Neutron cross section measurements for BUC approaches

Criticality safety analysis is required at various stages of the back-end of the fuel cycle, i.e. reprocessing, transport, storage and disposal of spent nuclear fuel (SNF). To account for the reduction in reactivity due to fuel burnup, the Bum-Up Credit (BUC) concept was introduced. Evidently, this concept depends on the quality of nuclear data, in particular the absorption cross sections of some key nuclides. A dedicated programme has been established at the GELINA facility of the JRC-Geel to produce accurate cross section data and validate the evaluated nuclear data libraries for neutron interactions with fission fragments that are relevant for a BUC approach. In this work, cross section data for Rh-103 and Gd-155 are presented and the results are compared with the main evaluation libraries, showing good agreement in the thermal energy region with ENDF/B-VIII.0 and JEFF -3.3, but not with JENDL-4.0 for Rh-103.