Evaluation of nuclear characteristics of minor actinide loaded core; Analyses of BFS-69 and BFS-66-2 critical experiments

Hazama, Taira ; Sato, Wakaei*

This report describes analysis results on BFS-69 and BFS-66-2 critical experiments carried out under the collaboration with Russian Institute of Physics and Power Engineering. In the experiments, various nuclear characteristics were measured in 2 kinds of cores with/without Np loading of about 8 kg. JAEA's standard analysis results were presented with 4 kinds of nuclear data (JENDL-3.2, JENDL-3.3, JENDL/AC-2008, and ENDF/B-VII). The results show (1) An overestimation trend appears in BFS-69 criticality results, especially with JENDL-3.3 and JENDL/AC-2008. The difference from ENDF/B-II mainly lies in the average cosine of the scattering angle around 1 MeV; (2) A discrepancy exists in BFS-69 Na void reactivity results with the three JENDL nuclear data. The difference from ENDF/B-II mainly lies in scattering cross sections around 1 MeV and fission cross section around 1 keV; (3) The analysis results simulate measured Np effects on nuclear characteristics within experimental errors.