Abstract
Many proposed advanced nuclear energy systems require so called high-assay low enriched uranium (HALEU), which has a 235U enrichment >5 wt% and <20 wt%, where the current fleet of light water reactors (LWRs) utilize enrichments of 5 wt% or less. With few benchmark experiments in HA-LEU enrichment range, the interplay of the cross sections for multiple nuclei become important, especially for LEU experiments where 1H, 16O, 235U, 238U and others are applied simultaneously in the calculation of the integral keff response. With continuing evidence that nuclear data are tuned to reproduce expected keff values for selected criticality experiments, which likely do not include those with 20 wt% 235U, particular attention must be given to validation.
This paper describes the impact of recent nuclear data changes on HA-LEU and provides a preliminary sensitivity/uncertainty-based assessment of the applicability of available of criticality experiments for the validation of licensing calculations for the transportation of small quantities of 20 wt% UF6.
