Experimental Analyses of ²⁴³Am and ²³⁵U Fission Reaction Rates at Kyoto University Critical Assembly

Abstract

Measurements of ²⁴³Am and ²³⁵U fission reaction rates are conducted with the use of two single fission chambers in the solid-moderated and solid-reflected core at the Kyoto University Critical Assembly (KUCA). Critical irradiation experiments of ²⁴³Am and ²³⁵U foils are carried out, and the measured result of ²⁴³Am/²³⁵U is 0.0424 ± 0.0019; also, calculation/experiment values between calculated (MCNP6.1 with JENDL-4.0, ENDF/B-VIII.0, and JEFF-3.3) and measured results of ²⁴³Am/²³⁵U range among 0.93 ± 0.04, 0.94 ± 0.04, and 0.93 ± 0.04, respectively. Through a comparison between the measured and calculated results, the ²⁴³Am fission cross-section data of the three major nuclear data libraries are successfully validated, demonstrating the same accuracy as that of previous minor actinide irradiation experiments at KUCA. Importantly, the comparison also provides the complemental data of integral experiments of ²⁴³Am fission reaction rates that confirm the accuracy of the ²⁴³Am fission cross-section data.

Keywords:

• Am-243
• fission reaction rates
• integral experiment
• KUCA, MCNP

Acknowledgments

The authors are grateful to all technical staff at KUCA for their assistance during the experiments and to Masao Yamanaka of Kyoto University (currently, Nuclear Engineering Ltd., Japan) for his invaluable comments and advice in this study.