling, and containment spray modes.

(7) Engineering judgment.


4-26

Table 4.1-5

KEY SAFETY FUNCTIONS AND MINIMUM SYSTEM REQUIREMENTS FOR SUCCESS (LEVEL 1) INITIATING EVENT: INTERMEDIATE LOCA





success)



Not required

Same

Vapor Suppression VSS and

1 of 2 SPMU

Same

High Pressure Injection HPCS and

1 of 2 SPMU (1)

Same


3 of 8 SRVs

Same

Low Pressure Injection (LPCS

or 1 of 3 LPCI)

And 1 of 2 SPMU

Same(3)

Alternate (Late) Injection

SSW Crosstie

Same(2), (3,)

Containment Heat Removal 1 of 2 SPMU

and [1 of 2 RHR (SPC or CS)

Or Containment Venting]

Same(4)


4-27

Notes To Table 4.1-5: (1) FW and Condensate are not credited because it assumed that the MLOCA may be in a

recirculation loop, thus preventing flow from reaching the core. (2) Engineering judgment. (3) LPCI and Core Spray have more than enough capacity to provide coolant makeup at the EPU

condition for an Intermediate LOCA. Refer to GGNS EPU MAAP run GGNSEPU7b which shows the one LPCI train is sufficient for a LLOCA; this bounds the MLOCA case.

(4) By plant design, the RHR system remains successful for the EPU condition. Also refer to

GGNSEPU12 MAAP run that shows that 1 loop of SPC is effective for 24 hrs. The PRA credits RHR suppression pool cooling and drywell spray modes for a MLOCA. The main condenser is not credited because the MSIVs will likely close due to accident signals. Shutdown cooling is also not credited for MLOCAs due to the potential break location in a recirculation loop.


calculations, or engineering judgment using conservative margins.


4-28

Table 4.1-6

KEY SAFETY FUNCTIONS AND MINIMUM SYSTEM REQUIREMENTS FOR SUCCESS (LEVEL 1) INITIATING EVENT: LARGE LOCA

Minimum Systems Required Safety Function Current PRA Power



success)



Not Required Same

Vapor Suppression VSS and

1 of 2 SPMU

Same(3)

High Pressure Injection HPCS(1)

and 1 of 2 SPMU

Same(1)


Not required Same

Low Pressure Injection (LPCS

or 1 of 3 LPCI)

and 1 of 2 SPMU

Same(2)

Alternate Injection SSW Crosstie(3) Same(2), (3)

Containment Heat Removal 1 of 2 SPMU

And [1 of 2 RHR (SPC or CS) (4)

or Containment Venting]

Same(3)


4-29

Notes To Table 4.1-6: (1) The LLOCA initiator results in rapid depressurization of the RPV, precluding the use of the FW and

RCIC. In addition, the CRD system fails due to depressurization of the RPV and inadequate makeup capacity. HPCS is sufficient for a LLOCA (e.g., see MAAP run GGNSEPU7a).

(2) LPCI and Core Spray have more than enough capacity to provide coolant makeup at the EPU

condition for Large LOCAs. Refer to GGNS EPU ECCS-LOCA analysis. GGNS MAAP runs GGNSEPU7b and GGNSEPU7bx show that LPCI is successful for LLOCA throughout the 24 hr PRA mission time.

(3) Engineering judgment. (4) By plant design, the RHR system remains successful for the EPU condition for containment heat

removal. The PRA credits RHR suppression pool cooling and containment spray modes for a LLOCA. The main condenser is not credited because the MSIVs will likely close due to accident signals. Shutdown cooling is also not credited for LLOCAs due to the potential break location in a recirculation loop.

(5) The success criteria applied for the power uprate configuration are based on MAAP calculations,

GE calculations, or engineering judgment using conservative margins.


4-30

Table 4.1-7

KEY SAFETY FUNCTIONS AND MINIMUM SYSTEM REQUIREMENTS FOR SUCCESS (LEVEL 1) INITIATING EVENT: ATWS



Reactivity Control ARI(1) or;

1 of 2 SLC trains and RPT (2)

Same (ADS Inhibit by definition)


PCS or

13 of 20 SRVs

PCS or;

15 of 20 SRVs(10)


Not modeled Same

High Pressure Injection 1 FW pump & 1 Cond. pump

Same(3)


3 of 8 SRVs Same(4)

Low Pressure Injection 1 LPCI pump or

LPCS or

Condensate

Same(5)

Alternate Injection SSW Crosstie(6) Same

Containment Heat Removal Main Condenser(7) or

1 of 2 RHR (7)

(SPC or SDC)

Same(9)


4-31

Notes To Table 4.1-7: (1) Alternate Rod Insertion (ARI) is a successful reactivity control measure only for electrical scram

failures. (2) The Recirculation Pump Trip (RPT) must actuate as designed and trip both recirculation pumps for

initial RPV pressure control during an isolation ATWS. If turbine bypass remains available then RPT is not needed for initial pressure control.

(3) By plant design and the EOPs, FW is successful for high pressure makeup during an ATWS. This is

true for the EPU condition (refer to GGNS MAAP run GGNSEPU13b). (4) The CLTP PRA uses 3 SRVs as the success criterion for RPV emergency depressurization during an

ATWS. This success criterion remains applicable to the EPU condition. (5) By plant design and the EOPs, LPCI and Core Spray are successful for low pressure makeup during

an ATWS. This is true for the EPU condition, as well. (6) Alternate low pressure injection systems are not credited because it is assumed that insufficient time

is available to perform the alignments during an ATWS. (7) The main condenser and RHR system remain successful for the EPU condition for containment

heat removal for mitigated ATWS scenarios. The PRA currently does not credit containment venting for ATWS scenarios.

(8) The success criteria applied for the power uprate configuration are based on MAAP calculations or

engineering judgment using conservative margins. (9) Engineering judgment. (10) Based on EPU ATWS analysis, 15 of 20 SRVs are required for the EPU condition for RPV initial

overpressure protection during an ATWS scenario.


4-32

Table 4.1-8

KEY SAFETY FUNCTIONS AND MINIMUM SYSTEM REQUIREMENTS FOR SUCCESS (LEVEL 1) INITIATING EVENT: INTERNAL FLOODS





success)



PCS or

1 of 20 SRVs(8)

Same(8), (9)


All SVs/SRVs must reclose Same (by definition)

High Pressure Injection 1 FW(1) or

HPCS or

RCIC or

CRD(3)

Same(10)


3 of 8 SRVs

Same(11)

Low Pressure Injection LPCS or

1 of 3 LPCI

Same(12)

Alternate Injection Condensate (2)

or

SSW Crosstie or

Firewater(4)

Same (12), (13,)

Containment Heat Removal Main Condenser or

1 of 2 RHR(5) (SPC, SDC, or CS)

or Containment Venting(6)

Same (6), (14)


4-33


injection for a transient type scenario (which is in general what an internal flood scenario is, other than the flood impacts on mitigation equipment). FW/CD operation requires the PCS be operable (i.e., MSIVs open, TBVs open, condenser vacuum maintained, and FW/CD).





(4) The fire protection water system alternate alignment requires three SRVs to depressurize the

reactor and one fire pump operating. The fire protection system is only considered successful in long term accident sequences when coolant makeup has been established for a period of time. The SSW crosstie provides injection to the RPV via the RHR system. Manual action for the alignment is required as well as depressurization of the RPV with 3 SRVs.

(5) 1 RHR pump, 1 RHR heat exchanger and 1 SSW pump are required for success. (6) By design and EOPs, emergency containment venting is a success in the PRA for the containment



calculations, or engineering judgment using conservative margins. (8) Grand Gulf currently requires only 1 SRV for pressure control during a transient. The PRA does not

model this due to the low probability of 20 of 20 SRVs failing to open.

GGNS MAAP runs GGNSEPU1a and GGNSEPU1b show that one SRV is required for initial RPV overpressure protection during an isolation transient as well as a LOFW transient for the EPU configuration.

(9) By plant design the GGNS turbine bypass is sufficient for RPV overpressure protection during a

transient with the condenser heat removal path available.

(10) FW/Condensate, HPCS, and RCIC, by design, have more than enough capacity to provide coolant makeup at the EPU condition for a transient initiator.

(11) MAAP run GGNSEPU1a shows that 3 SRV are sufficient for RPV Emergency Depressurization for

the EPU configuration for a transient initiator. The EPU risk assessment reasonably assumes the 3 SRVs success criterion for use of the alternate low flow LP injection sources in the CLTP PRA remains appropriate for the EPU.

(12) LPCI, Core Spray, and Condensate, by design, have more than enough capacity to provide coolant

makeup at the EPU condition. (Also refer to MAAP run GGNSEPU1a) for a transient initiator.


4-34

Notes To Table 4.1-8 (cont’d): (13) Engineering judgment.

(14) By plant design, the main condenser, RHR system and emergency containment vent options

remain successful for the EPU condition. Also refer to GGNSEPU12 MAAP run that shows that 1 loop of SPC is effective for 24 hrs. The PRA credits RHR suppression pool cooling, shutdown cooling, and containment spray modes.


4-35

Table 4.1-9

KEY SAFETY FUNCTIONS AND MINIMUM SYSTEM REQUIREMENTS FOR SUCCESS (LEVEL 1) INITIATING EVENT: ISLOCA, BOC




success)



Not required Same

Vapor Suppression Not required Same

High Pressure Injection HPCS(1) Same


3 of 8 SRVs(2) Same

Low Pressure Injection LPCS(3) or

1 of 3 LPCI(3)

Same

External Injection Sources SSW Crosstie(3)

Same

Containment Heat Removal N/A(4) Same


4-36

Notes To Table 4.1-9: (1) HPCS is used for small BOC breaks when RPV depressurization is not initiated. HPCS is not

credited for ISLOCA scenarios. (2) RPV emergency depressurization is required for small BOC breaks; 3/8 SRVs are required (same as

for Small LOCA). RPV ED not required for ISLOCA scenarios. (3) BOC scenarios credit LPCS, 1/3 LPCI pumps or SSW cross tie. ISLOCA scenarios credit only SSW

cross tie. (4) Decay heat removal active systems are not required for unisolated breaks outside containment, since

the decay heat is carried out of containment via the break. (5) The EPU would not change these ISLOCA/BOC success criteria.


4-37

Table 4.1-10

KEY SAFETY FUNCTIONS AND MINIMUM SYSTEM REQUIREMENTS FOR SUCCESS: LEVEL 2 (LERF) PRA


Safety Functions Current PRA Power

(CLTP) EPU Power

(113% CLTP)

Containment Isolation Containment not Bypassed and

Containment Isolation Occurs


RPV Depressurization post-core damage

3 of 8 SRVs (assumed same as Level 1 PRA)

Same

Arrest Core Melt Progression In-Vessel

Recovery of injection (large volume injection system assumed required)

Same

Combustible Gas Control 1 of 2 Igniter Trains Same (by definition)

Containment Remains Intact at RPV Breach

Containment Isolation and

No early containment failure modes (e.g., steam explosions) compromise

containment integrity


Ex-vessel Debris Coolability Drywell Flooding Same

Fission Product Scrubbing DW and Suppression Pool integrity maintained



4-

38

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

B21

-FO

-HE

BO

TT

LES

O

PE

RA

TO

R F

AIL

S

TO

CO

NN

EC

T G

AS

B

OT

TLE

S T

O A

DS

A

IR H

EA

DE

R

360

min

36

0 m

in

1.30

E-0

3 1.

30E

-03

Allo

wab

le ti

me

base

d on

tim

e fo

r S

RV

ac

cum

ulat

ors

to r

un o

ut o

f air

and

not

dire

ctly

dep

ende

nt o

n re

acto

r po

wer

.

B21

-FO

-HE

DE

P2-

I O

PE

RA

TO

R F

AIL

S

TO

MA

NU

ALL

Y

DE

PR

ES

SU

RIZ

E

VE

SS

EL

WIT

H

NO

N-A

DS

VA

LVE

S

45 m

in

38 m

in

3.20

E-0

4(3)

3.20

E-0

4(3)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fo

r a

tran

sien

t fro

m R

PV

leve

l cue

of

-19

2".

Allo

wab

le ti

me

win

dow

red

uced

16

% (

dete

rmin

ed fr

om M

AA

P r

un

GG

NS

EP

U10

a).

B21

-FO

-HE

DE

P2-

L F

AIL

UR

E T

O

MA

NU

ALL

Y

DE

PR

ES

SU

RIZ

E

VE

SS

EL

WIT

H

NO

N-A

DS

VA

LVE

S

(<2H

RS

)

240

min

22

4 m

in

1.20

E-0

5(3)

1.20

E-0

5(3)

Tim

e w

indo

w is

bas

ed o

n tim

e of

cor

e da

mag

e fo

r a

tran

sien

t sce

nario

with

hig

h pr

essu

re in

ject

ion

up u

ntil

t=2

hrs.

A

llow

able

tim

e w

indo

w r

educ

ed 6

.5%

(d

eter

min

ed fr

om M

AA

P r

un G

GN

SE

PU

3b).

B21

-FO

-HE

-L2D

EP

F

AIL

UR

E T

O

DE

PR

ES

SU

RIZ

E

BE

FO

RE

VE

SS

EL

FA

ILU

RE

2.5

hr

2.2

hr

1.00

E+

00

1.00

E+

00

Leve

l 2 P

RA

HE

P fo

r re

cove

ring

inje

ctio

n po

st-c

ore

dam

age

and

prio

r to

ves

sel

brea

ch.

Tim

ing

redu

ced

13%

for

the

EP

U

(bas

ed o

n M

AA

P r

un G

GN

SE

PU

6b).

T

imin

g ch

ange

s ha

ve n

o im

pact

on

the

1.00

pr

obab

ility

use

d in

the

GG

NS

CLT

P P

RA

. C

11-F

O-H

ED

RS

DV

O

PE

RA

TO

R F

AIL

S

TO

DR

AIN

SD

V A

T

LEV

EL

3 G

AL.

60 m

in

60 m

in

2.30

E-0

4 2.

30E

-04

Tim

ing

estim

ate

base

d on

scr

am e

xhau

st

valv

e as

sum

ed le

akag

e. N

ot d

irect

ly

depe

nden

t on

reac

tor

pow

er.


4-

39

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

C11

-FO

-HE

NE

GR

EA

C

CO

ND

ITIO

NA

L H

UM

AN

ER

RO

R.

FA

IL T

O IN

SE

RT

N

EG

AT

IVE

R

EA

CT

IVIT

Y.

10 m

in

10 m

in

5.00

E-0

4 5.

00E

-04

Sys

tem

tim

e w

indo

w in

bas

e P

RA

co

nser

vativ

ely

estim

ated

at a

nom

inal

10

min

utes

(sh

orte

r w

indo

w th

an s

yste

m ti

me

win

dow

for

SLC

initi

atio

n).

The

EP

U w

ould

no

t cha

nge

this

con

serv

ativ

e m

odel

ing

assu

mpt

ion.

C

41-F

O-H

E1P

MP

-S

HU

MA

N E

RR

OR

: F

AIL

UR

E T

O

MA

NU

ALL

Y

INIT

IAT

E S

LC (

ON

E

PU

MP

OP

ER

AT

ION

)

15 m

in

13.1

min

5.

40E

-04(3

) 5.

40E

-04(3

)A

ssum

ptio

n ba

sed

on ti

me

to s

uppr

essi

on

pool

hea

tup

and

flash

ing

durin

g an

AT

WS

sc

enar

io.

The

GG

NS

CLT

P P

RA

co

nser

vativ

ely

estim

ates

this

tim

e fr

ame

at

15 m

inut

es.

Thi

s tim

e w

indo

w is

red

uced

13

% (

refle

ctiv

e of

the

pow

er u

prat

e).

CIS

-FO

-HE

ISO

L-X

O

PE

RA

TO

R F

AIL

S

TO

MA

NU

ALL

Y

ISO

LAT

E

CO

NT

AIN

ME

NT

ON

LO

CA

SIG

NA

L

30 m

in

24 m

in

5.00

E-0

1 5.

00E

-01

GG

NS

CLT

P P

RA

use

s a

cons

erva

tive

0.5

HE

P fo

r th

is s

impl

e ac

tion.

Thi

s H

EP

doe

s no

t cha

nge

due

to th

e E

PU

.

E12

-FO

-HE

ISO

L-X

O

PE

RA

TO

R F

AIL

S

TO

ISO

LAT

E L

PC

I A

, B A

ND

C

INJE

CT

ION

LIN

ES

N/A

N

/A

5.00

E-0

1 5.

00E

-01

Leve

l 2 P

RA

HE

P fo

r pr

even

ting

cont

ainm

ent b

ypas

s du

ring

cert

ain

acci

dent

sc

enar

ios.

Tim

ing

in 3

0-60

min

. ran

ge.

No

spec

ific

failu

re p

roba

bilit

y us

ed.

Thi

s es

timat

e w

ould

not

be

impa

cted

by

EP

U.


4-

40

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

E12

-FO

-HE

SD

C-O

O

PE

RA

TO

R F

AIL

S

TO

PR

OP

ER

LY

ALI

GN

FO

R

SH

UT

DO

WN

C

OO

LIN

G

360

min

31

3 m

in

1.00

E-0

5(4)

1.40

E-0

5(4)

Allo

wab

le ti

me

base

d on

tran

sien

t acc

iden

t sc

enar

io ti

me

from

exc

eedi

ng H

CT

L to

co

ntai

nmen

t fai

lure

. T

he G

GN

S C

LTP

PR

A

cons

erva

tivel

y es

timat

es th

is ti

me

fram

e at

6

hour

s. M

AA

P r

uns

GG

NS

EP

U9a

and

9ax

sh

ow th

at th

is ti

me

win

dow

is c

onse

rvat

ive

for

both

the

pre-

EP

U a

nd E

PU

. T

his

cons

erva

tive

time

is r

educ

ed fu

rthe

r fo

r th

is

risk

asse

ssm

ent b

y 13

% (

refle

ctiv

e of

the

pow

er u

prat

e).

E12

-FO

-HE

SP

C-M

O

PE

RA

TO

R F

AIL

S

TO

MA

NU

ALL

Y

ALI

GN

FO

R

SU

PP

RE

SS

ION

P

OO

L C

OO

LIN

G

420

min

35

3 m

in

1.00

E-0

5(3)

1.20

E-0

5(3)

Allo

wab

le ti

me

base

d on

tim

e to

hea

tup

supp

ress

ion

pool

from

95

°F to

200

°F

(ass

umed

RC

IC fa

ilure

tem

pera

ture

) fo

r a

tran

sien

t. A

llow

able

tim

e w

indo

w r

educ

ed

16%

(de

term

ined

from

MA

AP

run

G

GN

SE

PU

4).

E12

-FO

-HE

V3S

-O

OP

ER

AT

OR

FA

ILS

T

O P

RO

PE

RLY

A

LIG

N L

PC

I TH

RU

S

HU

TD

OW

N

CO

OLI

NG

LIN

ES

15 m

in

13 m

in

1.70

E-0

1(4)

2.60

E-0

1(4)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fr

om ti

me

of R

PV

ED

dur

ing

an

AT

WS

sce

nario

with

no

high

pre

ssur

e in

ject

ion.

Allo

wab

le ti

me

win

dow

red

uced

13

% (

refle

ctiv

e of

pow

er u

prat

e). T

his

time

redu

ctio

n is

con

sist

ent w

ith M

AA

P r

un

GG

NS

EP

U14

b.


4-

41

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

E22

-FO

-DF

EA

TH

PC

S

OP

ER

AT

OR

FA

ILS

T

O D

EF

EA

T H

PC

S

INT

ER

LOC

K A

ND

S

TA

RT

HP

CS

IN

AN

AT

WS

20 m

in

17.4

min

1.

60E

-03(3

) 1.

60E

-03(3

)A

llow

able

tim

e ba

sed

on ti

me

to c

ore

dam

age

form

RP

V le

vel o

f -1

91”

@ t=

10

min

. for

an

AT

WS

in w

hich

insu

ffici

ent h

igh

pres

sure

pre

ferr

ed in

ject

ion

is a

vaila

ble.

A

llow

able

tim

e w

indo

w r

educ

ed 1

3%

(ref

lect

ive

of p

ower

upr

ate)

. T

his

time

redu

ctio

n is

con

sist

ent w

ith M

AA

P r

un

GG

NS

EP

U14

a.

E22

-FO

-HE

F01

5-I

OP

ER

AT

OR

FA

ILS

T

O O

PE

N S

P

SU

CT

ION

VA

LVE

10 m

in

10 m

in

1.70

E-0

2 1.

70E

-02

Allo

wab

le ti

me

base

d on

con

serv

ativ

e es

timat

e of

tim

e to

em

pty

CS

T fo

llow

ing

rece

ipt o

f low

CS

T v

olum

e. N

ot d

irect

ly

depe

nden

t on

reac

tor

pow

er.

E30

-FO

-MS

INT

PA

-V

FA

ILU

RE

TO

M

AN

UA

LLY

IN

ITIA

TE

-SP

MU

T

RA

IN B

10 m

in

10 m

in

1.10

E-0

1 1.

10E

-01

Allo

wab

le ti

me

base

d on

con

serv

ativ

e es

timat

e (a

ssum

ing

all E

CC

S p

umps

ru

nnin

g of

f S/P

) to

red

uce

S/P

leve

l fro

m

low

leve

l cue

of 1

8.34

ft to

clo

se to

the

top

of th

e S

/P v

ents

. N

ot d

irect

ly d

epen

dent

on

reac

tor

pow

er.

E30

-FO

-MS

INT

PB

-V

FA

ILU

RE

TO

M

AN

UA

LLY

IN

ITIA

TE

-SP

MU

T

RA

IN B

10 m

in

10 m

in

1.10

E-0

1 1.

10E

-01

Allo

wab

le ti

me

base

d on

con

serv

ativ

e es

timat

e (a

ssum

ing

all E

CC

S p

umps

ru

nnin

g of

f S/P

) to

red

uce

S/P

leve

l fro

m

low

leve

l cue

of 1

8.34

ft to

clo

se to

the

top

of th

e S

/P v

ents

. N

ot d

irect

ly d

epen

dent

on

reac

tor

pow

er.


4-

42

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

E51

-FO

-HE

F03

1A-G

O

PE

RA

TO

R F

AIL

S

TO

OP

EN

SP

S

UC

TIO

N V

ALV

E

F03

1-A

60 m

in

60 m

in

4.60

E-0

4 4.

60E

-04

The

bas

e P

RA

con

serv

ativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

, whi

ch is

re

flect

ive

of th

e tim

e to

cor

e da

mag

e fo

r a

loss

of a

ll in

ject

ion

at t=

0 sc

enar

io.

Thi

s as

sum

ptio

n is

con

serv

ativ

e fo

r th

is H

EP

w

hich

is u

sed

in s

cena

rios

with

RC

IC

runn

ing

up to

t=6

hrs.

Thi

s co

nser

vativ

e as

sum

ptio

n w

ould

not

be

chan

ged

by th

e E

PU

. E

51-F

O-H

EIS

OL8

-G

OP

ER

AT

OR

FA

ILS

T

O M

AN

UA

LLY

IS

OLA

TE

RC

IC

SY

ST

EM

12 m

in

10.5

min

3.

20E

-02(4

) 5.

00E

-02(4

)A

llow

able

tim

e ba

sed

on ti

me

estim

ate

for

RC

IC to

rea

ch M

SL

pene

trat

ion

from

the

L8

trip

. T

he c

urre

nt P

RA

est

imat

es a

tim

e w

indo

w o

f 12

min

utes

. Thi

s tim

e es

timat

e is

re

duce

d by

13%

(re

flect

ive

of E

PU

).

E51

-FO

-HE

TR

PB

YP

H

UM

AN

ER

RO

R

FA

IL T

O B

YP

AS

S

RC

IC

TE

MP

ER

AT

UR

E

TR

IPS

(E

OP

A

ttach

men

t 3)

50 m

in

43.5

min

4.

50E

-03(3

) 5.

60E

-03(3

)A

llow

able

tim

e ba

sed

on ti

me

to c

ore

dam

age

afte

r R

CIC

ass

umed

to fa

il du

e to

hi

gh r

oom

tem

pera

ture

at t

=10

min

s. T

he

base

PR

A u

ses

60 m

ins

as th

e tim

e to

cor

e da

mag

e af

ter

loss

of a

ll in

ject

ion

at t=

10

min

s. T

he o

vera

ll tim

e w

indo

w o

f 50

min

s.

is r

educ

ed 1

3% (

refle

ctiv

e of

the

EP

U).


4-

43

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

INH

IBIT

F

AIL

UR

E O

F

OP

ER

AT

OR

TO

IN

HIB

IT A

DS

/HP

CS

D

UR

ING

AN

AT

WS

765

sec

757

sec

2.50

E-0

4(3)

2.50

E-0

4(3)

Sys

tem

tim

e w

indo

w b

ased

on

time

to

auto

mat

ic A

DS

dur

ing

a tr

ansi

ent A

TW

S.

Aut

omat

ic A

DS

act

uatio

n re

quire

s R

PV

le

vel t

o be

bel

ow L

evel

1 fo

r 10

min

s be

fore

th

e 10

5 se

c tim

er is

sta

rted

. T

ime

to b

oil o

ff w

ater

dow

n to

Lev

el 1

(-1

50.3

") is

1 m

in. f

or

the

base

PR

A.

Boi

l off

time

to R

PV

L1

redu

ced

13%

for

EP

U (

dete

rmin

ed fr

om

MA

AP

run

GG

NS

EP

U14

a).

LEV

/PW

R-C

ON

TR

OL

OP

ER

AT

OR

FA

ILS

T

O C

ON

TR

OL

LEV

EL

AN

D

PO

WE

R D

UR

ING

A

TW

S

20 m

in

17.4

min

1.

00E

-3(3

) 1.

00E

-3(3

) A

llow

able

tim

e ba

sed

on ti

me

to c

ore

dam

age

for

a lo

w p

ress

ure

AT

WS

afte

r R

PV

E

D a

nd in

adeq

uate

leve

l con

trol

. T

he

GG

NS

CLT

P P

RA

ass

umes

the

avai

labl

e tim

e w

indo

w is

20

min

utes

. T

his

time

estim

ate

is r

educ

ed 1

3% (

refle

ctiv

e of

EP

U).

L2-L

OS

P-R

EC

F

AIL

TO

RE

CO

VE

R

OF

FS

ITE

PO

WE

R

BE

FO

RE

VE

SS

EL

BR

EA

CH

2.5

hr

2.2

hrs

1.00

E+

00

1.00

E+

00

Leve

l 2 P

RA

HE

P fo

r re

cove

ring

OS

P p

ost-

core

dam

age

and

prio

r to

ves

sel b

reac

h du

ring

SB

O s

cena

rio.

Tim

ing

redu

ced

13%

fo

r th

e E

PU

(ba

sed

on M

AA

P r

un

GG

NS

EP

U6b

).

Tim

ing

chan

ges

have

no

impa

ct o

n th

e 1.

00 p

roba

bilit

y us

ed in

the

GG

NS

CLT

P P

RA

. L2

-RE

C-I

NJ

FA

IL T

O R

EC

OV

ER

IN

VE

SS

EL

2.5

hr

2.2

hrs

1.00

E+

00

1.00

E+

00

Leve

l 2 P

RA

HE

P fo

r re

cove

ring

inje

ctio

n po

st-c

ore

dam

age

and

prio

r to

ves

sel

brea

ch.

Tim

ing

redu

ced

13%

for

the

EP

U

(bas

ed o

n M

AA

P r

un G

GN

SE

PU

6b).

T

imin

g ch

ange

s ha

ve n

o im

pact

on

the

1.00

pr

obab

ility

use

d in

the

GG

NS

CLT

P P

RA

.


4-

44

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

M41

-FO

-AV

VC

NT

-Q

OP

ER

AT

OR

FA

ILS

T

O V

EN

T

CO

NT

AIN

ME

NT

600

min

49

8 m

in

1.5E

-05(3

) 1.

5E-0

5(3)

Allo

wab

le ti

me

base

d on

tim

e to

pre

ssur

ize

cont

ainm

ent.

Ope

rato

r tim

e w

indo

w b

ased

on

tim

e fr

om 2

2.4

psig

to 5

6 ps

ig

cont

ainm

ent p

ress

ure.

Allo

wab

le ti

me

win

dow

red

uced

17%

(de

term

ined

from

M

AA

P r

un G

GN

SE

PU

9a).

N

11-F

O-H

EM

OD

SW

-G

OP

ER

AT

OR

FA

ILS

T

O T

UR

N T

HE

M

OD

E S

WIT

CH

TO

S

HU

TD

OW

N

15 m

in

12.6

min

2.

50E

-04(3

) 2.

50E

-04(3

)S

yste

m ti

me

win

dow

bas

ed o

n tim

e to

MS

IV

clos

ure

on R

PV

L1

from

RP

V L

evel

3 d

urin

g a

tran

sien

t. A

llow

able

tim

e w

indo

w r

educ

ed

16%

(de

term

ined

from

MA

AP

run

G

GN

SE

PU

15).

N

21-F

O-H

ELV

L9-I

(A

TW

S)

HU

MA

N E

RR

OR

: F

AIL

UR

E T

O

RE

ST

AR

T

RE

AC

TO

R F

EE

D

PU

MP

S

FO

LLO

WIN

G

LEV

EL

9 T

RIP

30 m

in

26.1

min

2.

10E

-03(3

) 2.

10E

-03(3

)A

llow

able

tim

e ba

sed

on ti

me

to M

SIV

cl

osur

e on

RP

V 1

sig

nal d

urin

g a

turb

ine

trip

A

TW

S a

nd fa

ilure

of F

W le

vel c

ontr

ol s

uch

that

FW

trip

s at

Lev

el 9

at t

= 2

0 m

ins.

A

llow

able

tim

e w

indo

w r

educ

ed 1

3%

(con

sist

ent w

ith E

PU

pow

er in

crea

se).

Thi

s tim

e re

duct

ion

is c

onsi

sten

t with

MA

AP

run

G

GN

SE

PU

13b.

N

21-F

O-H

ELV

L9-I

(T

rans

) H

UM

AN

ER

RO

R:

FA

ILU

RE

TO

R

ES

TA

RT

R

EA

CT

OR

FE

ED

P

UM

PS

F

OLL

OW

ING

LE

VE

L 9

TR

IP

22 m

in

19.1

min

3.

30E

-03(4

) 5.

7E-0

3(4)

Allo

wab

le ti

me

base

d on

tim

e to

MS

IV

clos

ure

on R

PV

L1

from

tim

e of

FW

trip

on

RP

V L

9 du

ring

a tr

ansi

ent.

Allo

wab

le ti

me

win

dow

red

uced

13%

(de

term

ined

from

M

AA

P r

un G

GN

SE

PU

15).


4-

45

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

N21

-FO

-HE

PC

S-G

(A

TW

S)

HU

MA

N E

RR

OR

F

AIL

TO

P

RO

PE

RLY

ALI

GN

T

HE

PC

S F

OR

IN

JEC

TIO

N

15 m

in

13.1

min

8.

30E

-04(3

) 8.

30E

-04(3

)A

llow

able

tim

e ba

sed

on ti

me

to M

SIV

cl

osur

e on

RP

V L

1 si

gnal

dur

ing

a tu

rbin

e tr

ip A

TW

S (

with

PC

S in

itial

ly a

vaila

ble)

and

fa

ilure

of F

W le

vel c

ontr

ol s

uch

that

FW

trip

s on

RP

V L

9 at

t =

5 m

ins.

Allo

wab

le ti

me

win

dow

red

uced

13%

(co

nsis

tent

with

EP

U

pow

er in

crea

se).

Thi

s tim

e re

duct

ion

is

cons

iste

nt w

ith M

AA

P r

un G

GN

SE

PU

13a.

N

21-F

O-H

EP

CS

-G

(Tra

nsie

nt)

HU

MA

N E

RR

OR

F

AIL

TO

P

RO

PE

RLY

ALI

GN

T

HE

PC

S F

OR

IN

JEC

TIO

N

15 m

in

12.6

min

8.

30E

-04(3

) 8.

30E

-04(3

)A

llow

able

tim

e ba

sed

on ti

me

to M

SIV

cl

osur

e on

RP

V L

1 si

gnal

from

RP

V L

3 du

ring

a tr

ansi

ent.

Allo

wab

le ti

me

win

dow

re

duce

d 16

% (

dete

rmin

ed fr

om M

AA

P r

un

GG

NS

EP

U15

).

NR

-AC

HW

R-1

HR

S

Fai

lure

to R

ecov

er

AC

Bus

Fai

lure

in 1

H

our

1 hr

50

min

6.

00E

-01

6.0

0E-0

1

The

bas

e P

RA

con

serv

ativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

(re

flect

ive

of ti

me

to c

ore

dam

age

for

a lo

ss o

f all

inje

ctio

n at

t=0

scen

ario

) fo

r ap

plic

atio

n of

th

is A

C b

us r

ecov

ery

term

. T

his

assu

mpt

ion

is c

onse

rvat

ive

give

n th

is r

ecov

ery

is u

sed

in s

cena

rios

with

RC

IC r

unni

ng u

p

t = 1

0 m

in. F

or th

e E

PU

, the

tim

e to

cor

e da

mag

e fo

r th

is A

C b

us r

ecov

ery

term

is

redu

ced

17%

(w

orst

cas

e re

duct

ion

from

bo

il of

f MA

AP

cas

es G

GN

SE

PU

10a,

G

GN

SE

PU

10b,

and

GG

NS

EP

U15

).

Rec

over

y fa

ilure

pro

babi

lity

does

not

ch

ange

due

to s

tep

func

tion

AC

bus

re

cove

ry m

odel

.


4-

46

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

-AC

HW

R-8

HR

S

Fai

lure

to R

ecov

er

AC

Bus

Fai

lure

in 8

ho

urs

8 hr

6.

7 hr

1.

00E

-02

1.00

E-0

2

Thi

s A

C b

us r

ecov

ery

term

is b

ased

on

time

to s

uppr

essi

on p

ool t

empe

ratu

re o

f 200

o F

with

RC

IC r

unni

ng a

nd n

o co

ntai

nmen

t hea

t re

mov

al.

For

the

EP

U, t

his

time

to 2

00°F

is

redu

ced

16%

(ba

sed

on M

AA

P r

un

GG

NS

EP

U4)

. R

ecov

ery

failu

re p

roba

bilit

y do

es n

ot c

hang

e du

e to

ste

p fu

nctio

n A

C

bus

reco

very

mod

el.

NR

C-D

G-C

F1H

RS

F

ailu

re to

Rec

over

D

iese

l Gen

erat

or

Com

mon

Cau

se

Fai

lure

in 1

hou

r

1 hr

50

min

9.

00E

-01

9.00

E-0

1

The

bas

e P

RA

con

serv

ativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

(re

flect

ive

of th

e tim

e to

cor

e da

mag

e fo

r a

loss

of a

ll in

ject

ion

at t=

0 sc

enar

io)

for

appl

icat

ion

of

this

DG

rec

over

y te

rm.

For

the

EP

U, t

his

time

to c

ore

dam

age

for

this

DG

rec

over

y te

rm is

red

uced

17%

(w

orst

cas

e re

duct

ion

from

boi

l off

MA

AP

cas

es G

GN

SE

PU

10a,

G

GN

SE

PU

10b,

GG

NS

EP

U15

). R

ecov

ery

failu

re p

roba

bilit

y do

es n

ot c

hang

e du

e to

st

ep fu

nctio

n D

G r

ecov

ery

mod

el.


4-

47

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

C-D

GH

W10

&F

W

Fai

lure

to R

ecov

er

DG

Har

dwar

e F

ailu

re o

r st

art F

W

in 1

0 ho

urs

10 h

r 8.

7 hr

2.

85E

-01

3.35

E-0

1 T

his

reco

very

term

is a

pplie

d to

cut

sets

in

volv

ing

initi

al R

PV

inje

ctio

n (a

nd

subs

eque

nt fa

ilure

) fo

r va

rious

tim

e le

ngth

s an

d co

vers

cut

sets

that

wou

ld p

rogr

ess

to

core

dam

age

in 8

-10

hrs

with

out i

njec

tion

reco

very

. T

he b

ase

PR

A a

ssum

es a

no

min

al 1

0 ho

ur ti

me

fram

e fo

r re

cove

ry to

ap

ply

to th

ese

case

s. T

his

time

is r

educ

ed

13%

(re

flect

ive

of th

e E

PU

pow

er in

crea

se).

T

his

reco

very

term

pro

babi

lity

is c

alcu

late

d as

the

prob

abili

ty o

f die

sel h

ardw

are

reco

very

failu

re w

ithin

10

hour

s (0

.5 fr

om

base

PR

A)

mul

tiplie

d by

the

HE

P fo

r fa

ilure

to

alig

n fir

e w

ater

sho

rt te

rm, e

vent

P64

-FO

-H

E-G

. HE

P P

64-F

O-H

E-G

incr

ease

s fr

om

0.57

to 0

.67

due

to E

PU

tim

ing

redu

ctio

n (r

efer

to P

64-F

O-H

E-G

ent

ry la

ter

in ta

ble)

w

hile

the

hard

war

e re

cove

ry te

rm r

emai

ns

the

sam

e du

e to

the

step

func

tion

reco

very

m

odel

.


4-

48

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

C-D

G-H

W1H

R

Fai

lure

to R

ecov

er

Die

sel G

ener

ator

H

ardw

are

Fai

lure

in

1 ho

ur

1 hr

50

min

9.

00E

-01

9.00

E-0

1 T

he b

ase

PR

A a

ssum

es a

60

min

ute

Sys

tem

Tim

e W

indo

w (

refle

ctiv

e of

the

time

to c

ore

dam

age

for

a lo

ss o

f all

inje

ctio

n at

t=

0 sc

enar

io)

for

appl

icat

ion

of th

is D

G

reco

very

term

. F

or th

e E

PU

, thi

s tim

e to

co

re d

amag

e fo

r th

is D

G r

ecov

ery

term

is

redu

ced

17%

(w

orst

cas

e re

duct

ion

from

bo

il of

f MA

AP

cas

es G

GN

SE

PU

10a,

G

GN

SE

PU

10b,

GG

NS

EP

U15

). R

ecov

ery

failu

re p

roba

bilit

y do

es n

ot c

hang

e du

e to

st

ep fu

nctio

n D

G r

ecov

ery

mod

el.

N

RC

-DG

-MA

1HR

F

ailu

re to

Rec

over

D

iese

l Gen

erat

or

from

Mai

nten

ance

in

1 ho

ur

1 hr

50

min

9.

00E

-01

9.00

E-0

1 T

he b

ase

PR

A a

ssum

es a

60

min

ute

Sys

tem

Tim

e W

indo

w (

refle

ctiv

e of

the

time

to c

ore

dam

age

for

a lo

ss o

f all

inje

ctio

n at

t=

0 sc

enar

io)

for

appl

icat

ion

of th

is D

G

reco

very

term

. F

or th

e E

PU

, thi

s tim

e to

co

re d

amag

e fo

r th

is D

G r

ecov

ery

term

is

redu

ced

17%

(w

orst

cas

e re

duct

ion

from

bo

il of

f MA

AP

cas

es G

GN

SE

PU

10a,

G

GN

SE

PU

10b,

GG

NS

EP

U15

). R

ecov

ery

failu

re p

roba

bilit

y do

es n

ot c

hang

e du

e to

st

ep fu

nctio

n D

G r

ecov

ery

mod

el.

N

RC

-OS

P-C

NT

F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N L

ON

G

TE

RM

C

ON

TA

INM

EN

T

FA

ILU

RE

20 h

r 16

.6 h

r 1.

21E

-02

3.09

E-0

2 A

llow

able

tim

e ba

sed

on ti

me

to

cont

ainm

ent f

ailu

re.

Allo

wab

le ti

me

win

dow

re

duce

d 17

% (

base

d on

MA

AP

run

G

GN

SE

PU

9a).

Pro

babi

lity

base

d on

co

nvol

utio

n ca

lcul

atio

n of

OS

P r

ecov

ery

curv

e an

d lo

ss o

f hea

t rem

oval

tim

ing.


4-

49

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

C-O

SP

-DLG

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 0

FT

R *

N

O S

SW

PH

V

FA

ILU

RE

S

Not

e (5

) N

ote

(5)

1.28

E-0

1 1.

59E

-01

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve

and

long

-ter

m R

CIC

op

erat

ion

acci

dent

sce

nario

tim

ing.

Ref

er to

N

ote

(5).

N

RC

-OS

P-D

SG

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

0 F

TR

* N

O S

SW

P

HV

FA

ILU

RE

S

Not

e (5

) N

ote

(5)

6.18

E-0

1 6.

59E

-01

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve

and

acci

dent

tim

ings

fo

r no

inje

ctio

n sc

enar

ios

or s

hort

-ter

m

RC

IC s

cena

rios.

Ref

er to

Not

e (5

).

NR

C-O

SP

-DS

G0S

SW

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

0 F

TR

* 1

OR

2 S

SW

P

HV

FT

S

Not

e (5

) N

ote

(5)

2.62

E-0

1 2.

80E

-01

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve,

equ

ipm

ent f

ailu

re

timin

gs d

ue to

loss

of v

entil

atio

n, a

nd

acci

dent

tim

ings

for

no in

ject

ion

scen

ario

s or

sho

rt-t

erm

RC

IC s

cena

rios.

Ref

er to

N

ote

(5).

N

RC

-OS

P-D

SG

1 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

1 F

TR

* N

O S

SW

P

HV

FA

ILU

RE

S

Not

e (5

) N

ote

(5)

1.05

E-0

1 1.

11E

-01

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve

and

acci

dent

tim

ings

fo

r no

inje

ctio

n sc

enar

ios

or s

hort

-ter

m

RC

IC s

cena

rios.

Ref

er to

Not

e (5

).

NR

C-O

SP

-DS

G2

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 2

FT

R *

NO

SS

W

PH

V F

AIL

UR

ES

Not

e (5

) N

ote

(5)

4.53

E-0

2 4.

77E

-02

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve

and

acci

dent

tim

ings

fo

r no

inje

ctio

n sc

enar

ios

or s

hort

-ter

m

RC

IC s

cena

rios.

Ref

er to

Not

e (5

).

NR

C-O

SP

-PS

G0

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

SR

V

LOC

A *

U2

* 0

FT

R

* N

O S

SW

PH

V

FA

ILU

RE

S

Not

e (5

) N

ote

(5)

7.63

E-0

1 7.

82E

-01

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve

and

acci

dent

tim

ing

for

SO

RV

sce

nario

with

no

inje

ctio

n at

t=0.

R

efer

to N

ote

(5).


