Use the results of measurements on KBR facility for testing of neutron data of main structural materials for fast reactors

Abstract

Several k ∞ experiments were performed on the KBR critical facility at the Institute of Physics and Power Engineering (IPPE), Obninsk, Russia during the 1970s and 80s for study of neutron absorption properties of Cr, Mn, Fe, Ni, Zr, and Mo. Calculations of these benchmarks with almost any modern evaluated nuclear data libraries demonstrate bad agreement with the experiment. Neutron capture cross sections of the odd isotopes of Cr, Mn, Fe, and Ni in the ROSFOND-2010 library have been reevaluated and another evaluation of the Zr nuclear data has been adopted. Use of the modified nuclear data for Cr, Mn, Fe, Ni, and Zr leads to significant improvement of the C/E ratio for the KBR assemblies. Also a significant improvement in agreement between calculated and evaluated values for benchmarks with Fe reflectors was observed. C/E results obtained with the modified ROSFOND library for complex benchmark models that are highly sensitive to the cross sections of structural materials are no worse than results obtained with other major evaluated data libraries. Possible improvement in results by decreasing the capture cross section for Zr and Mo at the energies above 1 keV is indicated.

HPRL – International cooperation to identify and monitor priority nuclear data needs for nuclear applications

“…These requests had also been put forward by SG-26. Additional recent capture requests concern structural material (minor isotopes of Cr [5]) and neutron absorbers (Gd-155,157 [6] and Hf-nat). A significant achievement is the fulfilment of the requests for U-235 and U-238 capture cross sections, which were the subject of intensive collaborative works in the framework of the CIELO project [7,8].…”

Description and outlook of the 50,53Cr(n,γ) cross section measurement at n_TOF and HiSPANoS

“…As criticality safety aims at preventing an uncontrolled self-sustained nuclear chain reaction, , 01004 (2024) EPJ Web of Conferences https://doi.org/10.1051/epjconf/202429401004 294 WONDER-2023 the knowledge of absorption cross sections in fuel elements and the structural materials is crucial for the calculations. In this context, the sizable abundance (11-26%) of chromium in stainless steel makes some criticality benchmarks that include large amounts of chromium (e.g., PU-MET-INTER-002 or HEU-COMP-INTER-005/4=KBR-15/Cr) very sensitive to its cross section, in particular capture on 50 Cr and 53 Cr [2,3]. These criticality benchmarks show clearly that the current differences in the order of 30% between evaluations have a significant impact of about 1000 pcm in the corresponding criticality safety calculations.…”

Newly Evaluated Neutron Reaction Data on Chromium Isotopes

“…Large discrepancies of several percent (1 % is equal to 1000 pcm) between calculated and measured reactivity were found when the ENDF/B-VII.1 (or ENDF/B-VIII.0) library was used. The largest disagreement of 11 % in the most chromium-sensitive experiment, KBR-15, (HEU-MET INTER-015 in ICBESP notation [11]) was traced to heavily underestimated neutron capture on natural chromium in the keV region [12]. Those authors attempted to address the issue [12] within the BROND-3.1 library [13] by fitting the 53 Cr(n, γ) cross sections published by Guber [4] at the NDST 2010 conference.…”

“…The largest disagreement of 11 % in the most chromium-sensitive experiment, KBR-15, (HEU-MET INTER-015 in ICBESP notation [11]) was traced to heavily underestimated neutron capture on natural chromium in the keV region [12]. Those authors attempted to address the issue [12] within the BROND-3.1 library [13] by fitting the 53 Cr(n, γ) cross sections published by Guber [4] at the NDST 2010 conference. The digitized capture yield data in EXFOR were interpreted as cross section data, therefore, neglecting important corrections such as multiple scattering and selfshielding effects, which may reach 80% in the keV region.…”