Investigation of the impact of the prediction accuracy of the burn-up code system SWAT4.0 on neutronics calculation

Tada, Kenichi   ; Sakino, Takao*

Criticality safety of the fuel debris is one of the most important issues, and the adoption of burnup credit is desired. To adopt the burnup credit, validation of the burnup calculation codes is required. In this study, assay data of the used nuclear fuel (2F2DN23, 2F1ZN2, and 2F1ZN3) are evaluated to validate the SWAT4.0 code. The calculation results revealed that the number densities of many heavy nuclides and fission products show good agreement with the experimental data. To investigate the applicability of SWAT4.0 to the criticality safety evaluation of fuel debris, we evaluated the effect of isotopic composition difference on . The differences in the number densities of U-235, Pu-239, Pu-241, and Sm-149 have a large impact on . However, the reactivity uncertainty related to the burnup analysis was less than 3%. SWAT4.0 appropriately analyses the isotopic composition of BWR fuel, and it has sufficient accuracy to be adopted in the burnup credit evaluation of fuel debris.