RELAP-7 Development Updates

Technical Report · Tue Sep 01 00:00:00 EDT 2015

DOI:https://doi.org/10.2172/1244635· OSTI ID:1244635

Zhang, Hongbin ^[1]; Zhao, Haihua ^[1]; Gleicher, Frederick Nathan ^[1]; DeHart, Mark David ^[1]; Zou, Ling ^[1]; Andrs, David ^[1]; Martineau, Richard Charles ^[1]

---

1. Idaho National Lab. (INL), Idaho Falls, ID (United States)

RELAP-7 is a nuclear systems safety analysis code being developed at the Idaho National Laboratory, and is the next generation tool in the RELAP reactor safety/systems analysis application series. RELAP-7 development began in 2011 to support the Risk Informed Safety Margins Characterization (RISMC) Pathway of the Light Water Reactor Sustainability (LWRS) program. The overall design goal of RELAP-7 is to take advantage of the previous thirty years of advancements in computer architecture, software design, numerical methods, and physical models in order to provide capabilities needed for the RISMC methodology and to support nuclear power safety analysis. The code is being developed based on Idaho National Laboratory’s modern scientific software development framework – MOOSE (the Multi-Physics Object-Oriented Simulation Environment). The initial development goal of the RELAP-7 approach focused primarily on the development of an implicit algorithm capable of strong (nonlinear) coupling of the dependent hydrodynamic variables contained in the 1-D/2-D flow models with the various 0-D system reactor components that compose various boiling water reactor (BWR) and pressurized water reactor nuclear power plants (NPPs). During Fiscal Year (FY) 2015, the RELAP-7 code has been further improved with expanded capability to support boiling water reactor (BWR) and pressurized water reactor NPPs analysis. The accumulator model has been developed. The code has also been coupled with other MOOSE-based applications such as neutronics code RattleSnake and fuel performance code BISON to perform multiphysics analysis. A major design requirement for the implicit algorithm in RELAP-7 is that it is capable of second-order discretization accuracy in both space and time, which eliminates the traditional first-order approximation errors. The second-order temporal is achieved by a second-order backward temporal difference, and the one-dimensional second-order accurate spatial discretization is achieved with the Galerkin approximation of Lagrange finite elements. During FY-2015, we have done numerical verification work to verify that the RELAP-7 code indeed achieves 2nd-order accuracy in both time and space for single phase models at the system level.

• Research Organization: Idaho National Laboratory (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE)
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 1244635
• Report Number(s): INL/EXT-15-36763; M3LW-15IN0704054
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
97 MATHEMATICS AND COMPUTING
ACCURACY
ALGORITHMS
BWR TYPE REACTORS
COMPUTERIZED SIMULATION
COUPLING
FLOW MODELS
GALERKIN-PETROV METHOD
HYDRODYNAMICS
NONLINEAR PROBLEMS
NUCLEAR POWER PLANTS
ONE-DIMENSIONAL CALCULATIONS
PERFORMANCE
PWR TYPE REACTORS
R CODES
REACTOR COMPONENTS
REACTOR SAFETY
RELAP-7 Update
SAFETY ANALYSIS
SYSTEMS ANALYSIS
VERIFICATION