Proposed re-evaluation of the 154Eu thermal n,γ capture cross-section based on spent fuel benchmarking studies

In this paper, the bias in 154Eu is characterized across eleven spent fuel destructive assay benchmarks from five different assemblies. Based on these studies, possible amendments to the ENDF/B-VII.0 and VII.1 evaluations of the 154Eun,γ155Eu are explored. By amending the location of the first resolved resonance for the 154Eu radiative capture cross-section (centered at 0.195 eV in ENDF/B-VII.0 and VII.1) to 0.188 eV and adjusting the neutron capture width proportional to 1/E, the amended cross-section evaluation was found to reduce the bias in predicted 154Eu inventories by approximately 5-7%. While the amended capture cross-section still results in a residual over-prediction of 154Eu (ranging from 2% to 9%), the effect is substantially attenuated compared with the nominal ENDF/B-VII.0 and VII.1 evaluations.