Industry Use of Thermal Hydraulic Codes Robert P. Martin Idaho National Laboratory.

Industry Use of Thermal Hydraulic Codes

Robert P. MartinIdaho National Laboratory

Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT

Talking Points

• Nuclear Plant Analysis Areas

– Industry design and safety processes

– Recurring and infrequent code applications

– Current limitations and challenges

• Developing Common Goals to Advance Codes

– How Industry Codes are LIKE Laboratory Codes

– How Industry Codes are UNLIKE Laboratory Codes

– Why do we need RELAP5/6/7?

• A Path Forward


Selected TH Codes• Codes for Fuel Performance

Analysis

– Westinghouse proprietary

– GE proprietary

– AREVA proprietary

– FRAP (PNL/INL)

– FALCON (EPRI)

• Codes for Containment Analysis

– CONTEMPT (INL)

– MELCOR (SNL)

– GOTHIC (EPRI)

• Codes for Severe Accidents

– SCDAP/RELAP (INL)

– MELCOR (SNL)

– MAAP (EPRI)

• Codes for LWR System Analysis

– RELAP5 (INL)

– TRAC (LANL)

– RAMONA (BNL)

– COBRA (PNL)

– CATHARE (CEA)

– ATHLET (GRS)

– CATHENA (AECL)

– TRACE (NRC)

– RETRAN (EPRI)

– FATHOM (ANSYS)

• Computational Fluid Dynamics

– COMMIX (ANL)

– FLUENT (ANSYS)

– STAR-CD (CD-Adapco)


Plant FSAR Contents


Nuclear Plant Analysis Areas

Core DesignCore Design

Core Performance

Core Performance

Fuel Burnup/ PerformanceFuel Burnup/ Performance Coolant

System Performance

Coolant System

Performance

Accident Management

Analysis

Accident Management

Analysis

Probabilistic Safety (Risk)

Analysis

Probabilistic Safety (Risk)

Analysis

Structural Loads

Analysis

Structural Loads

Analysis

Containment PerformanceContainment Performance

Instrumentation and Controls

Instrumentation and Controls

Fuel DesignFuel Design

Plant Simulator/Tra

ining

Plant Simulator/Tra

ining

Auxiliary Systems

Equipment Qualification/Survivability

Equipment Qualification/Survivability


General EM Framework

BE/Scale

SA Unc

Baseline

Perturbation

What If


Reoccurring Code Applications

Frequent Uses (reload, 18 months)

• Best-estimate (BE) fuel, reactor and BOP system analysis– FSAR chapters 4, 5 & 10

• Both conservative and BE Design-basis safety analysis

– FSAR chapter 4, 6 & 15

Occasional Use (every 2 or more reloads)

• Design/process modification (e.g., – Power uprate

– Component replacement

– Setpoints verification (I&C design) – FSAR chapter 7


Infrequent Code Applications• Diversity and Defense-in-depth

– BE DBA calcs to verify secondary/tertiary control system performance

– FSAR chapter 7

• Structural– Combustion and SA loads; water hammer; Jet impingement loads

– FSAR chapter 3

• Equipment qualification/survivability– FSAR chapter 3

• Severe accident/Probabilistic Risk Assessment (PRA)– FSAR chapter 19

• Spent fuel pool analysis– FSAR chapter 9

• Accident management/simulator/training– 10 CFR 50.34 (TMI-2 rulemaking)


Code Application Challenges

Recognized code limitations• Code variability

– Solution convergence– Limited first principles understanding of phenomena– Model approximations, bifurcations and discontinuities– Errors in the Equation-of-State

• Spatial resolution to refine distributed transport phenomena• Incomplete phenomenological models, e.g., two-phase flows• Best-estimate plus uncertainty (BEPU) methods have exposed…

– Need for faster calculations (more calcs necessary)

– Limitations in range of applicability

– Inherent code bias and large uncertainty

• Many opportunities for the User to misapply the code• Multi-physics (coupled tools), e.g., Rx kinetics, fuel/containment


R5-3D Code Variability Illustration*

*Martin, “Quantifying Code Variability for LBLOCA with RELAP5-3D,” 2001 IRUG Meeting


How Industry Codes are LIKE Laboratory Codes

• Inherited code architecture– Basic input/output format

– Governing equations and physical models

– Order-of-solution

– Bugs

• Inherited developmental assessment

• New models/capability motivated by regulatory initiatives– Multi-dimensional modeling

– Multi-physics

– New experimental data (e.g., for assessments, improved water properties, etc.)

• Dwindling number of developers and competent users

Developing Common Goals to Advance Codes



How Industry Codes are UNLIKE Laboratory Codes

• Certain “advanced” capability neglected– RELAP5 examples: multi-dimensional reactor kinetics, code coupling

feature, FORTRAN 90/95

• Regulations and NRC’s Standard Review Plan often restrict application of best-estimate models or preclude certain legacy code models (e.g., Forslund-Rohsenow film boiling)

• Expanded developmental assessment in application areas– LOCA Example: Fuel vendors advertise 130+ benchmarks

• Accommodation for uncertainty treatment

• Integrated multi-physics capability

• Production applications are automated

Differences reflect the manner in which industry applies these codes


• Industry’s focus has been on methodology– Reflecting new plants

– Reg. Guide 1.203 (Evaluation Methodology Development and Assessment Process, EMDAP, 2005)

• Lab focus has been on modernization, sustainability, and science-based

– Modernize legacy codes, e.g., FORTRAN 90/95, remove “unacceptable” models– Sustainability seems to mean new models to address current LWR issues, not

current analysis challenges– Science-based methods -> first principles models and correlations

• Industry needs to modernize codes– to be assured that they can continue to run– to have a reason to sponsor development and sustain developer competency

• LWR sustainability from labs by aligning capability with industry– Common code capability– Address current challenges



The TH Modeling and Simulation Mission

• Why do we need RELAP5?– Captures TH modeling and analysis advances of past 45+ years

– Broad constituency (government, industry, academia)

• Why do we need RELAP6?– Move beyond today’s code challenges and expand code architecture for

substantial improvement

– Stimulate new TH R&D and training methods

• Why do we need RELAP7?– To advance the mission of the lab to further understanding of TH and,

specifically, “tools to advance the theory of basic processes and the design of complex energy systems using advanced numerical modeling and computer simulations”


A Path Forward – Summary

• Industry needs to move forward with code modernization– For RELAP5-based methodologies, it might be easier to use current

version, modify i- and r-level routines, and integrate unique models

– PVM/MPI message passing capability should be added to open TH codes to enhancement available from tools catering to specific code needs

• Lab needs to recognize and act on industry needs – Integrate multi-physics capability as currently done in industry

– Address current problems• Code variability• Refine spatial resolution• Improve important phenomenological models• Accommodate BEPU methods• Examine opportunities to address the User-Effect (e.g., automation)


RELAP5-3D

MPI

PVM

ContainmentFUEL

SubChannel/CFD

MOOSE

Q&D Vision

Industry Use of Thermal Hydraulic Codes Robert P. Martin Idaho National Laboratory.

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