Void Reactivity in Lead and Bismuth Sample Reactivity Experiments at Kyoto University Critical Assembly

Sample reactivity and void reactivity experiments are carried out in the solid-moderated and solid-reflected cores at the Kyoto University Critical Assembly (KUCA) with the combined use of aluminum (Al), lead (Pb), and bismuth (Bi) samples, and Al spacers simulating the void. MCNP6.2 eigenvalue calculations together with JENDL-4.0 provide good accuracy of sample reactivity with the comparison of experimental results. Also, experimental void reactivity is attained by using MCNP6.2 together with JENDL-4.0 and ENDF/B-VII.1 with a small relative difference between experiments and calculations. Uncertainty in sample reactivity and void reactivity due to the ENDF/B-VII.1 Al, Pb, and Bi nuclear data is quantified using sensitivities calculated by the ksen card in MCNP6.2 and covariances provided by SCALE6.2. A series of reactivity analyses with the Al spacer simulating the void demonstrates the means of analyzing the void in the solid-moderated and solid-reflected cores at KUCA.