4-

50

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

C-O

SP

-DS

G0-

L2

Fai

l to

Rec

over

OS

P

Giv

en U

2 *0

FT

R*

No

SS

W P

HV

F

ailu

res

LER

F

Not

e (5

) N

ote

(5)

3.28

E-0

1 3.

36E

-01

Sam

e pe

rcen

tage

incr

ease

as

NR

C-O

SP

-P

SG

0.

NR

C-O

SP

-DS

G0S

0L2

Fai

l to

Rec

over

OS

P

Giv

en U

2 *0

FT

R *

1

or 2

SS

W P

HV

FT

S

LER

F

Not

e (5

) N

ote

(5)

1.64

E-0

1 1.

75E

-01

Sam

e pe

rcen

tage

incr

ease

as

NR

C-O

SP

-D

SG

0SS

W0.

NR

C-O

SP

-DS

G1-

L2

Fai

l to

Rec

over

OS

P

Giv

en U

2 *

1 F

TR

*N

o S

SW

PH

V

Fai

lure

s LE

RF

Not

e (5

) N

ote

(5)

6.47

E-0

2 6.

84E

-02

Sam

e pe

rcen

tage

incr

ease

as

NR

C-O

SP

-D

SG

1.

NR

C-O

SP

-DS

G2-

L2

Fai

l to

Rec

over

OS

P

Giv

en U

2 *

2 F

TR

*N

o S

SW

PH

V

Fai

lure

s LE

RF

Not

e (5

) N

ote

(5)

3.00

E-0

2 3.

16E

-02

Sam

e pe

rcen

tage

incr

ease

as

NR

C-O

SP

-D

SG

2.

NR

C-O

SP

-PS

G0-

L2

Fai

l to

Rec

over

OS

P

Giv

en S

RV

LO

CA

*U

2 *0

FT

R *

No

SS

W P

HV

Fai

lure

s LE

RF

Not

e (5

) N

ote

(5)

3.28

E-0

1 3.

36E

-01

Sam

e pe

rcen

tage

incr

ease

as

NR

C-O

SP

-P

SG

0.


4-

51

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

-PC

S-6

0MN

F

AIL

UR

E T

O

RE

CO

VE

R P

CS

IN

60 M

INU

TE

S

1 hr

50

min

6.

00E

-01

6.00

E-0

1 T

ime

win

dow

is c

onse

rvat

ivel

y ba

sed

on

time

to c

ore

dam

age

in a

tran

sien

t sce

nario

w

ith n

o in

ject

ion

at t=

0. F

or th

e E

PU

, the

tim

e w

indo

w fo

r th

is r

ecov

ery

is r

educ

ed

17%

(w

orst

cas

e re

duct

ion

from

boi

l off

MA

AP

cas

es G

GN

SE

PU

10a,

G

GN

SE

PU

10b,

and

GG

NS

EP

U15

).

Rec

over

y fa

ilure

pro

babi

lity

does

not

ch

ange

due

to s

tep

func

tion

reco

very

m

odel

. N

RS

-GT

4HE

P

Set

a m

inim

um

defa

ult f

or c

utse

ts

with

mor

e th

an fo

ur

HR

A e

vent

s

- -

1.00

E-0

7 1.

00E

-07

Not

a c

alcu

late

d va

lue

base

d on

pla

nt

spec

ific

info

rmat

ion.

Thi

s ev

ent r

emai

ns

unch

ange

d in

the

EP

U.

P41

-FO

-HE

SW

XT

-G

(LO

CA

) O

PE

RA

TO

R F

AIL

S

TO

MA

NU

ALL

Y

ALI

GN

FO

R S

SW

C

RO

SS

-TIE

S

YS

TE

M

20 m

in

17.4

min

8.

90E

-02(4

) 1.

30E

-01(4

)A

llow

able

tim

e ba

sed

on ti

me

to c

ore

dam

age

for

a la

rge

LOC

A w

ith n

o in

ject

ion.

A

llow

able

tim

e w

indo

w r

educ

ed 1

3% fo

r th

e E

PU

(de

term

ined

from

MA

AP

run

G

GN

SE

PU

8).

P47

-FO

-HE

PS

W-X

O

PE

RA

TO

R F

AIL

S

TO

AC

TU

AT

E P

SW

P

UM

P

120

min

12

0 m

in

1.00

E-0

5 1.

00E

-05

Allo

wab

le ti

me

base

d on

tim

e to

sta

rt

stan

dby

pum

p be

fore

load

s af

fect

ed d

ue to

in

adeq

uate

PS

W fl

ow. N

ot d

irect

ly

depe

nden

t on

reac

tor

pow

er.

P47

-FO

-ST

OP

SC

RM

O

pera

tor

fails

to

aver

t scr

am

follo

win

g lo

ss o

f P

SW

Sys

tem

10 m

in

10 m

in

1.70

E-0

2 1.

70E

-02

Allo

wab

le ti

me

base

d on

tim

e to

re-

alig

n lo

ads

and

prev

ent a

scr

am b

efor

e lo

ads

affe

cted

by

inad

equa

te P

SW

flow

. N

ot

dire

ctly

dep

ende

nt o

n re

acto

r po

wer

.


4-

52

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

P51

-FO

-CM

ST

AR

T-T

F

ailu

re to

sta

rt

stan

dby

Ser

vice

Air

Com

pres

sor

60 m

in

50 m

in

4.60

E-0

4(3)

4.60

E-0

4(3)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e ba

sed

on lo

ss o

f fee

dwat

er d

ue to

lo

ss o

f ins

trum

ent a

ir. A

llow

able

tim

e w

indo

w r

educ

ed 1

7% (

wor

st c

ase

redu

ctio

n fr

om b

oil o

ff M

AA

P c

ases

GG

NS

EP

U10

a,

GG

NS

EP

U10

b, a

nd G

GN

SE

PU

15).

P

53-F

O-H

EC

OO

LIA

S

OP

ER

AT

OR

FA

ILS

T

O A

LIG

N S

SW

-B

TO

IAS

C

OM

PR

ES

SO

R

UP

ON

LO

SS

OF

T

BC

W

90 m

in

90 m

in

2.20

E-0

4 2.

20E

-04

Allo

wab

le ti

me

base

d on

tim

e to

fail

com

pres

sors

afte

r T

BC

W s

yste

m fa

ils w

ith

no c

oolin

g. N

ot d

epen

dent

on

reac

tor

pow

er.

P53

-FO

-HE

RE

INF

-T

OP

ER

AT

OR

FA

ILS

T

O R

EIN

ITIA

TE

IA

AS

PE

R

PR

OC

ED

UR

E

360

min

36

0 m

in

1.90

E-0

5 1.

90E

-05

Allo

wab

le ti

me

base

d on

tim

e to

rep

lace

A

DS

gas

bot

tles.

Not

dire

ctly

dep

ende

nt o

n re

acto

r po

wer

.

P64

-FO

-HE

-G

OP

ER

AT

OR

FA

ILS

T

O A

LIG

N

FIR

EW

AT

ER

S

YS

TE

M F

OR

IN

JEC

TIO

N

150

min

14

2 m

in

5.70

E-0

1(4)

6.70

E-0

1(4)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fo

r an

SB

O w

ith R

CIC

ope

ratio

n fo

r at

leas

t 2 h

rs.

Allo

wab

le ti

me

win

dow

re

duce

d 5%

(de

term

ined

from

MA

AP

run

G

GN

SE

PU

6a).

P

64-F

O-H

E-G

(Lo

ng

Ter

m)

OP

ER

AT

OR

FA

ILS

T

O A

LIG

N

FIR

EW

AT

ER

S

YS

TE

M F

OR

IN

JEC

TIO

N

480

min

45

6 m

in

1.10

E-0

2(4)

1.10

E-0

2(4)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fo

r an

SB

O w

ith R

CIC

ope

ratio

n fo

r at

leas

t 6 h

r (t

ime

to b

atte

ry d

eple

tion)

. A

llow

able

tim

e w

indo

w r

educ

ed 5

%

(det

erm

ined

from

MA

AP

run

GG

NS

EP

U6b

).


4-

53

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

R21

-FO

-HE

BO

PT

RM

O

PE

RA

TO

R F

AIL

S

TO

ALI

GN

A

LTE

RN

AT

E

PO

WE

R T

O B

OP

B

US

SE

S

60 m

in

50 m

in

4.50

E-0

4(4)

8.60

E-0

4(4)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fo

r a

tran

sien

t with

loss

of i

njec

tion

at t=

0. A

llow

able

tim

e w

indo

w r

educ

ed 1

7%

(wor

st c

ase

redu

ctio

n fr

om b

oil o

ff M

AA

P

case

s G

GN

SE

PU

10a,

GG

NS

EP

U10

b, a

nd

GG

NS

EP

U15

).

R21

-FO

-HE

ES

FT

RM

O

PE

RA

TO

R F

AIL

S

TO

TR

AN

SF

ER

TO

A

LTE

RN

AT

E

TR

AN

SF

OR

ME

R

60 m

in

50 m

in

4.50

E-0

4(4)

8.60

E-0

4(4)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fo

r a

tran

sien

t with

loss

of i

njec

tion

at t=

0. A

llow

able

tim

e w

indo

w r

educ

ed 1

7%

(wor

st c

ase

redu

ctio

n fr

om b

oil o

ff M

AA

P

case

s G

GN

SE

PU

10a,

GG

NS

EP

U10

b, a

nd

GG

NS

EP

U15

).

SC

RM

M

AN

UA

L S

CR

AM

F

AIL

UR

E

10 m

in

10 m

in

5.00

E-0

4 5.

00E

-04

Sys

tem

tim

e w

indo

w in

bas

e P

RA

co

nser

vativ

ely

estim

ates

at a

nom

inal

10

min

utes

(sh

orte

r w

indo

w th

an s

yste

m ti

me

win

dow

for

SLC

initi

atio

n).

The

EP

U w

ould

no

t cha

nge

this

con

serv

ativ

e m

odel

ing

assu

mpt

ion.

X

2-A

TW

S

OP

ER

AT

OR

FA

ILS

T

O

DE

PR

ES

SU

RIZ

E

DU

RIN

G A

TW

S

20 m

in

17.4

min

1.

00E

-03(3

) 1.

00E

-03(3

)A

llow

able

tim

e ba

sed

on ti

me

to c

ore

dam

age

form

RP

V le

vel o

f -1

91”

@ t=

10

min

. for

an

AT

WS

in w

hich

insu

ffici

ent h

igh

pres

sure

pre

ferr

ed in

ject

ion

is a

vaila

ble.

A

llow

able

tim

e w

indo

w r

educ

ed 1

3%

(ref

lect

ive

of p

ower

upr

ate)

. T

his

time

redu

ctio

n is

con

sist

ent w

ith M

AA

P r

un

GG

NS

EP

U14

a.


4-

54

Tab

le 4

.1-1

1

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

X3

X3-

-D

EP

RE

SU

RIZ

AT

ION

VIA

RC

IC

90 m

in

75 m

in

8.40

E-0

3(4)

1.80

E-0

2(4)

Bas

ed o

n tim

e to

cor

e da

mag

e af

ter

6 ho

urs

of in

ject

ion

usin

g R

CIC

dur

ing

an S

BO

. A

llow

able

tim

e w

indo

w r

educ

ed 1

7%

(det

erm

ined

from

MA

AP

run

GG

NS

EP

U6b

).

X77

-FO

-HE

C00

1A-U

O

PE

RA

TO

R F

AIL

S

TO

TR

AN

SF

ER

F

AN

TO

HIG

H

SP

EE

D

360

min

36

0 m

in

1.00

E-0

5 1.

00E

-05

Bas

ed o

n tim

e to

HP

CS

die

sel f

ailu

re d

ue to

hi

gh te

mpe

ratu

re.

Not

dire

ctly

dep

ende

nt

on r

eact

or p

ower

.

X77

-FO

-HE

C00

1B-U

O

PE

RA

TO

R F

AIL

S

TO

TR

AN

SF

ER

F

AN

TO

HIG

H

SP

EE

D

360

min

36

0 m

in

1.00

E-0

5 1.

00E

-05

Bas

ed o

n tim

e to

HP

CS

die

sel f

ailu

re d

ue to

hi

gh te

mpe

ratu

re. N

ot d

irect

ly d

epen

dent

on

reac

tor

pow

er.

X77

-FO

-HE

CO

O2C

-U

OP

ER

AT

OR

FA

ILS

T

O T

RA

NS

FE

R

FA

N T

O H

IGH

S

PE

ED

360

min

36

0 m

in

1.00

E-0

5 1.

00E

-05

Bas

ed o

n tim

e to

HP

CS

die

sel f

ailu

re d

ue to

hi

gh te

mpe

ratu

re. N

ot d

irect

ly d

epen

dent

on

reac

tor

pow

er.

Y47

-FO

-HE

MO

D-U

O

PE

RA

TO

R F

AIL

S

TO

PR

OV

IDE

A

LTE

RN

AT

E

CO

OLI

NG

210

min

21

0 m

in

3.80

E-0

4 3.

80E

-04

Bas

ed o

n tim

e to

tem

pera

ture

indu

ced

failu

res

in S

SW

pum

p ho

uses

follo

win

g a

failu

re o

f the

ven

tilat

ion

syst

em.

Not

dire

ctly

de

pend

ent o

n re

acto

r po

wer

.


4-55

Notes to Table 4.1-11 (1) The time window in these columns is the “System Time Window”, TSW of the HEP calculations. This

is the time between the cue and the end of the allowable time window (i.e., the point at which performance of the action is moot).

(2) Multiple methods are used for calculating the probabilities for the Grand Gulf HEPs. This includes the HCR/ORE and the ERPI Cause-Based methodologies. The GGNS PRA uses the higher of the HCR/ORE or Cause-Based HEP calculation. Note that HEPs probabilities from the Cause-Based method do not change with small changes in allowable operator action timing.

(3) HEP calculated using Cause-Based method.

(4) HEP calculated using the HCR/ORE method.

(5) The probabilities of the offsite AC recovery terms summarized in this table are based on convolution calculations of the OSP recovery curve and one or more of the following timing variables (as described in GGNS PRA Calculation PRA-GG-01-001S09):

• τP : Time from non-recovered cutset occurrence to core uncovery for an SORV

scenario with no injection at t=0. Estimated at 0.5 hrs for the GGNS CLTP PRA. • τS : Time from non-recovered cutset occurrence to core uncovery for a transient with

core cooling lost within the first 2 hours. Estimated at 1.0 hr for the GGNS CLTP PRA (assumes loss of all injection at t=0).

• τL : Time from non-recovered cutset occurrence to core uncovery for a transient with core cooling lost after the first 2 hours. Estimated at 2.0 hrs for the GGNS CLTP PRA.

• τR : Time from non-recovered cutset occurrence to core uncovery for a transient with RCIC failure due to battery depletion or suppression pool heatup. Estimated at 6.0 hr for the GGNS CLTP PRA.

• τV : Time from loss of SSW pump house ventilation to DG failure. Estimated at 2.0 hrs for the GGNS CLTP PRA.

• Time to containment failure due to overpressurization during a transient with loss of containment heat removal. Estimated at 20 hrs for the GGNS CLTP PRA.

The τV variable is not directly based on core power level and as such is not adjusted for the EPU risk assessment. The other timing variables are adjusted for the EPU, as follows:

• τP : Reduced 11% to 0.445 hours (percentage reduction based on MAAP run GGNSEPU2b).

• τS : Reduced 16% to 0.84 hours (percentage reduction based on MAAP run GGNSEPU10a).

• τL : Reduced 16% to 1.68 hours (percentage reduction based on MAAP run GGNSEPU6a).

• τR : Reduced 16% to 5 hours (percentage reduction based on MAAP run GGNSEPU4).

• Time to containment failure due to overpressurization during a transient with loss of containment heat removal 6educed 17% to 16.6 hours (percentage reduction based on MAAP run GGNSEPU9a).


4-56

4.2 LEVEL 1 PRA Section 4.1 summarized possible effects of the EPU by examining each of the PRA

elements. This section examines possible EPU effects from the perspective of accident

sequence progression. The dominant accident scenario types (classes) that can lead to

core damage are examined with respect to the changes in the individual PRA elements

discussed in Section 4.1.

Loss of Inventory Makeup Transients Loss of inventory accidents (non-LOCA) are determined by the number of systems, their

success criteria, and operator actions for responding to their demands. The following

bullets summarize key issues:

• FW, Condensate, HPCS, RCIC and LP ECCS systems - all of these systems have substantial margin in their success criteria relative to the EPU power increase to match the coolant makeup flow required for postulated accidents.

• CRD - the CLTP PRA credits CRD only after another system provides

flow for 5 hours. Depressurization of the RPV prevents operation of CRD due to cavitation. Based on MAAP evaluation (GGNSEPU12) CRD remains successful after 5 hours.

• Alternative LP RPV Injection Systems – the CLTP PRA credits SSW

and FPS crossties. Their use is sequence specific. No changes are identified to the modeling of these systems for the EPU.

• The success criterion used in the CLTP PRA for the number of SRVs

required to function to assure RPV emergency depressurization is three (3) SRVs. Based on the MAAP evaluations (e.g., GGNSEPU1a), the three (3) SRVs success criterion remains adequate for the EPU condition.


4-57

Operator actions include emergency depressurization and system control and initiation.

The injection initiation/recovery and emergency depressurization timings are slightly

impacted by the EPU. As such, changes to the existing risk profile associated with loss

of inventory makeup accidents result.

ATWS Following a failure to scram coupled with additional failures, a higher power level and

increase in suppression pool temperature would result for the EPU configuration

compared with the current Grand Gulf configuration (assuming similar failures).

The necessary relief capacity to prevent exceeding the Service Level C RPV pressure limit

of 1500 psig is modeled in the current GGNS CLTP PRA as requiring 13 of 20 SRVs to

open. As discussed earlier in Section 4.1.2.5, this PRA success criterion is assessed to

be 15 of 20 SRVs required to open for the EPU condition.

The increased power level reduces the time available to perform operator actions. Refer

to Table 4.1-11 for changes in ATWS related HEPs, as well as HEPs for other accident

types. Given these ATWS HEP changes, changes to the existing risk profile associated

with ATWS accidents result.

LOCAs Dynamic loads would increase slightly because of the increased stored thermal energy.

This change would not quantitatively influence the PRA results. The containment

analyses for LOCA under EPU conditions indicate that dynamic loads on containment

remain acceptable.

The success criteria for the systems to respond to a LOCA are discretized by system

trains. Sufficient margin is available in these success criteria to allow adequate core

cooling for EPU.


4-58

SBO Station Blackout represents a unique subset of the loss of inventory accidents identified

above. The station blackout scenario response is almost totally dominated by AC and DC

power issues. In all other respects, SBO sequences are like the transients discussed

above. Extended power uprate will not increase the loads on diesel-generators or

batteries. As discussed earlier, the success criteria for mitigating systems is unchanged

for the EPU.

The dominant operator action during SBO accidents is offsite AC recovery. The AC

recovery failure probability is based on calculation using convolution integrals [22].

The convolution integrals and a few operator actions are impacted by the reduced

available timings of the EPU, and are propagated through the accident sequences (refer

to Table 4.1-11).

In addition, an accident sequence assumption in the CLTP related to the length of time

that RCIC can operate in long term scenarios before the pool heats up to the 200F

challenge point for RCIC is adjusted for the EPU. The CLTP assumes that pool heatup

to 200F during long-term SBO scenarios with RCIC operating (with batteries being

charged) occurs at t=6 hrs. This time frame is reduced to t=5 hrs for the EPU condition

(refer to Appendix E MAAP run GGNSEPU4 and GGNSEPU4x). This issue is

addressed in the LOSP convolution calculations.

As such, minor changes to the existing risk profile associated with SBO accidents result.

Loss of Containment Heat Removal Sequences which involve the loss of containment heat removal (Class II accident

sequences) are affected slightly in terms of the time to reach the EOP containment

pressure limit (and ultimate pressure). However, the success criteria for the key


4-59

systems (RHR, Main Condenser, and containment vent) in the loss of containment heat

removal accident sequences are not affected.

Other systems (e.g., DW coolers, RWCU) are considered marginal or inadequate for

containment heat removal even for the CLTP PRA. Such systems remain inadequate

for the EPU PRA.

The time available to initiate containment heat removal measures is measured in many

hours (>20 hrs) in the PRA for non-ATWS scenarios. The reduction in this very long

time frame due to the EPU has no significant impact on the HEPs for containment heat

removal initiation for non-ATWS scenarios (refer to Table 4.1-11).

The increased power level decreases the time to reach the EOP Heat Capacity

Temperature Limit Curve (HCTL). The EOPs direct RPV emergency depressurization

upon reaching or exceeding the HCTL curve. These HEP changes will have a minor

impact on the Class II accident sequences.

Minor changes to the risk profile associated with Class II (loss of decay heat removal)

accidents result.

4.3 INTERNAL FIRES INDUCED RISK The Grand Gulf plant risk due to internal fires was evaluated in 1995 as part of the

GGNS Individual Plant Examination of External Events (IPEEE) Submittal [10]. EPRI

FIVE Methodology and Fire PRA Implementation Guide screening approaches and data

were used to perform the GGNS IPEEE fire PRA study. [5,6,7]

Consistent with the FIVE Methodology and the requests of the NRC IPEEE Program,

the GGNS IPEEE fire PRA is an analysis that identifies the most risk significant fire

areas in the plant using a screening process and by calculating conservative core

damage frequencies for fire scenarios. As such, the accident sequence frequencies


4-60

calculated for the GGNS fire PRA are not a best estimate calculation of plant fire risk

and are not acceptable for integration with the best estimate GGNS internal events PRA

results for comparison with Regulatory Guide 1.174 acceptance guidelines. The

screening attributes of the fire PRA are summarized below.

4.3.1 Attributes of Fire PRA Fire PRAs are useful tools to identify design or procedural items that could be clear

areas of focus for improving the safety of the plant. Fire PRAs use a structure and

quantification technique similar to that used in the internal events PRA.

Historically, since less attention has been paid to fire PRAs, conservative modeling is

common in a number of areas of the fire analysis to provide a “bounding” methodology

for fires. This concept is contrary to the base internal events PRA which has had more

analytical development and is judged to be closer to a realistic assessment (i.e., not

conservative) of the plant.

There are a number of fire PRA topics involving technical inputs, data, and modeling

that prevent the effective comparison of the calculated core damage frequency figure of

merit between the internal events PRA and the fire PRA. These areas are identified as

follows:

Initiating Events: The frequency of fires and their severity are generally

conservatively overestimated. A revised NRC fire events database indicates the trend toward both lower frequency and less severe fires. This trend reflects the improved housekeeping, reduction in transient fire hazards, and other improved fire protection steps at nuclear utilities. In addition, it reflects conservative judgments regarding fire severity.


4-61

System Response: Fire protection measures such as sprinklers, CO2, and fire brigades may be given minimal (conservative) credit in their ability to limit the spread of a fire. Therefore, the severity of the fire and its impact on requirements is exacerbated.

In addition, cable routings are typically characterized

conservatively because of the lack of data regarding the routing of cables or the lack of the analytic modeling to represent the different routings. This leads to limited credit for balance of plant systems that are extremely important in CDF mitigation.

Sequences: Sequences may subsume a number of fire scenarios

to reduce the analytic burden. The subsuming of initiators and sequences is done to envelope those sequences included. This causes additional conservatism.

Fire Modeling: Fire damage and fire propagation are conservatively

characterized. Fire modeling presents bounding approaches regarding the fire immediate effects (e.g., all cables in a tray are always failed for a cable tray fire) and fire propagation.

HRA: There is little industry experience with crew actions

under conditions of the types of fires modeled in fire PRAs. This has led to conservative characterization of crew actions in fire PRAs. Because the CDF is strongly correlated with crew actions, this conservatism has a profound influence on the calculated fire PRA results.

Level of Detail: The fire PRAs may have a reduced level of detail in

the mitigation of the initiating event and consequential system damage.

Quality of Model: The peer review process for fire PRAs is less well

developed than for internal events PRAs. For example, no industry standard, such as NEI 00-02, exists for the structured peer review of a fire PRA. This may lead to less assurance of the realism of the model.


4-62

The fire PRA is subject to more modeling uncertainty than the internal events PRA

evaluations. While the fire PRA is generally self-consistent within its calculational

framework, the fire PRA calculated quantitative risk metric does not compare well with

internal events PRAs because of the number of conservatisms that have been included

in the fire PRA process. Therefore, the use of the fire PRA figure of merit as a reflection

of CDF may be inappropriate. Any use of fire PRA results and insights should properly

reflect consideration of the fact that the “state of the technology” in fire PRAs is less

evolved than the internal events PRA.

Relative modeling uncertainty is expected to narrow substantially in the future as more

experience is gained in the development and implementation of methods and

techniques for modeling fire accident progression and the underlying data.

Fire PRA risk is dominated by fire-induced equipment failures. As such, fire PRA results

are less impacted by changes in operator actions timings than the internal events PRA

results.

Grand Gulf has updated the fire PRA since the IPEEE, but not as recently as the internal

events PRA. The current GGNS fire PRA is based on Revision 2 of the Level 1 PRA and

the corresponding LERF model. The fire PRA model was rerun for this EPU risk

assessment using the same changes incorporated into the internal events PRA with the

knowledge that the results would not necessarily reflect the most up to date model of

the Grand Gulf plant.

The results of the changes to the GGNS fire PRA due to the reduced timings available

show a small increase (3%) in the fire CDF.


4-63

The impact of the EPU on the different aspects of fire risk modeling are assessed here

with the approach above, and based on knowledge of fire PRA and the modifications for

the EPU (e.g., no significant changes to fire protection systems, combustible loadings,

etc.). Based on this assessment, it is concluded that no unique or significant impacts on

fire risk result from the EPU.

4.4 SEISMIC RISK The Grand Gulf seismic risk analysis was performed as part of the Individual Plant

Examination of External Events (IPEEE) [10]. Given the Grand Gulf seismic design

basis and the comparably low seismic hazard at the site, NUREG-1407 (IPEEE

Submittal guidance) placed Grand Gulf in the Reduced Scope Review Level Earthquake

IPEEE seismic category. Grand Gulf performed a seismic margins assessment (SMA)

following the guidance of NUREG-1407 and EPRI NP-6041. The SMA is a deterministic

evaluation process that does not calculate risk on a probabilistic basis. No core

damage frequency sequences were quantified as part of the seismic risk evaluation.

Based on a review of the Grand Gulf IPEEE and the key general conclusions identified

earlier in this assessment, the conclusions of the SMA are judged to be unaffected by

the EPU. The EPU has little or no impact on the seismic qualifications of the systems,

structures and components (SSCs). Specifically, the power uprate results in additional

thermal energy stored in the RPV, but the additional blowdown loads on the RPV and

containment given a coincident seismic event, are judged not to alter the results of the

SMA.

The decrease in time available for operator actions, and the associated increases in

calculated HEPs, is judged to have a non-significant impact on seismic-induced risk.

Industry BWR seismic PRAs have typically shown (e.g., Peach Bottom NUREG-1150

study [18]; Limerick Generating Station Severe Accident Risk Assessment [19];

NUREG/CR-4448 [20]) that seismic risk is overwhelmingly dominated by seismic

induced equipment and structural failures.


4-64

Based on the above discussion it is judged that the percentage increase in the GGNS

seismic risk due to the EPU is much less than that calculated for internal events.

This seismic impact assessment did not involve re-performing the GGNS IPEEE SMA.

Similarly, SMA plant walkdowns were not re-performed in support of this assessment.

EPU equipment replacements are judged to be installed using anchorages that are similar

to the existing equipment anchorages. Based on this assessment, it is concluded that no

unique or significant impacts on seismic risk result from the EPU.

4.5 OTHER EXTERNAL EVENTS RISK In addition to internal fires and seismic events, the GGNS IPEEE Submittal analyzed a

variety of other external hazards:

• High Winds/Tornadoes

• External Floods

• Transportation and Nearby Facility Accidents

• Other External Hazards The GGNS IPEEE analysis of high winds, tornadoes, external floods, transportation

accidents, nearby facility accidents, and other external hazards was accomplished by

reviewing the plant environs against regulatory requirements regarding these hazards.

Based upon this review, it was concluded that GGNS meets the applicable NRC

Standard Review Plan requirements and therefore has an acceptably low risk with

respect to these hazards.

Note that internal flooding scenarios are analyzed as internal events and already are

included in the GGNS internal events at-power PRA used in this EPU risk assessment.


4-65

4.6 SHUTDOWN RISK The impact of the Extended Power Uprate (EPU) on shutdown risk is similar to the

impact on the at-power Level 1 PRA. Based on the insights of the at-power PRA impact

assessment, the areas of review appropriate to shutdown risk are the following:


• Success Criteria


• Outage schedule

• Shutdown management The following qualitative discussion applies to the shutdown conditions of Hot Shutdown

(Mode 3), Cold Shutdown (Mode 4), and Refueling (Mode 5). The EPU risk impact

during the transitional periods such as at-power (Mode 1) to Hot Shutdown and Startup

(Mode 2) to at-power is judged to be subsumed by the at-power Level 1 PRA. This is

consistent with the U.S. PRA industry, and with NRC Regulatory Guide 1.174 which

states that not all aspects of risk need to be addressed for every application. While

higher conditional risk states may be postulated during these transition periods, the

short time frames involved produce an insignificant impact on the long-term annualized

plant risk profile.

4.6.1 Shutdown Initiating Events Shutdown initiating events include the following major categories:

• Loss of RCS Inventory

− Inadvertent Draindown

− LOCAs

• Loss of Decay Heat Removal (includes LOOP)

No new initiating events or increased potential for initiating events during shutdown

(e.g., loss of DHR train) can be postulated due to the 113% EPU.


4-66

4.6.2 Shutdown Success Criteria The impact of the EPU on the success criteria during shutdown is similar to the Level 1

PRA. The increased power level decreases the time to boil down. However, because

the reactor is already shutdown, the boil down times are much longer compared to the

at-power PRA. Further discussion regarding boil down times is provided in Section

4.6.3 in the discussion of the impacts on shutdown operator action response times.

The increased decay heat loads associated with the EPU impacts the time when low

capacity decay heat removal (DHR) systems can be considered successful alternate

DHR systems. The EPU condition delays the time after shutdown when low capacity

DHR systems may be used as an alternative to Shutdown Cooling (SDC). However,

shutdown risk is dominated during the early time frame soon after shutdown when the

decay heat level is high and, in this time frame, low capacity DHR alternatives are

already not viable DHR systems.

Other success criteria are marginally impacted by the EPU. The EPU has a minor

impact on shutdown RPV inventory makeup during loss of decay heat removal

scenarios in shutdown because of the low decay heat level. The heat load to the

suppression pool during loss of decay heat removal scenarios in shutdown (i.e., during

shutdown phases with the RPV intact) is also lower because of the low decay heat level

such that the margins for suppression pool cooling capacity are adequate for the EPU

condition.

The EPU impact on the success criteria for blowdown loads, RPV overpressure margin,

and SRV actuation is estimated to be negligible because of the low RPV pressure and

low decay heat level during shutdown.

The EPU does not have a significant effect on the reliability or availability of equipment

used for shutdown conditions or contingency plans (e.g., re-establishing containment).


4-67

4.6.3 Shutdown HRA Impact Similar to the at-power Level 1 PRA, the decreased boil down time due to the EPU

decreases the time available for operator actions. The significant, time critical operator

actions impacted in the at-power Level 1 PRA are related to RPV depressurization, SLC

injection, and SLC level control. These operator actions do not directly apply to

shutdown conditions because the RPV is at low pressure and the reactor is subcritical.

The risk significant operator actions during shutdown conditions include recovering a

failed DHR system or initiating alternate DHR systems. However, the longer boil down

times during shutdown results in the EPU having a minor impact on the shutdown HEPs

associated with recovering or initiating DHR systems.

The calculations in Appendix B of this assessment show that the times available to

perform loss of decay heat removal response actions during shutdown is many hours.

The reductions in these times due to the EPU are shown in Appendix B to be in the

range of 10 to 15% (depending on time after shutdown and water level configuration).

Such small changes in already lengthy operator action response times result in

negligible changes in human error probabilities.

4.6.4 Shutdown Schedule Although boiling times are reduced as discussed above, the EPU has no significant

impact on the time to achieve shutdown conditions during a controlled shutdown or the

scheduling of an outage. The time to achieve shutdown conditions during a planned

and methodical shutdown for the EPU condition will not significantly increase compared

to the CLTP condition.

The planned shutdown time is an operational goal that is subject to a number of factors

(e.g., plant resources, equipment outage windows, etc.). The time to transition from

Power Operation, to Cold Shutdown, and then to Refuel is controlled by a shutdown

schedule. For the EPU condition, the scheduled time to reach Refuel would not

materially differ from pre-EPU shutdown schedules. At power, the reactor coolant will be


4-68

at the same temperature and pressure for the pre-EPU and the EPU condition. In either

case, the operators follow cooldown rates and have operational flexibility within those

cooldown rates to achieve scheduled shutdown milestones. For EPU, the operators

would increase shutdown cooling flow as necessary to achieve the same or similar

Refuel milestone as for the CLTP case.

4.6.5 Shutdown Management Procedural controls are in place to ensure the risk impacts of EPU on shutdown

operations are not significant. Shutdown Risk Management at GGNS is described in

the Entergy Nuclear Management Manual procedure EN-OU-108, Shutdown Safety

Management Program (SSMP). The SSMP uses the philosophy and recommendations

stated in NUMARC 91-06, "Guidelines for Industry Actions to Assess Shutdown

Management." The SSMP is also designed to meet the applicable requirements of the

Maintenance Rule pertaining to risk assessment [10 CFR 50.65(a)(4)] and NUMARC

93-01, “Industry Guidance for Monitoring the Effectiveness of Maintenance at Nuclear

Power Plants.”

A defense-in-depth strategy is implemented to enforce minimum equipment availability

for critical safety functions such as Decay Heat Removal, Inventory Control, Electrical

Power Availability, Reactivity Control, and Containment. Outage Risk Contingency

Plans are developed to mitigate reductions in shutdown safety margins or losses of

safety functions commensurate with the level of risk the activity poses. Outage Goals

include shutdown safety as a key outage success factor. Shutdown Safety Goals are

defined as no shutdown safety events or near misses, minimizing the number of times

plant conditions require risk to be elevated, minimizing the time spent in elevated risk,

and no preventable unplanned loss of key safety functions.

The shutdown cooling analysis for EPU determined that the time needed for cooling the

reactor to 125˚F during normal reactor shutdown is increased from 10.6 hours to

approximately 16.4 hours. The following decay heat removal defense-in-depth


4-69

considerations minimize the impact of this extended time: 1) Develop the outage

schedule such that several methods of decay heat removal are provided, including

primary, backup, and alternate methods; 2) Thoroughly evaluate the scheduling of

activities on components within or that directly support the decay heat removal system

for their effects on defense-in-depth, especially during reduced inventory conditions or

other higher risk evolutions; 3) Schedule activities that may impact the decay heat

removal systems/components during periods of low decay heat, high coolant inventory,

or defueled conditions. Develop contingency plans if activities that potentially impact

decay heat removal systems must be scheduled during periods of high decay heat or

reduced inventory; 4) Avoid scheduling work on components or systems needed for

decay heat removal or defense-in-depth; and 5) Develop the outage schedule in a

manner that ensures that spent fuel pool cooling is sufficient and defense-in-depth is

commensurate with the risk associated with losing spent fuel pool cooling.

4.6.6 Shutdown Risk Summary Based on a review of the potential impacts on initiating events, success criteria, and

HRA, the 113% EPU is assessed to have a non-significant impact (delta CDF of

approximately 2% per calculations in Appendix B) on shutdown risk.

This assessment is consistent with GE’s generic conclusions on this issue [15]:

“The shutdown risks for BWR plants are generally low and the impact of CPPU on the CDF and LERF during shutdown is expected to be negligible.”


4-70

4.7 RADIONUCLIDE RELEASE (LEVEL 2 PRA) The Level 2 PRA calculates the containment response under postulated severe

accident conditions and provides an assessment of the containment adequacy. In the

process of modeling severe accidents (i.e., the MAAP code), the complex plant

structure has been reduced to a simplified mathematical model which uses basic

thermal hydraulic principles and experimentally derived correlations to calculate the

radionuclide release timing and magnitude [9]. Changes in plant response due to EPU

represent relatively small changes to the overall challenge to containment under severe

accident conditions.

The following aspects of the Level 2 analysis are briefly discussed:

• Level 1 input

• Accident Progression


• Success Criteria

• Containment Capability

• Radionuclide Release Magnitude and Timing Level 1 Input The front-end evaluation (Level 1) involves the assessment of those scenarios that could

lead to core damage. The subsequent treatment of mitigative actions and the inter-

relationship with the containment after core damage is then treated in the Containment

Event Tree (Level 2).

In the Grand Gulf Level 1 PRA, accident sequences are postulated that lead to core

damage and potentially challenge containment. The Grand Gulf Level 1 PRA has

identified discrete accident sequences that contribute to the core damage frequency and

represent the spectrum of possible challenges to containment.


4-71

The Level 1 core damage sequences are also directly propagated through the Level 2

PRA containment event trees. Changes to the Level 1 PRA modeling directly impact the

Level 2 PRA results. However, the percentage increase in total CDF due to the EPU is

not a direct translation to the percentage increase in total LERF. For example, a change

to loss of decay heat removal or long-term SBO core damage accidents would not impact

the LERF results, as such accidents do not result in Level 2 LERF sequences.

Therefore, the Level 2 at-power internal events PRA model is also requantified as part of

this EPU risk assessment.

Accident Progression As discussed earlier in Section 4.1.3, the EPU does not change the plant configuration

and operation in a manner that produces new accident sequences or changes accident

sequence progression phenomenon. This is particularly true in the case of the Level 2

post-core damage accident progression phenomena. The minor changes in decay heat

levels and system configurations of the EPU will not impact significantly quantification

and modeling of post-core damage accident progression.

Therefore, no changes are made as part of this assessment to the Level 2 models

(either in structure or basic event phenomenon probabilities) with respect to accident

progression modeling.

Human Reliability Analysis Level 2 PRA operator actions that are significant contributors to LERF are recovery actions

that are assigned 1.0 HEPs (e.g., failure to restore AC power before vessel breach, failure

to depressurize the RPV post-core damage and prior to vessel breach, failure to recover

RPV injection prior to vessel breach). The EPU does not impact these human error

probabilities. The remaining Level 2 PRA actions are non-significant contributors to LERF

(e.g., manually close a containment isolation valve) and would not change the results or


4-72

conclusions of this study (refer to the HEP screening process discussed in Section 4.1.6

and Appendix D).

Success Criteria No changes in success criteria have been identified with regard to the Level 2

containment evaluation. The slight changes in accident progression timing and decay

heat load has a minor or negligible impact on Level 2 PRA safety functions, such as

containment isolation, ex-vessel debris coolability and challenges to the ultimate

containment strength. (Refer to Section 4.1.2.8 of this report). Therefore, no changes

to Level 2 modeling with respect to success criteria are made as part of this analysis.

Containment Capability As discussed in Section 4.1.7 earlier in this report, no issues have been identified with

respect to the EPU that have any impact on the capacity of the GGNS containment as

analyzed in the PRA.

The issues related to EPU impacts on containment challenges under severe accident

conditions (i.e., post core damage) are summarized below.

• Containment Isolation: Containment isolation is demanded early in an accident scenario before extreme containment conditions manifest. The EPU has no impact on the failure probabilities of containment isolation signals or containment isolation valves.

• Quasi-Static Pressure/Temperature Loading: Containment integrity is

challenged as the containment pressurizes and temperatures increase. Containment failure can occur in a variety of locations and due to different mechanisms (e.g., high temperature seal failure, structural failure, penetration failure, etc.). The increased decay heat load of the EPU has no impact on these containment loading profiles, the EPU only impacts the time required to reach the loading challenges. MAAP runs performed for the EPU show that the time to reach the containment ultimate failure point (as assessed in the PRA) is tens of hours for both the CLTP and EPU conditions. Changes in such lengthy timings have a negligible impact on


4-73

human error rates and thus a negligible impact on the calculated risk profile.

• Containment Dynamic Loading: These challenges include un-mitigated

ATWS, LOCA loads and energetic phenomena post core damage (see bullet below). Un-mitigated (inadequate level/power control, SLC failure) ATWS scenarios are modeled in the PRA as leading directly to a containment failure, this is a standard PRA modeling approach and is not changed due to the EPU. EPU LOCA dynamic loads on the containment have been calculated to be within safety and design limits.

• Energetic Phenomena: A variety of severe challenges to the containment

post core damage have been identified in the GGNS PRA and in industry studies and guidelines. These energetic phenomena may manifest at the time of the onset of core damage, the time of core slump into the lower RPV head, the time of RPV melt-through, or after core debris falls to the drywell floor. These energetic phenomena include (among others): in-vessel steam explosions, hydrogen deflagration, ex-vessel steam explosions and core-concrete interaction. The likelihood of each of these phenomena, and the required conditions, are based on industry generic studies and are not influenced by initial reactor power level. This is a standard PRA industry practice.

Release Magnitude and Timing The GGNS radionuclide release categories are based on accident sequence

characteristics (e.g., containment bypass, unscrubbed release pathway, etc.). The

GGNS plant changes for the EPU have no impact on the usage and appropriateness of

this release categorization scheme.

Level 2 (LERF) Impact Summary Based on the above discussion, the impact of the EPU on the GGNS Level 2 (LERF) PRA,

independent of the Level 1 analysis, is judged to be minor. As discussed previously, no

Level 2 PRA HEPs significant to LERF would change due to the EPU. The only change in

the LERF risk profile is due to changes in the Level 1 PRA models used as input to the

Level 2 quantification.


5-1

Section 5

CONCLUSIONS

The Extended Power Uprate (EPU) for Grand Gulf has been reviewed to determine the

net impact on the risk profile associated with Grand Gulf operation at an increase in

power level to 4408 MWt. This examination involved the identification and review of

plant and procedural changes, plus changes to the risk spectrum due to changes in the

plant response.

The change in plant response, procedures, hardware, and setpoints associated with the

increase in power have been investigated using the Grand Gulf Revision 3 Level 1 and

Level 2 PRA models (fault trees ggr3.caf and GGLERFR3.caf, respectively) [2, 9]; the

1995 GGNS IPEEE study for seismic, internal fires and other external events [10]; and a

qualitative evaluation of shutdown events.

This section summarizes the risk impacts of the EPU implementation on the following

areas:

• Level 1 Internal Events PRA

• Fire Induced Risk

• Seismic Induced Risk

• Internal Flooding Risk

• Shutdown Risk

• Level 2 PRA

The review has indicated that small perturbations on individual inputs could be

identified.

