Industry Use of Thermal Hydraulic Codes Robert P

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

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 RELAP 5/6/7? • A Path Forward Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT

Selected TH Codes • • Codes for LWR System Analysis – RELAP 5 (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) • • • 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) Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT

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

Nuclear Plant Analysis Areas Fuel Design Core Design Instrumentation and Controls Equipment Qualification/ Survivability Fuel Burnup/ Performance Structural Loads Analysis Coolant System Performance Containment Performance Core Performance Accident Management Analysis Plant Simulator/Tr aining Probabilistic Safety (Risk) Analysis Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT Auxiliary Systems

General EM Framework BE/Scale SA Baseline Unc Perturbation What If Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT

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

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

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

R 5 -3 D Code Variability Illustration* *Martin, “Quantifying Code Variability for LBLOCA with RELAP 5 -3 D, ” 2001 IRUG Meeting Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT

Developing Common Goals to Advance Codes 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 Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT

Developing Common Goals to Advance Codes How Industry Codes are UNLIKE Laboratory Codes • Certain “advanced” capability neglected – RELAP 5 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 Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT

Developing Common Goals to Advance 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 sciencebased – 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 Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT

The TH Modeling and Simulation Mission • Why do we need RELAP 5? – Captures TH modeling and analysis advances of past 45+ years – Broad constituency (government, industry, academia) • Why do we need RELAP 6? – 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 RELAP 7? – To advance the mission of the lab to further understanding of TH and, specifically, “tools to advance theory of basic processes and the design of complex energy systems using advanced numerical modeling and computer simulations” Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT

A Path Forward – Summary • Industry needs to move forward with code modernization – For RELAP 5 -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) Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT

Q&D Vision Sub. Channel/CFD PVM FUEL Containment RELAP 5 -3 D MPI MOOSE Martin - Industry Use of Thermal Hydraulic Codes – 2010 IRUG, West Yellowstone, MT