This presentation describes a project whereby GSE provided an integrated multi-unit implementation of EPRI's Modular Accident Analysis Code (MAAP).

1. info@gses.com
Multi-Unit Severe Accident
Simulation

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What is MAAP?
• MAAP: Modular Accident Analysis Program from EPRI
• Industry standard code for severe accident analysis of BWRs,
PWRs, and CANDUs
• Large user group
– Extensively benchmarked
– Every US utility is an EPRI member, thus they have a MAAP license
– Many utilities have already modeled plant in MAAP for PRA
– Able to simulate RCS, SG (PWR), Containment/ Auxiliary Building and
Spent Fuel Pool
– Fast running compared to MELCOR

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GSE’s MAAP Based Products

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The MAAP code is incorporated into GSE’s SimExec™ platform
• Maintain the integrity of the MAAP code
– Does not change the physics behind the code
– Opens the black-box of the code
– User can access and interact with MAAP internal variables
• Exact repeatability
– Conventional MAAP restart files are not repeatable
– GSE’s MAAP implementation is digit-to-digit repeatable
– SNAP and RESET to any problem time without losing fidelity of
simulation
MAAP Under SimExecTM Platform

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Exact Repeatability
• Allow user to access the entire internal memory of MAAP
• Snap and Reset the initial conditions (IC) files to ensure exact
repeatability, which is only available through GSE’s SimExecTM
Platform
PSA-HD or
DesignEP

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Exact Repeatability
GSE has significantly improved the repeatability of
the original MAAP code.

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• SimExecTM enhanced user interface
– Bring the classic text format to contemporary software
– Trend and monitor all MAAP variables
– Less burden for code users
MAAP Under SimExecTM Platform

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Intuitive Human Machine Interface

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Intuitive Human Machine Interface

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Multi-Unit Capability
• SimExecTM synchronizes,
executes, and interfaces
computer models
together
– Most nuclear computer codes
are not designed for multi-unit
analysis (thus requires
substantial changes to source
code)
– SimExec Client-Server structure
enables Multi-Unit simulation
without changing MAAP code

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Multi-Unit Case Study 1: Safety Analysis

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Multi-Unit Case Study 1: Safety Analysis
• Multi-Unit simulation is required
by Canadian Nuclear Safety
Commission after Fukushima
• Development of a multi-unit
version of MAAP is cost and time
prohibitive
• SimExecTM synchronizes simulation
and exchanges the flows and
pressures between all MAAP
instances
• Dummy node approach: No
change to the MAAP source code
physics or code structure

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2-Unit PWR with shared auxiliary building
Multi-Unit Case Study 2: Full-Scope Simulator

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Multi-Unit Case Study 2: Full-Scope Simulator

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Severe Accident in Simulator
Full-scope Simulator Severe Accident
NOPs EOPs SAMGs EDMGs
Other
codes
ANSI/ANS-3.5

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Severe Accident Transition
RELAP5 Instance #1
RCS
RELAP5 Instance #2
Steam Generator
Core, BOP, Electrical, etc.
Containment Model
PSA-HD
Steam Generator
PSA-HD
Containment
PSA-HD
RCS
Normal Operations DBA BDBA (Severe Accident)
NOPs EOPs SAMGs
PSA-HD
Dose
PSA-HD Instance #1
Transition
Radionuclides Tracking Model

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GSE’s PSA-HDTM & DesignEPTM are proven
and available now
More installations of MAAP based
products than any other simulator vendor
Cost effective by leveraging what you
already have
Based on EPRI’s MAAP code that is used
throughout the industry for PRA/PSA
Why GSE?

18. Thank you.
For more information, go to:
www.GSES.com
info@gses.com
Or call 800-638-7912