Guidelines from the NRC (Regulatory Guide 1.174) are followed to assess the change

in risk as characterized by core damage frequency (CDF) and Large Early Release

Frequency (LERF).


5-2

5.1 LEVEL 1 PRA Qualitative engineering insights regarding the adequacy of procedures and systems to

prevent postulated core damage scenarios are among the principal results of the Level

1 portion of the PRA. These insights deal with the adequacy of or improvements to,

Grand Gulf procedures or systems (frontline or support) to accomplish their safety

mission of preventing core damage. The severe accident scenarios that have been

identified in the Level 1 PRA have been reviewed and the relatively small perturbations

due to power uprate do not affect the scenario development or the qualitative insights.

Table 5.1-1 provides a summary of the PRA model changes incorporated as a result of

the power uprate evaluation. Table 5.1-1 provides the following information:

• Basic event identification and description

• Basic event probability in the current model

• Revised probability for EPU

No modeling structure changes to the GGNS PRA were necessary to reflect the EPU.

The SRV fault tree logic for RPV overpressure protection during an ATWS was not

changed, the probability was conservatively increased to account for the increase in

thermal energy due to the EPU. The relatively low probability of the scram system

prevents the basic event for failure of the SRVs to open during an ATWS to appear in

any cutsets.

The results of the Level 1 PRA quantification for the GGNS EPU condition are

summarized in Table 5.1-2 along side the CLTP GGNS PRA results as a function of

initiating event type. The EPU is estimated to increase the Grand Gulf internal events

PRA CDF from the base value of 2.68E-6/yr to 2.91E-6/yr, an increase of 2.3E-7

(8.6%). As can be seen from Table 5.1-2, the distribution of the EPU results remains

virtually unchanged (a percentage point or less increase or decrease) with respect to

the base GGNS PRA.


5-3

5.2 FIRE INDUCED RISK Based on the results of the internal events PRA evaluation for a 113% power uprate

and a review of the GGNS Fire PRA, it is concluded that the effects on any increase in

risk contribution associated with fire induced sequences is minor, estimated at a 3%

increase in fire CDF (refer to Section 4.3 of this report).

5.3 SEISMIC RISK Based on a review of the Grand Gulf IPEEE, the conclusions of the GGNS seismic

margins assessment (SMA) are judged to be unaffected by the EPU. The power uprate

has little or no impact on the seismic qualifications of the systems, structures and

components (SSCs). Specifically, the power uprate results in additional thermal energy

stored in the RPV, but the additional blowdown loads on the RPV and containment given

a coincident seismic event, are judged not to alter the results of the SMA. Refer to

Section 4.4 of this report for further discussion.

5.4 OTHER EXTERNAL HAZARDS Based on review of the Grand Gulf IPEEE, the power uprate has no significant impact

on the plant risk profile associated with tornadoes, external floods, transportation

accidents, and other external hazards. Refer to Section 4.5 of this report for further

discussion.


5-

4

Tab

le 5

.1-1

GG

NS

PR

A M

OD

EL

CH

AN

GE

S T

O R

ELE

CT

EP

U

PR

A E

lem

ent

Par

amet

er ID

Mod

el E

lem

ent D

escr

iptio

n G

GN

S C

LTP

P

RA

Val

ue

EP

U

Val

ue

E12

-FO

-HE

SD

C-O

F

AIL

UR

E T

O A

LIG

N R

HR

FO

R S

HU

TD

OW

N C

OO

LIN

G

1.0E

-05

1.4E

-05

(2)

Pos

t-In

itiat

or

HE

Ps

- In

depe

nden

t E

12-F

O-H

ES

PC

-M

FA

ILU

RE

TO

ST

AR

T S

UP

PR

ES

SIO

N P

OO

L C

OO

LIN

G

1.0E

-05

1.2E

-05

(2)

E

12-F

O-H

EV

3S-O

F

AIL

UR

E T

O A

LIG

N L

PC

I TH

RO

UG

H S

HU

TD

OW

N C

OO

LIN

G

LIN

ES

(A

TW

S)

1.7E

-01

2.6E

-01(2

)

E

51-F

O-H

EIS

OL8

-G

FA

ILU

RE

TO

MA

NU

ALL

Y IS

OLA

TE

RC

IC A

FT

ER

A L

EV

EL

8 S

IGN

AL

3.2E

-02

5.0E

-02(2

)

E

51-F

O-H

ET

RP

BY

P

OP

ER

AT

OR

FA

ILS

TO

BY

PA

SS

HIG

H T

EM

P IS

OLA

TIO

N

4.5E

-03

5.6E

-03

(2)

N

21-F

O-H

ELV

L9-I

F

AIL

TO

RE

ST

OR

E F

EE

DW

AT

ER

AF

TE

R L

EV

EL

9 T

RIP

3.

3E-0

3 5.

7E-0

3(2)

P

41-F

O-H

ES

WX

T-L

F

AIL

UR

E T

O A

LIG

N S

ER

VIC

E W

AT

ER

CR

OS

S-T

IE T

O R

HR

IN

JEC

TIO

N

8.9E

-02

1.3E

-01(2

)

P

64-F

O-H

E-G

F

AIL

UR

E T

O A

LIG

N F

PW

FO

R L

ON

G T

ER

M IN

JEC

TIO

N

5.7E

-01

6.7E

-01(2

)

R

21-F

O-H

EB

OP

TR

M

FA

ILU

RE

TO

ALI

GN

AL

TO

ER

NA

TE

PO

WE

R T

O 4

.16

KV

OR

6.9

KV

B

US

ES

4.

5E-0

4 8.

6E-0

4(2)

R

21-F

O-H

EE

SF

TR

M

OP

ER

AT

OR

FA

ILS

TO

TR

AN

SF

ER

TO

ALT

ER

NA

TE

T

RA

NS

FO

RM

ER

4.

5E-0

4 8.

6E-0

4(2)

X

3 F

AIL

UR

E T

O M

AN

UA

LLY

DE

PR

ES

SU

RIZ

E U

SIN

G R

CIC

8.

4E-0

3 1.

8E-0

2(2)

NR

S-A

LTP

W&

BO

T

FA

ILU

RE

TO

ALI

GN

ALT

ER

NA

TE

PO

WE

R A

ND

CO

NN

EC

T A

IR

BO

TT

LES

TO

SR

VS

1.

0E-0

6 1.

1E-0

6(5)

Pos

t-In

itiat

or

(HE

Ps)

-

Dep

ende

nt(1

) N

RS

-ALT

PW

&B

YP

F

AIL

UR

E T

O A

LIG

N A

LTE

RN

AT

E P

OW

ER

AN

D B

YP

AS

S R

CIC

T

EM

P T

RIP

S

2.0E

-06

4.8E

-06(5

)


5-

5

Tab

le 5

.1-1

GG

NS

PR

A M

OD

EL

CH

AN

GE

S T

O R

ELE

CT

EP

U

PR

A E

lem

ent

Par

amet

er ID

Mod

el E

lem

ent D

escr

iptio

n G

GN

S C

LTP

P

RA

Val

ue

EP

U

Val

ue

NR

S-A

LTP

WR

&F

PW

F

AIL

UR

E T

O A

LIG

N A

LTE

RN

AT

E P

OW

ER

AN

D A

LIG

N F

PW

5.

0E-0

6 9.

5E-0

6(5)

Pos

t-In

itiat

or

(HE

Ps)

-

Dep

ende

nt

(con

t’d)

NR

S-B

YP

&B

OT

F

AIL

UR

E T

O B

YP

AS

S R

CIC

TE

MP

ER

AT

UR

E T

RIP

S A

ND

C

ON

NE

CT

AIR

BO

TT

LES

TO

SR

VS

6.

0E-0

6 7.

4E-0

6(5)

N

RS

-BY

P&

CO

ND

F

AIL

UR

E T

O B

YP

AS

S R

CIC

TE

MP

ER

AT

UR

E T

RIP

S A

ND

ALI

GN

C

ON

DE

NS

AT

E IN

JEC

TIO

N

8.2E

-06

1.0E

-05(5

)

N

RS

-LS

S&

FW

S

FA

ILU

RE

TO

RE

SE

T L

SS

PA

NE

L A

ND

ALI

GN

FIR

E W

AT

ER

2.

9E-0

4 3.

4E-0

4(5)

N

RS

-PC

&R

C&

DE

P

FA

ILU

RE

TO

RE

ST

OR

E F

EE

DW

AT

ER

, TR

IP R

CIC

AN

D

DE

PR

ES

SU

RIZ

E

3.3E

-06

4.0E

-06(5

)

N

RS

-PC

S&

BY

P

FA

ILU

RE

TO

RE

ST

OR

E F

EE

DW

AT

ER

AN

D B

YP

AS

S R

CIC

TE

MP

T

RIP

S

4.5E

-05

4.6E

-05(5

)

N

RS

-PC

S&

CR

D

FA

ILU

RE

TO

RE

ST

OR

E F

EE

DW

AT

ER

AN

D S

TA

RT

CR

D

1.4E

-06

2.4E

-06(5

)

NR

S-P

CS

&R

C&

DE

P

FA

ILU

RE

TO

RE

ST

AR

T F

EE

DW

AT

ER

, TR

IP R

CIC

AN

D

DE

PR

ES

SU

RIZ

E

1.3E

-05

2.8E

-05(5

)

NR

S-P

CS

&R

CIC

F

AIL

UR

E T

O R

ES

TO

RE

FE

ED

WA

TE

R A

ND

TR

IP R

CIC

6.

6E-0

5 8.

1E-0

5(5)

N

RS

-PC

S&

RC

ICL8

F

AIL

UR

E T

O R

ES

TA

RT

FE

ED

WA

TE

R A

ND

TR

IP R

CIC

2.

6E-0

4 5.

6E-0

4(5)

N

RS

-PC

SL8

&B

YP

F

AIL

UR

E T

O R

ES

TO

RE

FE

ED

WA

TE

R A

ND

BY

PA

SS

RC

IC T

EM

P

TR

IPS

1.

8E-0

4 3.

1E-0

4(5)

N

RS

-PC

SL8

&C

ON

D

FA

ILU

RE

TO

RE

ST

OR

E F

EE

DW

AT

ER

AN

D A

LIG

N C

ON

DE

NS

AT

E

INJE

CT

ION

6.

0E-0

6 1.

0E-0

5(5)

N

RS

-PC

SL8

&D

EP

F

AIL

UR

E T

O R

ES

TO

RE

FE

ED

WA

TE

R A

ND

MA

NU

ALL

Y

DE

PR

ES

SU

RIZ

E

1.7E

-05

1.8E

-05(5

)


5-

6

Tab

le 5

.1-1

GG

NS

PR

A M

OD

EL

CH

AN

GE

S T

O R

ELE

CT

EP

U

PR

A E

lem

ent

Par

amet

er ID

Mod

el E

lem

ent D

escr

iptio

n G

GN

S C

LTP

P

RA

Val

ue

EP

U

Val

ue

NR

S-R

CIC

L8&

DE

P

FA

ILU

RE

TO

TR

IP R

CIC

ON

LE

VE

L 8

SIG

NA

L A

ND

MA

NU

ALL

Y

DE

PR

ES

SU

RIZ

E

1.0E

-05

1.6E

-05(5

) P

ost-

Initi

ator

(H

EP

s) -

D

epen

dent

(c

ont’d

) N

RS

-Y47

&B

YP

F

AIL

UR

E O

F S

SW

VE

NT

ILA

TIO

N A

ND

MA

NU

AL

DE

PR

ES

SU

RIZ

E

1.7E

-06

2.1E

-06(5

)

N

RS

-Y47

&F

PW

F

AIL

UR

E O

F S

SW

VE

NT

ILA

TIO

N A

ND

ALI

GN

FP

W

2.2E

-04

2.6E

-04

(5)

Rec

over

y T

erm

s N

RC

-DG

HW

10&

FW

F

AIL

UR

E T

O R

EC

OV

ER

DG

HA

RD

WA

RE

FA

ILU

RE

OR

ST

AR

T F

W

IN 1

0 H

OU

RS

2.

85E

-01

3.35

E-0

1(2)

N

RC

-OS

P-C

NT

F

AIL

TO

RE

CO

VE

R O

SP

GIV

EN

LO

NG

TE

RM

CO

NT

AIN

ME

NT

F

AIL

UR

E

1.21

E-0

2 3.

09E

-02(2

)

N

RC

-OS

P-D

LG0

FA

IL T

O R

EC

OV

ER

OS

P G

IVE

N 0

FT

R *

NO

SS

W P

HV

FA

ILU

RE

S

1.28

E-0

1 1.

59E

-01(2

)

N

RC

-OS

P-D

SG

0 F

AIL

TO

RE

CO

VE

R O

SP

GIV

EN

U2

* 0

FT

R *

NO

SS

W P

HV

F

AIL

UR

ES

6.

18E

-01

6.59

E-0

1(2)

N

RC

-OS

P-D

SG

0SS

W0

FA

IL T

O R

EC

OV

ER

OS

P G

IVE

N U

2 *

0 F

TR

* 1

OR

2 S

SW

PH

V

FT

S

2.62

E-0

1 2.

80E

-01(2

)

N

RC

-OS

P-D

SG

1 F

AIL

TO

RE

CO

VE

R O

SP

GIV

EN

U2

* 1

FT

R *

NO

SS

W P

HV

F

AIL

UR

ES

1.

05E

-01

1.11

E-0

1(2)

N

RC

-OS

P-D

SG

2 F

AIL

TO

RE

CO

VE

R O

SP

GIV

EN

U2

* 2

FT

R *

NO

SS

W P

HV

F

AIL

UR

ES

4.

53E

-02

4.77

E-0

2(2)

N

RC

-OS

P-P

SG

0 F

AIL

TO

RE

CO

VE

R O

SP

GIV

EN

SR

V L

OC

A *

U2

* 0

FT

R *

NO

S

SW

PH

V F

AIL

UR

ES

7.

63E

-01

7.82

E-0

1(2)


5-

7

Tab

le 5

.1-1

GG

NS

PR

A M

OD

EL

CH

AN

GE

S T

O R

ELE

CT

EP

U

PR

A E

lem

ent

Par

amet

er ID

Mod

el E

lem

ent D

escr

iptio

n G

GN

S C

LTP

P

RA

Val

ue

EP

U

Val

ue

LER

F R

ecov

ery

Ter

ms

NR

C-O

SP

-DS

G0-

L2

Fai

l to

Rec

over

OS

P G

iven

U2

* 0

FT

R *

No

SS

W P

HV

Fai

lure

s LE

RF

2.

92E

-01

3.11

E-0

1

N

RC

-OS

P-D

SG

0S0L

2 F

ail t

o R

ecov

er O

SP

Giv

en U

2 *0

FT

R *

1 o

r 2

SS

W P

HV

FT

S L

ER

F

1.64

E-0

1 1.

75E

-01

N

RC

-OS

P-D

SG

1-L2

F

ail t

o R

ecov

er O

SP

Giv

en U

2 *

1 F

TR

*N

o S

SW

PH

V F

ailu

res

LER

F

6.47

E-0

2 6.

84E

-02

N

RC

-OS

P-D

SG

2-L2

F

ail t

o R

ecov

er O

SP

Giv

en U

2 *

2 F

TR

*N

o S

SW

PH

V F

ailu

res

LER

F

3.00

E-0

2 3.

16E

-02

N

RC

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P-P

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0-L2

F

ail t

o R

ecov

er O

SP

Giv

en S

RV

LO

CA

*U

2 *0

FT

R *

No

SS

W P

HV

F

ailu

res

LER

F

3.28

E-0

1 3.

36E

-01

P1

O

NE

ST

UC

K-O

PE

N R

ELI

EF

VA

LVE

1.

13E

-2

1.

28E

-2(3

)

SO

RV

P

roba

bilit

y

P2

TW

O O

R M

OR

E S

TU

CK

-OP

EN

RE

LIE

F V

ALV

ES

1.

52E

-3

1.

72E

-3(3

)

M

8 O

R M

OR

E O

F 2

0 S

RV

S F

AIL

TO

OP

EN

DU

RIN

G A

TW

S

1.0E

-08

N/A

(4)

RP

V

Ove

rpre

ssur

e P

rote

ctio

n fo

r A

TW

S

M

6 O

R M

OR

E O

F 2

0 S

RV

S F

AIL

TO

OP

EN

DU

RIN

G A

TW

S

N/A

(4)

1.0E

-07


5-8

Notes to Table 5.1-1: (1) Dependent operator actions with HEPs that remain below the GGNS PRA 1.0E-6 HEP minimum

value threshold remain at 1.0E-6 in the PRA model and are not changed for the EPU quantification. The dependent HEPs below 1.0E-6 are not listed in this table.

(2) Refer to Table 4.1-11. (3) Refer to Section 4.1.2.6. (4) Basic event M, “8 OR MORE OF 20 SRVS FAIL TO OPEN DURING ATWS”, is revised to “6 OR

MORE OF 20 SRVS FAIL TO OPEN DURING ATWS” to reflect the change in success criteria for the EPU requirement of 15 of 20 SRVs (The CLTP requires 13 of 20). The CLTP-based probability was calculated by extrapolating the INEEL CCF Analyses common cause failure of smaller groups. The CLTP-based probability is conservatively increased from 1.0E-08 to 1.0E-07 to reflect the increase in thermal energy due to the EPU.

(5) Dependent HEPs affected by the change in the independent HEP probabilities identified in Table 4.1-

11 are also revised for the EPU risk assessment using the same methodologies used in the GGNS CLTP PRA. [26]


5-9

Table 5.1-2

GGNS CLTP CDF VS EPU CDF AS A FUNCTION OF INITIATING EVENT TYPE

Percentage of CDF

Initiating Event Type GGNS CLTP EPU

LOOP 38.6% 39.5%

PCS Available Transient 20.9% 20.5%

Loss of PCS 12.9% 12.4%

Loss of AC or DC Bus or Transformer

9.2% 9.8%

Loss of Feedwater 8.6% 8.1%

Loss of Instrument Air 4.7% 4.6%

LOCAs 4.4% 4.2%

Flooding 0.1% 0.1%

Others 0.8% 0.8%

TOTAL CDF: 2.68E-06 2.91E-06


5-10

5.5 SHUTDOWN RISK As in the at-power PRA, shutdown risk is affected by the EPU increase in decay heat

power. However, the lower power operating conditions during shutdown (e.g., lower

decay heat level, lower RPV pressure) allow for additional margin for mitigation systems

and operator actions. Based on a review of the potential impacts on initiating events,

success criteria, and HRA, the EPU implementation is judged to have a minor impact

(delta CDF ~2%) on shutdown risk. Refer to Section 4.6 and Appendix B of this report

for further discussion.

5.6 LEVEL 2 PRA The Level 2 PRA calculates the containment response under postulated severe

accident conditions and provides an assessment of the containment adequacy. The

EPU change in power represents a relatively small change to the overall challenge to

containment under severe accident conditions (refer to Section 4.7 for further

discussion).

The EPU is estimated to increase the Grand Gulf at-power internal events LERF from

the base value of 1.44E-7/yr to 1.48E-7/yr, an increase of 4.3E-9/yr (3%).


5-11

5.7 QUANTITATIVE BOUNDS ON RISK CHANGE 5.7.1 Sensitivity Studies As discussed in the previous sections, the best estimate change in the GGNS risk profile

due to the EPU is a 8.6% increase in CDF and a 4.8% increase in LERF. One of the

methods to provide valuable input into the decision-making process is to perform

sensitivity calculations for situations with different assumed conditions to bound the

results.

These sensitivity studies investigate the impact on the at-power internal events CDF

and LERF. As the change in CDF and LERF is minor, only conservative sensitivity

cases (i.e., those that will increase the calculated risk increases) are analyzed here.

Six (6) quantitative sensitivity cases are performed and discussed below.

Sensitivity #1 This sensitivity increases the PCS Available Transient initiator frequency to bound the

various changes to the BOP side of the plant (e.g., main turbine modifications). The

revision to the PCS Available Transient frequency uses an approach that assumes an

additional turbine trip is experienced in the first year following start-up in the EPU

condition and an additional 0.5 event in the second year. The change in the long-term

average of the PCS Available Transient (%T3A) frequency is calculated as follows for

this sensitivity case:

• Base long-term PCS Available Transient frequency is 7.98E-1/Rx-yr or 7.43E-1/yr

• 10 years is used as the “long-term” data period

• End of 10 years does not reach the end-of-life portion of the bathtub curve


5-12

• Revised PCS Available Transient frequency for this sensitivity case is calculated as:

(10 x 0.743) + 1.0 + 0.5 = 0.893/yr or 9.59E-1/Rx-yr(1)

10

All other parameters are maintained the same as the EPU base case. The model

changes made for this sensitivity case are summarized in Table 5.7-1.

Sensitivity #2 This sensitivity case conservatively assumes that the potential impact on transient

initiator frequencies is manifested in the MSIV Closure initiator frequency and not the

Turbine Trip frequency. The GGNS base MSIV Closure initiator frequency (%T2M) of

2.01E-1/Rx-yr or 1.87E-1/yr is revised in this sensitivity case in the same manner as

that discussed in Sensitivity Case #1:

(10 x 1.87E-1) + 1 + 0.5 = 3.37E-1/yr or 3.62E-1/Rx-yr(1)

10 All other parameters are maintained the same as the EPU base case. The model

changes made for this sensitivity case are summarized in Table 5.7-1.

Sensitivity #3 The EPU base quantification does not modify the DBA LOCA frequency.

Acknowledging that the increased flow rates of the EPU can result in increased piping

erosion/corrosion rates, this sensitivity case conservatively doubles the Large LOCA

initiator (%A) frequency. All other parameters are maintained the same as the EPU

(1) The GGNS PRA is quantified in units of per reactor-year, and assumes 100% plant availability; as

such, the initiator frequencies in the PRA are in units of per reactor-year as well. The GGNS average unavailability of 93.1% (based on years 2001-2005) is used to convert from a calendar-year estimate in this sensitivity case to a reactor-year basis.


5-13

base case. The model changes made for this sensitivity case are summarized in Table

5.7-1.

Sensitivity #4 This sensitivity case combines the changes of Sensitivity Case #1 with the changes of

Sensitivity Case #3. All other parameters are maintained the same as the EPU base

case. The model changes made for this sensitivity case are summarized in Table

5.7-1.

Sensitivity #5 This sensitivity case combines the changes of Sensitivity Case #2 with the changes of

Sensitivity Case #3. All other parameters are maintained the same as the EPU base

case. The model changes made for this sensitivity case are summarized in Table 5.7-1.

Sensitivity #6 The base analysis uses MAAP runs of the CLTP and EPU conditions to estimate

changes in the operator action timing windows (refer to Table 4.1-11). This sensitivity

changes the base approach and estimates the decreases in operator action time

windows by reducing the time available by 13% (reflective of the percentage power

uprate) for al HEPs in Table 4.1-11 that are affected by core power (the other HEPs

remain at the CLTP PRA base values). The model changes made for this sensitivity

case are summarized in Table 5.7-1.

5.7.1.2 Sensitivity Results The results of the six (6) sensitivity cases performed in support of this risk assessment

are summarized in Table 5.7-1.


5-14

Sensitivity #1

Increasing the PCS Available initiating event frequency results in delta risk results of

3.5E-7 and 1.2E-8 for CDF and LERF, respectively. Both of these results remain within

RG-1.174 Region III.

Sensitivity #2 Increasing the MSIV Closure initiating event frequency results in delta risk results of



Sensitivity #3 Doubling the initiating event frequency for Large LOCAs results in delta risk results of



Sensitivity #4 Combining the changes from Sensitivity Cases #1 and #3 results in delta risk results of



Sensitivity #5 The changes of Sensitivity Cases #2 and #3 result in delta risk results of 4.2E-7 and

1.6E-8 for CDF and LERF, respectively. Both of these results remain within RG-1.174

Region III.

Sensitivity #6 Reducing the HEP time windows by a constant factor equal to the power uprate of 13%

instead of accident specific calculations (e.g. MAAP runs) results in delta risk results of


5-15



5.7.2 Results Summary The key result of the PRA evaluation is the following:

Minor risk increases were calculated for both CDF and LERF. The risk increase is primarily associated with reduced times available for certain operator actions.

The best estimate of the risk increase for at-power internal events due to the EPU at

Grand Gulf is a delta CDF of 2.3E-7/yr (an increase of 8.6% over the base CLTP CDF

of 2.68E-6/yr). The best estimate at-power internal events LERF increase due to the

EPU is a delta LERF of 4.3E-9/yr (an increase of 3% over the base CLTP LERF of

1.44E-7/yr).

Using the NRC guidelines established in Regulatory Guide 1.174 and the calculated

results from the Level 1 and 2 PRA, the best estimate for the CDF risk increase

(2.3E-7/yr) and the best estimate for the LERF increase (4.3E-9/yr) are both within

Region III (i.e., changes that represent very small risk changes of RG-1.174) (refer to

Figures 5.7-1 and 5.7-2).

The quantitative sensitivity cases performed in this analysis show that both the delta

CDF and the delta LERF remain within RG-1.174 Region III for all six (6) of the cases.

Based on these results, the proposed GGNS 113% Extended Power Uprate is

acceptable on a risk basis without the requirement for special compensatory measures.


5-16

Table 5.7-1

RESULTS OF GGNS EPU PRA SENSITIVITY CASES

Parameter ID

GGNS CLTP PRA

GGNS EPU Base

Case Sensitivity Case #1

Sensitivity Case #2

Sensitivity Case #3

Sensitivity Case #4

Sensitivity Case #5

Sensitivity Case #6

Post-Initiator HEPs Base CLTP

Values EPU Values (Tbl 4.1-11)

EPU Values (Tbl 4.1-11)





13% Time(1) Decrease

PCS Available IE Base CLTP (7.98E-1)

Base CLTP (7.98E-1) 9.59E-1

Base CLTP Value

Base CLTP Value 9.59E-1

Base CLTP Value

Base CLTP Value

MSIV Closure IE Base CLTP (2.01E-1)

Base CLTP (2.01E-1)


Base CLTP Value


Base CLTP Value

LLOCA IE Base CLTP (3.19E-5)

Base CLTP (3.19E-5)

Base CLTP Value

Base CLTP Value 6.38E-5 6.38E-5 6.38E-5

Base CLTP Value

CDF: 2.68E-06 2.91E-06 3.03E-06 3.00E-06 3.01E-06 3.13E-06 3.10E-06 2.98E-06

delta CDF: - 2.3E-07 3.5E-07 3.2E-07 3.3E-07 4.5E-07 4.2E-07 3.0E-07

LERF: 1.44E-07 1.48E-7 1.56E-07 1.56E-07 1.52E-07 1.61E-07 1.60E-07 1.45E-07

delta LERF: - 4.3E-09 1.2E-08 1.2E-08 8.0E-09 1.7E-08 1.6E-08 1.8E-09


5-17

Notes to Table 5.7-1: (1) HEP changes for Sensitivity Case #6:

Allowable Action Time HEP

Name Current PRA Power (CLTP)

EPU Sensitivity #6

Current PRA Power (CLTP)

EPU Sensitivity #6

B21-FO-HEDEP2-I 45 min 39.0 3.20E-04 3.20E-04

B21-FO-HEDEP2-L 240 min(1c) 208.8 1.20E-05 1.20E-05

C41-FO-HE1PMP-S 15 min 13.1 5.40E-04 5.40E-04

E12-FO-HESDC-O 360 min 313.2 1.00E-05 1.40E-05

E12-FO-HESPC-M 420 min 365.4 1.00E-05 1.00E-05

E12-FO-HEV3S-O 15 min 13.1 1.70E-01 2.50E-01

E22-FO-DFEATHPCS 20 min 17.4 1.60E-03 1.60E-03

E51-FO-HEISOL8-G 12 min 10.5 min 3.20E-02 5.00E-02

E51-FO-HETRPBYP 50 min 43.5 4.50E-03 5.60E-03

INHIBIT 765 sec 665.6 2.50E-04 2.50E-04

M41-FO-AVVCNT-Q 600 min 522.0 1.5E-05 1.5E-05

N11-FO-HEMODSW-G 15 min 13.1 2.50E-04 2.50E-04

N21-FO-HELVL9-I (ATWS) 30 min 26.1 2.10E-03 2.10E-03

N21-FO-HELVL9-I (Trans) 22 min 19.1 3.30E-03 5.70E-03

N21-FO-HEPCS-G (ATWS) 15 min 13.1 8.30E-04 8.30E-04

N21-FO-HEPCS-G (Transient) 15 min 13.1 8.30E-04 8.30E-04

NR-ACHWR-8HRS 8 hr 8 hr 1.00E-02 1.00E-02

NRC-DG-CF1HRS 1 hr 52 min 9.00E-01 9.00E-01

NRC-DGHW10&FW 10 hr 8.7 2.85E-01 4.45E-01

NRC-DG-HW1HR 1 hr 52 min 9.00E-01 9.00E-01

NRC-DG-MA-1HR 1 hr 52 min 9.00E-01 9.00E-01

NRC-OSP-CNT 20hr 16.6hr 1.21E-02 3.09E-02

NRC-OSP-DLG0 Note (1a) Note (1a) 1.28E-01 1.59E-01

NRC-OSP-DSG0 Note (1a) Note (1a) 6.18E-01 6.59E-01

NRC-OSP-DSG0SSW0 Note (1a) Note (1a) 2.62E-01 2.80E-01



NRC-OSP-PSG0 Note (1a) Note (1a) 7.63E-01 7.82E-01

NR-PCS-60MN 60 min 52 min 6.00E-01 6.00E-01

P41-FO-HESWXT-G (LOCA) 20 min 17.4 8.90E-02 1.30E-01

P51-FO-CMSTART-T 60 min 52.2 4.60E-04 4.60E-04

P64-FO-HE-G 150 min 130.5 5.70E-01 8.90E-01

P64-FO-HE-G (Long Term) 480 min 417.6 1.10E-02 1.10E-02

R21-FO-HEBOPTRM 60 min 52.2 4.50E-04 6.80E-04


5-18

Allowable Action Time HEP

Name Current PRA Power (CLTP)

EPU Sensitivity #6

Current PRA Power (CLTP)

EPU Sensitivity #6

R21-FO-HEESFTRM 60 min 52.2 4.50E-04 6.80E-04

X2-ATWS 20 min 17.4 1.00E-03 1.00E-03

X3 90 min 78.3 8.40E-03 1.50E-02

NRS-ALTPW&BOT Note (1b) Note (1b) 6.00E-07 9.00E-07

NRS-ALTPW&BYP Note (1b) Note (1b) 2.00E-06 3.80E-06

NRS-ALTPW&DEP Note (1b) Note (1b) 1.50E-07 2.20E-07

NRS-ALTPWR&FPW Note (1b) Note (1b) 5.00E-06 7.50E-06

NRS-ALTPW&Y47 Note (1b) Note (1b) 1.70E-07 2.60E-07

NRS-BYP&BOT Note (1b) Note (1b) 6.00E-06 7.40E-06

NRS-BYP&COND Note (1b) Note (1b) 8.20E-06 1.00E-05

NRS-DHRLT Note (1b) Note (1b) 1.30E-10 1.30E-10

NRS-LSS&FWS Note (1b) Note (1b) 2.90E-04 4.60E-04

NRS-PCS-BYP Note (1b) Note (1b) 4.50E-05 4.60E-05

NRS-PCS&CRD Note (1b) Note (1b) 1.40E-06 2.40E-06

NRS-PCS&RC&DEP Note (1b) Note (1b) 1.30E-05 2.80E-05

NRS-PCS&CS Note (1b) Note (1b) 4.20E-08 7.60E-08 NRS-PCS&RCICL8 Note (1b) Note (1b) 2.60E-04 5.60E-04 NRS-PCSL8&BYP Note (1b) Note (1b) 1.80E-04 3.10E-04 NRS-PCSL8&COND Note (1b) Note (1b) 6.00E-06 1.00E-05 NRS-PCSL8&DEP Note (1b) Note (1b) 1.70E-05 1.80E-05 NRS-PCSL8&HPCS Note (1b) Note (1b) 8.00E-05 8.00E-05 NRS-SPC&DEP Note (1b) Note (1b) 5.00E-07 5.00E-07 NRS-Y47&BYP Note (1b) Note (1b) 1.70E-06 2.10E-06 NRS-Y47&FPW Note (1b) Note (1b) 2.20E-04 3.40E-04

Notes: (1a): These AC convolution terms adjusted in same manner as that shown in Table 4.1-11. (1b): Dependent HEPs adjusted using the same methodologies used in the GGNS CLTP PRA. [26]. (1c): The system time window was changed for the base HEP to 90 mins and the manipulation

time was modified to 4 mins. These changes were determined to be a better representation of the accident scenario. Neither of these changes affects the probability in the base CLTP PRA or base EPU PRA models. A change of 13% in allowable time was applied to the time window of 90 mins reducing it to 78 mins. The probability remains unchanged for this sensitivity case.


5-19

Region I - No Changes Allowed

Region II - Small Changes - Track Cumulative Impacts

Region III - Very Small Changes - More Flexibility with Respect to Baseline CDF - Track Cumulative Impacts

REGION I

REGION II

REGION III

10-6

10-5

CD

F

10-5 10-4CDF

Figure 5.7-1 GGNS EPU Risk Assessment CDF Result Versus RG 1.174 Acceptance Guidelines* for Core Damage Frequency (CDF)

* The analysis will be subject to increased technical review and management attention as indicated by the darkness of the shading of the figure. In the context of the integrated decision-making, the boundaries between regions should not be interpreted as being definitive; the numerical values associated with defining the regions in the figure are to be interpreted as indicative values only.


5-20

Region I- No Changes Allowed

Region II- Small Changes- Track Cumulative Impacts

Region III- Very Small Changes- More Flexibility with Respect

to Baseline LERF- Track Cumulative Impacts

REGION I

REGION II

REGION III

10-7

10-6

LE

RF

10-6 10-5LERF

Figure 5.7-2 GGNS EPU Risk Assessment LERF Result Versus RG 1.174Acceptance Guidelines* for Large Early Release Frequency (LERF)

* The analysis will be subject to increased technical review and management attention asindicated by the darkness of the shading of the figure. In the context of the integrated decision-making, the boundaries between regions should not be interpreted as being definitive; thenumerical values associated with defining the regions in the figure are to be interpreted asindicative values only.

10-4

Region I- No Changes Allowed

Region II- Small Changes- Track Cumulative Impacts

Region III- Very Small Changes- More Flexibility with Respect

to Baseline LERF- Track Cumulative Impacts

REGION I

REGION II

REGION III

10-7

10-6

LE

RF

Upper bound estimate of LERF change for power uprate


R-1 C247090004-9013-07/09/10

REFERENCES

[1] Grand Gulf Nuclear Station, “Grand Gulf Nuclear Station Individual Plant

Examination (IPE) Submittal”, December 1992. [2] Grand Gulf Nuclear Station, “GGNS Level-1 Revision 3 PSA Summary Report”,

PRA-GG-01-001, Rev. 0. [3] Idaho National Engineering and Environmental Laboratory, Rates of Initiating

Events at U.S. Nuclear Power Plants: 1987-1995, NUREG/CR-5750, February 1999.

[4] NEI, PRA Peer Review Guidelines, NEI 00-02, Rev. A3, 3/20/2000. [5] Professional Loss Control, Inc., Fire-Induced Vulnerability Evaluation (FIVE),

EPRI TR-100370, April 1992. [6] Letter from W.H. Rasin (NUMARC) to NUMARC Administrative Points of

Contact, “Revision 1 to EPRI Final Report dated April 1992, TR-100370, ‘Fire Induced Vulnerability Evaluation Methodology’ “, September 29, 1993.

[7] Science Applications International Corporation, Fire PRA Implementation Guide,

EPRI TR-105928, Final Report, 1995. [8] Grand Gulf Nuclear Station, “GGNS At Power Level 1 Accident Sequence

Analysis,” PRA-GG-01-001S01, Rev 0, February 2007. [9] Grand Gulf Nuclear Station, “GGNS PRA LERF Model,” PRA-GG-01-001S12,

Rev. 1. [10] Grand Gulf Nuclear Station, “Grand Gulf Nuclear Station Individual Plant

Examination for External Events (IPEEE) Submittal”, November 1995. [11] U.S. Nuclear Regulatory Commission, “Individual Plant Examination of External

Events (IPEEE) for Severe Accident Vulnerabilities - 10CFR50.54(f)”, Generic Letter 88-20, Supplement 4, June 28, 1991.

[12] U.S. Nuclear Regulatory Commission, Procedural and Submittal Guidance for

the Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities, NUREG-1407, June 1991.

[13] General Electric, Generic Guidelines for General Electric Boiling Water Reactor

Extended Power Uprate, NEDC-32424P-A, February 1999.


R-2 C247090004-9013-07/09/10

[14] General Electric, Generic Evaluations for General Electric Boiling Water Reactor Extended Power Uprate, NEDC-32523P-A, February 2000.

[15] General Electric, Licensing Topical Report; Constant Pressure Power Uprate,

NEDC-33004P-A, Rev. 4, July 2003. [16] U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation

Review Standard for Extended Power Uprates, RS-001, Draft, December 2002. [17] U.S. Nuclear Regulatory, Individual Plant Examination Program: Perspectives on

Reactor Safety and Plant Performance, Parts 2-5, Vol. 2, NUREG-1560, December 1997.

[18] Sandia National Laboratories, Analysis of Core Damage Frequency: Peach

Bottom, Unit 2 External Events, NUREG/CR-4550, Vol. 4, Rev. 1, Part 3, December 1990.

[19] Philadelphia Electric Company, Limerick Generating Station Severe Accident

Risk Assessment, April 1983. [20] Sandia National Laboratories, Shutdown Decay Heat Removal Analysis, GE

BWR3/Mark I Case Study, NUREG/CR-4448, December 1986. [21] EPRI, PSA Applications Guide, EPRI TR-105396, Final Report, August 1995. [22] Grand Gulf Nuclear Station, “GGNS Loss of Offsite Power Work Package,”

PRA-GG-01-001S09, Rev 0, November 2006. [23] Grand Gulf Nuclear Station, “Grand Gulf Human Reliability Analysis/Rule

Recovery Work Package,” PRA-GG-01-001S03, Rev. 0, December 2007. [24] Grand Gulf Nuclear Station, “GGNS Common Cause Failure Calculation,”

PRA-GG-01-001S04, Rev 0, February 2007. [25] Grand Gulf Nuclear Station, “GGNS PSA At-Power Level 1 Initiating Events Data

Analysis,” PRA-GG-01-001S06, Rev 0, November 2006. [26] ERIN letter to A.P. Pittman (Entergy), “Transmittal of HEP XLS files for Grand

Gulf EPU Risk Assessment”, C247090004-9311, May 12, 2010. [27] EPRI, MAAP Users Group News Bulletin, “Under-Prediction of Break Flow for

BWR Small LOCAs with Injection”, MAAP-FLAASH #69, November 10, 2009. [28] EPRI, MAAP Users Group News Bulletin, “BWR HPCI/RCIC Turbine Gas

Exhaust Enthalpy is Not Set”, MAAP-FLAASH #70, November 10, 2009.


R-3 C247090004-9013-07/09/10


Appendix A

TRUNCATION STUDY RESULTS


A-1

Appendix A

TRUNCATION STUDY RESULTS

Convergence

The PRA model is subject to a number of approximations. One of these approximations

is because the cutsets generated by the Boolean logic are truncated during the

quantification process. This truncation limit is established due to both computational

time and computer storage capacity limitations. In order to determine a reasonable

truncation limit to provide an appropriate risk metric calculation, a truncation study is

performed to assess the model convergence as a function of the truncation limit

imposed on retained cutsets.

Pre-EPU CDF Truncation Study As part of the review of the Grand Gulf model a truncation study was performed to

assess the adequacy of the truncation level chosen for the Level 1 PRA model.

The truncation study was performed with the Level 1 result cutsets (GGR3a 1E-12

baseline.cut). Table A.1-1 summaries the CDF results based on various truncation

values. Figure A.1-1 shows this data in graphical form.

Pre-EPU LERF Truncation Study As part of the review of the Grand Gulf model a truncation study was performed to

assess the adequacy of the truncation level chosen for the LERF PRA model.

The truncation study was performed with the LERF result cutsets (GGR3a 1E-12

baseline.cut). Table A.1-2 summaries the CDF results based on various truncation

values. Figure A.1-2 shows this data in graphical form.


A-2

Post-EPU CDF Truncation Study A truncation study was performed on the Level 1 EPU model to confirm that the chosen

truncation limit was still adequate and no risk significant cutsets were being lost.

The truncation study was performed with the Level 1 EPU result cutsets. Table A.1-3

summaries the CDF results based on various truncation values. Figure A.1-3 shows

this data in graphical form.

Post-EPU LERF Truncation Study A truncation study was performed on the LERF EPU model to confirm that the chosen

truncation limit was still adequate and no risk significant cutsets were being lost.

The truncation study was performed with the LERF EPU result cutsets. Table A.1-3

summaries the CDF results based on various truncation values. Figure A.1-3 shows

this data in graphical form.


