Evaluation of the ²³Na(n,2n) ²²Na Reaction for ENDF/B-V

The ²³Na(n,2n) reaction produces the radioactive product ²²Na, with a half-life of 2.61 years. For sodium-containing systems this reaction can result in a radioactive contamination problem. Currently available experimental cross sections for this reaction are in strong conflict. Comprehensive nuclear model calculations performed as part of the sodium evaluation for ENDF/B-V are in agreement with one of the experimental data sets. Acceptance of this data set results in an (n,2n) cross section larger than was given in ENDF/B-IV by ∼37% at 15 MeV and by as much as a factor of 4 at 20 MeV.