Effects of nuclear data library and ultra-fine group calculation for large size sodium-cooled fast reactor OECD benchmarks

Kugo, Teruhiko ; Sugino, Kazuteru; Uematsu, Mari Mariannu; Numata, Kazuyuki*

The present paper summarizes calculation results for an international benchmark proposed under the framework of the Working Party on scientific issues of Reactor Systems (WPRS) of the Nuclear Energy Agency of the OECD. It focuses on the large size oxide-fueled SFR. Library effect for core performance characteristics and reactivity feedback coefficients is analyzed using sensitivity analysis. The effect of ultra-fine energy group calculation in effective cross section generation is also analyzed. The discrepancy is about 0.4% for a neutron multiplication factor by changing JENDL-4.0 with JEFF-3.1. That is about -0.1% by changing JENDL-4.0 with ENDF/B-VII.1. The main contributions to the discrepancy between JENDL-4.0 and ENDF/B-VII.1 are Pu capture, U inelastic scattering and Pu fission. Those to the discrepancy between JENDL-4.0 and JEFF-3.1 are Na inelastic scattering, Fe inelastic scattering, Pu fission, Pu capture, Pu fission, U inelastic scattering, Pu fission and Pu nu-value. As for the sodium void reactivity, JEFF-3.1 and ENDF/B-VII.1 underestimate by about 8% compared with JENDL-4.0. The main contributions to the discrepancy between JENDL-4.0 and ENDF/B-VII.1 are Na elastic scattering, Na inelastic scattering and Pu fission. That to the discrepancy between JENDL-4.0 and JEFF-3.1 is Na inelastic scattering. The ultra-fine energy group calculation increases the sodium void reactivity by 2%.