Speaker
Description
Due to its significant presence in stainless steel, chromium plays a crucial role in criticality safety benchmarks focused on structural materials. The found discrepancies of ~30% in the neutron capture cross sections of $^{50}$Cr and $^{53}$Cr have an impact of about 1% on k-eff [1]. This issue was highlighted in the latest evaluation (INDEN), which proposed an important increase of these cross sections [2] but called for new data to confirm or deny it. For this reason, the Nuclear Energy Agency (NEA) opened an entry in its High Priority Request List (HPRL) [3] to measure the $^{50,53}$Cr(n,$\gamma$) cross sections with an accuracy of 8 to 10% between 1 and 100 keV, with emphasis on the region below 10 keV.
As a response to the request, two measurements have been performed. First, a time-of-flight measurement was performed at the EAR1 of CERN n_TOF facility [4], where the capture yield of both isotopes was measured with C$_6$D$_6$ detectors. An analysis performed with SAMMY [5] has led to a new set of proposed resonance parameters. Additionally, a neutron activation measurement of $^{50}$Cr was performed at the HiSPANoS facility of CNA [6] to determine its MACS at kT=30 keV for the first time. The results from both experiments are consistent and point to a clear overestimation in the new INDEN evaluation by 20-40% for both isotopes. Here we present a description of both measurements, the results obtained and their potential implications in future re-evaluation efforts of these chromium isotopes.
[1] Trkov A., INDC (NDS)-0751 (2018)
[2] Nobre. et al., Nuclear Data Sheets, 173, 1 (2021)
[3] Dupont E. et al., EPJ Web of Conferences. 239, 15005 (2020)
[4] Guerrero C. et al., The European Physical Journal, 49, 1 (2013)
[5] N. M. Larson, Technical report ORNL/TM-9179/R8 (2008)
[6] Macías M. et al., Radiation Physics and Chemistry, 168, 108538 (2020)
| Session | Microscopic and Integral Measurements |
|---|