Uncertainty Quantification of Lead and Bismuth Sample Reactivity Worth at Kyoto University Critical Assembly

Abstract

Uncertainty quantification of lead (Pb) and bismuth (Bi) sample reactivity worth is numerically determined using the SCALE6.2 code system and experimental results obtained from the solid-moderated and solid-reflected core at the Kyoto University Critical Assembly (KUCA) to demonstrate the sensitivity coefficients of aluminum (Al) and Bi scattering reactions. From the results of the numerical analyses, the impact of ²⁷Al and ²⁰⁹Bi scattering cross sections obtained using SCALE6.2/TSAR is disclosed on the Bi sample reactivity worth using Al reference and Bi test samples, although the uncertainty itself is small in the Bi sample reactivity worth. In future studies, the actual impact of ²⁰⁹Bi inelastic scattering reactions in liquid Pb-Bi eutectic needs to be considered under numerical simulations of the void reactivity in the accelerator-driven system. Also, in the KUCA experiments, conventional modeling of void evolution by the Al reference sample is expected to be altered by a void (air) in terms of the ²⁷Al elastic and inelastic scattering reactions of the Al reference sample.

Keywords:

• Uncertainty
• lead
• bismuth, SCALE6.2, KUCA

Acknowledgments

The authors are grateful to all the technical staff at KUCA for their assistance during the experiments.