A LOCA Analysis Tool: Coupling RELAP5-3D to BISON

Technical Report · Mon Mar 31 00:00:00 EDT 2025

DOI:https://doi.org/10.2172/3029197· OSTI ID:3029197

Gamble, Kyle A ^[1]; Vanwasshenova, Daniel J ^[1]; Cornelius Vermaak, Jan Izak ^[1]; Tano Retamales, Mauricio Eduardo ^[1]; Hales, Jason D ^[1]

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1. Idaho National Laboratory

Experimental evidence illustrates that at burnups slightly above the current regulatory limit of a rod-averaged burnup of 62 MWd/kgU, the ceramic UO2 inside light-water reactor fuel rods becomes susceptible to a phenomenon known as fuel fragmentation, relocation, and dispersal (FFRD) during a loss of coolant accident (LOCA) transient. The severity of FFRD is strongly influenced by the zirconium-based (Zircaloy) cladding behavior during the LOCA transient. A Technology Commercialization Fund (TCF) project was awarded to an Electric Power Research Institute (EPRI)/Idaho National Laboratory team to create a LOCA analysis tool that couples BISON to the systems/thermal-hydraulics code RELAP5-3D [1] for analysis of LOCA scenarios. In addition, further refinements to existing BISON models were identified as necessary to more accurately represent more recent experimental evidence from the Studsvik Cladding Integrity Project (SCIP) and other experimental programs. The project was broken down into six key areas: (1) interaction with Collaborative Research on Advanced Fuel Technologies for LWRs (CRAFT), where LWR stands for light-water reactor, (2) data curation, (3) BISON refinements for higher burnup application, (4) RELAP-5 BISON coupling, (5) verification and validation, and (6) introducing a Best-Estimate Plus Uncertainty (BEPU) framework into the LOCA analysis tool. Since the start of the TCF project in March of 2023, members of the research team have engaged with CRAFT program members on multiple occasions. These engagements have facilitated an exchange of information, both updates on project progress and suggestions on project directions. Through collaboration with EPRI, this project was able to identify key experimental programs and data to consider for use in the validation of the BISON improvements and coupled tool. Key experimental programs include Halden, Loss-of-Fluid Test (LOFT), Transient Reactor Test Facility (TREAT), REBEKA, QUENCH, and SCIP. EPRI’s guidance in this area has been invaluable. BISON improvements are in areas such as axial fuel relocation, axial gas communication, and cladding ballooning and rupture, including fuel rod array modeling. Coupling of BISON and RELAP5-3D was done in two independent ways. The first approach was to utilize Python and file-based exchanges of information. The second was to employ in-memory exchanges of information via functionality provided by MOOSE (Multiphysics Object-Oriented Simulation Environment). Verification and validation problems explored in this work follow the feature development mentioned above. Of particular interest is the performance of the coupled code. Studies showed very good comparisons in standard problems and to experimental data. For best estimate plus uncertainty calculations, the stochastic tools module in MOOSE provided the requested statistical information. This area is one that could be explored in much more detail as a variety of LOCA scenarios are evaluated. While this project has greatly advanced the ability to model challenging fuel rod conditions, much more development in this area could be done. LWR LOCA modeling remains challenging and is a rich field for further research.

• Research Organization: Idaho National Laboratory (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE); USDOE Office of Nuclear Energy (NE)
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 3029197
• Report Number(s): INL/RPT-25-84367
• Country of Publication: United States
• Language: English

Related Subjects

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS
BISON
In-memory Coupling
RELAP5-3D