New measurement of 50Cr and 53Cr (n, γ) cross sections at nTOF: a call for chromium nuclear data revision

50Cr and 53Cr are very relevant in criticality safety benchmarks related to nuclear reactors. The discrepancies of up to 30% between the neutron capture cross section evaluations have an important effect on the keff and k∞ in criticality benchmarks particularly sensitive to chromium. In this work, the 50, 53Cr (n, γ) cross sections are to be determined between 1 and 100 keV with an 8–10% accuracy following the requirements of the NEA High Priority Request List (HPRL) to solve the current discrepancies. We have measured these reactions by the time-of-flight technique at the EAR1 experimental area of the nTOF facility, using an array of four C6D6 detectors with very low neutron sensitivity. The highly-enriched samples used are significantly thinner than in previous measurements, thus minimizing the multiple-scattering effects. We have produced, and analysed with the R-matrix analysis code SAMMY, capture yields featuring 33 resonances of 50Cr and 51 of 53Cr with an accuracy between 5% and 9%, hence fulfilling the requirements made by the NEA. The differential and integral cross sections have been compared to previous data and evaluations. The new measured 50, 53Cr (n, γ) cross sections provide a valuable input for upcoming evaluations, which are deemed necessary given that the results presented herein do not support the increase in both cross sections proposed in the recent INDEN evaluation.