CASMO-4/SIMULATE-3 Benchmarking Against High Plutonium Content Pressurized Water Reactor Mixed-Oxide Fuel Critical Experiment

A benchmark study is presented of new methodologies of the Studsvik CASMO-4/SIMULATE-3 advanced nuclear design code system against a pressurized water reactor (PWR)-type mixed-oxide (MOX) fuel critical experiment with high plutonium content. Both CASMO-4 two-dimensional transport core calculations and SIMULATE-3 nodal core calculations that use the pin power reconstruction model are performed for the experimental geometries. All the assembly two-group constants for SIMULATE-3, including those for MOX assemblies, are generated by CASMO-4 singleassembly calculations. The CASMO-4 improved transmission probability method and the SIMULATE-3 improved nodal and spectral interaction models are verified to be effective for accurate prediction of the pin power distribution inside high plutonium content PWR MOX assemblies and UO₂ assemblies that are adjacent to the MOX assemblies.