The Los Alamos evaluation of $^{239}$Pu neutron-induced reactions in the fast energy range

TL;DR

This paper presents a comprehensive revision of the $^{239}$Pu neutron-induced reaction cross sections in the fast energy range, extending from 2.5 keV to 30 MeV, with improved data and modeling.

Contribution

It introduces a new, reproducible evaluation of $^{239}$Pu reactions using detailed modeling, updated data, and version control with a Git repository, enhancing transparency and accuracy.

Findings

Evaluation covers 2.5 keV to 30 MeV energy range.

Results are compatible with older evaluations and validated against experimental benchmarks.

The evaluation is stored in a reproducible, version-controlled format.

Abstract

A major revision of the evaluation of $^{239}$Pu neutron-induced reaction cross sections is reported in the fast energy range. The evaluation starts at 2.5 keV incident neutron energy and has been extended up to 30 MeV. Several other notable changes are included in this evaluation since the release of ENDF/B-VIII.0 including the adoption of the Standards fission cross section, inclusion of new radiative capture data of Mosby et al., inclusion of the (n,2n) data of Meot et al., in addition to advances in the treatment of reaction modeling. In contrast to previous evaluation efforts, this evaluation is reproducible with detailed information stored chronologically utilizing a Git repository. The final evaluation results have been compiled into an ENDF-formatted file, which has been processed successfully through NJOY, checked for internal consistency, benchmarked versus older evaluations and validated against a suite of critical assemblies and pulsed-spheres.