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ContainmentModelingUsingMAAP

This product / presentation includes references to EPRI Technology

EPRI (www.epri.com) conducts research and development relating to the generation, delivery and use of electricity for the benefit of the

public. An independent nonprofit organization, EPRI brings together its scientists and engineers as well as experts from academia and

industry to help address challenges in electricity including reliability, efficiency, health, safety and the environment. EPRI does not endorse

products or services, and specifically does not endorse containment modeling in MAAP or GSE. Interested vendors may contact EPRI for

a license to MAAP 5.0

LEGALDISCLAIMERS

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•  MAAP: Modular Accident Analysis Program •  Integral systems analysis code for assessing off-normal transients that

can progress to and include severe accidents.

•  Owner: •  EPRI, and Specific funders

•  Developer: •  Fauske & Associates, LLC (FAI)

•  Primary applicaMons: •  PRA and SAMG’s

•  NQA-1 Compliance

WHATISMAAP?

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•  MAAP has separate code versions for different types of reactors •  PWR

•  BWR

•  CANDU

•  VVER

•  MAAP code models •  RCS/SG (hardwired nodalizaMon)

•  Containment(configurable)•  Auxiliary building (configurable)

•  Engineered safeguards (driver)

•  Spent Fuel Pool

•  Neutronics

•  Fission Products transport

•  Dose, in-plant and ex-plant

WHATISMAAP?

MAAP is an engineering-grade soluMon that is used consistently across the global nuclear fleet. GSE has extensive experience developing real Mme applicaMons for MAAP.

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WHYUPDATECONTAINMENTMODELS?

Many Industry Containment Models are Legacy Models In Need of UpdaMng For Compliance, Accuracy, and/or OpMmizaMon

•  Obsolescence •  Compliance with ANSI Standard for RepresentaMve Plant ConfiguraMon

•  Lack of fidelity

•  Single-Phase Model

•  Under-Nodalized Model – OversimplificaMon or HomogenizaMon of Response

•  Expanded use of Simulator Beyond Training •  Engineering Use of Simulator (or Desktop) for Model RealizaMon, Tool FamiliarizaMon

•  Beyond Design Basis Accident Models •  Not a Mandate, But Could Become One

•  Advantages in OpMmizing Severe Accident Strategies and Training Through SimulaMon

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BEYONDCONTAINMENT–SEVEREACCIDENTS8.4 Initiate rulemaking to require more realistic, hands-on training and exercises on SAMGs and EDMGs for all staff expected to implement the strategies and those licensee staff expected to make decisions during emergencies, including emergency coordinators and emergency directors.

NEI-13-06 Rev 1

2.1 Each licensee should establish an overall framework for strategies that would be used to mitigate and manage the consequences of a beyond design basis event and severe accident….

3.2.3.2 …..Verification and validation processes should assess the technical accuracy and adequacy of the instructions, and the ability of personnel to follow and implement them.

NEI-14-01 Rev 1

Although simulator modificaMon is not required, there may be good reasons to update the simulator…

Guidance for implemenMng beyond design basis coping strategies.

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BEYONDCONTAINMENT–SEVEREACCIDENTS

Use the Simulator as a Design Tool, a ValidaMon Tool, as well as a Training Tool to Add Value to the StaMon

•  ConsideraMons for Beyond Design Basis Accident SimulaMon •  Strategy Design

•  Simulator can be used as a design tool to develop effecMve strategies •  Use of the simulator beyond the tradiMonal uses

•  ValidaMon and VerificaMon •  Strategies can be progressed in real Mme to determine effecMveness

•  RealisMc Training •  More realisMc training = More effecMve training (pracMce like you play) •  Command and control •  Certain scenarios can limit training (SBO, control room habitability)

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ADVANTAGESOFAMAAPCONTAINMENTMODEL•  Use of MAAP to Update the Site’s containment model has several potenMal

to the site where the simulator can add value…. •  Model Fidelity

•  Engineering grade soluMon – used in PRA analyses •  Built in funcMonality for difficult to model phenomena:

•  Containment spray •  Sparging effects •  Post-LOCA effects (e.g. equipment condensaMon)

•  Community of PracMce •  MAAP is consistently used at nuclear sites (more experMse on site)

•  Engineers on site who will understand the model and can make changes as needed

•  ExisMng licenses are likely in place

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ADVANTAGESOFAMAAPCONTAINMENTMODEL

The ExisMng Design Basis MAAP Parameter File Can Be Used To Maximize Model Pedigree, Decrease DuplicaMon of Work Scope

•  Use of ExisMng Engineering MAAP Parameter File •  Basis for parameter file is highly pedigreed from design models •  Design basis inputs and constants consistent with site engineering models •  Generally able to keep the boundaries of the engineering model and

subdivide the internal nodes as needed for fidelity •  Highly detailed input model (more detailed nodes compared to other/

sogware soluMons)

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ADVANTAGESOFAMAAPCONTAINMENTMODEL

MAAP Repeatability Is Proven Excellent When Using GSE HD Server.

