CRITICAL EXPERIMENT OF THORIUM LOADED THERMAL CORES AT KUCA (1) A NEW CRITICAL EXPERIMENT OF THORIUM LOADED CORE WITH HARDER NEUTRON SPECTRUM IN KUCA

¹ Kindai University Atomic Energy Research Institute 3-4-1, Kowakae, Higashiosaka-shi, Osaka, Japan
² Institute for Integrated Radiation and Nuclear Science, Kyoto University 2-1010, Asashiro-nishi, Kumatori-cho, Sennan-gun, Osaka, Japan
³ Graduate School of Science and Engineering, Kindai University 3-4-1, Kowakae, Higashiosaka-shi, Osaka, Japan

t-sano@kindai.ac.jp
hori@rri.kyoto-u.ac.jp
zelloseve@naver.com
ytaka@rri.kyoto-u.ac.jp
takahashi.kazuki0524@gmail.com
unesaki@rri.kyoto-u.ac.jp

Published online: 22 February 2021

Abstract

In order to perform integral evaluation of ²³²Th capture cross section, a series of critical experiments for thorium-loaded and solid-moderated cores in KUCA had been carried out. In these experimental cores, H/²³⁵U nuclide ratio ranged about from 150 to 315, and ²³²Th/²³⁵U nuclide ratio ranged about from 13 to 19. In this study, a new critical experiment with Th loaded core in KUCA, which had about 70 of the H/²³⁵U ratio and 12.7 of ²³²Th/²³⁵U ratio, was carried out. As results, the excess reactivity was 0.086 ± 0.003 (% dk/k) and the k_eff was 1.0009 ± 0.0003, where the effective delayed neutron fraction was 7.656E-3. The k_eff was also calculated by MVP3.0 with different nuclear libraries. The respective calculations with JENDL-4.0, JENDL-3.3 and ENDF/B-VII.0 lead to 1.0056 ± 0.0086 (%), 1.0048 ± 0.0085 (%) and 1.0056 ± 0.0086 (%).On the other hand, the further MVP3.0 calculations, where only the ²³²Th cross sections were taken from JENDL-4.0, JENDL-3.3 or ENDF/B-VII.0 but all other nuclides were done from JENDL-4.0, were carried out to examine an impact of the difference of ²³²Th cross section among these nuclear libraries to the k_eff. The k_eff calculated with respective ²³²Th cross sections from JENDL-3.3 and ENDF/B-VII.0 was 1.0038 ± 0.0086 (%) and 1.0040 ± 0.0086 (%).