A-3

0.00

E+00

5.00

E‐07

1.00

E‐06

1.50

E‐06

2.00

E‐06

2.50

E‐06

3.00

E‐06

1.0E

‐08

1.0E

‐09

1.0E

‐10

1.0E

‐11

1.0E

‐12

1.0E

‐13

Trun

cation

CDF (/RX‐yr)

Fig

ure

A.1

-1 T

runc

atio

n Li

mit

for

Pre

-EP

U C

DF


A-4

0.00

E+00

2.00

E‐08

4.00

E‐08

6.00

E‐08

8.00

E‐08

1.00

E‐07

1.20

E‐07

1.40

E‐07

1.60

E‐07

1.0E

‐09

1.0E

‐10

1.0E

‐11

1.0E

‐12

1.0E

‐13

Trun

cation

LERF (Rx‐yr)

Fig

ure

A.1

-2 T

runc

atio

n Li

mit

for

Pre

-EP

U L

ER

F


A-5

Table A.1-1

GRAND GULF PRE-EPU LEVEL 1 TRUNCATION LIMIT EVALUATION

Internal Events and Flooding Only

Truncation CDF % Change

1.00E-08 6.91E-07 -

1.00E-09 1.52E-06 120.68%

1.00E-10 2.14E-06 40.42%

1.00E-11 2.52E-06 17.80%

1.00E-12 2.68E-06 6.47%

1.00E-13* 2.75E-06 2.46%

*Model run using FTREX

Table A.1-2

GRAND GULF PRE-EPU LERF TRUNCATION LIMIT EVALUATION

Truncation LERF % Change

1.00E-09 3.44E-08 -

1.00E-10 8.37E-08 143.31%

1.00E-11 1.10E-07 31.42%

1.00E-12 1.36E-07 23.64%

1.00E-13 1.44E-13 5.51%


A-6

0.00

E+00

5.00

E‐07

1.00

E‐06

1.50

E‐06

2.00

E‐06

2.50

E‐06

3.00

E‐06

3.50

E‐06

1.0E

‐08

1.0E

‐09

1.0E

‐10

1.0E

‐11

1.0E

‐12

1.0E

‐13

Trun

cation

CDF (/RX‐yr)

Fig

ure

A.1

-3 T

runc

atio

n Li

mit

for

Pos

t-E

PU

CD

F


A-7

0.00

E+00

2.00

E‐08

4.00

E‐08

6.00

E‐08

8.00

E‐08

1.00

E‐07

1.20

E‐07

1.40

E‐07

1.60

E‐07

1.0E

‐09

1.0E

‐10

1.0E

‐11

1.0E

‐12

1.0E

‐13

Trun

cation

LERF (Rx‐yr)

Fig

ure

A.1

-4 T

runc

atio

n Li

mit

for

Pos

t-E

PU

LE

RF


A-8

Table A.1-3

GRAND GULF POST-EPU LEVEL 1 TRUNCATION LIMIT EVALUATION

Internal Events and Flooding Only

Truncation CDF % Change

1.00E-08 7.46E-07 -

1.00E-09 1.65E-06 121.33%

1.00E-10 2.32E-06 40.85%

1.00E-11 2.74E-06 17.69%

1.00E-12 2.91E-06 6.40%

1.00E-13 2.98E-06 2.34%

Table A.1-4

GRAND GULF POST-EPU LERF TRUNCATION LIMIT EVALUATION

Truncation LERF % Change

1.00E-09 3.57E-08 -

1.00E-10 8.68E-08 143.13%

1.00E-11 1.22E-07 40.86%

1.00E-12 1.40E-07 14.81%

1.00E-13 1.48E-07 5.35%


A-9

Truncation Conclusion The Pre-EPU truncation limit for both CDF and LERF fall within reasonable limits for

accurate modeling.

The truncation at 1E-12/yr shows that it is a reasonable value for base (Pre-EPU) CDF

model quantification. Extending the truncation to 1E-13/yr (an additional decade)

results in a 2.5% increase in the CDF risk metric. This is well within the NRC’s stated

desire of including 95% of the CDF.

The truncation at 1E-13/yr shows that it is a reasonable value for base (Pre-EPU) LERF

model quantification. Extending the truncation to 1E-14/yr (an additional decade) would

result in a <5% increase in the CDF risk metric. This is well within the NRC’s stated

desire of including 95% of the CDF.

The truncation studies for both the Level 1 CDF and LERF EPU models shows that the

above truncation levels remain adequate for the EPU study.


Appendix B

IMPACT OF EPU ON SHUTDOWN OPERATOR ACTION RESPONSE TIMES


B-1

Appendix B IMPACT OF EPU ON SHUTDOWN OPERATOR ACTION RESPONSE TIMES This appendix describes the thermal hydraulic analyses performed to support the

assessment that the GGNS EPU has a negligible impact on human response times during

plant shutdown accident scenarios.

B.1 INTRODUCTION The risk due to accidents during shutdown is strongly dependent upon the time available

from the start of the event to the onset of core damage. As time elapses after shutdown,

accidents leading to boiling of coolant within the RPV and consequential inventory losses

take more time to evolve. The burden on plant systems decreases as well, introducing the

chance of accident mitigation with non-safety, low capacity systems.

The effect of decreasing decay heat on the times to boil and core damage is accounted for

in two ways. The first is the calculation of decay heat present at a particular point in the

outage. The second takes into consideration the heat capacity of the water and structures

in the system available to absorb decay heat before boiling and core damage occur. Both

of these aspects are addressed in this appendix to support the assessment of the

relationship of decay heat levels and times available in which to perform human actions to

prevent core damage during shutdown accident scenarios.

B.2 ASSUMPTIONS The following assumptions were used in the calculation of the times to boil off the fuel

coolant and reach core damage. These assumptions allow for some simplifications in the

calculation, and also allow for an appropriate degree of conservatism in the results.

• The time to boil and time to core damage calculations are appropriate for conditions of RPV vented and maintained at atmospheric pressure.


B-2

• The time to core damage is conservatively estimated by calculating the time to reach 2/3 core height, and then extrapolating the time to gap release based on decay heat level ratios by assuming that gap release occurs 0.5 hours after 2/3 core height is reached one day after shutdown. Gap release is the release of fission products in the fuel pin gap, which occurs immediately after failure of the fuel cladding and is the first radiological indication of core damage. This approach is based on calculations performed by Sandia and summarized in SECY-93-190. [B-4]

• There is no heat loss from the system to the surroundings via the water surface or through the vessel walls.

• The calculation of decay heat levels and times to boiling and core damage in this assessment conservatively do not include removal of spent fuel out of the core.

• The decay heat as a function of time after shutdown is derived from a curve fit to the ASB 9-2 Branch Technical Position methodology assuming 100% initial power and 16,000 hours of power operation.

B.3 DECAY HEAT LEVEL CALCULATION There are several methods available to calculate decay heat as a function of time after

shutdown. The NRC has provided an acceptable method of calculating the decay heat

rate in Branch Technical Position ASB 9-2 [B-1]. This method uses the following equation:

11 11

Ps = Po (1+K)(1/200) ∑Anexp(-ants) – (1/200) ∑Anexp[-an(ts + t0)]

[ n=1 n=1

] (Eqn. B-1)

Where: Ps = decay heat level (MBtu/hr)

Po = normal operating power (MBtu/hr)

ts = time after shutdown (seconds)

to = operating history

K = uncertainty factor

= 0.2 for ts < 103, 0.1 for 103 < ts <107

An, an = fit coefficients as specified in Reference B-1.


B-3

Other less complex formulas have been developed and provide reasonable estimates of

decay heat rates. Reference B-2 provides the simplest of these, assuming an infinite

power history:

P S(t) = P O (0.0950) t S-0.26 (Eqn. B-2)

where Ps(t), PO and tS are as defined above. A comparison of Equation B-2 to Equation B-

1, assuming 16,000 hours of power operation, shows that Equation B-2 underestimates

the decay heat in the first day or two by 10-20%, and it overestimates the decay heat

thereafter (by 10-75%). At 70 days after shutdown, the decay heat calculated by Equation

B-2 is about 75% higher than that calculated using the ASB 9-2 method [B-1].

Another abbreviated formula is found in Reference B-3. This formula, called the Wigner-

Way formula, also includes a factor for the power history:

P S(t) = P O (0.0622) [t S-0.2 - (tO + tS)-0.2] (Eqn. B-3)

As with Equation B-1, tO is the operating history in seconds, also assumed to be 16,000

hours for comparison purposes. Equation B-3 shows a better correlation late in the

outage, but the first twenty to thirty days after shutdown are under predicted (by 10-20%

compared to the ASB 9-2 formula). A separate curve fit to the ASB 9-2 equation can be

developed of the form:

P S(t) = P O (0.02561) t S(hrs)-0.42371 (Eqn. B-4)

where tS(hrs) is the time since shutdown in hours. This simple equation is considered to

have an advantage over Equations B-2 and B-3 because it agrees with the ASB 9-2 data

to within about 10% over the full time period of interest. Although the agreement is not

quite as good as the Wigner-Way formula after about 40 days, the agreement at the


B-4

critical earlier times is much better. Equation B-4 is often used in industry BWR PSSAs to

support boil off timing calculations.

Using Equation B-4, the decay heat level as a function of time after shutdown is given as:

GGNS CLTP: P S(t) = (3898 MWt) (3.4118E6 Btu/hr / 1 MWt) (0.02561) t S(hrs)-0.42371

P S(t) = (3.41E8) t S(hrs)-0.42371 Btu/hr (Eqn. B-5a)

GGNS 113% CLTP: P S(t) = (4408 MWt) (3.4118E6 Btu/hr / 1 MWt) (0.02561) t S(hrs)-0.42371

P S(t) = (3.85E8) t S(hrs)-0.42371 Btu/hr (Eqn. B-5b)

B.4 RPV HEATUP AND BOIL OFF CALCULATIONS Once the core decay heat rate has been calculated using Equation B-5, the times to fuel

coolant boiling and core damage can be calculated using simple heat transfer formulas

based on the volume of water available. The principal shutdown states are represented by

the following water level configurations:

• normal level

• at the flange level

• reactor cavity flooded

Nominal water volumes and associated heat capacities for use in this calculation are

summarized in Table B-1.


B-5

Time to Boil The time required for the vessel water to reach the boiling temperature (given loss of

coolant decay heat removal) is represented by the following equation:

tb = Eboil / Ps(t) hrs. (Eqn. B-6) where: tb = time to boil (hours) Eboil = Ewater + Estruct Ewater = energy absorbed by heated water volume to reach saturation (MBtu) Estruct = energy absorbed by fuel and clad (MBtu) Ps(t) = decay heat level (MBtu/hr), and Ewater = V/v * (hTsat - hTinit) V = volume of water that heats up to the saturation temperature (ft3) v = specific volume of water at Tinit (assumed constant at 0.0167 ft3/lbm over the temperature range of interest) hTsat = enthalpy of water at Tsat, 212°F (Btu/lbm), hTinit = enthalpy of water at the initial RPV temperature, Tinit (Btu/lbm), and Estruct = MCpstruct (Tsat - Tinit) MCpstruct = configuration specific structure heat capacity (Btu/°F - See Table B-1)


B-6

Since the specific heat of water is 1.0 Btu/lbm°F, the difference in the enthalpies in the

Ewater expression above (hTsat - hTinit) is equivalent to the temperature difference in the Estruct

expression (Tsat - Tinit). This allows the complete expression for Eboil to simplify to:

Eboil = [(V/v) + MCpSTRUCT] * [TSAT - Tinit] (Eqn. B-7)

Substituting in the appropriate constant values, Equation B-7 can be rewritten as:

Eboil = C * [212 - Tinit] (Eqn. B-8) where the constant C is calculated for each of the water volumes and structure capacities

given in Table B-1. Thus, with the initial temperature, Tinit in °F and the decay heat load,

Ps(t) in Btu/hr, the time to reach saturation for the different configurations are given by

Equations B-9 through B-13.

t b, 2/3 core height = 3.57E5 * (212 - Tinit) / Ps(t) hours (Eqn. B-9) t b,TAF = 4.08E5 * (212 - Tinit) / Ps(t) hours (Eqn. B-10) t b,Normal Level = 7.42E5 * (212 - Tinit) / Ps(t) hours (Eqn. B-11) t b,Flange Level = 1.03E6 * (212 - Tinit) / Ps(t) hours (Eqn. B-12) t b,Cavity Flooded = 2.94E6 * (212 - Tinit) / Ps(t) hours (Eqn. B-13)

where Ps(t) is the decay heat level (refer to Equation B-5) and Tinit is the initial water temperature (e.g., 140F early in the outage before cavity flooded and 100F later in the outage after the cavity flooded).


B-7

Table B-1

NOMINAL WATER VOLUMES AND HEAT CAPACITIES FOR THE TIME TO BOIL AND TIME TO CORE DAMAGE CALCULATIONS

Heat Capacity (Btu/°F) (1)

Water Level

Water Volume (ft3)

Water

Structure

2/3 Core Height 6629 (3) 3.97E5 (2)

Top of Active Fuel 7814 (4) 4.68E5 (2)

Normal Level 13,391 (5) 8.02E5 (2)

Flange Level 18,259 (6) 1.09E6 (2)

Cavity Flooded 48,822 (7) 2.92E6 (2)


B-8

NOTES TO TABLE B-1: (1) The term heat capacity is used in Eq. B-8. The water heat capacity is defined as Volume/v (where v is

the specific volume of water and is assumed constant at 0.0167 ft3/lbm). Refer to text on preceding pages for further details.

(2) Structural heat capacities are conservatively not credited in this calculation. (3) Calculated using RPV zone volumes from Reference [B-5]: = B + C + D + E + (2/3) F + (2/3) G + (1/6)S3 + S4 + S5 = 594 + 2321 + 921 + 387 + (2/3) * 1103 + (2/3) * 1005 + (1/6) * 578.7 + 537 + 366.8 = 6628.58 ft3 (4) Calculated using RPV zone volumes from Reference [B-5]: = 2/3 Core Height + (5/6)S3 + (1/3)F + (1/3)G = 6628.58 + (5/6) * 578.7 + (1/3) * 1103 + (1/3) * 1005 = 7813.5 ft3 (5) Calculated using RPV zone volumes from Reference [B-5]: = TAF + H + J + K + S1 + S2 + R + L = 7813.5 + 218 + 929 + 321 + 436.3 + 403.8 + 2755 + 514 = 13,390.6 ft3 (6) Calculated using RPV zone volumes from Reference [B-5]: = Normal Level + M + N + P = 13,390.6 + 624 + 1165 + 3079 = 18,258.6 ft3 (7) Calculated using References [B-5 and B-7]: = Flangewatervolume + Reactor Cavity water volume [B-7] = 18,258.6 + 30563.6 = 48,822.2 ft3


B-9

Time to Uncover Fuel (Boil Off) and Core Damage The time to uncover the core due to boil off (due to loss of coolant decay heat removal) is

the sum of the time required to bring the full heated water volume to saturation and the

time to boil off an equivalent volume of water that lies above the core. This can be

represented by an equation similar in format to the time to boil equation (Equation B-6):

tcu = Etotal / PS (t) (Eqn. B-14)

where:

tcu = time to uncover the core (hours) Etotal = Eboil + Eboil off Eboil = energy absorbed to reach saturation as defined for Equation B-6

(MBtu) Eboil off = energy absorbed by the water that vaporizes during boil off (MBtu), and Eboil off = Vb / vsat * (hfg) Vb = equivalent volume of water that must vaporize for the collapsed level to reach TAF (ft3) vsat = specific volume of water at saturation (Tsat = 212°F), or 0.0167 ft3/lbm hfg = heat of vaporization at 212°F and 14.7 psia, or 970.32 Btu/lbm.


B-10

With constant values again assumed where appropriate, Equations B-15 through B-17

below provide the time to uncover the core for the different shutdown water level

configurations:

tcu,Normal Level = [8.02E5 * (212 - Tinit) + 3.24E8] / PS(t) hours (Eqn. B-15) tcu,Flange Level = [1.09E6 * (212 - Tinit) + 6.07E8] / PS(t) hours (Eqn. B-16) tcu,Cavity Flooded = [2.92E6 * (212 - Tinit) + 2.46E9] / PS(t) hours (Eqn. B-17) where Ps(t) is the decay heat level (refer to Equation B-5)

This analysis assumes the initial bulk water temperatures is 140F for days 0 through 5;

120F for days 6 through 10; and 100F for days 11 and beyond (to the end of the 30-day

refueling outage assumed in this simplified assessment).

The time to boil off RPV inventory down to TAF (given loss of RCS cooling) with the

existing power level (CLTP) is 7.5 hours (6.6 hrs for the 113% CLTP case) at one day into

the outage with the initial water level at the flange elevation. The time to core recovery

(given loss of RCS cooling) exceeds 24 hours (for both the CLTP and EPU cases) after

one day into the outage with the water level initially flooded up into the refueling cavity.

For the impact on shutdown human error probabilities, it is necessary to know the

approximate time of core damage so that this time can be used as the maximum allowable

time window rather than conservatively estimating the time to reach an uncovered core.

As stated in Section B.2, the time to core damage is estimated by incorporating the

additional time available from boil off from TAF down to 2/3 core height, and then

extrapolating the time to gap release by assuming that gap release occurs 0.5 hours after

2/3 core height is reached one day after shutdown. The resulting equation for core

damage, tcd, is:

tcd = tcu + [6.9E7 + 0.5 * PS(1d)] / PS(t) hours (Eqn. B-18)


B-11

where:

6.9E7 represents the amount of decay heat required to boil down from TAF to 2/3 core height. Using the Eboiloff term of Eqn. B-14, (the Eboil term is not applicable given the RCS coolant is already boiling at this time), this value is calculated as [7814 ft3 - 6629 ft3) / 0.0167] 970.32 = 6.9E-7. PS(1d) is the decay heat 1 day after shutdown (refer to Eqn. B-5) PS(t) is the decay heat as a function of time after shutdown (refer to Eqn. B-5)

This equation for estimating the time to core damage during refueling incidents is the

approach typically used in U.S. industry BWR PSSAs. This equation was developed in the

BWR PSSA industry to reflect BWR fuel heatup timing estimates provided in NSAC-169

and SECY-93-190. [B-4, 10] SECY-93-190 reports that fuel heatup calculations performed

by Sandia (for Grand Gulf) show that at 4 days after shutdown approximately 5 hours are

available between reaching TAF and before fuel pin gap release occurs; and almost

9 hours is available at 15 days after shutdown.

Given the nature of shutdown risk, the time to core damage due to boil off is not static but

increases with increasing times after shutdown. An equation is used for ease of modeling

shutdown incidents. Although one may use MAAP runs to estimate the time to core

damage (as is done in the at-power PRA), it is not practical given that numerous different

runs would be required for different times after shutdown.

Comparisons of the time to core damage due to boil off (given loss of coolant decay heat

removal) for the normal and RPV flange water level configurations for the CLTP and the

113% CLTP cases are provided in Tables B-2 and B-3. For example, at one day into the

outage from the flange level configuration, the time to core damage for the existing power

level (CLTP) is 8.8 hours versus 7.8 hrs for the 113% CLTP case.

Information is not summarized for the flood-up configuration as the times to core damage

are 40-50 hours and greater (much longer than the time frames typically considered in


B-12

PRAs, and time frames at which changes in human error probabilities are negligible) after

3-4 days into the shutdown (i.e., the approximate time flood-up would have been

completed).

B.5 EPU IMPACT ON SHUTDOWN RISK Impact Due to Changes in HEPs The primary impact of the EPU on risk during shutdown operations is the decrease in

allowable operator action times in responding to off-normal events.(1) However, as can be

seen from Tables B-2 and B-3, the reduction in times to core damage (i.e., 113% CLTP

case compared to CLTP case) are on the order of 10-15%. Such small changes in

already lengthy allowable operator response times result in negligible changes (<<1%) in

calculated human error probabilities.

The allowable operator action timings to respond to loss of heat removal scenarios during

shutdown operations are many hours long. Very early in an outage the times available for

operator response to prevent core damage for loss of shutdown cooling events are 7-8

hours; later in an outage the times are dozens of hours. A reduction from 8 hours to 7

hours in allowable action timings would not result in any significant increase in human

error probabilities for most operator actions using current human reliability analysis

methods.

Impact Due to Changes in Offsite AC Recovery Failure Probabilities In addition to traditional human error probabilities, the offsite AC recovery failure

probabilities can be influenced by changes in allowable timings. An approximate

calculation is performed here to estimate the impact on shutdown risk due to changes in

the offsite AC recovery failure probability. The calculation is described as follows:

(1) Another postulated impact is any changes to system success criteria during shutdown operations (specifically

with respect to decay heat removal systems) that may result from the EPU. A postulated impact would be that the time into the outage at which backup low capacity heat removal options would be sufficient to prevent coolant boiling would be extended a number of hours. Such a postulated impact is judged to result in an insignificant change in shutdown risk (e.g., 1% or less change in shutdown CDF).


B-13

• A 30-day refueling outage is assumed and is divided into the following five (5) phases:

- Day 1 of the outage - Day 2 of the outage - Day 3 of the outage - Days 4-28 of the outage - Days 29-30 of the outage

• These phases are defined to address the higher decay heat in the

beginning days (1-3) of the outage, the “flooded-up” days (4-28) in the middle of the outage when decay heat issues are not the main risk contributor, and the end of the outage (29-30) when the coolant level is lowered back down into the vessel.

• The following initial water level configurations are assumed for the

phases:

- Day 1 of the outage (NORMAL RPV LEVEL) - Day 2 of the outage (RPV FLANGE LEVEL) - Day 3 of the outage (FLOODED UP) - Days 4-28 of the outage (FLOODED UP) - Days 29-30 of the outage (NORMAL)

• A review of industry BWR PSSAs (Cooper, Dresden, Fermi, Quad

Cities, LaSalle, CGS) was performed to assist in defining the contribution of LOOP/SBO accident scenarios to the CDF of each of the above general phases. Based on the review, the CDF contribution from LOOP/SBO scenarios is high (40%-90%) in the first few days of the outage when the decay heat is higher, it drops significantly (e.g., 20%-40%) in the middle of the outage when decay heat is lower and the cavity is flooded (draindown events dominate these periods), and then it increases at the end of the outage when the coolant level is lowered back down into the vessel.

• The review of industry PSSAs also supported the estimation of the

contributions to overall shutdown CDF during the different phases of the outage.

• Table 4-1 of NUREG/CR-6890 is used here to estimate changes in

offsite AC recovery failure probabilities due to reductions in allowable timings. [B-6]

• The assessment is performed on a normalized CDF basis.


B-14

This calculation is summarized In Table B-4. As can be seen from Table B-4, the increase

in shutdown CDF due to increases in AC power recovery failure probabilities due to the

EPU is estimated at approximately 2%.

Summary

Based on the above discussions and calculations, the qualitative conclusion of this

assessment is that the GGNS EPU has an insignificant impact on shutdown risk. The

impact is approximated as roughly a 2% increase in shutdown CDF.


B-15

Table B-2

TIME TO CORE DAMAGE DUE TO BOIL OFF

(Initial Water Level: Normal Level)

Time to Core Damage (hrs.) Days After Shutdown

Initial Water Temperature

CLTP

113% CLTP

1 140°F 5.6 5.0

5 (1) 140°F 11.0 9.9

10 (1) 120°F 15.3 13.7

15 (1) 100°F 18.7 16.8

20 (1) 100°F 21.2 18.9

25 (1) 100°F 23.3 20.8

30 100°F 25.1 22.5

NOTE: (1) This list of days after shutdown is summarized to show the increasing trend of time available. Thirty days

is shown here to correspond with the current industry trend toward refueling outages on the order of a month in duration. Note that the days marked with the footnote are not directly applicable to a real outage schedule for this water level configuration (i.e., the first day or two the water level will be low, but then for the majority of the outage the water level will be at the spent fuel pool level, and then will be lowered again at the end of the outage).


B-16

Table B-3

TIME TO CORE DAMAGE DUE TO BOIL OFF (Initial Water Level: RPV Flange Level)

Time to Core Damage (hrs.) Days After Shutdown

Initial Water Temperature

CLTP

113% CLTP

1 140°F 8.8 7.8

5 (1) 140°F 17.4 15.5

10 (1) 120°F 23.8 21.2

15 (1) 100°F 28.8 25.6

20 (1) 100°F 32.5 29.0

25 (1) 100°F 35.8 31.8

30 100°F 38.6 34.4

NOTE: (1) This list of days after shutdown is summarized to show the increasing trend of time available. Thirty

days is shown here to correspond with the current industry trend toward refueling outages on the order of a month in duration. Note that the days marked with the footnote are not directly applicable to a real outage schedule for this water level configuration (i.e., the first day or two the water level will be low, but then for the majority of the outage the water level will be at the spent fuel pool level, and then will be lowered again at the end of the outage).


B

-17

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B-18

Notes to Table B-4: (1) Approximated based on review of industry BWR PSSAs (Cooper, Dresden, Fermi, Quad Cities, LaSalle,

CGS). (2) Calculated using Eq. B-18. Day 15 is used to represent the “Days 4-28” period; Day 30 used to represent

the “Days 29-30” period. (3) Based on use of generic offsite AC recovery failure probability information from NUREG/CR-6890. The

integrated (i.e., integration of plant-centered, grid, and severe weather contributions) AC recovery failure data for shutdown conditions from Table 4-1 of NUREG/CR-6890 is used. For example, at t=5.3 hours the NUREG/CR-6890 AC recovery failure probability is 9.87E-2 and at t=4.8 hours the failure probability is 1.09E-1 (a factor of 1.10 higher).

(4) Calculated as: [ 3rd Column x ( 1.0 – 4th Column) ] + [ 3rd Column x 4th Column x 7th Column ] The first contribution is the non-LOOP portion of the phase CDF (i.e., the portion unaffected by changes

in offsite AC recovery failure probabilities). The second contribution is the LOOP portion of the phase CDF (i.e., the portion impacted by changes in offsite AC recovery failure probabilities).

(5) Changes in offsite AC non-recovery probabilities due to reduction of hours for time frames of many days

are reasonable assessed as non-significant.


B-19

REFERENCES [B-1] USNRC, Branch Technical Position 9-2, "Residual Decay Heat Energy for

Light-Water Reactors for Long-Term Cooling." [B-2] M.M. El-Wakil, Nuclear Heat Transport, International Textbook Company, 1971. [B-3] K. Way, E. Wigner, "The Rate of Decay of Fission Products," (Phys. Rev., 73,

1948, pp. 1318-1330) [B-4] USNRC, "Regulatory Approach to Shutdown and Low Power Operations,"

SECY-93-190, July 12, 1993, Enclosure: Draft Regulatory Analysis in Accordance with 10CFR50.109 dated February 1993.

[B-5] Grand Gulf Drawings 762E268 and 762E268D, “Reactor System Data.” [B-6] NUREG/CR-6890, Re-Evaluation of Station Blackout at Nuclear Power Plants:

1986-2004, Volume 1, December 2005. [B-7] Grand Gulf calculation XC-Q1J11-95002, “Refueling Outage Decay Heat Issues.” [B-8] Not Used [B-9] Electric Power Research Institute, Safety Assessment of BWR Risk During

Shutdown Operations, NSAC-175L, Final Report, August 1992. [B-10] Electric Power Research Institute, Analysis of BWR Fuel Heatup During a Loss of

Coolant While Refueling, NSAC-169, September 1991.


Appendix C

GRAND GULF PRA QUALITY


C-1

Appendix C

GRAND GULF PRA QUALITY

The quality of the Grand Gulf PRA models used in performing the risk assessment for

the Grand Gulf EPU is manifested by the following:

• Level of detail in PRA

• Maintenance of the PRA

• Comprehensive Critical Reviews C.1 LEVEL OF DETAIL The Grand Gulf PRA modeling is highly detailed, including a wide variety of initiating

events, modeled systems, operator actions, and common cause events.

C.1.1 Initiating Events [25] The Grand Gulf at-power PRA explicitly models a large number of internal initiating events:

• General transients

• LOCAs

• Support system failures

• Internal Flooding events The initiating events explicitly modeled in the Grand Gulf at-power PRA are summarized in

Table C-1. The number of internal initiating events modeled in the Grand Gulf at-power

PRA is similar to the majority of U.S. BWR PRAs currently in use.


C-2

Table C-1

INITIATING EVENTS FOR GRAND GULF PRA

Initiator ID Description

LOCAs

%A Large LOCA

%S1 Intermediate LOCA

%S2 Small LOCA

%S3 Small-Small LOCA

%VLPCIC ISLOCA in RHR C Injection Line (Pen 22)

%VLPCS ISLOCA in LPCS Injection Line (Pen 31)

%VSDC ISLOCA in Shutdown Cooling Supply Header (Pen 14)

%BOC-FWLB Feedwater Line Break Outside of Containment

%BOC-MSLB Main Steam/RCIC Steam Line Break

%R Vessel Rupture

Loss of Offsite Power

%T1 (1) Loss of Offsite Power Initiator

%T1P (2) Loss of Preferred Power Initiator

Transients

%T2 Loss of PCS Initiator

%T2M MSIV Closure

%T2c Loss of PCS Initiator – Loss of Condenser Vacuum

%T3A PCS Available Transient

%T3B Loss of Feedwater Transient

%T3C Inadvertent Open Relief Valve

%TAC1 Loss of AC Division 1 Initiator

%TAC2 Loss of AC Division 2 Initiator

%TDC1 Loss of DC Division 1 Initiator

%TDC2 Loss of DC Division 2 Initiator


C-3

Table C-1

INITIATING EVENTS FOR GRAND GULF PRA

Initiator ID Description

%TST11 Loss of Service Transformer 11

%TST21 Loss of Service Transformer 21

%TIA Loss of Instrument Air Initiator

%TPSW Loss of Plant Service Water Initiator

%TBCW Loss of Turbine Cooling Water Initiator

%TCCW Loss of Component Cooling Water Initiator

%TCRD Loss of Control Rod Drive

%PSWFD PSW Flooding Initiator

%SSWFD SSW Flooding Initiator

Notes to Table C-1:

(1) Multiple variations of the LOOP initiator (e.g., LOOP due to severe weather, LOOP due to Grid

Degradation) are modeled in the GGNS PRA.

(2) Multiple variation of the Loss of Preferred Power initiator (e.g., loss of 500kV power- circuit breaker work in switchyard; loss of 500kV power- severe weather) are modeled in the GGNS PRA.


C-4

C.1.2 Accident Sequence Models [8] Individual event tree structures are developed for each initiating event type:

• Large LOCA event tree

• Intermediate LOCA event tree

• Small LOCA event tree

• SBO event tree

• Transient event tree

• Loss of FW event tree

• ISLOCA/BOC event tree

• RPV Rupture event tree

• Internal Flooding event tree

• ATWS event tree The event trees are constructed consistent with typical and accepted industry practices.

The critical safety functions pertinent to each initiator type are ordered in a chronological

fashion. The event tree nodes define the fault tree gates used to model the top events

and the core damage or OK end states for each sequences.

C.1.3 System Models The Grand Gulf at-power PRA explicitly models a large number of frontline and support

systems that are credited in the accident sequence analyses. The Grand Gulf systems

are modeled in the Grand Gulf at-power PRA using fault tree structures for the majority of

the systems. The number and level of detail of plant systems modeled in the Grand Gulf

at-power PRA is consistent with industry practices.


C-5

C.1.4 Operator Actions [23] The Grand Gulf at-power PRA explicitly models a large number of operator actions:

• Pre-Initiator actions

• Post-Initiator actions

• Recovery Actions Over two hundred initiator operator actions, including pre-initiators and post-initiators,

are explicitly modeled. Given the large number of actions modeled in the Grand Gulf at-

power internal events PRA, a summary table of the individual actions modeled is not

provided here.

The human error probabilities for the actions are modeled with accepted industry HRA

techniques and include input based on discussion with plant operators, trainers, and

other cognizant personnel.

The number of operator actions modeled in the Grand Gulf at-power PRA, and the

approach to their quantification is consistent with industry practices.

C.1.5 Common Cause Events [24] The Grand Gulf at-power PRA explicitly models a large number of common cause

component failures. Approximately one hundred and fifty common cause terms are

included in the GGNS PRA. Given the large number of CCF terms modeled in the Grand

Gulf at-power internal events PRA, a summary table of them is not provided here. The

number and level of detail of common cause component failures modeled in the Grand

Gulf at-power PRA is consistent with industry practices.


C-6

C.1.6 Level 2 (LERF) PRA [9] The Grand Gulf Level 2 links the Level 1 PRA accident sequences and systems logic

with Level 2 containment event tree sequence logic and systems logic.

The following summarizes the aspects of the GGNS Level 2 (LERF) PRA model:

• Dependencies from Level 1 accidents are carried forward directly into the Level 2 Containment Event Tree (CET) by transfer of sequences to ensure that their effects on Level 2 response is accurately treated.

• The CET models the following severe accident progression issues for LERF:

− Level 1 core damage accident type and timing

− Containment Isolation

− Hydrogen igniters (combustible gas control)

− RPV depressurization post core damage

− Termination of core melt progression in-vessel

− Severe accident energetic phenomenon before or at the time of RPV breach

− Containment flooding process

− Radionuclide scrubbing as a function of release pathway

• Severe accident phenomena (e.g., hydrogen deflagration, steam explosions) identified by the NRC and industry for inclusion in BWR Mark III Level 2 analyses are treated in the CET.

C.2 MAINTENANCE OF PRA The Grand Gulf PRA model and documentation has been maintained living and has

been periodically updated since the IPE to reflect the current plant configuration and to

reflect the accumulation of additional plant operating history and component failure

data. In addition, Entergy maintains a Model Change Requests (MCRs) database to

keep track of plant hardware or other modifications that may affect the PRA model.

These MCRs are used in the process of revising the model.


C-7

The latest Level 1 and Level 2 (LERF) models are Revision 3. These were completed

in September 2009 and January 2010 respectively. These models are reflective of the

as-built, as -operated plant.

The PRA models are routinely implemented and studied by plant PRA personnel in the

performance of their duties.

Formal comprehensive model reviews are discussed in Section C.3.

C.3 COMPREHENSIVE CRITICAL REVIEWS NEI PRA Peer Review The Grand Gulf internal events PRA received a formal industry PRA Peer Review in

August 1997; the final report was issued in October 1997. [C-1] The purpose of the PRA

Peer Review process is to provide a method for establishing the technical quality of a

PRA for the spectrum of potential risk-informed plant licensing applications for which the

PRA may be used. The PRA Peer Review process uses a team composed of PRA and

system analysts, each with significant expertise in both PRA development and PRA

applications. This team provides both an objective review of the PRA technical

elements and a subjective assessment, based on their PRA experience, regarding the

acceptability of the PRA elements. The team uses a set of checklists as a framework

within which to evaluate the scope, comprehensiveness, completeness, and fidelity of

the PRA products available.

The Grand Gulf review team used the “BWROG PSA Peer Review Certification

Implementation Guidelines”, Revision 3, January 1997.

The general scope of the implementation of the PRA Peer Review includes review of

eleven main technical elements, using checklist tables (to cover the elements and sub-

elements), for an at-power PRA including internal events, internal flooding, and


C-8

containment performance, with focus on large early release frequency (LERF). The

eleven technical elements are shown in Tables C-2 through C-4.

The comments from the PRA Peer Review were prioritized into four categories A-D

based upon importance to the completeness of the model. All comments in Categories

A and B (recommended actions and items for consideration) were identified to Grand

Gulf as priority items to be resolved in the next model update. The comments in

Categories C and D (good practices and editorial) are potential enhancements and

remain for consideration in future updates of the Level 1 and 2 PRA models.

All of the ‘A’ and ‘B’ priority PRA Peer Review comments have been addressed by

GGNS and incorporated into the Grand Gulf PRA model as appropriate, except for one

documentation item for the Internal Flood analysis and those related to the Level 2

PRA. The LERF model and internal flooding model are being updated at this time and

will address these items. These items do not significantly impact the results of this risk

assessment or change the conclusions. A summary of these open items is provided

below.

• Sub-Element DE-4 (“B” Priority F&O): Observation notes that Instrument

Air dependency not noted in the internal flooding analysis notebook. It is judged that this observation was mis-classified by the review team, and should be a “C” priority. Flooding scenarios and the instrument air system are included in the GGR3.caf (Level 1) and GGLERFR3.caf (LERF) single-top fault tree models used for this EPU risk assessment.

• Sub-Element L2-7 (“B” Priority F&O): Observation notes that PDS (Plant

Damage States) proceeding into the Level 2 PRA do not appear to include ISLOCA, BOC, ATWS and loss of containment heat removal. This observation applies to an older version of the Level 2 PRA that used the EVENTRE software. The current GGNS LERF model, GGLERFR3.caf, is a CAFTA software based model and includes these accident scenarios. This F&O has not been officially closed pending completion of an update to the Level 2 PRA on-going at this time.


C-9

• Sub-Element L2-13 (two “B” Priority F&Os): Observations note that containment isolation fault tree does not include CCF of PCIVs and that the PDS (Plant Damage States) proceeding into the Level 2 PRA do not appear to include the containment isolation logic. This observation applies to an older version of the Level 2 PRA that used the EVENTRE software. The current GGNS LERF model, GGLERFR3.caf, is a CAFTA software based model and includes the Containment Isolation fault tree logic and CCF basic events for PCIVs. This F&O has not been officially closed pending completion of an update to the Level 2 PRA on-going at this time.

• Sub-Elements L2-8 and L2-16 (two “B” Priority F&Os): Observations note that hydrogen combustion modeling is modeled as various separate issues and it was suggested that they be consolidated, documentation enhanced and various sensitivity studies performed. This observation applies to an older version of the Level 2 PRA that used the EVENTRE software. The current GGNS LERF model, GGLERFR3.caf, is a CAFTA software based model with hydrogen combustion modeled in the IGNITERS and CONTAINMENT FAILURE BEFORE OR AT VB nodes in the containment event tree. This F&O has not been officially closed pending completion of an update to the Level 2 PRA on-going at this time.

• Sub-Element L2-16 (“B” Priority F&O): Observations note that hydrogen combustion modeling should consider three additional issues: 1) a spark always exist; 2) steam inerted environment suppresses deflagration; and 3) AC recovery during SBO results in inappropriate igniter operation. This observation applies to an older version of the Level 2 PRA that used the EVENTRE software. The current GGNS LERF model, GGLERFR3.caf, is a CAFTA software based model with hydrogen combustion modeled in the IGNITERS and CONTAINMENT FAILURE BEFORE OR AT VB nodes in the containment event tree. This F&O has not been yet been implemented and will be addressed and closed pending completion of an update to the Level 2 PRA on-going at this time. Clinton (another BWR Mark III plant) PRA personnel were consulted regarding these suggestions. Clinton models these issues similar to suggested in this observation. However, Clinton uses a 0.9 probability that insufficient steam environment exists to suppress the hydrogen deflagration; this is comparable to the GGNS assumption of 1.0 probability of steam environment suppressing the deflagration. During a SBO scenario, the Clinton model results in approximately a 20% likelihood that hydrogen deflagration results in containment failure. The GGNS likelihood of containment failure induced by hydrogen deflagration during an SBO scenario is approximately 18%. These results are comparable. Based on this information it is expected that implementation of the above


C-10

suggestions will not significantly impact the results of this EPU risk assessment or change the conclusions.

• Sub-Element L2-19 (“B” Priority F&O): Observation notes that the following drywell failure/isolation failure modes should be modeled: WW-DW vacuum breakers failed; low suppression pool level; and personnel hatch seal. This observation applies to an older version of the Level 2 PRA that used the EVENTRE software. The current GGNS LERF model, GGLERFR3.caf, is a CAFTA software based model. Vapor suppression system failures, low suppression pool level, and personnel hatch failures are currently evaluated as low likelihood failures in the Level 2 PRA and not specifically modeled in the fault trees. Explicit modeling of these failures would not significantly impact the delta risk results of this risk application or change the conclusions. This F&O has not been officially closed pending completion of an update to the Level 2 PRA on-going at this time.

• Sub-Element L2-19 (“B” Priority F&O): Observation notes that ATWS core

damage scenarios should consider multiple containment failure locations in the Level 2 PRA. This observation applies to an older version of the Level 2 PRA that used the EVENTRE software. The current GGNS LERF model, GGLERFR3.caf, is a CAFTA software based model and considers whether the ATWS containment failure is into the Auxiliary Building or the Enclosure Building. This F&O has not been officially closed pending completion of an update to the Level 2 PRA on-going at this time.

• Sub-Element L2-22 (“B” Priority F&O): Observation notes to adopt a LERF timing definition of 4-6 hours instead of 2 hrs after General Emergency declaration. This observation applies to an older version of the Level 2 PRA that used the EVENTRE software. The current GGNS LERF model, GGLERFR3.caf, is a CAFTA software based model and considers the GGNS Emergency Plan and accident sequences with initial coolant injection to define the end of the Early time frame in the LERF analysis. Such sequences have continued core cooling for at least 6 hrs. This approach is judged reasonable and appropriate. This F&O has not been officially closed pending completion of an update to the Level 2 PRA on-going at this time.

Assessments Against PRA Standard A self-assessment of the GGNS PRA against the ASME/ANS PRA Standard has yet to be

completed. The self-assessment is to be completed prior to the upcoming second industry

peer review of the GGNS PRA.


C-11

C.4 PRA QUALITY SUMMARY The quality of modeling and documentation of the Grand Gulf PRA models has been

demonstrated by the foregoing discussions on the following aspects:

• Level of detail in PRA

• Maintenance of the PRA

• Comprehensive Critical Reviews The Grand Gulf Level 1 and Level 2 PRAs provide the necessary and sufficient scope

and level of detail to allow the calculation of CDF and LERF changes due to the

Extended Power Uprate for the full power internal events challenges.


C-12

Table C-2

PRA PEER REVIEW TECHNICAL ELEMENTS FOR LEVEL 1

PRA ELEMENT CERTIFICATION SUB-ELEMENTS

Initiating Events • Guidance Documents for Initiating Event Analysis

• Groupings

- Transient - LOCA - Support System/Special - ISLOCA - Break Outside Containment - Internal Floods

• Subsumed Events

• Data

• Documentation

Accident Sequence Evaluation (Event Trees)

• Guidance on Development of Event Trees

• Event Trees (Accident Scenario Evaluation)

- Transients - SBO - LOCA - ATWS - Special - ISLOCA/BOC - Internal Floods

• Success Criteria and Bases

• Interface with EOPs/AOPs

• Accident Sequence Plant Damage States

• Documentation

Thermal Hydraulic Analysis • Guidance Document

• Best Estimate Calculations (e.g., MAAP)

• Generic Assessments

• FSAR

• Room Heat Up Calculations

• Documentation


C-13

Table C-2 (Continued)



System Analysis (Fault Trees)

• System Analysis Guidance Document(s)

• System Models

- Structure of models - Level of Detail - Success Criteria - Nomenclature - Data (see Data Input) - Dependencies (see Dependency Element) - Assumptions

• Documentation of System Notebooks

Data Analysis • Guidance

• Component Failure Probabilities

• System/Train Maintenance Unavailabilities

• Common Cause Failure Probabilities

• Unique Unavailabilities or Modeling Items

- AC Recovery - Scram System

- EDG Mission Time - Repair and Recovery Model - SORV - LOOP Given Transient - BOP Unavailability - Pipe Rupture Failure Probability

• Documentation

Human Reliability Analysis • Guidance

• Pre-Initiator Human Actions

- Identification - Analysis - Quantification

• Post-Initiator Human Actions and Recovery

- Identification - Analysis - Quantification

• Dependence among Actions

• Documentation


C-14

Table C-2 (Continued)



Dependencies • Guidance Document on Dependency Treatment

• Intersystem Dependencies

• Treatment of Human Interactions (see also HRA)

• Treatment of Common Cause

• Treatment of Spatial Dependencies

• Walkdown Results

• Documentation

Structural Capability • Guidance

• RPV Capability (pressure and temperature)

- ATWS - Transient

• Containment (pressure and temperature)

• Reactor Building

• Pipe Overpressurization for ISLOCA

• Documentation

Quantification/Results Interpretation

• Guidance

• Computer Code

• Simplified Model (e.g., cutset model usage)

• Dominant Sequences/Cutsets

• Non-Dominant Sequences/Cutsets

• Recovery Analysis

• Truncation

• Uncertainty

• Results Summary


C-15

Table C-3

PRA CERTIFICATION TECHNICAL ELEMENTS FOR LEVEL 2


Containment Performance Analysis • Guidance Document • Success Criteria • L1/L2 Interface • Phenomena Considered • Important HEPs • Containment Capability Assessment • End state Definition • LERF Definition • CETs • Documentation


C-16

Table C-4

PRA CERTIFICATION TECHNICAL ELEMENTS FOR MAINTENANCE AND UPDATE PROCESS


Maintenance and Update Process • Guidance Document • Input - Monitoring and Collecting New Information • Model Control • PRA Maintenance and Update Process • Evaluation of Results • Re-evaluation of Past PRA Applications • Documentation


C-17

REFERENCES

[C-1] Grand Gulf PRA Peer Review Certification Report, BWROG, October 1997.


