Benchmark analysis of fission-rate distributions in a series of spherical depleted-uranium assemblies for hybrid-reactor design

Abstract The nuclear performance of a fission blanket in a hybrid reactor has been validated by analyzing fission-rate experiments with a series of spherical depleted-uranium assemblies. Calculations were made with the Monte–Carlo transport code MCNP5 and the ENDF/B-V.0 continuous-energy cross sections and compared to the measured results. The ratios of calculated to experimental values (C/E) for the fission rate and the fission-rate ratio of 238 U to 235 U are presented along with a discussion of the validation of the ENDF/B-V.0 library regarding its use in the design of the fission blanket. Overestimations are observed in the calculation of the 238 U and 235 U fission rates at all positions, except the ones near the outer surfaces of the assemblies, and the C/Es of the fission rate decreased as the thickness of the depleted-uranium (DU) layer increased, while most of the C/Es of the fission-rate ratio of 238 U to 235 U were close to unity, being within the range of 0.95–1.05.