Sensitivity uncertainty analysis and new neutron capture cross-sections for gadolinium odd-isotopes to support nuclear safety

This paper presents the results of a sensitivity and uncertainty (S&U) analysis on keff performed on a BWR fuel assembly (FA) poisoned with gadolinia, as well as of a criticality and sensitivity study of the ZED-2 research reactor, in whose moderator has been dissolved. The evidence collected from the ZED-2 analysis, the BWR FA S&U analysis, and from other criticality benchmarks indicates that improvements should be introduced in the 157Gd (n, γ) cross section evaluation, especially in the thermal and near-thermal ranges, and in its uncertainty. In 2016, to cope with this need, the n_TOF Collaboration conducted an experimental campaign to obtain new 157Gd and 155Gd cross section measurements. The preliminary information available from the analysis of the experimental data suggests that these new data have the potential to correct some of the discrepancies found between some experimental benchmarks and their simulation.