Appendix D

HEP ASSESSMENTS


D-1

Appendix D

HUMAN ERROR PROBABILITY (HEP) ASSESSMENTS

The Grand Gulf risk profile, like other plants, is dependent on the operating crew actions

for successful accident mitigation. The success of these actions is in turn dependent on a

number of performance shaping factors. The performance shaping factor that is

principally influenced by the power uprate is the time available within which to detect,

diagnose, and perform required actions. The higher power level results in reduced times

available for some actions. To quantify the potential impact of this performance shaping

factor, deterministic thermal hydraulic calculations using the MAAP computer code are

used.

Not all operator actions in the GGNS PRA have a significant impact on the results. To

minimize the resources required to requantify all operator actions in the PRA due to the

EPU, a screening process was first performed to identify those operator actions that have

an impact on the PRA results. This is consistent with past EPU risk assessments and is

reasonable. Potential HEP changes for operator actions screened out from explicit

assessment in this EPU risk assessment will not have a significant impact on the

quantitative results. The non-significant HEPs if adjusted would be expected to impact the

risk profile by a fraction of a percent.

The screening process was performed against the following criteria:

• FV (with respect to CDF) importance measure >= 5E-3

• RAW (with respect to CDF) importance measure >= 2.0

• FV (with respect to LERF) importance measure >= 5E-3

• RAW (with respect to LERF) importance measure >= 2.0

• Time critical (<=30 min. available) action

These criteria have been used in past EPU risk assessments. If any of the above criteria

are met for an operator action, the action is maintained for explicit consideration in the


D-2

EPU risk assessment. The HEP screening process is summarized in Table D-1. Table D-

1 summarizes only the independent post-initiator HEPs. The dependent HEP combination

events associated with the adjusted independent HEPs are also adjusted.

As can be seen from Table D-1, forty-nine (49) operator actions of risk importance in the

PRA were identified; and an additional thirteen (13) time critical HEPs (i.e., less than or

equal to 30 minutes available for operator action, and not risk significant) were identified

for explicit re-evaluation in this EPU risk assessment.

These independent post-initiator operator actions were then investigated for changes in

allowable operator action timings using the MAAP runs performed for this analysis (refer to

Appendix E). The independent HEPs (and associated dependent HEP combination

events) were then recalculated using the same human reliability analysis techniques

(HRA) as used in the GGNS PRA. [26]

The changes in allowable operator action timings are not always directly linear with

respect to the EPU power increase (i.e., a 13% power uprate does not always correspond

to a 13% reduction in operator action timings):

• Allowable time windows for some actions are not impacted by the power uprate (e.g., timings based on battery life, timings based on internal flood rates, etc.)

• Allowable time windows for LOCAs may be driven more by the inventory loss than the decay heat.

• Allowable time windows for actions related directly to RCS boil off time during non-LOCA events are also not necessarily linear with respect to the power uprate percentage. It is not uncommon that some actions have reductions many percentage points more than the uprate percentage. This is due to various factors, such as higher initial fuel temperature for the EPU providing more initial sensible heat to the RCS water in the early time frame after a plant trip than the CLTP condition, or more integrated fluid release out SRVs in the early time frame compared to the CLTP condition.

• Some operator action time windows are dominated by a portion of the window not impacted by decay heat (e.g., RCIC operating for 6 hrs then fails


D-3

due to battery depletion, remainder of window to core damage impacted by decay heat).

The HEPs for the GGNS base (CLTP) PRA and for the EPU condition are summarized in

Table D-2. Values that meet the screening criteria above are highlighted in bold.


D

-4

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

B21

-FO

-HE

BO

TT

LES

O

pera

tor

fails

to

conn

ect g

as b

ottl

es to

A

DS

air

head

er

1.30

E-0

3 5.

93E

-02

33.9

N

/A

N/A

36

0 m

in

Bas

ed o

n tim

e fo

r S

RV

ac

cum

ula

tors

to r

un o

ut o

f ai

r an

d no

t dir

ect

ly

dep

ende

nt o

n re

acto

r po

we

r.

B21

-FO

-HE

DE

P2-

I O

PE

RA

TO

R F

AIL

S T

O

MA

NU

AL

LY

DE

PR

ES

SU

RIZ

E

VE

SS

EL

WIT

H N

ON

-A

DS

VA

LVE

S

3.20

E-0

4 3.

59E

-01

499.

2 6.

33E

-01

865.

6 45

min

B

ased

on

time

to c

ore

dam

age

for

a tr

ansi

ent

from

RP

V le

vel c

ue o

f -19

2”.

Cha

nge

to

allo

wa

ble

tim

e of

16%

de

term

ined

fro

m M

AA

P

run

GG

NS

EP

U10

a.

B21

-FO

-HE

DE

P2-

L F

AIL

UR

E T

O

MA

NU

AL

LY

DE

PR

ES

SU

RIZ

E

VE

SS

EL

WIT

H N

ON

-A

DS

VA

LVE

S (

>2H

RS

)

1.20

E-0

5 1.

94E

-04

120

00.0

N

/A

216

73.7

24

0 m

in

Tim

e w

ind

ow

is b

ased

on

time

of c

ore

dam

age

for

a tr

ansi

ent

sce

nario

with

hi

gh

pres

sure

inje

ctio

n u

p un

til t=

2 hr

s.

Cha

nge

to

allo

wa

ble

tim

e of

6.5

%

dete

rmin

ed fr

om

MA

AP

ru

n G

GN

SE

PU

3b.

B21

-FO

-HE

-L2D

EP

F

AIL

UR

E T

O

DE

PR

ES

SU

RIZ

E

BE

FO

RE

VE

SS

EL

FA

ILU

RE

1.00

E+

00

N/A

N

/A

5.06

E-0

2 1.

0 2.

5 hr

Le

vel 2

PR

A H

EP

bas

ed

on ti

me

to v

esse

l bre

ach.

P

roba

bilit

y is

set

to 1

.0 in

P

RA

and

is n

ot c

hang

ed

for

the

EP

I.

C11

-FO

-HE

DR

SD

V

OP

ER

AT

OR

FA

ILS

TO

D

RA

IN S

DV

AT

LE

VE

L 3

GA

L.

2.30

E-0

4 8.

39E

-04

4.7

9.33

E-0

3 30

.5

60 m

in

Con

serv

ativ

e e

stim

ate

until

aut

omat

ic s

cram

ba

sed

on s

ize

of le

ak.

Not

di

rect

ly d

epe

nden

t on

reac

tor

pow

er.


D

-5

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

C11

-FO

-HE

NE

GR

EA

C

CO

ND

ITIO

NA

L H

UM

AN

E

RR

OR

. F

AIL

TO

IN

SE

RT

NE

GA

TIV

E

RE

AC

TIV

ITY

.

5.00

E-0

4 N

/A

N/A

N

/A

N/A

10

min

S

yste

m ti

me

win

dow

in

base

PR

A c

on

serv

ativ

ely

es

timat

es a

t a n

omin

al 1

0 m

inut

es (

shor

ter

win

dow

th

an s

yste

m ti

me

win

dow

fo

r S

LC in

itiat

ion)

. T

he

EP

U w

ou

ld n

ot c

hang

e th

is m

odel

ing

assu

mpt

ion.

C

41-F

O-H

E1P

MP

-S

HU

MA

N E

RR

OR

: F

AIL

UR

E T

O

MA

NU

ALL

Y I

NIT

IAT

E

SLC

(O

NE

PU

MP

OP

ER

AT

ION

)

5.40

E-0

4 3.

24E

-04

1.1

5.10

E-0

3 1.

4 15

min

A

ssum

ptio

n ba

sed

on ti

me

to s

uppr

essi

on

poo

l he

atu

p an

d fla

shin

g du

ring

an A

TW

S s

cena

rio.

Cha

nge

to a

llow

abl

e tim

e of

0.6

% d

eter

min

ed

from

M

AA

P r

un G

GN

SE

PU

11.

CIS

-FO

-HE

ISO

L-X

O

PE

RA

TO

R F

AIL

S T

O

MA

NU

ALL

Y I

SO

LAT

E

CO

NT

AIN

ME

NT

ON

LO

CA

SIG

NA

L

5.00

E-0

1 N

/A

N/A

<

5E-3

~

1.0

<30

min

. N

o sp

ecifi

c tim

ing.

Le

ss

than

30

min

s a

ssum

ed

here

. C

onse

rvat

ive

0.5

HE

P u

sed

in th

e G

GN

S

base

PR

A fo

r th

is s

impl

e ac

tion.

E12

-FO

-HE

ISO

L-X

O

PE

RA

TO

R F

AIL

S T

O

ISO

LAT

E L

PC

I A

,B

AN

D C

INJE

CT

ION

LI

NE

S

5.00

E-0

1 N

/A

N/A

1.

73E

-02

1.02

N

/A

Leve

l 2 P

RA

HE

P fo

r pr

eve

ntin

g co

nta

inm

ent

b

ypas

s d

urin

g ce

rtai

n ac

cide

nt s

cena

rios.

T

imin

g in

30-

60

min

. ra

nge.

N

o sp

eci

fic ti

min

g;

cons

erva

tive

failu

re

prob

abili

ty u

sed.


D

-6

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

E12

-FO

-HE

SD

C-O

O

PE

RA

TO

R F

AIL

S T

O

PR

OP

ER

LY A

LIG

N

FO

R S

HU

TD

OW

N

CO

OLI

NG

1.00

E-0

5 2.

23E

-05

2.2

N/A

N

/A

360

min

B

ased

on

tran

sien

t ac

cide

nt s

cena

rio t

ime

from

exc

eed

ing

HC

TL

to

cont

ainm

ent f

ailu

re.

Cha

nge

to a

llow

abl

e tim

e of

17%

det

erm

ined

from

M

AA

P r

un G

GN

SE

PU

9a.

E12

-FO

-HE

SP

C-M

O

PE

RA

TO

R F

AIL

S T

O

MA

NU

ALL

Y A

LIG

N

FO

R S

UP

PR

ES

SIO

N

PO

OL

CO

OLI

NG

1.00

E-0

5 1.

86E

-03

8.8

N/A

N

/A

420

min

B

ased

on

time

to R

CIC

fa

ilure

due

to S

/P h

eatu

p.

Cha

nge

in a

llow

abl

e tim

e of

16%

det

erm

ined

from

M

AA

P r

un G

GN

SE

PU

4.

E12

-FO

-HE

V3S

-O

OP

ER

AT

OR

FA

ILS

TO

P

RO

PE

RLY

ALI

GN

LP

CI T

HR

U

SH

UT

DO

WN

CO

OLI

NG

LI

NE

S

1.70

E-0

1 N

/A

N/A

N

/A

N/A

15

min

B

ased

on

time

to c

ore

dam

age

dur

ing

an

AT

WS

sc

enar

io a

fter

RP

V E

D

initi

ated

. B

ase

PR

A

estim

ates

15

min

s av

aila

ble

. EP

U r

isk

asse

ssm

ent

red

uce

d b

y 13

% (

refle

ctiv

e o

f E

PU

).

E22

-FO

-DF

EA

TH

PC

S

OP

ER

AT

OR

FA

ILS

TO

D

EF

EA

T H

PC

S

INT

ER

LOC

K A

ND

S

TA

RT

HP

CS

IN

AN

A

TW

S

1.60

E-0

3 N

/A

N/A

N

/A

N/A

20

min

B

ased

on

time

to c

ore

dam

age

for

an A

TW

S

from

RP

V le

vel o

f -19

2”.

Cha

nge

in a

llow

abl

e tim

e of

12%

det

erm

ined

from

M

AA

P r

un G

GN

SE

PU

14a.

E22

-FO

-HE

F01

5-I

OP

ER

AT

OR

FA

ILS

TO

O

PE

N S

P S

UC

TIO

N

VA

LVE

1.70

E-0

2 N

/A

N/A

N

/A

N/A

10

min

B

ased

on

cons

erva

tive

estim

ate

of ti

me

to e

mpt

y C

ST

follo

win

g re

ceip

t of

low

CS

T v

olum

e.

Not

di

rect

ly d

epe

nden

t on

reac

tor

pow

er.


D

-7

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

E30

-FO

-MS

INT

PA

-V

FA

ILU

RE

TO

M

AN

UA

LLY

IN

ITIA

TE

-S

PM

U T

RA

IN B

1.10

E-0

1 N

/A

N/A

N

/A

N/A

10

min

B

ased

on

cons

erva

tive

estim

ate

(ass

umin

g al

l E

CC

S p

umps

run

nin

g of

f S

/P)

to r

educ

e S

/P le

vel

from

low

leve

l cue

of

18.3

4 ft

to c

lose

to th

e to

p of

the

S/P

ven

ts.

Not

di

rect

ly d

epe

nden

t on

reac

tor

pow

er.

E

30-F

O-M

SIN

TP

B-V

F

AIL

UR

E T

O

MA

NU

ALL

Y I

NIT

IAT

E-

SP

MU

TR

AIN

B

1.10

E-0

1 N

/A

N/A

N

/A

N/A

10

min

B

ased

on

cons

erva

tive

estim

ate

(ass

umin

g al

l E

CC

S p

umps

run

nin

g of

f S

/P)

to r

educ

e S

/P le

vel

from

low

leve

l cue

of

18.3

4 ft

to c

lose

to th

e to

p of

the

S/P

ven

ts.

Not

di

rect

ly d

epe

nden

t on

reac

tor

pow

er.

E

51-F

O-H

EF

031A

-G

OP

ER

AT

OR

FA

ILS

TO

O

PE

N S

P S

UC

TIO

N

VA

LVE

F03

1-A

4.60

E-0

4 6.

26E

-03

1.2

1.08

E-0

2 N

/A

60 m

in

The

bas

e P

RA

co

nser

vativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

, w

hic

h is

re

flect

ive

of th

e tim

e to

co

re d

amag

e fo

r a

loss

of

all i

nje

ctio

n at

t=0

scen

ario

. T

his

assu

mpt

ion

is

cons

erva

tive

for

this

HE

P

wh

ich

is u

sed

in s

cena

rios

w

ith R

CIC

ru

nnin

g u

p to

t=

6 hr

s. T

his

cons

erva

tive

assu

mpt

ion

wo

uld

not

be

chan

ged

by

the

EP

U.


D

-8

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

E51

-FO

-HE

ISO

L8-G

O

PE

RA

TO

R F

AIL

S T

O

MA

NU

ALL

Y I

SO

LAT

E

RC

IC S

YS

TE

M

3.20

E-0

2 5.

50E

-05

1.0

4.62

E-0

5 1.

0 12

min

B

ased

on

time

estim

ate

for

RC

IC to

rea

ch M

SL

pen

etra

tion

from

the

L8

trip

. T

he c

urre

nt P

RA

es

timat

es a

tim

e w

indo

w

of 1

2 m

inut

es.

Thi

s es

timat

e is

red

uced

by

13%

(re

flect

ive

of

EP

U)

wh

ich

ma

y be

co

nser

vativ

ely

give

n th

e es

timat

e is

bas

ed o

n R

CIC

flo

w r

ate

and

RP

V

volu

mes

. E

51-F

O-H

ET

RP

BY

P

HU

MA

N E

RR

OR

FA

IL

TO

Byp

ass

RC

IC

Tem

pera

ture

Trip

s (E

OP

Atta

chm

ent

3)

4.50

E-0

3 2.

99E

-02

1.1

4.89

E-0

2 1.

0 50

min

B

ased

on

time

to c

ore

dam

age

afte

r R

HR

ve

ntila

tion

failu

re tr

ips

RC

IC.

RH

R is

ass

ume

d to

fail

due

to h

igh

tem

p an

d tr

ip R

CIC

10

min

s af

ter

vent

ilatio

n fa

ilure

. T

he b

ase

PR

A u

ses

60

min

s as

the

time

to c

ore

dam

age

. T

he ti

me

to c

ore

dam

age

in th

e ba

se P

RA

is

not

cha

nge

d du

e to

R

CIC

op

erat

ion

for

10

min

s.

Cha

nge

in th

e al

low

ab

le ti

me

of 1

6% fo

r th

e E

PU

det

erm

ine

d fr

om

MA

AP

run

GG

NS

EP

U10

a.


D

-9

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

INH

IBIT

F

AIL

UR

E O

F

OP

ER

AT

OR

TO

IN

HIB

IT A

DS

/HP

CS

D

UR

ING

AN

AT

WS

2.50

E-0

4 2.

94E

-04

1.0

2.41

E-0

3 1.

5 76

5 s

ec

Sys

tem

tim

e w

indo

w

base

d on

tim

e to

au

tom

atic

AD

S d

urin

g a

tran

sie

nt A

TW

S.

Aut

omat

ic A

DS

act

uatio

n re

quire

s R

PV

leve

l to

be

belo

w L

evel

1 f

or 1

0 m

ins

befo

re th

e 10

5 se

c tim

er is

st

arte

d. T

otal

tim

e is

tim

e to

boi

l wat

er o

ff to

Lev

el 1

(-

150.

3”)

in th

e b

ase

PR

A

is 1

min

. C

han

ge to

the

allo

wa

ble

tim

e of

13%

de

term

ined

fro

m M

AA

P

run

GG

NS

EP

U14

a.

LEV

/PW

R_C

ON

TR

OL

OP

ER

AT

OR

FA

ILS

TO

C

ON

TR

OL

LEV

EL

AN

D

PO

WE

R D

UR

ING

A

TW

S

1.00

E-0

3 3.

32E

-04

1.05

2.

75E

-03

1.39

20

min

B

ased

on

time

to c

ore

dam

age

for

a lo

w p

ress

ure

AT

WS

.

L2-F

O-H

E-E

DV

EN

T

Em

erge

ncy

Dir

ecto

r A

ppro

ves

MS

IV V

entin

g P

rior

to E

ffect

ive

Eva

cuat

ion

1.00

E-0

1 N

/A

N/A

5.

41E

-02

1.49

N

/A

Leve

l 2 H

EP

bas

ed o

n en

gin

eer

ing

judg

emen

t th

at E

mer

genc

y D

irec

tor

will

app

rove

ve

nt b

efor

e th

e co

mpl

etio

n of

an

evac

uat

ion.

Thi

s as

sum

ptio

n w

ill r

emai

n un

chan

ged

by

the

EP

U.

L2-L

OS

P-R

EC

F

ail t

o R

ecov

er O

ffsite

P

ow

er B

efor

e V

esse

l B

reac

h

1.00

E+

00

N/A

N

/A

2.76

E-0

1 1.

00

2.5

hr

Leve

l 2 H

EP

bas

ed o

n tim

e to

ves

sel b

reac

h du

ring

a S

BO

acc

iden

t sc

enar

io.

Pro

bab

ility

is

set t

o 1.

0 in

PR

A a

nd is

no

t cha

nge

d fo

r th

e E

PU

.


D

-10

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

L2-R

EC

-IN

J F

AIL

TO

RE

CO

VE

R IN

V

ES

SE

L 1.

00E

+00

N

/A

N/A

7.

24E

-01

1.00

2.

5 hr

Le

vel 2

PR

A H

EP

bas

ed

on ti

me

to v

esse

l bre

ach

duri

ng a

SB

O a

ccid

ent

scen

ario

. P

rob

abili

ty is

se

t to

1.0

in P

RA

and

is

not c

han

ged

for

the

EP

U.

M41

-FO

-AV

VC

NT

-Q

OP

ER

AT

OR

FA

ILS

TO

V

EN

T C

ON

TA

INM

EN

T

1.50

E-0

5 1.

15E

-03

18.9

N

/A

N/A

60

0 m

in

Bas

ed o

n tim

e to

pr

essu

rize

cont

ainm

ent t

o fa

ilure

afte

r pr

essu

re

incr

ease

s to

22.

4 ps

ig.

C

hang

e in

allo

wa

ble

time

of -

-% d

eter

min

ed fr

om

MA

AP

run

GG

NS

EP

U9a

. N

11-F

O-H

EM

OD

SW

-G

OP

ER

AT

OR

FA

ILS

TO

T

UR

N T

HE

MO

DE

S

WIT

CH

TO

S

HU

TD

OW

N

2.50

E-0

4 5.

38E

-05

1.2

8.07

E-0

5 1.

3 15

min

S

yste

m ti

me

win

dow

ba

sed

on ti

me

to M

SIV

cl

osur

e at

Lev

el 1

fo

llow

ing

a S

CR

AM

from

lo

w R

PV

leve

l (Le

vel 3

=

+11

.4”)

. C

han

ge in

al

low

ab

le ti

me

of 5

.3%

de

term

ined

fro

m M

AA

P

run

GG

NS

EP

U1b

. N

21-F

O-H

ELV

L9-I

(A

TW

S)

HU

MA

N E

RR

OR

: F

AIL

UR

E T

O R

ES

TA

RT

R

EA

CT

OR

FE

ED

P

UM

PS

FO

LLO

WIN

G

LEV

EL

9 T

RIP

2.10

E-0

3 N

/A

N/A

1.

37E

-01

N/A

30

min

B

ased

on

time

to M

SIV

cl

osur

e at

Lev

el 1

sig

nal

fo

llow

ing

a T

urbi

ne

Trip

A

TW

S a

nd fa

ilure

of F

W

leve

l con

trol

suc

h th

at F

W

trip

s at

Lev

el 9

at t

= 5

m

ins.

C

han

ge in

al

low

ab

le ti

me

of 9

%

dete

rmin

ed fr

om

MA

AP

ru

n G

GN

SE

PU

13a.


D

-11

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

N21

-FO

-HE

LVL9

-I

(Tra

nsie

nt)

HU

MA

N E

RR

OR

: F

AIL

UR

E T

O R

ES

TA

RT

R

EA

CT

OR

FE

ED

P

UM

PS

FO

LLO

WIN

G

LEV

EL

9 T

RIP

3.30

E-0

3 7.

65E

-02

N/A

1.

37E

-01

1.1

22 m

in

Bas

ed o

n tim

e to

MS

IV

clos

ure

at L

eve

l 1 fr

om

Leve

l 8 a

fter

feed

wat

er

trip

s.

N21

-FO

-HE

PC

S-G

(A

TW

S)

HU

MA

N E

RR

OR

FA

IL

TO

PR

OP

ER

LY A

LIG

N

TH

E P

CS

FO

R

INJE

CT

ION

8.30

E-0

4 9.

77E

-02

1.2

1.75

E-0

1 1.

9 15

min

B

ased

on

time

to M

SIV

cl

osur

e at

Lev

el 1

sig

nal

fo

llow

ing

a T

urbi

ne

Trip

A

TW

S a

nd fa

ilure

of F

W

leve

l con

trol

suc

h th

at F

W

trip

s at

Lev

el 9

at t

= 5

m

ins.

C

han

ge in

al

low

ab

le ti

me

of 9

%

dete

rmin

ed fr

om

MA

AP

ru

n G

GN

SE

PU

13a.

N

21-F

O-H

EP

CS

-G

(Tra

nsie

nt)

HU

MA

N E

RR

OR

FA

IL

TO

PR

OP

ER

LY A

LIG

N

TH

E P

CS

FO

R

INJE

CT

ION

8.30

E-0

4 N

/A

N/A

N

/A

N/A

15

min

B

ased

on

time

to M

SIV

cl

osur

e on

Lev

el 1

sig

nal

from

Lev

el 3

(1

1.4”

) lo

w

wat

er r

eact

or tr

ip.

Cha

nge

in

allo

wa

ble

time

of 5

.3%

de

term

ined

form

MA

AP

ru

n G

GN

SE

PU

1b.

NR

-AC

HW

R-1

HR

S

Fai

lure

to R

eco

ver

AC

B

us F

ailu

re in

1 H

our

6.00

E-0

1 1.

09E

-02

1.0

3.43

E-0

3 1.

0 1

hr

The

bas

e P

RA

co

nser

vativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

, w

hic

h is

re

flect

ive

of th

e tim

e to

co

re d

amag

e fo

r a

loss

of

all i

nje

ctio

n at

t=0

scen

ario

. T

his

assu

mpt

ion

is

cons

erva

tive

for

this

HE

P

wh

ich

is u

sed

in s

cena

rios

w

ith R

CIC

ru

nnin

g u

p to

2

hour

s.


D

-12

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

-AC

HW

R-8

HR

S

Fai

lure

to R

eco

ver

AC

B

us F

ailu

re in

8 h

ours

1.

00E

-02

1.56

E-0

2 2.

6 5.

25E

-06

1.0

8 hr

B

ased

on

time

to

supp

ress

ion

pool

te

mpe

ratu

re o

f 200

F w

ith

RC

IC r

unni

ng

and

no

cont

ainm

ent h

eat r

emov

al.

NR

C-D

G-C

F1

HR

S

Fai

lure

to R

eco

ver

Die

sel G

ener

ator

C

omm

on C

ause

Fai

lure

in

1 h

our

9.00

E-0

1 5.

84E

-03

1.0

3.96

E-0

3 1.

0 1

hr

The

bas

e P

RA

co

nser

vativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

, w

hic

h is

re

flect

ive

of th

e tim

e to

co

re d

amag

e fo

r a

loss

of

all i

nje

ctio

n at

t=0

scen

ario

.


D

-13

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

C-D

GH

W1

0&

FW

F

ailu

re to

Rec

ove

r D

G

Har

dw

are

Fai

lure

or

star

t FW

in 1

0 ho

urs

2.85

E-0

1 8.

43E

-03

1.0

6.84

E-0

3 1.

02E

+00

10

hr

Thi

s re

cove

ry t

erm

is

app

lied

to c

utse

ts

invo

lvin

g in

itial

RP

V

inje

ctio

n (a

nd s

ubse

quen

t fa

ilure

) fo

r va

rious

tim

e le

ngth

s an

d co

vers

cut

sets

th

at w

oul

d pr

ogr

ess

to

core

dam

age

in 8

-10

hrs

with

out i

njec

tion

reco

very

. T

he b

ase

PR

A a

ssum

es a

no

min

al 1

0 ho

ur ti

me

fram

e fo

r re

cove

ry t

o ap

ply

to t

hese

cas

es.

T

his

reco

very

ter

m

prob

abili

ty is

cal

cula

ted

as

the

prob

abili

ty o

f die

sel

hard

wa

re r

eco

very

failu

re

with

in 1

0 h

ours

(0.

5 fr

om

base

PR

A)

mu

ltipl

ied

by

the

HE

P fo

r fa

ilure

to a

lign

fire

wat

er s

hort

term

, ev

ent

P64

-FO

-HE

-G

(0.5

7).

Eve

nt P

64-F

O-H

E-

G is

red

uced

due

to ti

min

g w

hile

the

har

dw

are

re

cove

ry fu

nctio

n re

ma

ins

the

sam

e du

e to

the

step

fu

nctio

n it

is b

ase

d on

.


D

-14

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

C-D

G-H

W1

HR

F

ailu

re to

Rec

ove

r D

iese

l Gen

erat

or

Har

dw

are

Fai

lure

in 1

ho

ur

9.00

E-0

1 1.

06E

-02

1.0

4.62

E-0

3 1.

00E

+00

1

hr

The

bas

e P

RA

co

nser

vativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

, w

hic

h is

re

flect

ive

of th

e tim

e to

co

re d

amag

e fo

r a

loss

of

all i

nje

ctio

n at

t=0

scen

ario

. N

RC

-DG

-MA

1H

R

Fai

lure

to R

eco

ver

Die

sel G

ener

ator

from

M

aint

ena

nce

in 1

hou

r

9.00

E-0

1 1.

94E

-02

1.0

9.33

E-0

3 1.

00E

+00

1

hr

The

bas

e P

RA

co

nser

vativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

, w

hic

h is

re

flect

ive

of th

e tim

e to

co

re d

amag

e fo

r a

loss

of

all i

nje

ctio

n at

t=0

scen

ario

. N

RC

-OS

P-C

NT

F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N L

ON

G

TE

RM

CO

NT

AIN

ME

NT

F

AIL

UR

E

1.21

E-0

2 5.

16E

-03

1.4

N/A

N

/A

20 h

r B

ased

on

time

to

cont

ainm

ent f

ailu

re

NR

C-O

SP

-DL

G0

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

0 F

TR

*

NO

SS

W P

HV

F

AIL

UR

ES

1.28

E-0

1 1.

22E

-02

1.1

N/A

N

/A

8 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

SG

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

0 F

TR

*

NO

SS

W P

HV

F

AIL

UR

ES

6.18

E-0

1 2.

60E

-01

1.2

N/A

N

/A

1 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

SG

0SS

W0

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 0

FT

R

* 1

OR

2 S

SW

PH

V F

TS

2.62

E-0

1 5.

78E

-03

1.0

N/A

N

/A

4 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s


D

-15

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

C-O

SP

-DS

G1

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 1

FT

R

* N

O S

SW

PH

V

FA

ILU

RE

S

1.05

E-0

1 7.

89E

-02

1.7

N/A

N

/A

2 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

SG

2 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

2 F

TR

*

NO

SS

W P

HV

F

AIL

UR

ES

4.53

E-0

2 1.

24E

-02

1.3

N/A

N

/A

2+ h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-P

SG

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N S

RV

LO

CA

*

U2

* 0

FT

R *

NO

SS

W

PH

V F

AIL

UR

ES

7.63

E-0

1 1.

33E

-02

1.0

N/A

N

/A

30 m

in

Pro

b ca

lcul

ate

d fr

om

conv

olu

tion

calc

s ba

sed

on ti

me

to c

ore

dam

age

in

cert

ain

acci

den

t sc

enar

ios

NR

C-O

SP

-PS

G0-

L2

Fai

l to

Rec

over

OS

P

Giv

en S

RV

LO

CA

*U

2 *0

FT

R *

No

SS

W P

HV

F

ailu

res

LER

F

3.28

E-0

1 N

/A

N/A

5.

88E

-03

1.01

30

min

P

roba

bilit

y ca

lcul

ate

d fr

om

conv

olu

tion

calc

s ba

sed

on ti

me

to c

ore

dam

age

in

cert

ain

scen

ario

s.

NR

C-O

SP

-DS

G0-

L2

Fai

l to

Rec

over

OS

P

Giv

en U

2 *

0 F

TR

*N

o S

SW

PH

V F

ailu

res

LER

F

2.92

E-0

1 N

/A

N/A

1.

87E

-01

1.45

1

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.

N

RC

-OS

P-D

SG

0S0L

2 F

ail t

o R

ecov

er O

SP

G

iven

U2

*0 F

TR

* 1

or

2 S

SW

PH

V F

TS

LE

RF

1.64

E-0

1 N

/A

N/A

6.

14E

-03

1.03

4

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.

N

RC

-OS

P-D

SG

1-L2

F

ail t

o R

ecov

er O

SP

G

iven

U2

* 1

FT

R *

No

SS

W P

HV

Fai

lure

s LE

RF

6.47

E-0

2 N

/A

N/A

6.

79E

-02

1.98

2

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.

N

RC

-OS

P-D

SG

2-L2

F

ail t

o R

ecov

er O

SP

G

iven

U2

* 2

FT

R *

No

SS

W P

HV

Fai

lure

s LE

RF

3.00

E-0

2 N

/A

N/A

9.

10E

-03

1.29

2+

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.


D

-16

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

-PC

S-6

0MN

F

AIL

UR

E T

O

RE

CO

VE

R P

CS

IN 6

0 M

INU

TE

S

6.00

E-0

1 3.

87E

-02

1.0

6.55

E-0

2 1.

04

60 m

in

Tim

e w

ind

ow

is

cons

erva

tivel

y ba

sed

on

time

to c

ore

dam

age

in a

tr

ansi

ent

sce

nario

with

no

inje

ctio

n at

t=0.

P

roba

bilit

y ta

ken

from

N

UR

EG

/CR

-45

50 fo

r P

CS

re

cove

ry in

40-

60 m

inut

es.

Cha

nge

in ti

me

(16

%)

does

not

affe

ct e

vent

pr

obab

ility

. N

RS

-GT

4HE

P

Set

a m

inim

um d

efau

lt fo

r cu

tset

s w

ith m

ore

than

four

HR

A e

vent

s

1.00

E-0

7 7.

83E

-04

777

0.0

N/A

N

/A

N/A

N

ot a

cal

cula

ted

valu

e ba

sed

on p

lant

spe

cific

in

form

atio

n.

Thi

s ev

ent

rem

ains

unc

ha

nge

d in

the

EP

U.

P41

-FO

-HE

SW

XT

-G

(LO

CA

) O

PE

RA

TO

R F

AIL

S T

O

MA

NN

UA

LLY

ALI

GN

F

OR

SS

W C

RO

SS

-TIE

S

YS

TE

M

8.90

E-0

2 4.

30E

-03

1.0

1.46

E-0

2 1.

1 20

min

B

ased

on

time

to c

ore

dam

age

afte

r a

larg

e LO

CA

. C

hang

e in

al

low

ab

le ti

me

of 2

0%

dete

rmin

ed fr

om

MA

AP

ru

n G

GN

SE

PU

8.

P47

-FO

-HE

PS

W-X

O

PE

RA

TO

R F

AIL

S T

O

AC

TU

AT

E P

SW

PU

MP

1.

00E

-05

1.84

E-0

5 2.

8 1.

43E

-05

2.4

120

min

B

ased

on

time

if si

x pu

mps

ru

nnin

g u

ntil

load

s af

fect

ed a

fter

7th

pum

ps

trip

s an

d n

ot d

irec

tly

dep

ende

nt o

n re

acto

r po

we

r.


D

-17

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

P47

-FO

-ST

OP

SC

RM

O

pera

tor

fails

to

aver

t sc

ram

follo

win

g lo

ss o

f P

SW

Sys

tem

1.70

E-0

2 N

/A

N/A

N

/A

N/A

10

min

B

ased

on

time

befo

re

SC

RA

M is

req

uire

d du

e to

hi

gh te

mp

in s

cram

se

nsiti

ve c

omp

one

nts

or

loss

of C

ircu

latin

g W

ater

pu

mp

subm

erg

ence

. N

ot

dire

ctly

dep

end

ent o

n re

acto

r po

we

r.

P51

-FO

-CM

ST

AR

T-T

F

ailu

re to

sta

rt s

tand

by

Ser

vice

Air

Com

pres

sor

4.60

E-0

4 3.

86E

-03

9.0

2.92

E-0

4 N

/A

60 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge b

ased

on

loss

of

feed

wat

er d

ue

to lo

ss o

f in

stru

me

nt a

ir.

Cha

nge

in

allo

wa

ble

tim

e of

16%

de

term

ined

fro

m M

AA

P

run

GG

NS

EP

U10

a.

P53

-FO

-HE

CO

OLI

AS

O

PE

RA

TO

R F

AIL

S T

O

ALI

GN

SS

W-B

TO

IAS

C

OM

PR

ES

SO

R U

PO

N

LOS

S O

F T

BC

W

2.20

E-0

4 1.

09E

-02

48.0

N

/A

N/A

90

min

B

ased

on

time

to fa

il co

mpr

esso

rs a

fter

TB

CW

sy

stem

fails

with

no

cool

ing

and

not

dep

end

ent

on r

eact

or p

ow

er.

P53

-FO

-HE

RE

INF

-T

OP

ER

AT

OR

FA

ILS

TO

R

EIN

ITIA

TE

IA A

S P

ER

P

RO

CE

DU

RE

1.90

E-0

5 1.

03E

-03

9.7

N/A

N

/A

360

min

B

ased

on

time

to r

epla

ce

AD

S g

as b

ottle

s an

d no

t di

rect

ly d

epe

nden

t on

reac

tor

pow

er.

P

64-F

O-H

E-G

O

PE

RA

TO

R F

AIL

S T

O

ALI

GN

FIR

EW

AT

ER

S

YS

TE

M F

OR

IN

JEC

TIO

N

5.70

E-0

1 1.

11E

-01

1.1

4.76

E-0

5 N

/A

150

min

B

ased

on

time

to c

ore

dam

age

bas

ed o

n a

SB

O

and

inje

ctio

n o

pera

tion

for

at le

ast 2

hr.

C

han

ge in

al

low

ab

le ti

me

of 1

6%

dete

rmin

ed fr

om

MA

AP

ru

n G

GN

SE

PU

6a.


D

-18

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

P64

-FO

-HE

-G (

Lon

g T

erm

) O

PE

RA

TO

R F

AIL

S T

O

ALI

GN

FIR

EW

AT

ER

S

YS

TE

M F

OR

IN

JEC

TIO

N

1.10

E-0

2 1.

11E

-01

2.0

4.76

E-0

5 1.

0 48

0 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge b

ased

on

a S

BO

an

d in

ject

ion

ope

ratio

n fo

r at

leas

t 6 h

r (T

ime

to

batte

ry d

eple

tion)

. C

hang

e in

allo

wa

ble

time

of 0

.4%

det

erm

ine

d fr

om

MA

AP

run

GG

NS

EP

U6b

. R

21-F

O-H

EB

OP

TR

M

OP

ER

AT

OR

FA

ILS

TO

A

LIG

N A

LTE

RN

AT

E

PO

WE

R T

O B

OP

B

US

SE

S

4.50

E-0

4 1.

38E

-03

15.8

1.

05E

-03

1.3

60 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge w

ith n

o in

ject

ion

afte

r a

tran

sfor

mer

failu

re

or b

us tr

ip r

esu

lting

in a

sc

ram

. C

hang

e in

al

low

ab

le ti

me

of 1

6%

dete

rmin

ed fr

om

MA

AP

ru

n G

GN

SE

PU

10a.

R

21-F

O-H

EE

SF

TR

M

OP

ER

AT

OR

FA

ILS

TO

T

RA

NS

FE

R T

O

ALT

ER

NA

TE

T

RA

NS

FO

RM

ER

4.50

E-0

4 1.

97E

-02

15.8

3.

10E

-03

1.3

60 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge w

ith n

o in

ject

ion

afte

r a

tran

sfor

mer

failu

re

or b

us tr

ip r

esu

lting

in a

sc

ram

. C

hang

e in

al

low

ab

le ti

me

of 1

6%

dete

rmin

ed fr

om

MA

AP

ru

n G

GN

SE

PU

10a.

S

CR

M

MA

NU

AL

SC

RA

M

FA

ILU

RE

5.

00E

-04

8.39

E-0

4 1.

1 9.

33E

-03

N/A

5

min

S

yste

m ti

me

win

dow

in

base

PR

A c

on

serv

ativ

ely

es

timat

es a

t a n

omin

al 1

0 m

inut

es (

shor

ter

win

dow

th

an s

yste

m ti

me

win

dow

fo

r S

LC in

itiat

ion)

. T

he

EP

U w

ou

ld n

ot c

hang

e th

is m

odel

ing

assu

mpt

ion.


D

-19

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

X2-

AT

WS

O

PE

RA

TO

R F

AIL

S T

O

DE

PR

ES

SU

RIZ

E

DU

RIN

G A

TW

S

1.00

E-0

3 1.

88E

-04

1.1

1.76

E-0

3 2.

1 20

min

B

ased

on

time

to c

ore

dam

age

dur

ing

an

AT

WS

sc

enar

io fr

om R

PV

leve

l of

-192

”.

Cha

nge

in

allo

wa

ble

tim

e of

12%

de

term

ined

fro

m M

AA

P

run

GG

NS

EP

U14

a.

X3

X3-

-D

EP

RE

SU

RIZ

AT

ION

V

IA R

CIC

8.40

E-0

3 6.

12E

-03

1.6

N/A

N

/A

90 m

in

Bas

ed o

n lo

ng t

erm

SB

O

scen

ario

s tim

e es

timat

es

of c

ore

dam

ag

e fr

om R

PV

le

vel -

192”

afte

r 6

hour

s of

in

ject

ion.

C

hang

e in

al

low

ab

le ti

me

of 4

.9%

de

term

ined

form

MA

AP

ru

n G

GN

SE

PU

6b.

X7

7-F

O-H

EC

001A

-U

OP

ER

AT

OR

FA

ILS

TO

T

RA

NS

FE

R F

AN

TO

H

IGH

SP

EE

D

1.00

E-0

5 3.

56E

-05

8.7

1.29

E-0

5 4.

8 36

0 m

in

Bas

ed o

n tim

e to

HP

CS

di

esel

failu

re d

ue to

hig

h te

mp

and

not

dire

ctly

de

pen

dent

on

reac

tor

pow

er

X7

7-F

O-H

EC

001B

-U

OP

ER

AT

OR

FA

ILS

TO

T

RA

NS

FE

R F

AN

TO

H

IGH

SP

EE

D

1.00

E-0

5 4.

47E

-05

8.7

2.15

E-0

5 4.

8 36

0 m

in

Bas

ed o

n tim

e to

HP

CS

di

esel

failu

re d

ue to

hig

h te

mp

and

not

dire

ctly

de

pen

dent

on

reac

tor

pow

er

X7

7-F

O-H

EC

OO

2C-U

O

PE

RA

TO

R F

AIL

S T

O

TR

AN

SF

ER

FA

N T

O

HIG

H S

PE

ED

1.00

E-0

5 1.

14E

-04

8.7

1.10

E-0

4 4.

8 36

0 m

in

Bas

ed o

n tim

e to

HP

CS

di

esel

failu

re d

ue to

hig

h te

mp

and

not

dire

ctly

de

pen

dent

on

reac

tor

pow

er


D

-20

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

Y47

-FO

-HE

MO

D-U

O

PE

RA

TO

R F

AIL

S T

O

PR

OV

IDE

ALT

ER

NA

TE

C

OO

LIN

G

3.80

E-0

4 1.

33E

-02

12.9

1.

89E

-03

1.3

210

min

B

ased

on

time

to te

mp

failu

re in

SS

W p

ump

hous

es fo

llow

ing

a fa

ilure

of

the

vent

ilatio

n sy

stem

. N

ot d

irect

ly d

epe

nde

nt o

n re

acto

r po

we

r.

