Recommendation for computing neutron irradiation damage from evaluated nuclear data

Abstract

Accurate evaluation of displacement damage is important for studying the nuclear materials after irradiation. The present work investigates neutron-induced displacement damage evaluation via damage cross sections. There are potential discrepancies between different evaluations on the damage cross sections induced by the (n,γ) reaction and potential discontinuity at 20 MeV incident neutron energy. These two issues are however not important for evaluating neutron irradiation damage in fission and fusion reactors. Due to some issues associated with the recoil distributions in evaluated nuclear data files, the corresponding damage cross sections are questionable, such as those of 52Cr in JEFF-3.3, 55Mn in JEFF-3.3 and ENDF/B-VIII.0, and 180,182,183,184,186W in ENDF/B-VIII.0. Therefore, the present work recommends using two-body kinematic considerations and the differential cross sections of light particles for evaluating neutron irradiation damage (via either displacement cross sections or PKA spectra), unless the recoil distributions have been pre-validated/verified. The recommended method reduces the 70% discrepancy between different nuclear data evaluations to 13% for evaluated displacement damage of tungsten in ITER tokamak.