Discussion on variety of cross-section candidate obtained by cross-section adjustment method

Abstract

The cross-section adjustment method gives only one best-estimated cross-section set based on Bayesian theory. In this study, cross-section sets other than the best-estimated set were discussed. The cross-section sets were obtained by the random sampling method using a covariance matrix adjusted by the cross-section adjustment method. 1,000,000 cross-section sets were obtained by the random sampling method. From these cross-section sets, significant cross-section sets other than the best-estimated set were considered. 593,340 cross-section sets that accurately evaluate nuclear characteristics were obtained. The result of the cross-section adjustment method shows that the change due to U235 χ is the largest positive. However, keff is not changed to the positive side by U235 χ in 179,994 of the 593,340 cross-section sets obtained by the random sampling method. Although the best-estimated cross-section set is obtained by the cross-section adjustment method, the result suggests there are various candidates for the adjusted cross-section set.