TH

RE

SH

OLD

FO

R A

CT

ION

S S

CR

EE

NE

D F

RO

M F

UR

TH

ER

AN

ALY

SIS

(6)

C11

-FO

-MLC

RD

HP

-I

OP

ER

AT

OR

FA

ILS

TO

A

LIG

N C

RD

SY

ST

EM

F

OR

LO

NG

-TE

RM

C

OO

LIN

G M

OD

E

4.10

E-0

4 1.

08E

-04

1.1

N/A

N

/A

120

min

B

ased

on

time

to c

ore

dam

age

afte

r 2

hr

HP

CF

an

d R

CIC

ope

ratio

n

E12

-FO

-HE

CS

-N

OP

ER

AT

OR

FA

ILS

TO

A

CT

UA

TE

C

ON

TA

INM

EN

T

SP

RA

Y

1.30

E-0

5 1.

78E

-03

1.1

N/A

N

/A

120

min

B

ased

on

time

to R

CIC

fa

ilure

due

to S

/P h

eatu

p

E12

-FO

-HE

EC

CS

-G

OP

ER

AT

OR

FA

ILS

TO

IN

ITIA

TE

LP

EC

CS

2.

00E

-03

5.05

E-0

4 1.

1 1.

65E

-05

1.01

40

min

B

ased

on

time

to c

ore

dam

age

afte

r m

anu

al

depr

ess

E22

-FO

-HE

HP

CS

-I

OP

ER

AT

OR

FA

ILS

TO

M

AN

UA

LLY

AC

TU

AT

E

HP

CS

1.60

E-0

4 N

/A

N/A

N

/A

N/A

57

min

B

ased

on

time

to c

ore

dam

age

min

us ti

me

to

leve

l 2

E51

-FO

-HE

GR

P9

FA

ILU

RE

TO

RE

OP

EN

F

068

AF

TE

R G

RO

UP

9

ISO

LAT

ION

1.00

E+

00

3.80

E-0

7 1.

0 N

/A

N/A

N

/A

Res

tart

ing

RC

IC a

fter

fals

e G

roup

9 is

olat

ion

is

unlik

ely

sinc

e th

e G

roup

9

isol

atio

n si

gnal

s ar

e H

igh

Dry

wel

l Pre

ssur

e S

igna

l (>

1.39

psi

d) a

nd

Low

R

CIC

Ste

am S

upp

ly

Pre

ssur

e (6

0 ps

ig).

E

51-F

O-H

ES

YA

CT

-G

OP

ER

AT

OR

FA

ILS

TO

M

AN

UA

LLY

IN

ITIA

TE

R

CIC

1.60

E-0

4 N

/A

N/A

N

/A

N/A

57

min

B

ased

on

time

to c

ore

dam

age

(6

0 m

in)

min

us

the

time

to L

evel

2 (

est.

3 m

in.)

.


D

-21

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

E61

-FO

-MS

H13

-X

OP

ER

AT

OR

FA

ILS

TO

E

NE

RG

IZE

H

YD

RO

GE

N IG

NIT

ER

S

5.00

E-0

2 N

/A

N/A

2.

20E

-03

1.04

>

30

min

Le

vel 2

HE

P fo

r op

erat

ors

faili

ng

to in

itiat

e h

ydro

gen

igni

ters

. N

ot d

irect

ly

base

d on

re

acto

r po

we

r.

N19

-FO

-HE

CO

ND

-G

HU

MA

N E

RR

OR

F

AIL

UR

E T

O A

LIG

N

CO

ND

EN

SA

TE

S

YS

TE

M F

OR

LO

W

PR

ES

S R

PV

IN

JEC

TIO

N

1.80

E-0

3 8.

32E

-04

1.2

1.63

E-0

4 1.

02

40 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge a

fter

man

ual

de

pres

s

NR

C-D

GC

F1

0&

FW

F

ailu

re to

Rec

ove

r D

G

CC

F o

r st

art F

W in

10

hour

s

1.71

E-0

1 1.

60E

-03

1.0

1.51

E-0

3 1.

01

10 h

r

NR

C-D

G-C

F1

0H

RS

F

ailu

re to

Rec

ove

r D

iese

l Gen

erat

or

Com

mon

Cau

se F

ailu

re

in 1

0 h

ours

3.00

E-0

1 4.

96E

-04

1.0

N/A

N

/A

10 h

r

NR

C-D

G-C

F2

HR

S

Fai

lure

to R

eco

ver

Die

sel G

ener

ator

C

omm

on C

ause

Fai

lure

in

2 h

our

s

8.00

E-0

1 N

/A

N/A

N

/A

N/A

2

hr

NR

C-D

G-C

F4

HR

S

Fai

lure

to R

eco

ver

Die

sel G

ener

ator

C

omm

on C

ause

Fai

lure

in

4 h

our

s

6.00

E-0

1 N

/A

N/A

N

/A

N/A

4

hr

NR

C-D

G-H

W1

0HR

S

Fai

lure

to R

eco

ver

Die

sel G

ener

ator

H

ard

wa

re F

ailu

re in

10

hour

s

5.00

E-0

1 4.

88E

-03

1.0

3.94

E-0

5 1.

00

10 h

r

NR

C-D

G-H

W2

HR

F

ailu

re to

Rec

ove

r D

iese

l Gen

erat

or

Har

dw

are

Fai

lure

in 2

ho

urs

8.00

E-0

1 6.

73E

-05

1.0

6.60

E-0

5 1.

00

2 hr


D

-22

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

C-D

GH

W4

&F

W

Fai

lure

to R

eco

ver

DG

H

ard

wa

re F

ailu

re o

r st

art F

W in

4 h

ours

3.99

E-0

1 4.

64E

-03

1.0

4.21

E-0

3 1.

01

4 hr

NR

C-D

G-H

W4

HR

F

ailu

re to

Rec

ove

r D

iese

l Gen

erat

or

Har

dw

are

Fai

lure

in 4

ho

urs

7.00

E-0

1 2.

79E

-03

1.0

6.42

E-0

4 1.

00

4 hr

NR

C-D

GM

A1

0&

FW

F

ailu

re to

Rec

ove

r D

G

from

Mai

nten

ance

or

star

t FW

in 1

0 ho

urs

2.85

E-0

1 2.

78E

-03

1.0

2.33

E-0

3 1.

01

10 h

r

NR

C-D

G-M

A1

0HR

S

Fai

lure

to R

eco

ver

Die

sel G

ener

ator

from

M

aint

ena

nce

in 1

0 ho

urs

5.00

E-0

1 1.

49E

-03

1.0

N/A

N

/A

10 h

r

NR

C-D

G-M

A2

HR

F

ailu

re to

Rec

ove

r D

iese

l Gen

erat

or fr

om

Mai

nte

nanc

e in

2 h

ours

8.00

E-0

1 1.

16E

-04

1.0

1.16

E-0

4 1.

00

2 hr

NR

C-D

GM

A4&

FW

F

ailu

re to

Rec

ove

r D

G

from

Mai

nten

ance

or

star

t FW

in 4

hou

rs

4.56

E-0

1 4.

50E

-03

1.0

4.18

E-0

3 1.

00

4 hr

NR

C-D

G-M

A4

HR

F

ailu

re to

Rec

ove

r D

iese

l Gen

erat

or fr

om

Mai

nte

nanc

e in

4 h

ours

8.00

E-0

1 2.

51E

-03

1.0

4.53

E-0

5 1.

00

4 hr

NR

C-O

SP

-DL

G0S

SW

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 0

FT

R *

1

OR

2 S

SW

PH

V F

TS

9.25

E-0

2 6.

27E

-04

1.0

N/A

N

/A

10 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LG

0SS

W1

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

0 F

TR

* 1

S

SW

PH

V F

TR

2.40

E-0

2 2.

85E

-05

1.0

N/A

N

/A

10 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s


D

-23

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

C-O

SP

-DL

G0S

SW

2 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 0

FT

R *

2

SS

W P

HV

FT

R

1.17

E-0

2 N

/A

N/A

N

/A

N/A

10

+ h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LG

1 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 1

FT

R *

N

O S

SW

PH

V

FA

ILU

RE

S

3.46

E-0

2 2.

47E

-03

1.1

N/A

N

/A

8 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LG

1SS

W0

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

1 F

TR

* 1

O

R 2

SS

W P

HV

FT

S

3.31

E-0

2 8.

34E

-05

1.0

N/A

N

/A

10 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LG

1SS

W1

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

1 F

TR

* 1

S

SW

PH

V F

TR

1.41

E-0

2 7.

36E

-06

1.0

N/A

N

/A

10 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LG

1SS

W2

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

1 F

TR

* 2

S

SW

PH

V F

TR

8.76

E-0

3 N

/A

N/A

N

/A

N/A

10

+ h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LG

2 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 2

FT

R *

N

O S

SW

PH

V

FA

ILU

RE

S

1.71

E-0

2 8.

35E

-04

1.1

N/A

N

/A

8 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LG

2SS

W0

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

2 F

TR

* 1

O

R 2

SS

W P

HV

FT

S

1.70

E-0

2 1.

48E

-05

1.0

N/A

N

/A

10 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LG

2SS

W1

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

2 F

TR

* 1

S

SW

PH

V F

TR

1.01

E-0

2 2.

07E

-06

1.0

N/A

N

/A

10+

hr

Pro

b ca

lcul

ate

d fr

om

conv

olu

tion

calc

s ba

sed

on ti

me

to c

ore

dam

age

in

cert

ain

acci

den

t sc

enar

ios


D

-24

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

C-O

SP

-DL

G3

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

3 F

TR

*

NO

SS

W P

HV

F

AIL

UR

ES

1.12

E-0

2 2.

98E

-04

1.0

N/A

N

/A

8 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LG

3SS

W0

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

3 F

TR

* 1

O

R 2

SS

W P

HV

FT

S

1.12

E-0

2 N

/A

N/A

N

/A

N/A

10

hr

Pro

b ca

lcul

ate

d fr

om

conv

olu

tion

calc

s ba

sed

on ti

me

to c

ore

dam

age

in

cert

ain

acci

den

t sc

enar

ios

NR

C-O

SP

-DL

X0

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

0 F

TR

*

RC

IC D

EP

FA

ILU

RE

6.74

E-0

2 4.

36E

-03

1.1

N/A

N

/A

12 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LX

0S

SW

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 0

FT

R *

X3

* 1

OR

2 S

SW

PH

V F

TS

4.93

E-0

2 3.

14E

-04

1.0

N/A

N

/A

14 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LX

0S

SW

1 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 0

FT

R *

X3

* 1

SS

W P

HV

FT

R

1.29

E-0

2 9.

17E

-06

1.0

N/A

N

/A

14 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LX

0S

SW

2 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 0

FT

R *

X3

* 2

SS

W P

HV

FT

R

6.31

E-0

3 N

/A

N/A

N

/A

N/A

14

+ h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LX

1 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 1

FT

R *

R

CIC

DE

P F

AIL

UR

E

1.85

E-0

2 1.

05E

-03

1.1

N/A

N

/A

12 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LX

1S

SW

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 1

FT

R *

X3

* 1

OR

2 S

SW

PH

V F

TS

1.77

E-0

2 3.

10E

-05

1.0

N/A

N

/A

14 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s


D

-25

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

C-O

SP

-DL

X1

SS

W1

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

1 F

TR

* X

3 *

1 S

SW

PH

V F

TR

7.59

E-0

3 4.

61E

-07

1.0

N/A

N

/A

14 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LX

1S

SW

2 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 1

FT

R *

X3

* 2

SS

W P

HV

FT

R

4.75

E-0

3 N

/A

N/A

N

/A

N/A

14

+ h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LX

2 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 2

FT

R *

R

CIC

DE

P F

AIL

UR

E

9.19

E-0

3 2.

94E

-04

1.0

N/A

N

/A

12 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LX

2S

SW

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 2

FT

R *

X3

* 1

OR

2 S

SW

PH

V F

TS

9.15

E-0

3 4.

51E

-07

1.0

N/A

N

/A

14 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

LX

2S

SW

1 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 2

FT

R *

X3

* 1

SS

W P

HV

FT

R

5.48

E-0

3 N

/A

N/A

N

/A

N/A

14

hr

Pro

b ca

lcul

ate

d fr

om

conv

olu

tion

calc

s ba

sed

on ti

me

to c

ore

dam

age

in

cert

ain

acci

den

t sc

enar

ios

NR

C-O

SP

-DL

X3

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

3 F

TR

*

RC

IC D

EP

FA

ILU

RE

6.04

E-0

3 5.

16E

-05

1.0

N/A

N

/A

12 h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

SG

0SS

W1

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 0

FT

R

* 1

SS

W P

HV

FT

R

6.29

E-0

2 3.

16E

-04

1.0

N/A

N

/A

4 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

SG

0SS

W2

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 0

FT

R

* 2

SS

W P

HV

FT

R

2.99

E-0

2 N

/A

N/A

N

/A

N/A

4

hr

Pro

b ca

lcul

ate

d fr

om

conv

olu

tion

calc

s ba

sed

on ti

me

to c

ore

dam

age

in

cert

ain

acci

den

t sc

enar

ios


D

-26

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

C-O

SP

-DS

G1S

SW

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

1 F

TR

*

1 O

R 2

SS

W P

HV

FT

S

8.85

E-0

2 3.

01E

-03

1.0

N/A

N

/A

4 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

SG

1SS

W1

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 1

FT

R

* 1

SS

W P

HV

FT

R

3.62

E-0

2 2.

64E

-04

1.0

N/A

N

/A

4 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

SG

1SS

W2

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 1

FT

R

* 2

SS

W P

HV

FT

R

2.23

E-0

2 N

/A

N/A

N

/A

N/A

4+

hr

Pro

b ca

lcul

ate

d fr

om

conv

olu

tion

calc

s ba

sed

on ti

me

to c

ore

dam

age

in

cert

ain

acci

den

t sc

enar

ios

NR

C-O

SP

-DS

G2S

SW

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

2 F

TR

*

1 O

R 2

SS

W P

HV

FT

S

4.41

E-0

2 5.

14E

-05

1.0

N/A

N

/A

4 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

SG

2SS

W1

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 2

FT

R

* 1

SS

W P

HV

FT

R

2.58

E-0

2 N

/A

N/A

N

/A

N/A

4

hr

Pro

b ca

lcul

ate

d fr

om

conv

olu

tion

calc

s ba

sed

on ti

me

to c

ore

dam

age

in

cert

ain

acci

den

t sc

enar

ios

NR

C-O

SP

-DS

G3

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 3

FT

R

* N

O S

SW

PH

V

FA

ILU

RE

S

2.87

E-0

2 4.

54E

-03

1.2

N/A

N

/A

2+ h

r P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

SG

3SS

W0

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 3

FT

R

* 1

OR

2 S

SW

PH

V F

TS

2.86

E-0

2 5.

91E

-07

1.0

N/A

N

/A

4 hr

P

rob

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n ac

cide

nt

scen

ario

s N

RC

-OS

P-D

SG

2S0L

2 F

ail t

o R

ecov

er O

SP

G

iven

U2

*2 F

TR

* 1

or

2 S

SW

PH

V F

TS

LE

RF

2.95

E-0

2 N

/A

N/A

N

/A

N/A

4

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.


D

-27

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

C-O

SP

-DS

G3-

L2

Fai

l to

Rec

over

OS

P

Giv

en U

2 *

3 F

TR

*N

o S

SW

PH

V F

ailu

res

LER

F

1.93

E-0

2 N

/A

N/A

N

/A

N/A

2+

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.

N

RC

-OS

P-D

SG

3S0L

2 F

ail t

o R

ecov

er O

SP

G

iven

U2

*3 F

TR

* 1

or

2 S

SW

PH

V F

TS

LE

RF

1.93

E-0

2 N

/A

N/A

N

/A

N/A

4

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.

N

RC

-OS

P-D

LG

0-L2

F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 1

FT

R *

N

O S

SW

PH

V

FA

ILU

RE

S L

ER

F

4.56

E-0

2 N

/A

N/A

N

/A

N/A

8

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.

N

RC

-OS

P-D

LG

1-L2

F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 2

FT

R *

N

O S

SW

PH

V

FA

ILU

RE

S L

ER

F

2.34

E-0

2 N

/A

N/A

N

/A

N/A

8

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.

N

RC

-OS

P-D

SG

0S1L

2 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

0 F

TR

*

1 S

SW

PH

V F

TR

LE

RF

4.18

E-0

2 N

/A

N/A

N

/A

N/A

4

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.

N

RC

-OS

P-D

SG

1S0L

2 F

ail t

o R

ecov

er O

SP

G

iven

U2

*1 F

TR

* 1

or

2 S

SW

PH

V F

TS

LE

RF

5.79

E-0

2 N

/A

N/A

N

/A

N/A

4

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.

N

RC

-OS

P-D

SG

1S1L

2 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

1 F

TR

*

1 S

SW

PH

V F

TR

LE

RF

2.43

E-0

2 N

/A

N/A

N

/A

N/A

4

hr

Pro

babi

lity

calc

ulat

ed

from

co

nvo

lutio

n ca

lcs

base

d on

tim

e to

cor

e d

amag

e in

ce

rtai

n sc

enar

ios.

N

R-D

CH

WR

-1H

RS

F

AIL

UR

E T

O

RE

CO

VE

R D

C B

US

F

AIL

UR

E IN

1 H

OU

R

6.00

E-0

1 2.

70E

-04

1.0

3.25

E-0

4 1.

00

1 hr

NR

-DC

HW

R-8

HR

S

FA

ILU

RE

TO

R

EC

OV

ER

DC

BU

S

FA

ILU

RE

IN 8

HO

UR

S

1.00

E-0

2 N

/A

N/A

N

/A

N/A

8

hr


D

-28

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

NR

-PC

S-4

HR

S

FA

ILU

RE

TO

R

EC

OV

ER

PC

S I

N 4

H

OU

RS

6.00

E-0

2 1.

92E

-03

1.0

1.38

E-0

3 1.

02

4 hr

P41

-FO

-HE

SW

XT

-G

(Tra

nsie

nt)

OP

ER

AT

OR

FA

ILS

TO

M

AN

NU

AL

LY A

LIG

N

FO

R S

SW

CR

OS

S-T

IE

SY

ST

EM

7.90

E-0

3 4.

30E

-03

1.0

N/A

1.

00

40 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge a

fter

man

ual

de

pres

s

P42

-FO

-HE

SS

CC

W-W

O

PE

RA

TO

R F

AIL

S T

O

ALI

GN

SS

W-B

TO

CC

W

HX

S O

N L

OS

S O

F

PS

W

6.00

E-0

2 2.

29E

-06

1.0

N/A

N

/A

40 m

in

Bas

ed o

n tim

e to

CC

W

loa

d fa

ilure

P42

-FO

-MP

C00

1B-W

O

PE

RA

TO

R F

AIL

S T

O

MA

NU

ALL

Y I

NIT

IAT

E

PU

MP

B (

AF

TE

R

LOS

P)

3.60

E-0

4 N

/A

N/A

N

/A

N/A

12

0 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge a

fter

LO

SP

and

E

CC

S in

ject

ion

for

2 ho

urs

P43

-FO

-HE

TB

CW

C-W

H

UM

AN

ER

RO

R F

AIL

T

O O

PE

RA

TE

TB

CW

T

RA

IN C

1.20

E-0

5 N

/A

N/A

N

/A

N/A

36

0 m

in

Ass

umed

tim

e fo

r on

e he

at e

xch

ange

r to

car

ry

cool

ing

loa

d P

64-F

O-H

EF

10A

L-G

O

PE

RA

TO

R F

AIL

S T

O

OP

EN

MO

V F

A10

A

LOC

ALL

Y F

OLL

OW

ING

A

LO

SS

OF

PO

WE

R

6.80

E-0

4 N

/A

N/A

N

/A

1.00

48

0 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge b

ased

on

a S

BO

an

d R

CIC

ope

ratio

n fo

r 6

hr

P64

-FO

-HE

F10

BL-

G

OP

ER

AT

OR

FA

ILS

TO

O

PE

N M

OV

FA

10B

LO

CA

LLY

FO

LLO

WIN

G

A L

OS

S O

F P

OW

ER

6.80

E-0

4 N

/A

N/A

N

/A

1.00

48

0 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge b

ased

on

a S

BO

an

d R

CIC

ope

ratio

n fo

r 6

hr

P75

-FO

-HE

-DG

11-I

O

PE

RA

TO

R F

AIL

S T

O

MA

NU

ALL

Y I

NIT

IAT

E

DG

11

7.80

E-0

4 2.

22E

-05

1.0

N/A

N

/A

60 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge w

ith n

o co

re

cool

ing

P75

-FO

-HE

-DG

12-I

O

PE

RA

TO

R F

AIL

S T

O

MA

NU

ALL

Y I

NIT

IAT

E

DG

12

7.80

E-0

4 1.

85E

-05

1.0

N/A

N

/A

60 m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge w

ith n

o co

re

cool

ing


D

-29

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

P81

-FO

-HE

1C5-

F

OP

ER

AT

OR

FA

ILS

TO

T

RA

NS

FE

R T

O

CH

AR

GE

R 1

C5

7.50

E-0

3 N

/A

1.0

N/A

N

/A

120

min

B

ased

on

time

to b

atte

ry

dep

letio

n

P81

-FO

-HE

-DG

13-I

O

PE

RA

TO

R F

AIL

S T

O

MA

NU

ALL

Y I

NIT

IAT

E

DG

13

7.80

E-0

4 N

/A

N/A

N

/A

N/A

60

min

B

ased

on

time

to c

ore

dam

age

with

no

core

co

olin

g R

21-F

O-H

ELS

SR

SE

T

Fai

lure

to

Res

et L

SS

P

ane

l afte

r In

adv

erte

nt

Loa

d S

hed

5.10

E-0

4 1.

49E

-04

1.2

6.31

E-0

5 1.

12

60m

in

Bas

ed o

n tim

e to

cor

e da

ma

ge a

fter

load

sh

ed

R21

-FO

-HE

-XT

IE-A

F

AIL

UR

E O

F

OP

ER

AT

OR

TO

C

OM

PLE

TE

CR

OS

ST

IE

BE

TW

EE

N 1

5AA

&

17A

C

5.40

E-0

4 5.

63E

-04

1.1

2.40

E-0

5 1.

00

120

min

B

ased

on

time

to c

ore

dam

age

with

no

core

co

olin

g af

ter

2 hr

inje

ctio

n

R21

-FO

-HE

-XT

IE-B

F

AIL

UR

E O

F

OP

ER

AT

OR

TO

C

OM

PLE

TE

CR

OS

ST

IE

BE

TW

EE

N 1

6AB

&

17A

C

5.40

E-0

4 5.

91E

-04

1.1

2.40

E-0

5 1.

00

120

min

B

ased

on

time

to c

ore

dam

age

with

no

core

co

olin

g af

ter

2 hr

inje

ctio

n

Z77

-FO

-HE

B00

1A-U

O

PE

RA

TO

R F

AIL

S T

O

ST

AR

T S

UP

PLY

FA

N

1Z77

B0

01A

-A I

N H

IGH

S

PE

ED

8.30

E-0

4 N

/A

N/A

N

/A

N/A

12

0 m

in

Bas

ed o

n tim

e to

tem

p fa

ilure

of L

SS

pan

el

Z77

-FO

-HE

B00

1B-U

O

PE

RA

TO

R F

AIL

S T

O

ST

AR

T S

UP

PLY

FA

N

1Z77

B0

01B

-B I

N H

IGH

S

PE

ED

8.30

E-0

4 N

/A

N/A

N

/A

N/A

12

0 m

in

Bas

ed o

n tim

e to

tem

p fa

ilure

of L

SS

pan

el

Z77

-FO

-HE

C00

1A-U

O

PE

RA

TO

R F

AIL

S T

O

ST

AR

T E

XH

AU

ST

FA

N

1Z77

C00

1A

IN H

IGH

S

PE

ED

8.30

E-0

4 N

/A

N/A

N

/A

N/A

12

0 m

in

Bas

ed o

n tim

e to

tem

p fa

ilure

of L

SS

pan

el

Z77

-FO

-HE

C00

1B-U

O

PE

RA

TO

R F

AIL

S T

O

ST

AR

T E

XH

AU

ST

FA

N

1Z77

C00

1B

-B IN

HIG

H

SP

EE

D

8.30

E-0

4 N

/A

N/A

N

/A

N/A

12

0 m

in

Bas

ed o

n tim

e to

tem

p fa

ilure

of L

SS

pan

el


D

-30

Tab

le D

-1

SU

MM

AR

Y O

F O

PE

RA

TO

R A

CT

ION

SC

RE

EN

ING

PR

OC

ES

S(1

), (

4), (

5)

Nam

e D

escr

iptio

n P

roba

bilit

y F

V

(CD

F)(3

) R

AW

(C

DF

)(3)

FV

(L

ER

F)(3

) R

AW

(L

ER

F)(3

)

Allo

wa

ble

A

ctio

n T

ime(2

) N

otes

Z77

-FO

-HE

LSS

SH

-U

Fai

lure

to S

hutd

ow

n LS

S P

ane

l giv

en a

loss

of

SS

BR

V

1.00

E-0

5 N

/A

N/A

N

/A

N/A

50

min

B

ased

on

time

to te

mp

failu

re o

f LS

S p

anel

____

____

____

____

__

(1)

Thi

s op

erat

or a

ctio

n sc

reen

ing

was

per

form

ed u

sing

the

Gra

nd G

ulf R

evis

ion

3 Le

vel 1

and

Lev

el 2

PR

A m

odel

s (f

ault

tree

s gg

r3.c

af a

nd

GG

LER

FR3.

caf,

resp

ectiv

ely)

. (2

) A

llow

able

tim

e ba

sed

on “

syst

em ti

me

win

dow

” fr

om H

EP

cal

cula

tions

. (3

) F

V v

alue

s ba

sed

on “

In-M

odel

” H

EP

bas

ic e

vent

s. R

AW

val

ues

base

d on

cor

resp

ondi

ng H

EP

“re

cove

ry”

basi

c ev

ents

. (4

) E

ntrie

s in

BO

LD

indi

cate

par

amet

ers

that

mee

t the

HE

P s

cree

ning

crit

eria

. (5

) T

his

tabl

e ad

dres

ses

only

the

inde

pend

ent p

ost-

initi

ator

HE

Ps.

Dep

ende

nt H

EP

com

bina

tions

ass

ocia

ted

with

the

inde

pend

ent H

EP

s id

entif

ied

for

furt

her

anal

ysis

are

adj

uste

d as

wel

l in

this

ris

k as

sess

men

t. (6

) T

hese

act

ions

are

scr

eene

d fr

om th

is a

naly

sis

as n

on-s

igni

fican

t ris

k co

ntrib

utor

s (r

efer

to s

cree

ning

crit

eria

dis

cuss

ion

at b

egin

ning

of A

ppen

dix

D.)


D

-31

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

B21

-FO

-HE

BO

TT

LES

O

PE

RA

TO

R F

AIL

S

TO

CO

NN

EC

T G

AS

B

OT

TLE

S T

O A

DS

A

IR H

EA

DE

R

360

min

36

0 m

in

1.30

E-0

3 1.

30E

-03

Allo

wab

le ti

me

base

d on

tim

e fo

r S

RV

ac

cum

ulat

ors

to r

un o

ut o

f air

and

not

dire

ctly

dep

ende

nt o

n re

acto

r po

wer

.

B21

-FO

-HE

DE

P2-

I O

PE

RA

TO

R F

AIL

S

TO

MA

NU

ALL

Y

DE

PR

ES

SU

RIZ

E

VE

SS

EL

WIT

H

NO

N-A

DS

VA

LVE

S

45 m

in

38 m

in

3.20

E-0

4(3)

3.20

E-0

4(3)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fo

r a

tran

sien

t fro

m R

PV

leve

l cue

of

-19

2".

Allo

wab

le ti

me

win

dow

red

uced

16

% (

dete

rmin

ed fr

om M

AA

P r

un

GG

NS

EP

U10

a).

B21

-FO

-HE

DE

P2-

L F

AIL

UR

E T

O

MA

NU

ALL

Y

DE

PR

ES

SU

RIZ

E

VE

SS

EL

WIT

H

NO

N-A

DS

VA

LVE

S

(<2H

RS

)

240

min

22

4 m

in

1.20

E-0

5(3)

1.20

E-0

5(3)

Tim

e w

indo

w is

bas

ed o

n tim

e of

cor

e da

mag

e fo

r a

tran

sien

t sce

nario

with

hig

h pr

essu

re in

ject

ion

up u

ntil

t=2

hrs.

A

llow

able

tim

e w

indo

w r

educ

ed 6

.5%

(d

eter

min

ed fr

om M

AA

P r

un G

GN

SE

PU

3b).

B21

-FO

-HE

-L2D

EP

F

AIL

UR

E T

O

DE

PR

ES

SU

RIZ

E

BE

FO

RE

VE

SS

EL

FA

ILU

RE

2.5

hr

2.2

hr

1.00

E+

00

1.00

E+

00

Leve

l 2 P

RA

HE

P fo

r re

cove

ring

inje

ctio

n po

st-c

ore

dam

age

and

prio

r to

ves

sel

brea

ch.

Tim

ing

redu

ced

13%

for

the

EP

U

(bas

ed o

n M

AA

P r

un G

GN

SE

PU

6b).

T

imin

g ch

ange

s ha

ve n

o im

pact

on

the

1.00

pr

obab

ility

use

d in

the

GG

NS

CLT

P P

RA

. C

11-F

O-H

ED

RS

DV

O

PE

RA

TO

R F

AIL

S

TO

DR

AIN

SD

V A

T

LEV

EL

3 G

AL.

60 m

in

60 m

in

2.30

E-0

4 2.

30E

-04

Tim

ing

estim

ate

base

d on

scr

am e

xhau

st

valv

e as

sum

ed le

akag

e. N

ot d

irect

ly

depe

nden

t on

reac

tor

pow

er.


D

-32

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

C11

-FO

-HE

NE

GR

EA

C

CO

ND

ITIO

NA

L H

UM

AN

ER

RO

R.

FA

IL T

O IN

SE

RT

N

EG

AT

IVE

R

EA

CT

IVIT

Y.

10 m

in

10 m

in

5.00

E-0

4 5.

00E

-04

Sys

tem

tim

e w

indo

w in

bas

e P

RA

co

nser

vativ

ely

estim

ated

at a

nom

inal

10

min

utes

(sh

orte

r w

indo

w th

an s

yste

m ti

me

win

dow

for

SLC

initi

atio

n).

The

EP

U w

ould

no

t cha

nge

this

con

serv

ativ

e m

odel

ing

assu

mpt

ion.

C

41-F

O-H

E1P

MP

-S

HU

MA

N E

RR

OR

: F

AIL

UR

E T

O

MA

NU

ALL

Y

INIT

IAT

E S

LC (

ON

E

PU

MP

OP

ER

AT

ION

)

15 m

in

13.1

min

5.

40E

-04(3

) 5.

40E

-04(3

)A

ssum

ptio

n ba

sed

on ti

me

to s

uppr

essi

on

pool

hea

tup

and

flash

ing

durin

g an

AT

WS

sc

enar

io.

The

GG

NS

CLT

P P

RA

co

nser

vativ

ely

estim

ates

this

tim

e fr

ame

at

15 m

inut

es.

Thi

s tim

e w

indo

w is

red

uced

13

% (

refle

ctiv

e of

the

pow

er u

prat

e).

CIS

-FO

-HE

ISO

L-X

O

PE

RA

TO

R F

AIL

S

TO

MA

NU

ALL

Y

ISO

LAT

E

CO

NT

AIN

ME

NT

ON

LO

CA

SIG

NA

L

30 m

in

24 m

in

5.00

E-0

1 5.

00E

-01

GG

NS

CLT

P P

RA

use

s a

cons

erva

tive

0.5

HE

P fo

r th

is s

impl

e ac

tion.

Thi

s H

EP

doe

s no

t cha

nge

due

to th

e E

PU

.

E12

-FO

-HE

ISO

L-X

O

PE

RA

TO

R F

AIL

S

TO

ISO

LAT

E L

PC

I A

, B A

ND

C

INJE

CT

ION

LIN

ES

N/A

N

/A

5.00

E-0

1 5.

00E

-01

Leve

l 2 P

RA

HE

P fo

r pr

even

ting

cont

ainm

ent b

ypas

s du

ring

cert

ain

acci

dent

sc

enar

ios.

Tim

ing

in 3

0-60

min

. ran

ge.

No

spec

ific

failu

re p

roba

bilit

y us

ed.

Thi

s es

timat

e w

ould

not

be

impa

cted

by

EP

U.


D

-33

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

E12

-FO

-HE

SD

C-O

O

PE

RA

TO

R F

AIL

S

TO

PR

OP

ER

LY

ALI

GN

FO

R

SH

UT

DO

WN

C

OO

LIN

G

360

min

31

3 m

in

1.00

E-0

5(4)

1.40

E-0

5(4)

Allo

wab

le ti

me

base

d on

tran

sien

t acc

iden

t sc

enar

io ti

me

from

exc

eedi

ng H

CT

L to

co

ntai

nmen

t fai

lure

. T

he G

GN

S C

LTP

PR

A

cons

erva

tivel

y es

timat

es th

is ti

me

fram

e at

6

hour

s. M

AA

P r

uns

GG

NS

EP

U9a

and

9ax

sh

ow th

at th

is ti

me

win

dow

is c

onse

rvat

ive

for

both

the

pre-

EP

U a

nd E

PU

. T

his

cons

erva

tive

time

is r

educ

ed fu

rthe

r fo

r th

is

risk

asse

ssm

ent b

y 13

% (

refle

ctiv

e of

the

pow

er u

prat

e).

E12

-FO

-HE

SP

C-M

O

PE

RA

TO

R F

AIL

S

TO

MA

NU

ALL

Y

ALI

GN

FO

R

SU

PP

RE

SS

ION

P

OO

L C

OO

LIN

G

420

min

35

3 m

in

1.00

E-0

5(3)

1.20

E-0

5(3)

Allo

wab

le ti

me

base

d on

tim

e to

hea

tup

supp

ress

ion

pool

from

95

°F to

200

°F

(ass

umed

RC

IC fa

ilure

tem

pera

ture

) fo

r a

tran

sien

t. A

llow

able

tim

e w

indo

w r

educ

ed

16%

(de

term

ined

from

MA

AP

run

G

GN

SE

PU

4).

E12

-FO

-HE

V3S

-O

OP

ER

AT

OR

FA

ILS

T

O P

RO

PE

RLY

A

LIG

N L

PC

I TH

RU

S

HU

TD

OW

N

CO

OLI

NG

LIN

ES

15 m

in

13 m

in

1.70

E-0

1(4)

2.60

E-0

1(4)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fr

om ti

me

of R

PV

ED

dur

ing

an

AT

WS

sce

nario

with

no

high

pre

ssur

e in

ject

ion.

Allo

wab

le ti

me

win

dow

red

uced

13

% (

refle

ctiv

e of

pow

er u

prat

e). T

his

time

redu

ctio

n is

con

sist

ent w

ith M

AA

P r

un

GG

NS

EP

U14

b.


D

-34

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

E22

-FO

-DF

EA

TH

PC

S

OP

ER

AT

OR

FA

ILS

T

O D

EF

EA

T H

PC

S

INT

ER

LOC

K A

ND

S

TA

RT

HP

CS

IN

AN

AT

WS

20 m

in

17.4

min

1.

60E

-03(3

) 1.

60E

-03(3

)A

llow

able

tim

e ba

sed

on ti

me

to c

ore

dam

age

form

RP

V le

vel o

f -1

91”

@ t=

10

min

. for

an

AT

WS

in w

hich

insu

ffici

ent h

igh

pres

sure

pre

ferr

ed in

ject

ion

is a

vaila

ble.

A

llow

able

tim

e w

indo

w r

educ

ed 1

3%

(ref

lect

ive

of p

ower

upr

ate)

. T

his

time

redu

ctio

n is

con

sist

ent w

ith M

AA

P r

un

GG

NS

EP

U14

a.

E22

-FO

-HE

F01

5-I

OP

ER

AT

OR

FA

ILS

T

O O

PE

N S

P

SU

CT

ION

VA

LVE

10 m

in

10 m

in

1.70

E-0

2 1.

70E

-02

Allo

wab

le ti

me

base

d on

con

serv

ativ

e es

timat

e of

tim

e to

em

pty

CS

T fo

llow

ing

rece

ipt o

f low

CS

T v

olum

e. N

ot d

irect

ly

depe

nden

t on

reac

tor

pow

er.

E30

-FO

-MS

INT

PA

-V

FA

ILU

RE

TO

M

AN

UA

LLY

IN

ITIA

TE

-SP

MU

T

RA

IN B

10 m

in

10 m

in

1.10

E-0

1 1.

10E

-01

Allo

wab

le ti

me

base

d on

con

serv

ativ

e es

timat

e (a

ssum

ing

all E

CC

S p

umps

ru

nnin

g of

f S/P

) to

red

uce

S/P

leve

l fro

m

low

leve

l cue

of 1

8.34

ft to

clo

se to

the

top

of th

e S

/P v

ents

. N

ot d

irect

ly d

epen

dent

on

reac

tor

pow

er.

E30

-FO

-MS

INT

PB

-V

FA

ILU

RE

TO

M

AN

UA

LLY

IN

ITIA

TE

-SP

MU

T

RA

IN B

10 m

in

10 m

in

1.10

E-0

1 1.

10E

-01

Allo

wab

le ti

me

base

d on

con

serv

ativ

e es

timat

e (a

ssum

ing

all E

CC

S p

umps

ru

nnin

g of

f S/P

) to

red

uce

S/P

leve

l fro

m

low

leve

l cue

of 1

8.34

ft to

clo

se to

the

top

of th

e S

/P v

ents

. N

ot d

irect

ly d

epen

dent

on

reac

tor

pow

er.


D

-35

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

E51

-FO

-HE

F03

1A-G

O

PE

RA

TO

R F

AIL

S

TO

OP

EN

SP

S

UC

TIO

N V

ALV

E

F03

1-A

60 m

in

60 m

in

4.60

E-0

4 4.

60E

-04

The

bas

e P

RA

con

serv

ativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

, whi

ch is

re

flect

ive

of th

e tim

e to

cor

e da

mag

e fo

r a

loss

of a

ll in

ject

ion

at t=

0 sc

enar

io.

Thi

s as

sum

ptio

n is

con

serv

ativ

e fo

r th

is H

EP

w

hich

is u

sed

in s

cena

rios

with

RC

IC

runn

ing

up to

t=6

hrs.

Thi

s co

nser

vativ

e as

sum

ptio

n w

ould

not

be

chan

ged

by th

e E

PU

. E

51-F

O-H

EIS

OL8

-G

OP

ER

AT

OR

FA

ILS

T

O M

AN

UA

LLY

IS

OLA

TE

RC

IC

SY

ST

EM

12 m

in

10.5

min

3.

20E

-02(4

) 5.

00E

-02(4

)A

llow

able

tim

e ba

sed

on ti

me

estim

ate

for

RC

IC to

rea

ch M

SL

pene

trat

ion

from

the

L8

trip

. T

he c

urre

nt P

RA

est

imat

es a

tim

e w

indo

w o

f 12

min

utes

. Thi

s tim

e es

timat

e is

re

duce

d by

13%

(re

flect

ive

of E

PU

).

E51

-FO

-HE

TR

PB

YP

H

UM

AN

ER

RO

R

FA

IL T

O B

YP

AS

S

RC

IC

TE

MP

ER

AT

UR

E

TR

IPS

(E

OP

A

ttach

men

t 3)

50 m

in

43.5

min

4.

50E

-03(3

) 5.

60E

-03(3

)A

llow

able

tim

e ba

sed

on ti

me

to c

ore

dam

age

afte

r R

CIC

ass

umed

to fa

il du

e to

hi

gh r

oom

tem

pera

ture

at t

=10

min

s. T

he

base

PR

A u

ses

60 m

ins

as th

e tim

e to

cor

e da

mag

e af

ter

loss

of a

ll in

ject

ion

at t=

10

min

s. T

he o

vera

ll tim

e w

indo

w o

f 50

min

s.

is r

educ

ed 1

3% (

refle

ctiv

e of

the

EP

U).


D

-36

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

INH

IBIT

F

AIL

UR

E O

F

OP

ER

AT

OR

TO

IN

HIB

IT A

DS

/HP

CS

D

UR

ING

AN

AT

WS

765

sec

757

sec

2.50

E-0

4(3)

2.50

E-0

4(3)

Sys

tem

tim

e w

indo

w b

ased

on

time

to

auto

mat

ic A

DS

dur

ing

a tr

ansi

ent A

TW

S.

Aut

omat

ic A

DS

act

uatio

n re

quire

s R

PV

le

vel t

o be

bel

ow L

evel

1 fo

r 10

min

s be

fore

th

e 10

5 se

c tim

er is

sta

rted

. T

ime

to b

oil o

ff w

ater

dow

n to

Lev

el 1

(-1

50.3

") is

1 m

in. f

or

the

base

PR

A.

Boi

l off

time

to R

PV

L1

redu

ced

13%

for

EP

U (

dete

rmin

ed fr

om

MA

AP

run

GG

NS

EP

U14

a).

LEV

/PW

R-C

ON

TR

OL

OP

ER

AT

OR

FA

ILS

T

O C

ON

TR

OL

LEV

EL

AN

D

PO

WE

R D

UR

ING

A

TW

S

20 m

in

17.4

min

1.

00E

-3(3

) 1.

00E

-3(3

) A

llow

able

tim

e ba

sed

on ti

me

to c

ore

dam

age

for

a lo

w p

ress

ure

AT

WS

afte

r R

PV

E

D a

nd in

adeq

uate

leve

l con

trol

. T

he

GG

NS

CLT

P P

RA

ass

umes

the

avai

labl

e tim

e w

indo

w is

20

min

utes

. T

his

time

estim

ate

is r

educ

ed 1

3% (

refle

ctiv

e of

EP

U).

L2-L

OS

P-R

EC

F

AIL

TO

RE

CO

VE

R

OF

FS

ITE

PO

WE

R

BE

FO

RE

VE

SS

EL

BR

EA

CH

2.5

hr

2.2

hrs

1.00

E+

00

1.00

E+

00

Leve

l 2 P

RA

HE

P fo

r re

cove

ring

OS

P p

ost-

core

dam

age

and

prio

r to

ves

sel b

reac

h du

ring

SB

O s

cena

rio.

Tim

ing

redu

ced

13%

fo

r th

e E

PU

(ba

sed

on M

AA

P r

un

GG

NS

EP

U6b

).

Tim

ing

chan

ges

have

no

impa

ct o

n th

e 1.

