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Pre-submittal MeetingWestinghouse BWR ECCS Evaluation Model:Supplement 5 – Application to the ABWR
John Blaisdell WestinghouseDave Shum WestinghouseScott Head STPNOC
Westinghouse Non-Proprietary Class 3
Westinghouse Electric CompanyP.O. Box 355
Pittsburgh, PA 15230-0355
©2009 Westinghouse Electric Company LLCAll Rights Reserved
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Westinghouse Non-Proprietary Class 3
Agenda● Introduction● Attendees● Desired Outcomes● Overview of plan for ABWR fuel-related topicals● GOBLIN LOCA model for ABWR● Important features for ABWR LOCA transient● Benchmarking● Analysis and Results● Schedule
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Westinghouse Non-Proprietary Class 3
Introduction● STP Team Attendees
– Scott Head STPNOC– Nirmal Jain Westinghouse– John Blaisdell Westinghouse– David Shum Westinghouse– Brad Maurer Westinghouse– Robert Quinn Westinghouse– Jeremy King Westinghouse– John Ghergurovich Westinghouse– Fumihiko Ishibashi TANE– Hirohide Oikawa Toshiba– Yoshihiro Kojima Toshiba
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Westinghouse Non-Proprietary Class 3
Introduction● Desired Outcomes
– Provide an update to NRC on the plans for fuel related topical reports
– Provide NRC reviewers with an understanding of the scope content of the ABWR LOCA topical report
– Receive feedback from NRC
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Westinghouse Non-Proprietary Class 3
ABWR LOCA Model LTR● Supplement to an approved GOBLIN LTR for BWR
– WCAP-17116-P– Westinghouse BWR ECCS Evaluation Model:
Supplement 5 – Application to the ABWR– Submittal date : September 2009
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Westinghouse Non-Proprietary Class 3
ABWR LOCA Model for ABWR● Computer Codes
– Same as used for BWR applications– GOBLIN – system performance, hot assembly response
– Performs the analysis of the LOCA blowdown and reflood thermal hydraulic transient for the reactor, including interactions with various control and safety systems
– One dimensional, drift-flux, thermal equilibrium, point kinetics
– CHACHA – nodal heatup calculation– Performs detailed fuel rod mechanical and thermal response
analysis at a specified axial level within the hot assembly
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Westinghouse Non-Proprietary Class 3
Important Features of ABWR● 10 Reactor internal pumps (RIPs)
– On loss of offsite power, core flow decreases very rapidly
● Robust ECCS– 1 Reactor core isolation cooling (RCIC)
system (turbine driven) → FW piping– 2 High pressure core flooder (HPCF)
systems (motor driven) → upper plenum– 2 Low pressure flooder (LPFL) systems
(motor driven) → annulus– 1 LPFL system → FW piping– 8 Automatic depressurization system (ADS)
valves → suppression pool● Except for a small bottom drain line, all RPV
penetrations are above the top of active fuel– Two-phase mixture remains above the top of
active fuel throughout transients
Bottom of dryer
Top of separator
Bottom of separatorTop of shroud headdome
Top of fuel channel
Top of active fuel
Bottom of active fuelTop of core supportmounting flange
Top of pump deckTop of CRD housing
Steam line
Bottom of dryer skirt
Reactor internal pump
Steam dome
Core shroud
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Westinghouse Non-Proprietary Class 3
Important Features of ABWR LOCA Transient
● As an example - HPCF line break– Break of HPCF line disables the affected HPCF
system and the single failure of the emergency diesel generator feeding the other HPCF system results in the following ECCS components:RCIC+ 2 LPFL + 8 ADS
– The break area of the HPCF line is limited by the sparger nozzles residing in the upper plenum of the reactor (0.099 ft2)
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Westinghouse Non-Proprietary Class 3
ABWR HPCF Line Break Transient - PreliminaryShort Term Response
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
0 1 2 3 4 5 6 7 8 9 10
Time (s)
Nor
mal
ized
Par
amet
er (-
)
Pump Speed
Reactor Power
Dome Pressure
Long Term Response
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
0 100 200 300 400 500 600 700 800
Time (s)
Nor
mal
ized
Par
amet
er (-
)
Dome Pressure
System Mass
Core Flow
Hot Assembly Void - TAF
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Westinghouse Non-Proprietary Class 3
ABWR HPCF Line Break Transient - PreliminaryBreak Flow and ECCS Flow
0
200
400
600
800
1000
1200
1400
0 100 200 300 400 500 600 700 800
Time (s)
Flow
Rat
e (lb
/s)
10
15
20
25
30
35
40
45
Wid
e R
ange
Wat
er L
evel
(ft)
Break Flow
ECCS Flow
Wide Range Level
LWL 2
LWL 1.5
LWL 1
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Westinghouse Non-Proprietary Class 3
ABWR HPCF Line Break Transient (cont’d)
● Observations– Cladding temperature excursion is due to early dryout as
core flow decreases– Core remains covered by a two-phase mixture
throughout transient● Conclusions
– Pump modeling is important– Prediction of dryout is important– Hot assembly power can be set very conservatively– Peak cladding temperature is independent of ECCS
performance
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Westinghouse Non-Proprietary Class 3
Important Features of ABWR LOCA Transient● Initial Conditions
a,c
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Westinghouse Non-Proprietary Class 3
Pump Model Benchmarking● Pump model validation
– The coolant conservation and the pump angular momentum equations are coupled in GOBLIN through the pump homologous curves
a,c
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Westinghouse Non-Proprietary Class 3
Pump Model Benchmarking● ABWR Modeling
– Use homologous curves for ABWR internal pumps
– Biased inputs to predict pump
coastdown time constant design specification
– Pump efficiency– Pump / motor inertia
a,c
a,c
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Westinghouse Non-Proprietary Class 3
Pump Model Benchmarking● Olkiluoto 1 Pump Trip
– OL1 is an internal recirculation pump reactor operated by TVO in Finland
– GOBLIN was used to predict a pump trip test that was performed during startup
– Calculated core flow compares well with measured flow
● Conclusion– GOBLIN can be used to
conservatively model pump coastdown for LOCA applications
0
1000
2000
3000
4000
5000
6000
7000
0 1 2 3 4 5 6 7 8
Time (s)
Cor
e Fl
ow R
ate
(kg/
s)
GOBLINTVO1 Data
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Westinghouse Non-Proprietary Class 3
Boiling Transition Benchmarking
● The onset of boiling transition is calculated using a boiling length CPR correlation that was developed for the fuel being analyzed (e.g., SVEA-96 Optima2)
● The CPR correlation was developed from steady-state dryout test data collected from the FRIGG loop in Västerås Sweden.
