Evaluation of uranium-233 neutron capture cross section in keV region

TL;DR

This paper evaluates the neutron capture cross section of uranium-233 in the keV energy range using new experimental data, revealing significant reductions compared to existing nuclear data libraries and slight improvements in criticality benchmarks.

Contribution

It provides a revised uranium-233 neutron capture cross section based on recent measurements, improving nuclear data accuracy for reactor physics applications.

Findings

The evaluated cross section is systematically lower than existing library values.

Reduction of about 50% around 20 keV compared to JENDL-5.

Slight improvement in criticality benchmark fits.

Abstract

The uranium-233 neutron capture cross section between 3 keV and 1 MeV was evaluated with the new alpha value recently measured at the Los Alamos National Laboratory LANCE facility and compiled in the EXFOR library. The obtained capture cross section is systematically lower than those in the latest versions of the major general purpose nuclear data libraries, and the reduction from the JENDL-5 library is close to 50% around 20 keV. The newly evaluated cross section was benchmarked against 166 criticality experiments chosen from the ICSBEP handbook by performing Monte Carlo neutron transport calculation with the JENDL-5 library, and slight reduction of the cumulative chi-square value was achieved by adoption of the newly evaluated capture cross section.