EXFOR-based simultaneous evaluation for neutron-induced fission cross section of plutonium-242

TL;DR

This paper presents a new evaluation of the neutron-induced fission cross section of plutonium-242 using the EXFOR database, incorporating multiple datasets and methods, resulting in improved accuracy and consistency with recent evaluations.

Contribution

The study introduces a simultaneous evaluation method for $^{242}$Pu fission cross section using the EXFOR library and additional datasets, enhancing the accuracy over previous evaluations.

Findings

The evaluated cross section aligns with JENDL-5 below 1 MeV.

It systematically differs from JENDL-4.0 above 10 MeV.

The new evaluation better matches experimental data and criticality benchmarks.

Abstract

The $^{242}$Pu neutron-induced fission cross section was evaluated from 100 keV to 200 MeV. The experimental $^{242}$Pu and $^{235}$U fission cross sections and their ratios in the EXFOR library were reviewed and analysed by the least-squares method. Additional simultaneous evaluation was performed by including the experimental database of the $^{233,238}$U and $^{239,240,241}$Pu fission cross sections and their ratios developed for JENDL-5 evaluation. The $^{242}$Pu fission cross sections from our evaluation and JENDL-5 evaluation are close to each other below 1 MeV while systematically differ from each other above 10 MeV. The cross section from our evaluation is systematically lower than the JENDL-4.0 cross section in the prompt fission neutron spectrum peak region ($\sim$5% lower around 1 MeV). The newly evaluated $^{242}$Pu fission cross section was verified against the cross section measured in the $^{252}$Cf spontaneous fission neutron field and criticalities of small-sized LANL fast systems, and demonstrated better performance than the JENDL-4.0 cross section on the same level with the JENDL-5 cross section.