● GOBLIN was used to predict transient dryout experiments performed in the FRIGG loop
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Westinghouse Non-Proprietary Class 3
Boiling Transition Benchmarking● FRIGG tests benchmarked
● Results– All flow ramp tests predicted conservatively– Most power ramp tests predicted
conservatively– Note that typical ABWR LOCA
indicates power decreasing● Conclusion
– GOBLIN predicts dryout conservatively for LOCA transients
a,c
a,c
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Westinghouse Non-Proprietary Class 3
Analysis and Results
● Break Spectrum / Single Failure Study
– Case resulting in highest PCT will be evaluated in CHACHA to show compliance with 10CFR50.46 criteria.
– Case resulting in minimum inventory evaluated to demonstrate no core uncovery.
a,c
a,c
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Westinghouse Non-Proprietary Class 3
Analysis and Results
LPFL break + fail 1 EDG8111RHR (LPFL) injection line break
Fail 1 EDG8211Main steam line break (outside containment)
8
8
88
88
ADS
Fail 1 EDG211Drain line break
Fail 1 EDG211RHR shutdown suction line break
RCIC side break + fail 1 EDGLPFL side break, fail 1 EDG
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11
01
Feedwater line break
RCIC (turbine) break + fail 1 EDG
210Main steam line break(inside containment)
HPCF break + fail 1 EDG201HPCF line break
RemarksLPFLHPCFRCICBreak Location
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Westinghouse Non-Proprietary Class 3
Large and Small Breaks●HPCF line break (Small Break)
– Break area: 92 cm2 (0.099 ft2)– Limited by area of sparger nozzles
– Available ECCS: RCIC + 2 LPFL + 8 ADS● FW line break (Large Break)
– Break area: 838.9 cm2 (0.903 ft2)– Limited by area of sparger nozzles
– Available ECCS: 1 HPCF + 2 LPFL + 8 ADS
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Westinghouse Non-Proprietary Class 3
Comparison of FWLB and HPCF - Preliminary
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0 50 100 150 200 250 300 350 400 450 500
Time (s)
Syst
em M
ass
(Mlb
)
hpcf
fwlb
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 50 100 150 200 250 300 350 400 450 500
Time (s)Vo
id F
ract
ion
(TA
F)
hpcf
fwlb
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Westinghouse Non-Proprietary Class 3
Comparison of FWLB and HPCF - Preliminary
400
500
600
700
800
900
1000
1100
1200
1300
1400
0 100 200 300 400 500
Time (s)
Peak
Cla
d Te
mp
(F)
hpcf
fwlb
400
500
600
700
800
900
1000
1100
1200
1300
1400
0 5 10 15 20
Time (s)
Peak
Cla
d Te
mp
(F)
hpcf
fwlb
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Westinghouse Non-Proprietary Class 3
Spectrum Study Results - Preliminary
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Break Area (ft2)
Min
imum
Sys
tem
Mas
s (M
lb)
fwlb hpcf mslb
800
900
1000
1100
1200
1300
1400
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Break Area (ft2)
PCT
(F)
fwlb hpcf mslb
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Westinghouse Non-Proprietary Class 3
Results Summary●Observations
– PCT occurs before actuation of ECCS
– Hot assembly is cooled by a two-phase mixture throughout transient
– PCT is not a strong function of break size– Minimum inventory decreases with increasing
break size
a,c
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Westinghouse Non-Proprietary Class 3
Technical Contents of Topical Report●Overview of ABWR LOCA Methodology
– Differences between BWRs and ABWRs– Description of ABWR ECCS– Description of ABWR model nodalization– Break spectrum results
●Qualification of ABWR Evaluation Model– Pump coastdown prediction– Prediction of boiling transition
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Westinghouse Non-Proprietary Class 3
Conclusions● Major differences between BWRs and ABWRs
– Internal recirculation pumps coastdown much faster than external recirculation pumps– Early boiling transition
– All ABWR breaks are above top of active fuel– No core uncovery predicted for ABWR
● Topical report provides justification for the extension of the approved Westinghouse BWR LOCA methodology to the ABWR design
● Topical report to be submittal by September 30 as planned