00 p

roba

bilit

y us

ed in

the

GG

NS

CLT

P P

RA

. L2

-RE

C-I

NJ

FA

IL T

O R

EC

OV

ER

IN

VE

SS

EL

2.5

hr

2.2

hrs

1.00

E+

00

1.00

E+

00

Leve

l 2 P

RA

HE

P fo

r re

cove

ring

inje

ctio

n po

st-c

ore

dam

age

and

prio

r to

ves

sel

brea

ch.

Tim

ing

redu

ced

13%

for

the

EP

U

(bas

ed o

n M

AA

P r

un G

GN

SE

PU

6b).

T

imin

g ch

ange

s ha

ve n

o im

pact

on

the

1.00

pr

obab

ility

use

d in

the

GG

NS

CLT

P P

RA

.


D

-37

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

M41

-FO

-AV

VC

NT

-Q

OP

ER

AT

OR

FA

ILS

T

O V

EN

T

CO

NT

AIN

ME

NT

600

min

49

8 m

in

1.5E

-05(3

) 1.

5E-0

5(3)

Allo

wab

le ti

me

base

d on

tim

e to

pre

ssur

ize

cont

ainm

ent.

Ope

rato

r tim

e w

indo

w b

ased

on

tim

e fr

om 2

2.4

psig

to 5

6 ps

ig

cont

ainm

ent p

ress

ure.

Allo

wab

le ti

me

win

dow

red

uced

17%

(de

term

ined

from

M

AA

P r

un G

GN

SE

PU

9a).

N

11-F

O-H

EM

OD

SW

-G

OP

ER

AT

OR

FA

ILS

T

O T

UR

N T

HE

M

OD

E S

WIT

CH

TO

S

HU

TD

OW

N

15 m

in

12.6

min

2.

50E

-04(3

) 2.

50E

-04(3

)S

yste

m ti

me

win

dow

bas

ed o

n tim

e to

MS

IV

clos

ure

on R

PV

L1

from

RP

V L

evel

3 d

urin

g a

tran

sien

t. A

llow

able

tim

e w

indo

w r

educ

ed

16%

(de

term

ined

from

MA

AP

run

G

GN

SE

PU

15).

N

21-F

O-H

ELV

L9-I

(A

TW

S)

HU

MA

N E

RR

OR

: F

AIL

UR

E T

O

RE

ST

AR

T

RE

AC

TO

R F

EE

D

PU

MP

S

FO

LLO

WIN

G

LEV

EL

9 T

RIP

30 m

in

26.1

min

2.

10E

-03(3

) 2.

10E

-03(3

)A

llow

able

tim

e ba

sed

on ti

me

to M

SIV

cl

osur

e on

RP

V 1

sig

nal d

urin

g a

turb

ine

trip

A

TW

S a

nd fa

ilure

of F

W le

vel c

ontr

ol s

uch

that

FW

trip

s at

Lev

el 9

at t

= 2

0 m

ins.

A

llow

able

tim

e w

indo

w r

educ

ed 1

3%

(con

sist

ent w

ith E

PU

pow

er in

crea

se).

Thi

s tim

e re

duct

ion

is c

onsi

sten

t with

MA

AP

run

G

GN

SE

PU

13b.

N

21-F

O-H

ELV

L9-I

(T

rans

) H

UM

AN

ER

RO

R:

FA

ILU

RE

TO

R

ES

TA

RT

R

EA

CT

OR

FE

ED

P

UM

PS

F

OLL

OW

ING

LE

VE

L 9

TR

IP

22 m

in

19.1

min

3.

30E

-03(4

) 5.

7E-0

3(4)

Allo

wab

le ti

me

base

d on

tim

e to

MS

IV

clos

ure

on R

PV

L1

from

tim

e of

FW

trip

on

RP

V L

9 du

ring

a tr

ansi

ent.

Allo

wab

le ti

me

win

dow

red

uced

13%

(de

term

ined

from

M

AA

P r

un G

GN

SE

PU

15).


D

-38

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

N21

-FO

-HE

PC

S-G

(A

TW

S)

HU

MA

N E

RR

OR

F

AIL

TO

P

RO

PE

RLY

ALI

GN

T

HE

PC

S F

OR

IN

JEC

TIO

N

15 m

in

13.1

min

8.

30E

-04(3

) 8.

30E

-04(3

)A

llow

able

tim

e ba

sed

on ti

me

to M

SIV

cl

osur

e on

RP

V L

1 si

gnal

dur

ing

a tu

rbin

e tr

ip A

TW

S (

with

PC

S in

itial

ly a

vaila

ble)

and

fa

ilure

of F

W le

vel c

ontr

ol s

uch

that

FW

trip

s on

RP

V L

9 at

t =

5 m

ins.

Allo

wab

le ti

me

win

dow

red

uced

13%

(co

nsis

tent

with

EP

U

pow

er in

crea

se).

Thi

s tim

e re

duct

ion

is

cons

iste

nt w

ith M

AA

P r

un G

GN

SE

PU

13a.

N

21-F

O-H

EP

CS

-G

(Tra

nsie

nt)

HU

MA

N E

RR

OR

F

AIL

TO

P

RO

PE

RLY

ALI

GN

T

HE

PC

S F

OR

IN

JEC

TIO

N

15 m

in

12.6

min

8.

30E

-04(3

) 8.

30E

-04(3

)A

llow

able

tim

e ba

sed

on ti

me

to M

SIV

cl

osur

e on

RP

V L

1 si

gnal

from

RP

V L

3 du

ring

a tr

ansi

ent.

Allo

wab

le ti

me

win

dow

re

duce

d 16

% (

dete

rmin

ed fr

om M

AA

P r

un

GG

NS

EP

U15

).

NR

-AC

HW

R-1

HR

S

Fai

lure

to R

ecov

er

AC

Bus

Fai

lure

in 1

H

our

1 hr

50

min

6.

00E

-01

6.0

0E-0

1

The

bas

e P

RA

con

serv

ativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

(re

flect

ive

of ti

me

to c

ore

dam

age

for

a lo

ss o

f all

inje

ctio

n at

t=0

scen

ario

) fo

r ap

plic

atio

n of

th

is A

C b

us r

ecov

ery

term

. T

his

assu

mpt

ion

is c

onse

rvat

ive

give

n th

is r

ecov

ery

is u

sed

in s

cena

rios

with

RC

IC r

unni

ng u

p

t = 1

0 m

in. F

or th

e E

PU

, the

tim

e to

cor

e da

mag

e fo

r th

is A

C b

us r

ecov

ery

term

is

redu

ced

17%

(w

orst

cas

e re

duct

ion

from

bo

il of

f MA

AP

cas

es G

GN

SE

PU

10a,

G

GN

SE

PU

10b,

and

GG

NS

EP

U15

).

Rec

over

y fa

ilure

pro

babi

lity

does

not

ch

ange

due

to s

tep

func

tion

AC

bus

re

cove

ry m

odel

.


D

-39

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

-AC

HW

R-8

HR

S

Fai

lure

to R

ecov

er

AC

Bus

Fai

lure

in 8

ho

urs

8 hr

6.

7 hr

1.

00E

-02

1.00

E-0

2

Thi

s A

C b

us r

ecov

ery

term

is b

ased

on

time

to s

uppr

essi

on p

ool t

empe

ratu

re o

f 200

o F

with

RC

IC r

unni

ng a

nd n

o co

ntai

nmen

t hea

t re

mov

al.

For

the

EP

U, t

his

time

to 2

00°F

is

redu

ced

16%

(ba

sed

on M

AA

P r

un

GG

NS

EP

U4)

. R

ecov

ery

failu

re p

roba

bilit

y do

es n

ot c

hang

e du

e to

ste

p fu

nctio

n A

C

bus

reco

very

mod

el.

NR

C-D

G-C

F1H

RS

F

ailu

re to

Rec

over

D

iese

l Gen

erat

or

Com

mon

Cau

se

Fai

lure

in 1

hou

r

1 hr

50

min

9.

00E

-01

9.00

E-0

1

The

bas

e P

RA

con

serv

ativ

ely

assu

mes

a

60 m

inut

e S

yste

m T

ime

Win

dow

(re

flect

ive

of th

e tim

e to

cor

e da

mag

e fo

r a

loss

of a

ll in

ject

ion

at t=

0 sc

enar

io)

for

appl

icat

ion

of

this

DG

rec

over

y te

rm.

For

the

EP

U, t

his

time

to c

ore

dam

age

for

this

DG

rec

over

y te

rm is

red

uced

17%

(w

orst

cas

e re

duct

ion

from

boi

l off

MA

AP

cas

es G

GN

SE

PU

10a,

G

GN

SE

PU

10b,

GG

NS

EP

U15

). R

ecov

ery

failu

re p

roba

bilit

y do

es n

ot c

hang

e du

e to

st

ep fu

nctio

n D

G r

ecov

ery

mod

el.


D

-40

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

C-D

GH

W10

&F

W

Fai

lure

to R

ecov

er

DG

Har

dwar

e F

ailu

re o

r st

art F

W

in 1

0 ho

urs

10 h

r 8.

7 hr

2.

85E

-01

3.35

E-0

1 T

his

reco

very

term

is a

pplie

d to

cut

sets

in

volv

ing

initi

al R

PV

inje

ctio

n (a

nd

subs

eque

nt fa

ilure

) fo

r va

rious

tim

e le

ngth

s an

d co

vers

cut

sets

that

wou

ld p

rogr

ess

to

core

dam

age

in 8

-10

hrs

with

out i

njec

tion

reco

very

. T

he b

ase

PR

A a

ssum

es a

no

min

al 1

0 ho

ur ti

me

fram

e fo

r re

cove

ry to

ap

ply

to th

ese

case

s. T

his

time

is r

educ

ed

13%

(re

flect

ive

of th

e E

PU

pow

er in

crea

se).

T

his

reco

very

term

pro

babi

lity

is c

alcu

late

d as

the

prob

abili

ty o

f die

sel h

ardw

are

reco

very

failu

re w

ithin

10

hour

s (0

.5 fr

om

base

PR

A)

mul

tiplie

d by

the

HE

P fo

r fa

ilure

to

alig

n fir

e w

ater

sho

rt te

rm, e

vent

P64

-FO

-H

E-G

. HE

P P

64-F

O-H

E-G

incr

ease

s fr

om

0.57

to 0

.67

due

to E

PU

tim

ing

redu

ctio

n (r

efer

to P

64-F

O-H

E-G

ent

ry la

ter

in ta

ble)

w

hile

the

hard

war

e re

cove

ry te

rm r

emai

ns

the

sam

e du

e to

the

step

func

tion

reco

very

m

odel

.


D

-41

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

C-D

G-H

W1H

R

Fai

lure

to R

ecov

er

Die

sel G

ener

ator

H

ardw

are

Fai

lure

in

1 ho

ur

1 hr

50

min

9.

00E

-01

9.00

E-0

1 T

he b

ase

PR

A a

ssum

es a

60

min

ute

Sys

tem

Tim

e W

indo

w (

refle

ctiv

e of

the

time

to c

ore

dam

age

for

a lo

ss o

f all

inje

ctio

n at

t=

0 sc

enar

io)

for

appl

icat

ion

of th

is D

G

reco

very

term

. F

or th

e E

PU

, thi

s tim

e to

co

re d

amag

e fo

r th

is D

G r

ecov

ery

term

is

redu

ced

17%

(w

orst

cas

e re

duct

ion

from

bo

il of

f MA

AP

cas

es G

GN

SE

PU

10a,

G

GN

SE

PU

10b,

GG

NS

EP

U15

). R

ecov

ery

failu

re p

roba

bilit

y do

es n

ot c

hang

e du

e to

st

ep fu

nctio

n D

G r

ecov

ery

mod

el.

N

RC

-DG

-MA

1HR

F

ailu

re to

Rec

over

D

iese

l Gen

erat

or

from

Mai

nten

ance

in

1 ho

ur

1 hr

50

min

9.

00E

-01

9.00

E-0

1 T

he b

ase

PR

A a

ssum

es a

60

min

ute

Sys

tem

Tim

e W

indo

w (

refle

ctiv

e of

the

time

to c

ore

dam

age

for

a lo

ss o

f all

inje

ctio

n at

t=

0 sc

enar

io)

for

appl

icat

ion

of th

is D

G

reco

very

term

. F

or th

e E

PU

, thi

s tim

e to

co

re d

amag

e fo

r th

is D

G r

ecov

ery

term

is

redu

ced

17%

(w

orst

cas

e re

duct

ion

from

bo

il of

f MA

AP

cas

es G

GN

SE

PU

10a,

G

GN

SE

PU

10b,

GG

NS

EP

U15

). R

ecov

ery

failu

re p

roba

bilit

y do

es n

ot c

hang

e du

e to

st

ep fu

nctio

n D

G r

ecov

ery

mod

el.

N

RC

-OS

P-C

NT

F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N L

ON

G

TE

RM

C

ON

TA

INM

EN

T

FA

ILU

RE

20 h

r 16

.6 h

r 1.

21E

-02

3.09

E-0

2 A

llow

able

tim

e ba

sed

on ti

me

to

cont

ainm

ent f

ailu

re.

Allo

wab

le ti

me

win

dow

re

duce

d 17

% (

base

d on

MA

AP

run

G

GN

SE

PU

9a).

Pro

babi

lity

base

d on

co

nvol

utio

n ca

lcul

atio

n of

OS

P r

ecov

ery

curv

e an

d lo

ss o

f hea

t rem

oval

tim

ing.


D

-42

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

C-O

SP

-DLG

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N 0

FT

R *

N

O S

SW

PH

V

FA

ILU

RE

S

Not

e (5

) N

ote

(5)

1.28

E-0

1 1.

59E

-01

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve

and

long

-ter

m R

CIC

op

erat

ion

acci

dent

sce

nario

tim

ing.

Ref

er to

N

ote

(5).

N

RC

-OS

P-D

SG

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

0 F

TR

* N

O S

SW

P

HV

FA

ILU

RE

S

Not

e (5

) N

ote

(5)

6.18

E-0

1 6.

59E

-01

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve

and

acci

dent

tim

ings

fo

r no

inje

ctio

n sc

enar

ios

or s

hort

-ter

m

RC

IC s

cena

rios.

Ref

er to

Not

e (5

).

NR

C-O

SP

-DS

G0S

SW

0 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

0 F

TR

* 1

OR

2 S

SW

P

HV

FT

S

Not

e (5

) N

ote

(5)

2.62

E-0

1 2.

80E

-01

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve,

equ

ipm

ent f

ailu

re

timin

gs d

ue to

loss

of v

entil

atio

n, a

nd

acci

dent

tim

ings

for

no in

ject

ion

scen

ario

s or

sho

rt-t

erm

RC

IC s

cena

rios.

Ref

er to

N

ote

(5).

N

RC

-OS

P-D

SG

1 F

AIL

TO

RE

CO

VE

R

OS

P G

IVE

N U

2 *

1 F

TR

* N

O S

SW

P

HV

FA

ILU

RE

S

Not

e (5

) N

ote

(5)

1.05

E-0

1 1.

11E

-01

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve

and

acci

dent

tim

ings

fo

r no

inje

ctio

n sc

enar

ios

or s

hort

-ter

m

RC

IC s

cena

rios.

Ref

er to

Not

e (5

).

NR

C-O

SP

-DS

G2

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

U2

* 2

FT

R *

NO

SS

W

PH

V F

AIL

UR

ES

Not

e (5

) N

ote

(5)

4.53

E-0

2 4.

77E

-02

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve

and

acci

dent

tim

ings

fo

r no

inje

ctio

n sc

enar

ios

or s

hort

-ter

m

RC

IC s

cena

rios.

Ref

er to

Not

e (5

).

NR

C-O

SP

-PS

G0

FA

IL T

O R

EC

OV

ER

O

SP

GIV

EN

SR

V

LOC

A *

U2

* 0

FT

R

* N

O S

SW

PH

V

FA

ILU

RE

S

Not

e (5

) N

ote

(5)

7.63

E-0

1 7.

82E

-01

Pro

babi

lity

base

d on

con

volu

tion

calc

ulat

ion

of O

SP

rec

over

y cu

rve

and

acci

dent

tim

ing

for

SO

RV

sce

nario

with

no

inje

ctio

n at

t=0.

R

efer

to N

ote

(5).


D

-43

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

C-O

SP

-DS

G0-

L2

Fai

l to

Rec

over

OS

P

Giv

en U

2 *0

FT

R*

No

SS

W P

HV

F

ailu

res

LER

F

Not

e (5

) N

ote

(5)

3.28

E-0

1 3.

36E

-01

Sam

e pe

rcen

tage

incr

ease

as

NR

C-O

SP

-P

SG

0.

NR

C-O

SP

-DS

G0S

0L2

Fai

l to

Rec

over

OS

P

Giv

en U

2 *0

FT

R *

1

or 2

SS

W P

HV

FT

S

LER

F

Not

e (5

) N

ote

(5)

1.64

E-0

1 1.

75E

-01

Sam

e pe

rcen

tage

incr

ease

as

NR

C-O

SP

-D

SG

0SS

W0.

NR

C-O

SP

-DS

G1-

L2

Fai

l to

Rec

over

OS

P

Giv

en U

2 *

1 F

TR

*N

o S

SW

PH

V

Fai

lure

s LE

RF

Not

e (5

) N

ote

(5)

6.47

E-0

2 6.

84E

-02

Sam

e pe

rcen

tage

incr

ease

as

NR

C-O

SP

-D

SG

1.

NR

C-O

SP

-DS

G2-

L2

Fai

l to

Rec

over

OS

P

Giv

en U

2 *

2 F

TR

*N

o S

SW

PH

V

Fai

lure

s LE

RF

Not

e (5

) N

ote

(5)

3.00

E-0

2 3.

16E

-02

Sam

e pe

rcen

tage

incr

ease

as

NR

C-O

SP

-D

SG

2.

NR

C-O

SP

-PS

G0-

L2

Fai

l to

Rec

over

OS

P

Giv

en S

RV

LO

CA

*U

2 *0

FT

R *

No

SS

W P

HV

Fai

lure

s LE

RF

Not

e (5

) N

ote

(5)

3.28

E-0

1 3.

36E

-01

Sam

e pe

rcen

tage

incr

ease

as

NR

C-O

SP

-P

SG

0.


D

-44

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

NR

-PC

S-6

0MN

F

AIL

UR

E T

O

RE

CO

VE

R P

CS

IN

60 M

INU

TE

S

1 hr

50

min

6.

00E

-01

6.00

E-0

1 T

ime

win

dow

is c

onse

rvat

ivel

y ba

sed

on

time

to c

ore

dam

age

in a

tran

sien

t sce

nario

w

ith n

o in

ject

ion

at t=

0. F

or th

e E

PU

, the

tim

e w

indo

w fo

r th

is r

ecov

ery

is r

educ

ed

17%

(w

orst

cas

e re

duct

ion

from

boi

l off

MA

AP

cas

es G

GN

SE

PU

10a,

G

GN

SE

PU

10b,

and

GG

NS

EP

U15

).

Rec

over

y fa

ilure

pro

babi

lity

does

not

ch

ange

due

to s

tep

func

tion

reco

very

m

odel

. N

RS

-GT

4HE

P

Set

a m

inim

um

defa

ult f

or c

utse

ts

with

mor

e th

an fo

ur

HR

A e

vent

s

- -

1.00

E-0

7 1.

00E

-07

Not

a c

alcu

late

d va

lue

base

d on

pla

nt

spec

ific

info

rmat

ion.

Thi

s ev

ent r

emai

ns

unch

ange

d in

the

EP

U.

P41

-FO

-HE

SW

XT

-G

(LO

CA

) O

PE

RA

TO

R F

AIL

S

TO

MA

NU

ALL

Y

ALI

GN

FO

R S

SW

C

RO

SS

-TIE

S

YS

TE

M

20 m

in

17.4

min

8.

90E

-02(4

) 1.

30E

-01(4

)A

llow

able

tim

e ba

sed

on ti

me

to c

ore

dam

age

for

a la

rge

LOC

A w

ith n

o in

ject

ion.

A

llow

able

tim

e w

indo

w r

educ

ed 1

3% fo

r th

e E

PU

(de

term

ined

from

MA

AP

run

G

GN

SE

PU

8).

P47

-FO

-HE

PS

W-X

O

PE

RA

TO

R F

AIL

S

TO

AC

TU

AT

E P

SW

P

UM

P

120

min

12

0 m

in

1.00

E-0

5 1.

00E

-05

Allo

wab

le ti

me

base

d on

tim

e to

sta

rt

stan

dby

pum

p be

fore

load

s af

fect

ed d

ue to

in

adeq

uate

PS

W fl

ow. N

ot d

irect

ly

depe

nden

t on

reac

tor

pow

er.

P47

-FO

-ST

OP

SC

RM

O

pera

tor

fails

to

aver

t scr

am

follo

win

g lo

ss o

f P

SW

Sys

tem

10 m

in

10 m

in

1.70

E-0

2 1.

70E

-02

Allo

wab

le ti

me

base

d on

tim

e to

re-

alig

n lo

ads

and

prev

ent a

scr

am b

efor

e lo

ads

affe

cted

by

inad

equa

te P

SW

flow

. N

ot

dire

ctly

dep

ende

nt o

n re

acto

r po

wer

.


D

-45

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

P51

-FO

-CM

ST

AR

T-T

F

ailu

re to

sta

rt

stan

dby

Ser

vice

Air

Com

pres

sor

60 m

in

50 m

in

4.60

E-0

4(3)

4.60

E-0

4(3)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e ba

sed

on lo

ss o

f fee

dwat

er d

ue to

lo

ss o

f ins

trum

ent a

ir. A

llow

able

tim

e w

indo

w r

educ

ed 1

7% (

wor

st c

ase

redu

ctio

n fr

om b

oil o

ff M

AA

P c

ases

GG

NS

EP

U10

a,

GG

NS

EP

U10

b, a

nd G

GN

SE

PU

15).

P

53-F

O-H

EC

OO

LIA

S

OP

ER

AT

OR

FA

ILS

T

O A

LIG

N S

SW

-B

TO

IAS

C

OM

PR

ES

SO

R

UP

ON

LO

SS

OF

T

BC

W

90 m

in

90 m

in

2.20

E-0

4 2.

20E

-04

Allo

wab

le ti

me

base

d on

tim

e to

fail

com

pres

sors

afte

r T

BC

W s

yste

m fa

ils w

ith

no c

oolin

g. N

ot d

epen

dent

on

reac

tor

pow

er.

P53

-FO

-HE

RE

INF

-T

OP

ER

AT

OR

FA

ILS

T

O R

EIN

ITIA

TE

IA

AS

PE

R

PR

OC

ED

UR

E

360

min

36

0 m

in

1.90

E-0

5 1.

90E

-05

Allo

wab

le ti

me

base

d on

tim

e to

rep

lace

A

DS

gas

bot

tles.

Not

dire

ctly

dep

ende

nt o

n re

acto

r po

wer

.

P64

-FO

-HE

-G

OP

ER

AT

OR

FA

ILS

T

O A

LIG

N

FIR

EW

AT

ER

S

YS

TE

M F

OR

IN

JEC

TIO

N

150

min

14

2 m

in

5.70

E-0

1(4)

6.70

E-0

1(4)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fo

r an

SB

O w

ith R

CIC

ope

ratio

n fo

r at

leas

t 2 h

rs.

Allo

wab

le ti

me

win

dow

re

duce

d 5%

(de

term

ined

from

MA

AP

run

G

GN

SE

PU

6a).

P

64-F

O-H

E-G

(Lo

ng

Ter

m)

OP

ER

AT

OR

FA

ILS

T

O A

LIG

N

FIR

EW

AT

ER

S

YS

TE

M F

OR

IN

JEC

TIO

N

480

min

45

6 m

in

1.10

E-0

2(4)

1.10

E-0

2(4)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fo

r an

SB

O w

ith R

CIC

ope

ratio

n fo

r at

leas

t 6 h

r (t

ime

to b

atte

ry d

eple

tion)

. A

llow

able

tim

e w

indo

w r

educ

ed 5

%

(det

erm

ined

from

MA

AP

run

GG

NS

EP

U6b

).


D

-46

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

R21

-FO

-HE

BO

PT

RM

O

PE

RA

TO

R F

AIL

S

TO

ALI

GN

A

LTE

RN

AT

E

PO

WE

R T

O B

OP

B

US

SE

S

60 m

in

50 m

in

4.50

E-0

4(4)

8.60

E-0

4(4)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fo

r a

tran

sien

t with

loss

of i

njec

tion

at t=

0. A

llow

able

tim

e w

indo

w r

educ

ed 1

7%

(wor

st c

ase

redu

ctio

n fr

om b

oil o

ff M

AA

P

case

s G

GN

SE

PU

10a,

GG

NS

EP

U10

b, a

nd

GG

NS

EP

U15

).

R21

-FO

-HE

ES

FT

RM

O

PE

RA

TO

R F

AIL

S

TO

TR

AN

SF

ER

TO

A

LTE

RN

AT

E

TR

AN

SF

OR

ME

R

60 m

in

50 m

in

4.50

E-0

4(4)

8.60

E-0

4(4)

Allo

wab

le ti

me

base

d on

tim

e to

cor

e da

mag

e fo

r a

tran

sien

t with

loss

of i

njec

tion

at t=

0. A

llow

able

tim

e w

indo

w r

educ

ed 1

7%

(wor

st c

ase

redu

ctio

n fr

om b

oil o

ff M

AA

P

case

s G

GN

SE

PU

10a,

GG

NS

EP

U10

b, a

nd

GG

NS

EP

U15

).

SC

RM

M

AN

UA

L S

CR

AM

F

AIL

UR

E

10 m

in

10 m

in

5.00

E-0

4 5.

00E

-04

Sys

tem

tim

e w

indo

w in

bas

e P

RA

co

nser

vativ

ely

estim

ates

at a

nom

inal

10

min

utes

(sh

orte

r w

indo

w th

an s

yste

m ti

me

win

dow

for

SLC

initi

atio

n).

The

EP

U w

ould

no

t cha

nge

this

con

serv

ativ

e m

odel

ing

assu

mpt

ion.

X

2-A

TW

S

OP

ER

AT

OR

FA

ILS

T

O

DE

PR

ES

SU

RIZ

E

DU

RIN

G A

TW

S

20 m

in

17.4

min

1.

00E

-03(3

) 1.

00E

-03(3

)A

llow

able

tim

e ba

sed

on ti

me

to c

ore

dam

age

form

RP

V le

vel o

f -1

91”

@ t=

10

min

. for

an

AT

WS

in w

hich

insu

ffici

ent h

igh

pres

sure

pre

ferr

ed in

ject

ion

is a

vaila

ble.

A

llow

able

tim

e w

indo

w r

educ

ed 1

3%

(ref

lect

ive

of p

ower

upr

ate)

. T

his

time

redu

ctio

n is

con

sist

ent w

ith M

AA

P r

un

GG

NS

EP

U14

a.


D

-47

Tab

le D

-2

RE

-AS

SE

SS

ME

NT

OF

KE

Y O

PE

RA

TO

R A

CT

ION

HE

Ps

FO

R T

HE

EP

U

Allo

wab

le A

ctio

n T

ime

(1)

Nam

e A

ctio

n D

escr

iptio

n

Cur

rent

P

RA

P

ower

(C

LTP

)

EP

U P

ower

(1

13%

C

LTP

) B

ase

HE

P(2

) E

PU

H

EP

(2)

Not

es

X3

X3-

-D

EP

RE

SU

RIZ

AT

ION

VIA

RC

IC

90 m

in

75 m

in

8.40

E-0

3(4)

1.80

E-0

2(4)

Bas

ed o

n tim

e to

cor

e da

mag

e af

ter

6 ho

urs

of in

ject

ion

usin

g R

CIC

dur

ing

an S

BO

. A

llow

able

tim

e w

indo

w r

educ

ed 1

7%

(det

erm

ined

from

MA

AP

run

GG

NS

EP

U6b

).

X77

-FO

-HE

C00

1A-U

O

PE

RA

TO

R F

AIL

S

TO

TR

AN

SF

ER

F

AN

TO

HIG

H

SP

EE

D

360

min

36

0 m

in

1.00

E-0

5 1.

00E

-05

Bas

ed o

n tim

e to

HP

CS

die

sel f

ailu

re d

ue to

hi

gh te

mpe

ratu

re.

Not

dire

ctly

dep

ende

nt

on r

eact

or p

ower

.

X77

-FO

-HE

C00

1B-U

O

PE

RA

TO

R F

AIL

S

TO

TR

AN

SF

ER

F

AN

TO

HIG

H

SP

EE

D

360

min

36

0 m

in

1.00

E-0

5 1.

00E

-05

Bas

ed o

n tim

e to

HP

CS

die

sel f

ailu

re d

ue to

hi

gh te

mpe

ratu

re. N

ot d

irect

ly d

epen

dent

on

reac

tor

pow

er.

X77

-FO

-HE

CO

O2C

-U

OP

ER

AT

OR

FA

ILS

T

O T

RA

NS

FE

R

FA

N T

O H

IGH

S

PE

ED

360

min

36

0 m

in

1.00

E-0

5 1.

00E

-05

Bas

ed o

n tim

e to

HP

CS

die

sel f

ailu

re d

ue to

hi

gh te

mpe

ratu

re. N

ot d

irect

ly d

epen

dent

on

reac

tor

pow

er.

Y47

-FO

-HE

MO

D-U

O

PE

RA

TO

R F

AIL

S

TO

PR

OV

IDE

A

LTE

RN

AT

E

CO

OLI

NG

210

min

21

0 m

in

3.80

E-0

4 3.

80E

-04

Bas

ed o

n tim

e to

tem

pera

ture

indu

ced

failu

res

in S

SW

pum

p ho

uses

follo

win

g a

failu

re o

f the

ven

tilat

ion

syst

em.

Not

dire

ctly

de

pend

ent o

n re

acto

r po

wer

.


D-48

Notes to Table D-2 (1) The time window in these columns is the “System Time Window”, TSW of the HEP calculations. This

is the time between the cue and the end of the allowable time window (i.e., the point at which performance of the action is moot).

(2) Multiple methods are used for calculating the probabilities for the Grand Gulf HEPs. This includes the HCR/ORE and the ERPI Cause-Based methodologies. The GGNS PRA uses the higher of the HCR/ORE or Cause-Based HEP calculation. Note that HEPs probabilities from the Cause-Based method do not change with small changes in allowable operator action timing.

(3) HEP calculated using Cause-Based method.

(4) HEP calculated using the HCR/ORE method.

(5) The probabilities of the offsite AC recovery terms summarized in this table are based on convolution calculations of the OSP recovery curve and one or more of the following timing variables (as described in GGNS PRA Calculation PRA-GG-01-001S09):

• τP : Time from non-recovered cutset occurrence to core uncovery for an SORV

scenario with no injection at t=0. Estimated at 0.5 hrs for the GGNS CLTP PRA. • τS : Time from non-recovered cutset occurrence to core uncovery for a transient with

core cooling lost within the first 2 hours. Estimated at 1.0 hr for the GGNS CLTP PRA (assumes loss of all injection at t=0).

• τL : Time from non-recovered cutset occurrence to core uncovery for a transient with core cooling lost after the first 2 hours. Estimated at 2.0 hrs for the GGNS CLTP PRA.

• τR : Time from non-recovered cutset occurrence to core uncovery for a transient with RCIC failure due to battery depletion or suppression pool heatup. Estimated at 6.0 hr for the GGNS CLTP PRA.

• τV : Time from loss of SSW pump house ventilation to DG failure. Estimated at 2.0 hrs for the GGNS CLTP PRA.

• Time to containment failure due to overpressurization during a transient with loss of containment heat removal. Estimated at 20 hrs for the GGNS CLTP PRA.

The τV variable is not directly based on core power level and as such is not adjusted for the EPU risk assessment. The other timing variables are adjusted for the EPU, as follows:

• τP : Reduced 11% to 0.445 hours (percentage reduction based on MAAP run GGNSEPU2b).

• τS : Reduced 16% to 0.84 hours (percentage reduction based on MAAP run GGNSEPU10a).

• τL : Reduced 16% to 1.68 hours (percentage reduction based on MAAP run GGNSEPU6a).

• τR : Reduced 16% to 5 hours (percentage reduction based on MAAP run GGNSEPU4).

• Time to containment failure due to overpressurization during a transient with loss of containment heat removal 6educed 17% to 16.6 hours (percentage reduction based on MAAP run GGNSEPU9a).


Appendix E

GGNS EPU MAAP CALCULATIONS


E-1

Appendix E

GGNS EPU MAAP CALCULATIONS

The Modular Accident Analysis Package (MAAP) is used to calculate changes in the

thermal hydraulic profile for specific issues (e.g., boil down timing) to support the GGNS

EPU risk assessment.

MAAP is an industry recognized thermal hydraulics code used to evaluate design basis

and beyond design basis accidents. MAAP (Version 4.0.6) and the latest GGNS MAAP

parameter file (GG406_042710.par) have been used in this evaluation. The parameter file

contains plant specific parameters representing the primary system and containment.

A MAAP “INCLUDE” file (GG406_042710.inc) was also used for all of the MAAP runs.

This INCLUDE file contains workarounds for the latest MAAP Part 21 errors that have

been identified for MAAP versions 4.0.6 and 4.0.7 (MAAP FLAASH #69 and #70). The

suggested corrections have been included. See the INCLUDE file for further details of the

errors and corrections.

MAAP cases of various accident scenarios were defined and run to identify changes in

timings and success criteria due to the EPU. A separate run was made for the CLTP

power and for the EPU power level for each analyzed accident scenario. The pre-EPU

version of each scenario is identified with an ‘x’ in the case identifier (e.g., Case

GGNSEPU1a is an EPU power run and Case GGNSEPU1ax is the corresponding

CLTP power run). A summary of the MAAP runs performed in support of this risk

assessment is provided in Table E-1.


E-2

LOFW, SORV and RCIC In addition to performing MAAP runs to identify accident timing and success criteria

changes for consideration in the EPU risk assessment, a MAAP run was performed to

address NUREG-0737 Item II.K.3.44 (adequate core cooling for LOFW with an

additional single failure) for the GGNS EPU. This scenario is identified here as case

GGNSEPU5a. This scenario is a Loss of Feedwater (LOFW) initiated event with a

SORV and RCIC as the initial high pressure injection source.

Case GGNSEPU5a is designed to prevent RPV emergency depressurization. In this

scenario, LOFW is the initiating event (no credit is given for FW coast down flow into the

RPV). One (1) SRV sticks open during the initial pressure transient and remains stuck

open throughout the run. RCIC is the only high pressure injection source and it auto

initiates as designed. RCIC is not sufficient to prevent RPV level dipping below TAF for

the EPU; however, adequate core cooling is maintained throughout the sequence.

When RPV pressure reduces sufficiently to the LP ECCS interlock pressure, one (1)

train of LPCI auto injects into the RPV (RCIC subsequently trips on low steam

pressure). LPCI flow into the RPV begins at t=1.2 hrs. (pool temperature at this time is

140F).


E

-3

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U1a

M

SIV

Clo

sure

, no

HP

inje

ctio

n, d

ela

yed

ED

, and

1 L

PC

I pu

mp

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

at

t=0

(FW

coa

st d

ow

n flo

w c

redi

ted)

• O

nly

1 S

RV

ava

ilabl

e fo

r in

itial

pr

essu

re tr

ans

ient

• N

o H

P in

ject

ion

• In

itiat

e E

mer

gen

cy R

PV

D

epre

ssur

izat

ion

(usi

ng o

nly

3 S

RV

s)

at M

SC

RW

L (-

191”

)

• In

itiat

e 1

LPC

I pu

mp

at L

P in

terlo

ck

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

1 S

RV

suf

ficie

nt fo

r pr

essu

re c

ontr

ol t

o pr

even

t ex

ceed

ing

RP

V p

ress

ure

oper

abili

ty li

mits

for

Tra

nsie

nts

• V

erify

3 S

RV

s su

ffic

ient

for

RP

V E

D fo

r T

ran

sien

ts

• V

erify

1 L

PC

I pu

mp

succ

ess

ful

14 m

in

20 m

in

26 m

in

Max

tem

p. o

f 15

59o F

17 m

in.

MS

CR

WL

5 hr

. M

ax R

PV

pre

ssur

e of

11

09 p

si w

hen

onl

y 1

SR

V a

vaila

ble.

R

PV

ED

initi

ated

at

t=17

.2 m

in w

ith 3

S

RV

s. T

hus,

3 S

RV

s su

ffic

ient

for

RP

V E

D

for

EP

U fo

r tr

ansi

ents

an

d S

LOC

As

wh

en L

P

EC

CS

ava

ilabl

e.

GG

NS

EP

U1a

x S

ame

as G

GN

SE

PU

1a e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

18.1

min

23

.2 m

in

30.4

min

Max

tem

p of

13

84o F

21.3

min

MS

CR

WL

5 hr

. M

ax R

PV

pre

ssur

e of

10

99 p

si w

hen

onl

y 1

SR

V a

vaila

ble.

R

PV

ED

initi

ated

at t

=

21.3

min

with

3 S

RV

s.

Thu

s, 3

SR

Vs

suff

icie

nt

for

RP

V E

D fo

r C

LTP

fo

r tr

ansi

ents

an

d S

LOC

As

whe

n L

P

EC

CS

ava

ilabl

e.


E

-4

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U1b

LO

FW

, no

HP

inje

ctio

n, d

ela

yed

ED

, an

d 1

LPC

I pu

mp

• E

PU

po

wer

leve

l

• LO

FW

at t

=0

(no

FW

coa

st d

ow

n flo

w

cred

ited)

, SC

RA

M a

t RP

V le

vel

+11

.4”

• M

SIV

s re

mai

n op

en u

ntil

isol

ate

on

low

RP

V le

vel (

Lev

el 1

)

• O

nly

1 S

RV

ava

ilabl

e fo

r in

itial

pr

essu

re tr

ans

ient

• N

o H

P in

ject

ion

• In

itiat

e E

mer

gen

cy R

PV

D

epre

ssur

izat

ion

(usi

ng o

nly

3 S

RV

s)

at M

SC

RW

L (-

191”

)

• In

itiat

e 1

LPC

I pu

mp

at L

P in

terlo

ck

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

1 S

RV

suf

ficie

nt fo

r pr

essu

re c

ontr

ol t

o pr

even

t ex

ceed

ing

RP

V p

ress

ure

oper

abili

ty li

mits

for

Tra

nsie

nts

• V

erify

3 S

RV

suf

ficie

nt fo

r R

PV

ED

for

Tra

nsi

ents

• V

erify

tim

e to

MS

IV c

losu

re

from

RP

V L

evel

3

4.4

min

9.

9 m

in.

17.4

min

Max

tem

p. o

f 15

70o F

7.0

min

.

MS

CR

WL

5 hr

. S

ame

as c

ase

GG

NS

EP

U1a

exp

ect

LOF

W a

t t=

0.

Max

RP

V p

ress

ure

1043

psi

. T

here

fore

, ca

se G

GN

SE

PU

1a

boun

ds th

e R

PV

ov

erpr

essu

re s

ucce

ss

crite

ria fo

r tr

ansi

ents

w

ith M

SIV

clo

sure

for

the

EP

U c

ondi

tion.

M

SIV

s cl

ose

at t=

3 m

in.

RP

V E

D in

itiat

ed a

t t=

7.0

min

. (M

SC

RW

L)

with

3 S

RV

s. T

hus

, 3

SR

Vs

suff

icie

nt fo

r R

PV

ED

for

EP

U fo

r tr

ansi

ents

and

SLO

CA

s w

hen

LP

EC

CS

av

aila

ble.


E

-5

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U1b

x S

ame

as G

GN

SE

PU

1b e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

5.6

min

12

.0 m

in.

18.2

min

Max

tem

p. o

f 13

20o F

9.1

min

MS

CR

WL

5 hr

. M

ax R

PV

pre

ssur

e 10

98 p

si.

The

refo

re,

case

GG

NS

EP

U1a

x bo

unds

the

RP

V

Ove

rpre

ssu

re s

ucc

ess

cr

iteria

for

tran

sien

ts

with

MS

IV c

losu

re fo

r th

e C

LTP

con

ditio

n.

MS

IV c

lose

at t

=4

min

. R

PV

ED

initi

ated

at

t=9.

1 m

in (

MS

CR

WL)

. T

hus,

3 S

RV

s su

ffic

ient

fo

r R

PV

ED

for

CLT

P

for

tran

sien

ts a

nd

SLO

CA

s w

hen

LP

E

CC

S a

vaila

ble.


E

-6

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U1c

LO

FW

, no

HP

inje

ctio

n, d

ela

yed

ED

, an

d 1

LPC

I pu

mp

• E

PU

po

wer

leve

l

• LO

FW

du

e to

FW

trip

at L

evel

9 a

t t=

0 (n

o F

W c

oast

do

wn

flow

cre

dite

d)

• In

itial

RP

V le

vel a

t Lev

el 9

whe

n LO

FW

an

d sc

ram

occ

ur

• M

SIV

s re

mai

n op

en u

ntil

isol

ate

on

low

RP

V le

vel (

Lev

el 1

)

• O

nly

1 S

RV

ava

ilabl

e fo

r in

itial

pr

essu

re tr

ans

ient

• N

o H

P in

ject

ion

• R

PV

ED

(us

ing

onl

y 3

SR

Vs)

at

MS

CR

WL

(-19

1”)

• In

itiat

e 1

LPC

I pu

mp

at L

P in

terlo

ck

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

tim

e to

MS

IV c

losu

re

from

RP

V L

evel

9

9.5

min

16

min

n/

a

Max

tem

p. a

t t =

0

13.2

min

MS

CR

WL

5 hr

. M

SIV

s cl

ose

at L

evel

1

at t

= 7

.9 m

in fr

om

Le

vel 9

initi

al w

ater

le

vel.

GG

NS

EP

U1c

x S

ame

as G

GN

SE

PU

1c e

xcep

t Pre

-EP

U

(CLT

P)

pow

er

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

13 m

in

19 m

in

n/a

Max

tem

p. a

t t =

0

16 m

in

MS

CW

RL

5 hr

. M

SIV

s cl

ose

at L

evel

1

at t

= 9

.6 m

in fr

om

Le

vel 9

initi

al w

ater

le

vel.

GG

NS

EP

U2a

S

OR

V, M

SIV

Clo

sure

, no

inje

ctio

n,

RP

V E

D a

llow

ed

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

at

t=0

(FW

coa

st

dow

n flo

w c

redi

ted)

• N

o H

P o

r LP

inje

ctio

n

• R

PV

ED

at R

PV

leve

l -19

1”

• F

ind

time

to c

ore

dam

age

with

SO

RV

and

no

inje

ctio

n an

d R

PV

ED

11 m

in

15 m

in

23.5

min

Cor

e D

amag

e

14 m

in

MS

CR

WL

5 hr

. R

PV

ED

initi

ated

at

t=14

min

(M

SC

RW

L).