‘0’ Difference between runs ExcepMon: Any Items Specifically Due to CPU Time

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ADVANTAGESOFAMAAPCONTAINMENTMODEL

MAAP Containment Models Offer Advantages in Modeling Fidelity and Detail, Pedigree, Repeatability, and as a Step Towards Beyond Design Basis SimulaMon

•  TransiMon to Beyond Design Basis Modeling •  Interim step to transiMon to support

beyond design basis accident modeling •  Need to model other plant systems in

MAAP •  RCS •  Core •  Off-site dose transport model

(OpMonal)

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CHALLENGESOFAMAAPCONTAINMENTMODEL•  Use of MAAP to update the site’s containment model also brings

several challenges that should be noted: •  MAAP code not constrained to run in real Mme

•  Tuning to ensure MAAP Mme steps are not too long or too short may be necessary

•  Some funcMons for design basis models not well developed, parMcularly at the edge of a beyond design basis event

•  Models are complex and computaMonally intensive •  A smooth transiMon to beyond design basis takes experience •  Fine modeling such as ductwork not supported directly

MAAP Challenges Include ComputaMonal Complexity, Some Inherent Modeling

LimitaMons, and Complexity of Beyond Design Basis TransiMon GSESYSTEMS,INC.//

Node #

•  Two nodes for main steam pipe chase and turbine building not shown.

•  Each color was previously a single PRA node.

•  Torus subdivided based on individual SRV locaMon.

•  Only significant tuning for containment so far has been with the MAAP internal fan and chiller models.

•  Containment model conMnues to be in use through design basis and severe accident modes.

Example Containment NodalizaMon – Same for Design Basis and Severe Accident GSESYSTEMS,INC.//

CASESTUDY–USBWR-4PLANT

•  MAAP BWR RCS NodalizaMon is hard-wired with 17 nodes.

•  Updated from 11 nodes to 17 in version 5.04.

•  New BWR RCS model in 5.04 has many improvements and is more consistent with the MAAP PWR RCS model.

•  During severe accident, MAAP’s RCS model replaces previous RCS model and interfaces with the simulator.

•  Before severe accident, MAAP’s RCS model runs in the background and has drivers to follow the design basis RCS model.

•  Challenges can occur if the design basis RCS model is a lower fidelity model or has issues when pushing the model to the limits of design basis simulaMon.

From MAAP 5.04 User Manual

CASESTUDY–USBWR-4PLANT

GSE Designed The Model To Smoothly TransiMon from Design Basis to Severe Accident GSESYSTEMS,INC.//

CASESTUDY–USBWR-4PLANT

SimulaMon and RealisMc Graphical Output Can Be Used For Non TradiMonal (Training) Uses Such as MAAP Tool FamiliarizaMon and Transient VisualizaMon by Engineering

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CASESTUDY–USBWR-4PLANT

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GSEEXPERIENCE

GSE Has Significant Experience in Modeling MAAP Code for Various ApplicaMons and Has Developed SoluMons for the Challenges Imposed by Such a Model

GSE’sInstallaJonsofEPRI’sMAAPCodeCustomer/Plant Type Year

TEPCO Kashiwazaki 5, MAAP 3.0B BWR 1995

JAPC Tsuruga 1, MAAP 3.0B BWR 1998

JAPC, Tsuruga 2, MAAP 3.0B PWR 1998

JAPS Tokia 2, MAAP 3.0B BWR 1998

TEPCO Fukushima 2F2, MAAP 3.0B BWR 2002

Kansai Ohi 1, MAAP 4.0.4 PWR 2009

Kansai Takahama 2, MAAP 4.0.4 PWR 2010

JAPC, Tsuruga 2, MAAP 4.0.7 PWR 2013

JAPC, Tokai 2, MAAP 4.0.7 BWR 2013

KSU Ringhals 2, PSA-HD, MAAP 5.01 PWR 2013

KSU Ringhals 2, PSA-HD, MAAP 5.01 PWR 2013

KHNP Kori 3&4, PSA-HD MAAP 5.01 PWR 2014

Erin Engineering, DesignEP 2014

CNPRI PSA-HD MAAP 5.01 PWR 2014

POSTECH PSA-HD PWR 2014

Customer/Plant Type Year

AEP DC Cook PSA-HD MAAP 5.01 PWR 2014

Exelon Dresden, DesignEP BWR 2014

Exelon Peach Boqom, DesignEP BWR 2014

NEL Takahama 2, PSA-HD MAAP 5.01 PWR 2014

Southern Nuclear, Vogtle DesignEP PWR 2015

KHNP Hanul 3&4, PSA-HD MAAP 5.01 PWR 2015

OPG DesignEP CANDU 2015

City Univ. of Hong Kong, DesignEP PWR 2015

KSU Forsmark 3, DesignEP BWR 2016

KHNP Hanul 1, PSA-HD MAAP 5.01 PWR 2017

Southern Vogtle PSA-HD MAAP 5.01 PWR 2018

Southern Hatch, PSA-HD MAAP 5.01 BWR 2018

Southern Farley, PSA-HD MAAP 5.01 PWR 2018

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CONCLUSION

Containment Models in MAAP, Though More Complex, Add Value to the StaMon

•  MAAP is an engineering and licensing grade code that can be used to improve pedigree of simulaMon

•  MAAP can be used to develop, streamline, and validate beyond design basis strategies

•  Advantages of design-basis containment models in MAAP: ‒  Beqer fidelity ‒  Broad user community of pracMce ‒  Interim step towards simulaMon of beyond design basis events

•  Challenges of containment models in MAAP: ‒  More complex model, more labor and computaMonal intensive ‒  TransiMon from design basis to beyond design basis

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