Monte Carlo analyses of light-water-moderated and light-water-reflected cores with highly-enriched uranium fuel at Kyoto University Critical Assembly

Abstract

ABSTRACT The applicability of Monte–Carlo calculations is examined for the analyses of light-water-moderated and light-water-reflected cores at the Kyoto University Critical Assembly with the use of the experimental data of criticality, reactivity, and reaction rates. For the well-thermalized cores, criticality demonstrates the dependence of eigenvalue bias on the neutron spectrum at a critical state, using MCNP6.2 with ENDF/B-VII.1 and JENDL-4.0. Also, reactivity and reaction rate analyses provide reasonable results within acceptable allowance of uncertainty between experiments and calculations. Furthermore, no significant difference is evident between two major nuclear data libraries. From the results, issues of overestimating criticality need to be highlighted in the well-thermalized cores composed of the HEU fuel and the light-water moderator.