Cor

e da

mag

e oc

curs

at

t = 2

3.5

min

.


E

-7

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U2a

x S

ame

as G

GN

SE

PU

2a e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

12 m

in

18 m

in

27.7

min

Cor

e D

amag

e

15 m

in

MS

CR

WL

5 hr

. R

PV

ED

initi

ated

at

t=15

min

, C

ore

dam

age

occu

rs a

t t =

27.

7 m

in.

GG

NS

EP

U2b

S

OR

V, M

SIV

Clo

sure

, no

inje

ctio

n, n

o R

PV

ED

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

at

t=0

(FW

coa

st

dow

n flo

w c

redi

ted)

• N

o H

P o

r LP

inje

ctio

n

• N

o R

PV

ED

• F

ind

time

to c

ore

dam

age

with

SO

RV

and

no

inje

ctio

n an

d no

RP

V E

D

11 m

in

20 m

in

28.1

min

Cor

e D

amag

e

1.8

hr

HC

TL

5 hr

. S

ame

as G

GN

SE

PU

2a

exce

pt w

ith n

o R

PV

E

D.

Cor

e da

mag

e oc

curs

at

t=28

.1 m

in.

GG

NS

EP

U2b

x S

ame

as G

GN

SE

PU

2b e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

12 m

in

22 m

in

31.4

min

Cor

e D

amag

e

2.2

hr.

HC

TL

5 hr

. C

ore

dam

age

occu

rs a

t t =

31.

4 m

in.

GG

NS

EP

U3a

M

SIV

Clo

sure

, RC

IC In

itial

Suc

cess

, R

PV

ED

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

at

t=0

(FW

coa

st

dow

n flo

w c

redi

ted)

• R

CIC

aut

o in

itiat

es

• R

CIC

man

ual

con

trol

to m

aint

ain

RP

V le

vel a

t nor

mal

• R

CIC

fails

at t

= 2

hrs,

no

othe

r in

ject

ion

• R

PV

ED

if E

OP

s di

rect

(e.

g. H

CT

L

or R

PV

leve

l -19

1”)

• F

ind

time

to c

ore

dam

age

with

inje

ctio

n fa

ilure

at t

=2

hr

and

RP

V E

D

2.86

hr

2.97

hr

3.24

hr

Cor

e D

amag

e

2.95

hr

MS

CR

WL

5 hr

. R

CIC

aut

o in

itiat

es a

nd

cont

rols

rea

ctor

wat

er

leve

l at n

orm

al (

+36

.7”)

un

til fa

ilure

at t

= 2

hr.

R

PV

ED

initi

ated

at

t=2.

95 h

r (M

SC

RW

L).

Cor

e da

mag

e oc

curs

at

t = 3

.24

hr.

GG

NS

EP

U3a

x S

ame

as G

GN

SE

PU

3a e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

3.03

hr

3.16

hr

3.45

hr

Cor

e D

amag

e

3.13

hr

MS

CR

WL

5 hr

. R

PV

ED

initi

ated

at

t=3.

13 h

r (M

SC

RW

L).

Cor

e da

mag

e oc

curs

at

t = 3

.45

hr.


E

-8

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U3b

M

SIV

Clo

sure

, RC

IC In

itial

Suc

cess

, no

RP

V E

D

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

at

t=o

(FW

coa

st

dow

n flo

w c

redi

ted)

• R

CIC

aut

o in

itiat

es

• R

CIC

man

ual

con

trol

to m

aint

ain

RP

V le

vel a

t nor

mal

• R

CIC

fails

at t

= 2

hrs,

no

othe

r in

ject

ion

• N

o R

PV

ED

• F

ind

time

to c

ore

dam

age

with

inje

ctio

n fa

ilure

at t

=2

hr

and

no R

PV

ED

2.86

hr

3.21

hr

3.43

hr

Cor

e D

amag

e

2.97

hr

MS

CR

WL

5 hr

. S

ame

as G

GN

SE

PU

3a

exce

pt w

ith n

o R

PV

E

D.

Cor

e da

mag

e oc

curs

at

t = 3

.43

hr.

Ope

rato

r A

ctio

ns:

• B

21-F

O-H

ED

EP

2-L

GG

NS

EP

U3b

x S

ame

as G

GN

SE

PU

3b e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

3.03

hr

3.45

hr

3.67

hr

Cor

e D

amag

e

3.16

hr

MS

CR

WL

5 hr

. C

ore

dam

age

occu

rs a

t 3.

67 h

r.

GG

NS

EP

U4

SB

O w

ith R

CIC

inje

ctio

n, N

o ot

her

inje

ctio

n

• E

PU

po

wer

leve

l

• S

BO

at t

=0

(no

FW

coa

st d

own

flow

cr

edite

d)

• A

ll S

Vs/

SR

Vs

ava

ilab

le f

or in

itia

l pr

essu

re tr

ans

ient

• O

nly

RC

IC a

vaila

ble

for

inje

ctio

n,

suct

ion

from

the

pool

onl

y

• R

CIC

ope

rate

s u

ntil

failu

re a

t S/P

te

mp

= 2

00F

• N

o S

PM

U o

r S

PC

• F

ind

time

to h

igh

supp

ress

ion

pool

te

mpe

ratu

re o

f 200

F w

hen

RC

IC is

ope

ratin

g (a

nd n

o co

ntai

nmen

t hea

t re

mov

al)

6.26

hr

6.38

hr

6.69

hr

Cor

e D

amag

e

6.36

hr

MS

CR

WL

24 h

r.

S/P

tem

p >

200o F

at

t=5.

12 h

r.

With

RC

IC tr

ippe

d of

f at

S/P

tem

p >

200o F

co

re d

amag

e oc

curs

at

t = 6

.69

hr.

Ope

rato

r A

ctio

ns:

• E

12-F

O-H

ES

PC

-M

• N

R-A

CH

WR

-8H

RS

GG

NS

EP

U4

x S

ame

as G

GN

SE

PU

4 ex

cept

Pre

-EP

U

(CLT

P)

pow

er

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

7.40

hr

7.56

hr

7.92

hr

Cor

e D

amag

e

7.55

hr

MS

CR

WL

5 hr

. S

/P te

mp

>20

0o F a

t t=

6.11

hr.

C

ore

dam

age

occu

rs a

t t =

7.9

2 hr

.


E

-9

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U5a

LO

FW

, SO

RV

, RC

IC fo

r in

itial

inje

ctio

n,

no R

PV

ED

, and

1 L

PC

I pum

p

• E

PU

po

wer

leve

l •

LOF

W a

t t=

0 (

no F

W c

oast

do

wn

flow

cr

edite

d)

• M

SIV

s re

mai

n op

en u

ntil

isol

ate

on

low

RP

V le

vel

• A

ll S

RV

s/S

Vs

avai

labl

e fo

r in

itial

pr

essu

re c

ontr

ol

• O

ne (

1) S

OR

V

• O

nly

HP

inje

ctio

n is

RC

IC (

auto

in

itiat

es)

• N

o R

PV

ED

•

1 LP

CI p

ump

inje

cts

at E

CC

S L

P

inte

rlock

•

SP

C w

/1 R

HR

trai

n in

itiat

ed a

t poo

l te

mp.

90°

F(3

)

• V

erify

that

RC

IC a

nd th

en 1

LP

CI p

ump

is s

uffic

ient

to

prev

ent c

ore

dam

age

durin

g LO

FW

w/S

OR

V (

also

app

lies

to S

LOC

A c

ase)

11.2

min

n/

a n/

a

Max

tem

p. a

t t =

0

N/A

5

hr.

RC

IC o

n at

t=45

sec

. M

SIV

s cl

ose

at t

= 6

.15

min

due

to lo

w w

ater

le

vel.

RP

V le

vel d

ips

belo

w T

AF

at

t=1

1.2

min

, nev

er r

each

es

MS

CW

RL,

and

the

n le

vel i

ncr

ea

ses

back

ab

ove

TA

F a

nd

cont

inue

s to

ris

e.

LPC

I flo

w b

egin

s at

t=

1.2

hr.

RC

IC th

en 1

LP

CI

pum

p is

suc

cess

ful f

or

LOF

W w

/ SO

RV

. T

his

case

add

ress

es

II.K

.3.4

4 of

NU

RE

G-

0737

(ad

equ

ate

core

co

olin

g fo

r LO

FW

with

an

add

ition

al s

ingl

e fa

ilure

) fo

r E

PU

.


E

-10

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U5a

x S

ame

as G

GN

SE

PU

5a e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

N/A

n/

a n/

a

Max

tem

p. a

t t =

0

N/A

5

hr.

Sam

e co

mm

ent

as o

f ca

se G

GN

SE

PU

5a,

exce

pt c

ase

is fo

r C

LTP

. LP

CI f

low

be

gins

a t

= 1

.0 h

r.

RP

V le

vel d

ips

and

reco

vers

in s

ame

man

ner

as E

PU

cas

e,

but T

AF

is n

ot r

eac

hed

for

this

pre

-EP

U c

ase

(leve

l dip

s to

6”

abov

e T

AF

).

GG

NS

EP

U6a

S

BO

with

RC

IC in

ject

ion,

No

othe

r in

ject

ion

• E

PU

po

wer

leve

l

• S

BO

at t

=0

(no

FW

coa

st d

own

flow

cr

edite

d)

• A

ll S

Vs/

SR

Vs

ava

ilab

le f

or in

itia

l pr

essu

re tr

ans

ient

• R

CIC

man

ual

con

trol

to m

aint

ain

RP

V le

vel a

t nor

mal

• R

CIC

ope

rate

s u

ntil

failu

re a

t t=

2 hr

• N

o S

PM

U o

r S

PC

• N

o R

PV

ED

• V

erify

tim

ing

to c

ore

dam

age

afte

r R

CIC

inje

ctio

n fa

ils a

t t=

2hr

2.90

hr

3.23

hr

3.45

hr

Cor

e D

amag

e

3.00

hr

MS

CR

WL

5 hr

. R

CIC

suc

tion

fro

m

CS

T.

Cor

e da

mag

e oc

curs

at

t = 3

.45

hr.

Ope

rato

r A

ctio

ns:

• P

64-F

O-H

E-G

GG

NS

EP

U6a

x S

ame

as G

GN

SE

PU

6a e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

2.98

hr

3.38

hr

3.62

hr

3.08

hr

MS

CR

WL

5 hr

C

ore

dam

age

occu

rs a

t t =

3.6

2 hr

.


E

-11

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U6b

S

BO

with

RC

IC in

ject

ion,

No

othe

r in

ject

ion

• E

PU

po

wer

leve

l

• S

BO

at t

=0

(no

FW

coa

st d

own

flow

cr

edite

d)

• A

ll S

Vs/

SR

Vs

ava

ilab

le f

or in

itia

l pr

essu

re tr

ans

ient

• R

CIC

man

ual

con

trol

to m

aint

ain

RP

V le

vel a

t nor

mal

• R

CIC

ope

rate

s u

ntil

failu

re a

t t=

6 hr

• N

o S

PM

U o

r S

PC

• N

o R

PV

ED

• V

erify

tim

ing

to c

ore

dam

age

afte

r R

CIC

inje

ctio

n fa

ils a

t t=

6 hr

7.22

hr

7.61

hr

7.90

hr

Cor

e D

amag

e

2.42

hr

HC

TL

7.34

hr

MS

CR

WL

24 h

r.

Cor

e da

mag

e oc

curs

at

t = 7

.90

hr.

Ves

sel B

reac

h oc

curs

at

t =

11.

3 hr

.

Ope

rato

r A

ctio

ns:

• P

64-F

O-H

E-G

(LO

NG

T

ER

M)

• X

3

GG

NS

EP

U6b

x S

ame

as G

GN

SE

PU

6b e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

7.51

hr

7.96

hr

8.28

hr

Cor

e D

amag

e

2.92

hr

HC

TL

7.66

hr

MS

CR

WL

24 h

r C

ore

dam

age

occu

rs a

t t =

8.2

8 hr

.

Ves

sel B

reac

h oc

curs

at

t =

12.

2 hr

.

GG

NS

EP

U7a

La

rge

Wat

er B

reak

LO

CA

, HP

CS

• E

PU

po

wer

leve

l

• LL

OC

A in

rec

irc s

uctio

n lin

e at

t=0

• N

o R

PV

Em

erge

ncy

De

pres

suriz

atio

n

• S

PC

w/ 1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erif

y su

cce

ss o

f H

PC

S

inje

ctio

n fo

r LL

OC

A (

LLO

CA

E

T s

ucc

ess

crit

erio

n)

5.6

sec

8.3

sec

n/a

Max

tem

p. a

t t =

0

6.2

sec

MS

CR

WL

24 h

r H

PC

S a

uto

initi

ates

an

d au

to c

ycle

s at

t=32

se

c.

Ca

se s

ho

ws

HP

CS

su

cces

sful

for

a LL

OC

A fo

r 24

ho

urs

for

the

EP

U c

ondi

tion.

GG

NS

EP

U7a

x S

ame

as G

GN

SE

PU

7a e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

5.7

sec

8.8

sec

n/a

Max

tem

p. a

t t =

0

6.4

sec

MS

CR

WL

24 h

r C

ase

show

s H

PC

S

succ

essf

ul fo

r a

LLO

CA

for

24 h

our

s fo

r th

e C

LTP

con

ditio

n.


E

-12

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U7b

La

rge

Wat

er B

reak

LO

CA

, 1 L

PC

I pum

p

• E

PU

po

wer

leve

l

• LL

OC

A in

rec

irc s

uctio

n lin

e at

t=0

• N

o R

PV

Em

erge

ncy

De

pres

suriz

atio

n

• In

itiat

e 1

LPC

I pu

mp

at L

P in

terlo

ck

• N

o H

P in

ject

ion

• S

PC

w/ 1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

suc

cess

of

1 LP

CI

pum

p in

ject

ion

for

LLO

CA

(L

LOC

A E

T s

ucce

ss c

riter

ion)

5.6

sec

8.3

sec

n/a

Max

tem

p. a

t t =

0

6.2

sec

MS

CR

WL

24 h

r LP

CI a

uto

initi

ates

and

au

to c

ycle

s at

t=33

se

c.

Ca

se s

ho

ws

LP

CI

succ

essf

ul fo

r a

LLO

CA

for

24 h

our

s fo

r th

e E

PU

con

ditio

n.

GG

NS

EP

U7b

x S

ame

as G

GN

SE

PU

7b e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

5.7

sec

8.8

sec

n/a

Max

tem

p. a

t t =

0

6.4

sec

MS

CW

RL

24 h

r C

ase

sho

ws

LPC

I su

cces

sful

for

a LL

OC

A fo

r 24

ho

urs

for

the

CLT

P c

ondi

tion.

GG

NS

EP

U8

Larg

e W

ater

Bre

ak L

OC

A, N

o in

ject

ion

• E

PU

po

wer

leve

l

• LL

OC

A in

rec

irc s

uctio

n lin

e at

t=0

• N

o R

PV

Em

erge

ncy

De

pres

suriz

atio

n

• N

o LP

or

HP

inje

ctio

n

• S

PC

w/ 1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

tim

e to

cor

e da

mag

e fo

r LL

OC

A

14.4

sec

29

.5 s

ec

5.5

min

Cor

e D

amag

e

15.4

sec

MS

CR

WL

5 hr

C

ore

dam

age

occu

rs a

t t =

5.5

min

for

LLO

CA

an

d no

inje

ctio

n.

Ope

rato

r A

ctio

ns:

• P

41-F

O-H

ES

WX

T-G

(L

OC

A)

GG

NS

EP

U8

x S

ame

as G

GN

SE

PU

8 ex

cept

Pre

-EP

U

(CLT

P)

pow

er

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

15.4

sec

29

.8 s

ec

6.3

min

Cor

e D

amag

e

16.1

sec

MS

CR

WL

5 hr

C

ore

dam

age

occu

rs a

t t =

6.3

min

for

LLO

CA

an

d no

inje

ctio

n.


E

-13

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U9a

T

rans

ient

with

loss

of c

onta

inm

ent h

eat

rem

oval

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

at

t=0

(no

FW

coa

st

dow

n flo

w c

redi

ted)

• A

ll S

Vs/

SR

Vs

avai

labl

e fo

r in

itial

pr

essu

re tr

ans

ient

• H

PC

S o

nly

inje

ctio

n so

urce

• R

PV

ED

on

HC

TL

• N

o R

HR

SP

C o

r co

ntai

nmen

t ven

ting

avai

labl

e

• A

ll in

ject

ion

fails

at

time

of

cont

ainm

ent f

ailu

re

• Id

entif

y tim

e fr

ames

for

cont

ainm

ent v

entin

g, R

HR

S

PC

initi

atio

n, a

nd u

ltim

ate

cont

ainm

ent f

ailu

re d

ue to

ov

erpr

essu

re

• Id

entif

y tim

e to

cor

e da

mag

e fo

llow

ing

inje

ctio

n fa

ilure

at

time

of c

onta

inm

ent f

ailu

re

23.2

hr

23.4

hr

23.8

hr

Cor

e D

amag

e

2.3

hr

HC

TL

48 h

r.

Thi

s ru

n m

odel

s co

ntai

nmen

t fai

lure

due

to

ove

rpre

ssur

e at

64.

9 ps

ig (

whi

ch o

ccu

rs a

t 22

.3 h

r.)

S/P

tem

p >

200o F

at

t=3.

7 hr

and

>2

60o F

at

t=11

.2 h

r.

Ope

rato

r A

ctio

ns:

• N

RC

-OS

P-C

NT

•

M41

-FO

-AV

VC

NT

-Q

Tim

e fr

om 2

2.4

psi

g to

56

psi

g co

ntai

nmen

t pr

essu

re r

educ

ed 1

7%

for

the

EP

U.

GG

NS

EP

U9a

x S

ame

as G

GN

SE

PU

11a

exce

pt P

re-

EP

U (

CLT

P)

pow

er o

f 389

8 M

Wth

. <

Sam

e as

cas

e ab

ove>

27

.9 h

r 28

.0 h

r 28

.5 h

r

Cor

e D

amag

e

2.7

hr

HC

TL

48 h

r.

Thi

s ru

n m

odel

s co

ntai

nmen

t fai

lure

due

to

ove

rpre

ssur

e at

64.

9 ps

ig (

whi

ch o

ccu

rs a

t t=

26.9

hr.

) S

/P te

mp

>20

0o F a

t t=

4.3

hr a

nd >

26

0o F a

t t=

13.4

hr.


E

-14

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U9b

T

rans

ient

with

loss

of c

onta

inm

ent h

eat

rem

oval

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

at

t=0

(no

FW

coa

st

dow

n flo

w c

redi

ted)

• A

ll S

Vs/

SR

Vs

avai

labl

e fo

r in

itial

pr

essu

re tr

ans

ient

• H

PC

S o

nly

inje

ctio

n so

urce

• R

PV

ED

(us

ing

onl

y 3

SR

Vs)

on

HC

TL

• N

o R

HR

SP

C

• C

onta

inm

ent v

ent w

ith 2

0” d

ia.

emer

genc

y ve

nt p

ath

at c

onta

inm

ent

pres

sure

of 2

2.4

psig

• In

ject

ion

afte

r ve

nt is

CR

D 2

pum

ps

(fai

l HP

CS

at t

ime

of v

ent)

• V

erify

con

tain

me

nt v

ent

succ

essf

ul f

or lo

ss o

f co

ntai

nmen

t hea

t re

mov

al

N/A

N

/A

N/A

N

/A

24 h

r.

Em

erge

ncy

vent

in

itiat

ion

occu

rs a

t t=

9.9

hrs.

E

mer

genc

y co

ntai

nmen

t ven

t is

a su

cces

sful

con

tain

men

t he

at r

emov

al o

ptio

n.

GG

NS

EP

U9b

x S

ame

as G

GN

SE

PU

11b

exce

pt P

re-

EP

U (

CLT

P)

pow

er o

f 389

8 M

Wth

. <

Sam

e as

cas

e ab

ove>

N

/A

N/A

N

/A

N/A

24

hr.

E

mer

genc

y ve

nt

initi

atio

n oc

curs

at

t=11

.8 h

rs.

Em

erge

ncy

cont

ainm

ent v

ent i

s a

succ

essf

ul c

onta

inm

ent

heat

rem

oval

opt

ion.


E

-15

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U10

a M

SIV

Clo

sure

, no

inje

ctio

n an

d no

RP

V

ED

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

at

t=0

(no

FW

coa

st

dow

n flo

w c

redi

ted)

• A

ll S

Vs/

SR

Vs

avai

labl

e fo

r in

itial

pr

essu

re tr

ans

ient

• N

o H

P o

r LP

inje

ctio

n

• N

o R

PV

ED

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

tim

e to

cor

e da

mag

e fo

r a

loss

of i

njec

tion

HP

cor

e da

mag

e tr

ans

ient

14.5

min

24

.4 m

in

32.8

min

Cor

e D

amag

e

16.6

min

MS

CR

WL

5 hr

. C

ore

dam

age

occu

rs a

t t =

32.

8 m

in w

/ no

inje

ctio

n or

RP

V E

D.

Ope

rato

r A

ctio

ns:

• B

21-F

O-H

ED

EP

2-I

• E

51-F

O-H

ET

RP

BY

P

• N

R-P

CS

-60M

IN

• P

51-F

O-C

MS

TA

RT

-T

GG

NS

EP

U10

ax

Sam

e as

GG

NS

EP

U10

a ex

cept

Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

17.6

min

29

.8 m

in

39.2

min

Cor

e D

amag

e

20.2

min

MS

CR

WL

5 hr

. C

ore

dam

age

occu

rs a

t t =

39.

2 m

in.

GG

NS

EP

U10

b M

SIV

Clo

sure

, no

inje

ctio

n an

d no

RP

V

ED

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

at

t=0

(no

FW

coa

st

dow

n flo

w c

redi

ted)

• A

ll S

Vs/

SR

Vs

avai

labl

e fo

r in

itial

pr

essu

re tr

ans

ient

• N

o H

P o

r LP

inje

ctio

n

• R

PV

ED

(us

ing

onl

y 3

SR

Vs)

at R

PV

le

vel -

191”

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

tim

e to

cor

e da

mag

e fo

r a

loss

of i

njec

tion

LP c

ore

dam

age

tra

nsie

nt

14.5

min

17

.6 m

in

26.5

min

Cor

e D

amag

e

15.2

min

MS

CR

WL

5 h

r.

Sam

e as

G

GN

SE

PU

10a

exc

ept

with

RP

V E

D.

RP

V E

D in

itiat

ed a

t t=

15.2

min

(M

SC

RW

L).

Cor

e da

mag

e oc

curs

at

t = 2

6.5

min

. O

pera

tor

Act

ions

:

• R

21-F

O-H

EB

OP

TR

M

• R

21-F

O-H

EE

SF

TR

M

• N

R-A

CH

WR

-1H

RS


E

-16

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U10

bx

Sam

e as

GG

NS

EP

U10

b ex

cept

Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

17.6

min

21

.6 m

in

32.1

min

Cor

e D

amag

e

18.5

min

MS

CR

WL

5 hr

. R

PV

ED

initi

ated

at

t=18

.5 m

in (

MS

CR

WL)

. C

ore

dam

age

occu

rs a

t t =

32.

1 m

in.

GG

NS

EP

U11

Is

olat

ion

AT

WS

, HP

CS

, no

leve

l co

ntro

l, no

SLC

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

AT

WS

at t

=0

(no

FW

co

ast d

own

flow

cre

dite

d)

• R

PT

(bo

th p

ump

s) s

ucce

ssfu

l

• N

o R

CIC

• H

PC

S a

uto

initi

ate

and

auto

con

trol

• N

o S

PC

• V

erify

tim

e av

aila

ble

to

initi

ate

SLC

(T

ime

to S

P

flash

ing)

77 s

ec

1.45

hr

1.67

hr

Cor

e D

amag

e

97 s

ec

MS

CR

WL

17.6

min

H

CT

L

5 hr

. S

/P te

mp

>21

2o F a

t t=

49.1

min

. S

/P te

mp

>26

0o F a

t t=

1.42

hr.

O

pera

tor

Act

ions

:

• C

41-F

O-H

E1P

MP

-S

GG

NS

EP

U11

x •

Sam

e as

GG

NS

EP

U9a

exc

ept P

re-

EP

U (

CLT

P)

pow

er o

f 389

8 M

Wth

. <

Sam

e as

cas

e ab

ove>

92

sec

1.

45 h

r 1.

70 h

r

Cor

e D

amag

e

116

sec

MS

CR

WL

17.6

min

HC

TL

5 hr

. S

/P te

mp

>21

2o F a

t t=

49.4

min

. S

/P te

mp

>26

0o F a

t t=

1.42

hr.


E

-17

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U12

M

SIV

Clo

sure

, no

RP

V E

D

• E

PU

po

wer

leve

l

• M

SIV

Clo

sure

at

t=0

(no

FW

coa

st

dow

n flo

w c

redi

ted)

• A

ll S

Vs/

SR

Vs

avai

labl

e fo

r in

itial

pr

essu

re tr

ans

ient

• H

PC

S in

ject

ion

until

t =

5hr

• N

o R

PV

ED

• N

o C

RD

inje

ctio

n a

t t=

0

• 2

CR

D p

umps

at

200

gpm

tota

l at

t=5h

rs

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erif

y C

RD

inje

ctio

n s

ucc

ess

cr

iteria

n/

a n/

a n/

a 6.

07 h

r

HC

TL

24 h

r A

ssum

es C

ST

has

un

limite

d vo

lum

e. C

ST

w

ill r

un o

ut o

f w

ate

r at

t=

13.4

hr

for

the

pre-

EP

U c

ase

and

t=11

.6

hr f

or th

e E

PU

cas

e.

CR

D is

suc

cess

ful f

or

the

EP

U c

ondi

tion

as

for

the

pre

-EP

U a

fter

anot

her

inje

ctio

n so

urce

run

s la

sts

for

5 ho

urs.

GG

NS

EP

U12

x S

ame

as G

GN

SE

PU

12 e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

n/a

n/a

n/a

n/a

24 h

r.

CR

D is

suc

cess

ful f

or

the

CLT

P a

fter

ano

ther

in

ject

ion

sour

ce r

uns

for

5 ho

urs

.


E

-18

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U13

a T

urbi

ne T

rip A

TW

S, w

ith F

W t

rip a

t L9

• E

PU

po

wer

leve

l

• T

urbi

ne T

rip a

t t=

0

• F

ailu

re to

scr

am

• R

PT

(bo

th p

ump

s) s

ucce

ssfu

l

• A

ll S

Vs/

SR

Vs

avai

labl

e fo

r in

itial

pr

essu

re tr

ans

ient

• A

uto

cont

rol F

W (

do n

ot p

erf

orm

A

TW

S le

vel r

educ

tion)

• F

W u

ncon

trol

led

trip

occ

urs

at t

= 5

m

ins

• N

o R

PV

ED

• R

CIC

aut

o in

itiat

es

• N

o ot

her

inje

ctio

n av

aila

ble

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

tim

e to

MS

IV c

losu

re

for

AT

WS

sce

nari

o w

ith F

W

trip

at t

=5m

ins

6.3

min

n/

a n/

a

Max

tem

p at

t =

0

6.5

min

MS

CR

WL

5 hr

. F

eed

wat

er tr

ips

afte

r 5

min

s an

d re

acto

r w

ate

r le

vel d

rops

bel

ow T

AF

be

fore

RC

IC in

itiat

es.

Tim

e to

MS

IV c

losu

re

at le

vel 1

afte

r F

W tr

ip

is 7

1 se

c.

Ope

rato

r A

ctio

ns:

• N

21-F

O-H

EP

CS

-G

(AT

WS

)

GG

NS

EP

U13

ax

Sam

e as

GG

NS

EP

U13

a ex

cept

Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

6.5

min

n/

a n/

a

Max

tem

p at

t =

0

6.6

min

MS

CR

WL

5 hr

. T

ime

to M

SIV

clo

sure

at

RP

V le

vel 1

afte

r F

W

trip

is 7

8 se

c.


E

-19

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U13

b T

urbi

ne T

rip A

TW

S, w

ith F

W t

rip a

t L9

• E

PU

po

wer

leve

l

• T

urbi

ne T

rip a

t t=

0

• F

ailu

re to

scr

am

• R

PT

(bo

th p

ump

s) s

ucce

ssfu

l

• A

ll S

Vs/

SR

Vs

avai

labl

e fo

r in

itial

pr

essu

re tr

ans

ient

• A

uto

cont

rol F

W (

do n

ot p

erf

orm

A

TW

S le

vel r

educ

tion)

• F

W u

ncon

trol

led

ram

p-up

to L

evel

9

trip

occ

urs

at t

= 2

0min

s

• N

o R

PV

ED

• R

CIC

aut

o in

itiat

es

• N

o ot

her

inje

ctio

n av

aila

ble

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

tim

e to

MS

IV c

losu

re

for

AT

WS

sce

nari

o w

ith F

W

trip

on

RP

V L

9 at

t =

20m

ins

21.2

min

26

.7 m

in

34.8

min

7.

0 m

in

HC

TL

21.5

min

MS

CR

WL

5 hr

. T

ime

to M

SIV

clo

sure

on

RP

V L

1 af

ter

FW

tr

ip is

70

sec.

O

pera

tor

Act

ions

:

• N

21-F

O-H

ELV

L9-I

(A

TW

S)

GG

NS

EP

U13

bx

Sam

e as

GG

NS

EP

U13

b ex

cept

Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

21.5

min

n/

a n/

a

Max

tem

p at

t =

0

21.7

min

MS

CR

WL

5 hr

. T

ime

to M

SIV

clo

sure

on

RP

V L

1 af

ter

FW

tr

ip is

78

sec.

GG

NS

EP

U14

a Is

olat

ion

AT

WS

, no

HP

inje

ctio

n, n

o R

PV

ED

• E

PU

po

wer

leve

l

• M

SIV

clo

sure

at t

=0

• R

PT

(bo

th p

ump

s) s

ucce

ssfu

l

• A

ll S

Vs/

SR

Vs

avai

labl

e fo

r in

itial

pr

essu

re tr

ans

ient

• N

o H

P in

ject

ion

• N

o R

PV

ED

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

tim

e to

cor

e da

mag

e fo

r H

P A

TW

S s

cena

rio

69 s

ec

3.5

min

9.

7 m

in

Cor

e D

amag

e

102

sec

MS

CR

WL

5 hr

. R

PV

L1

occu

rs a

t t=

60

sec.

C

ore

dam

age

occu

rs a

t t =

9.7

min

. O

pera

tor

Act

ions

:

• E

22-F

O-D

FE

AT

HP

CS

• IN

HIB

IT

• X

2-A

TW

S

Boi

l off

tim

e to

RP

V L

1 re

duce

d 13

% fo

r E

PU

.


E

-20

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U14

ax

Sam

e as

GG

NS

EP

U14

a ex

cept

Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

79 s

ec

4.0

min

11

.0 m

in

113

sec

MS

CR

WL

5 hr

. R

PV

L1

occu

rs a

t t=

69

sec.

GG

NS

EP

U14

b Is

olat

ion

AT

WS

, no

inje

ctio

n, R

PV

ED

• E

PU

po

wer

leve

l

• M

SIV

clo

sure

at t

=0

• R

PT

(bo

th p

ump

s) s

ucce

ssfu

l

• A

ll S

Vs/

SR

Vs

ava

ilab

le f

or in

itia

l pr

essu

re tr

ans

ient

• N

o H

P in

ject

ion

• R

PV

ED

at R

PV

leve

l -19

1”

• N

o LP

inje

ctio

n

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

tim

e to

cor

e da

mag

e fo

r LP

AT

WS

sce

nario

69

sec

2.

4 m

in

8.9

min

Cor

e D

amag

e

78 s

ec

MS

CR

WL

5 hr

. R

PV

dep

ress

is

initi

ated

at t

= 7

8 se

c (M

SC

RW

L).

Cor

e da

mag

e oc

curs

at

t = 8

.9 m

ins.

O

pera

tor

Act

ions

:

• E

12-F

O-H

EV

35-O

GG

NS

EP

U14

bx

Sam

e as

GG

NS

EP

U14

b ex

cept

Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

79 s

ec

2.6

min

10

.1 m

in

Cor

e D

amag

e

90 s

ec

MS

CR

WL

5 hr

. R

PV

dep

ress

initi

ated

at

t =

90

sec

(MS

CR

WL)

. C

ore

dam

age

occu

rs a

t t =

10.

1 m

in.


E

-21

Tab

le E

-1

LEV

EL

1 P

RA

MA

AP

RU

NS

FO

R G

RA

ND

GU

LF E

XT

EN

DE

D P

OW

ER

UP

RA

TE

(8)

Cas

e ID

MA

AP

Run

Des

crip

tion

(5)

Pur

pose

Tim

e to

T

AF

(4)

Tim

e to

Rea

ch

1/3

Cor

e H

eigh

t(5)

T

ime

to M

ax

Cor

e T

emp

or T

ime

to

CD

(1)

T

ime

HC

TL

(2)

Exc

eede

d o

r M

SC

RW

L(4)

T

ime

of

Run

Com

men

ts

GG

NS

EP

U15

T

urbi

ne T

rip w

ith F

W tr

ip a

t L9

• E

PU

po

wer

leve

l

• T

urbi

ne T

rip a

t t=

0

• A

ll S

Vs/

SR

Vs

ava

ilab

le f

or in

itia

l pr

essu

re tr

ans

ient

• F

W u

ncon

trol

led

trip

occ

urs

at t

= 3

m

ins

• N

o R

PV

ED

• N

o in

ject

ion

avai

labl

e

• S

PC

w/1

RH

R tr

ain

initi

ated

at p

ool

tem

p. 9

0°F

(3)

• V

erify

tim

e to

MS

IV c

losu

re

for

Tu

rbin

e T

rip s

cena

rio w

ith

FW

trip

at o

n R

PV

L9

t=

3 m

ins

34.9

min

50

.1 m

in

59.5

min

Cor

e D

amag

e

39.1

min

MS

CR

WL

5 hr

. F

eed

wat

er tr

ips

on L

9 (p

er r

un d

efin

ition

) at

t=

3 m

in.

RP

V L

3 at

t=7.

9 m

in.

RP

V L

1 (M

SIV

clo

sure

) at

t=30

.6 m

ins.

O

pera

tor

Act

ions

:

• N

21-F

O-H

ELV

L9-1

(T

rans

)

• N

21-F

O-H

EP

CS

-G

(Tra

ns)

• N

11-F

O-H

EM

O D

SW

-G

GG

NS

EP

U15

x S

ame

as G

GN

SE

PU

15 e

xcep

t Pre

-E

PU

(C

LTP

) po

wer

of 3

898

MW

th.

<S

ame

as c

ase

abov

e>

40.6

min

58

.6 m

in

68.9

min

Cor

e D

amag

e

45.3

min

MS

CR

WL

5 hr

. F

eed

wat

er tr

ips

on L

9 (p

er r

un d

efin

ition

) at

t=

3 m

in.

RP

V L

3 at

t=7.

7 m

in.

RP

V L

1 (M

SIV

clo

sure

) at

t=34

.8 m

ins.


E-22

Notes to Tables E-1:

(1) Core damage is defined in the GGNS PRA MAAP runs as 1800°F in the core (based on the MAAP variable TCRHOT).

(2) The suppression pool Heat Capacity Temperature Limit, HCTL, is one of the key parameters (along with low RPV

water level) requiring RPV Emergency Depressurization per the EOPs.

(3) The MAAP parameter file initiates SPC no earlier than t=15 mins to account for various issues such as operator focus on other tasks. As such, the directives in these input decks that state SPC initiation at a pool temperature of 90F means that SPC initiation occurs at t=15 mins (i.e., the pool is assumed to start at 80F at t=0 per the GGNS MAAP parameter file and it reaches 90F before t=15 mins for all isolation scenarios, SPC alignment occurs at the earliest allowed time point of t=15 mins.).

(4) The time to TAF (Top of Active Fuel, -166.7” at GGNS) shown in this table is based on the MAAP variable XWSH

(water level in the shroud), and is indicative of level indication available to the operator. The same variable is used in this table for MSCRWL (Minimum Steam Cooling RPV Water Level, -191” at GGNS).

(5) The time to 1/3 core height in this table is based on the MAAP variable XWCOR (2-phase water level in the core).

(6) The MAAP runs are performed using GGNS MAAP version 4.0.6 parameter file GG406_042710.par.

(7) In all runs CRD injection is not used unless specifically called out.

(8) The runs are performed with the MAAP 4 corrections to address the Part 21 issues identified by MAAP users in

2009. The corrections provided by the MAAP Users Group [27,28] are incorporated into the INCLUDE file used in each of these GGNS MAAP runs. At the time of finalizing this report, a review of all the MAAP run log files was performed to confirm that these Part 21 corrections were included in each run (all runs contained these corrections).


Attachment 14

GNRO-2010/00056

List of Regulatory Commitments

Attachment 14 GNRO-2010/00056 Page 1 of 4

List of Regulatory Commitments The following table identifies those actions committed to by Entergy in this document. Any other statements in this submittal are provided for information purposes and are not considered to be regulatory commitments.

TYPE (Check one)

COMMITMENT

ONE-TIME

ACTION

CONTINUING COMPLIANCE

SCHEDULED COMPLETION

DATE (If Required)

1. The Operating License (OL) and Technical Specifications (TSs) Markups submitted as part of the Extended Power Uprate (EPU) will be revised, if required, to be consistent with the NRC approved Power Range Neutron Monitoring System (PRNMS) TSs. (Attachment 1)

x

2. The Linear Heat Generation Rate (LHGR) and Minimum Critical Power Ratio (MCPR) limits for two inoperable main turbine bypass valves will be specified in the COLR. (Attachment 1)

x

3. EPU startup testing will be performed as described in Attachment 9, “Extended Power Uprate Startup Test Plan.”

x

4. Vibration analysis and testing will be performed as described in Attachment 10, “Vibration Analysis and Testing Program.”

x

5. A change to MDEQ Air Permit 0420-00023 will be submitted to reflect the increase in particulate emissions for Emission Point 008 (Natural Draft Cooling Tower and Auxiliary Cooling Tower) and the VOC emissions associated with the two (2) 60-gallon radial well pump lube oil tanks prior to placing these components in service. (Attachment 4)

x

6. Approximately 216 MVAR of additional reactive power capability will be distributed appropriately at designated load centers throughout the system to ensure system reliability. (Attachment 12)

x

7. The GGNS Containment Leakage Rate Program will be updated to incorporate the EPU Pa value. (PUSAR Section 2.2.4.1)

x

Attachment 14 to GNRO-2010-00056 Page 2 of 4

TYPE (Check one)

COMMITMENT

ONE-TIME

ACTION



DATE (If Required)

8. The 480 VAC motor control center (MCC) minimum voltages supplied from off-site power are only marginally affected by EPU (0.51 VAC maximum voltage drop). This 0.11% voltage drop has a negligible effect on valve torque and will be incorporated into the affected MOV calculations. (PUSAR Section 2.2.4.2)

x

9. Relief valves required by the modification to increase the fuel pool cooling and cleanup system heat removal capability will be added to the inservice testing program scope. (PUSAR Section 2.2.4.2)

x

10. EQ file updates will be completed as required by 10 CFR 50.49 prior to EPU implementation. Remaining life determinations will be made for all Group II items and any required modifications or replacement of equipment will also be completed prior to EPU implementation. (PUSAR Section 2.3.1)

x

11. The changes to the GGNS EQ program brought about by the implementation of EPU will be documented and administered per Entergy Administrative Procedure, “Environmental Qualification (NUREG-0588 / 10 CFR 50.49)” 01-S-06-57, Revision 0. (PUSAR Section 2.3.1)

x

12. The existing protective relay settings for the main generator will have to be recalculated due to the increased EPU power output. (PUSAR Section 2.3.2.2)

x

13. Because the high pressure turbine will be modified to support achieving the EPU RTP level, new allowable values (AVs) (both upper bound and lower bound) in units of psig must be established. The AVs (in psig) will be revised prior to EPU implementation. .(PUSAR Section 2.4.1.3.4)


TYPE (Check one)

COMMITMENT

ONE-TIME

ACTION



DATE (If Required)

14. The RWL HPSP AL (in psig) will be revised prior to EPU implementation. The RCIS RWL setpoint (in psig) will be validated during power uprate plant ascension start-up testing to ensure the actual plant interlock is cleared consistent with the safety analysis.(PUSAR Section 2.4.1.3.5)

x

15. Instrumentation and controls listed in PUSAR Table 2.4-2 will be recalibrated and rescaled as required to support EPU.

x

16. High pressure turbine operating restrictions will be implemented by GGNS to assure operation at speeds other than at speeds within the natural frequency ranges. (PUSAR Section 2.5.1.2.2)

x

17. Fuel rod thermal-mechanical performance will be evaluated as part of the reload analysis performed for the cycle-specific core. Documentation of acceptable fuel rod thermal-mechanical response will be included in the Supplemental Reload Licensing Report (SRLR) or Core Operating Limits Report (COLR) consistent with Limitation and Condition 9.10 of NEDC-33173P-A. (PUSAR Section 2.8.5.2.1)

x

18. GGNS procedures, including system operating, abnormal, and emergency operating procedures, will be revised prior to implementing EPU. (PUSAR Section 2.11.1)

x


TYPE (Check one)

COMMITMENT

ONE-TIME

ACTION



DATE (If Required)

19. As determined by the training analysis process, appropriate classroom, simulator and in-plant training will be conducted prior to power escalation or as required to operate modified systems for plant start up. The simulator will be modified to maintain the required fidelity in accordance with site procedures and ANSI/ANS 3.5 - 1998 (Reference 89). The simulator changes include hardware changes for new and modified instrumentation and controls, software updates for modeling EPU changes and re-tuning of the core physics model for cycle-specific data. Simulator performance will be validated using design analysis data and startup and test data from the EPU project and implementation program. (PUSAR Section 2.11.1.5)

x

20. When EPU conditions are obtained and data collected at EPU conditions, a final stress analysis will be performed and submitted to the NRC. (Attachment 11

x

21. During the refueling outage following the first complete cycle of operation with the replacement steam dryer, inspections of the dryer will be conducted as recommended in General Electric Service Information Letter (SIL) 644, “BWR Steam Dryer Integrity.” (Attachment 11, Appendix F)

x

22. During the refueling outage following the first complete cycle of operation with the replacement steam dryer, inspections of the dryer will be conducted as recommended by SIL 644. (Attachment 11, Appendix F)

x