Validation of Continuous-Energy ENDF/B-VIII.0 ¹⁶O, ⁵⁶Fe, and ^63,65Cu Cross Sections for Nuclear Criticality Safety Applications

Abstract

Recently completed cross-section evaluations sponsored in part by the Nuclear Criticality Safety Program were incorporated into the 2018 release of the ENDF/B-VIII.0 cross-section library. Evaluated isotopes of interest to the nuclear data and criticality safety community include ¹⁶O, ⁵⁶Fe, and ^63,65Cu. For performance validation, benchmark models defined in the International Criticality Safety Benchmark Evaluation Project Handbook were selected based on energy-integrated k_eff sensitivities to total cross sections of interest and compared with experimental values. Of the 102 benchmark configurations that were utilized, 63 are sensitive to ¹⁶O, 32 sensitive to ^63,65Cu, and 25 sensitive to ⁵⁶Fe. Selected benchmarks were modeled in SCALE 6.2.3 Criticality Safety Analysis Sequence (CSAS) continuous-energy Monte Carlo k_eff calculations with ENDF/B-VII.1, with a hybrid ENDF/B-VII.1 with ENDF/B-VIII.0 data substituted for individual isotopes of interest, and with ENDF/B-VIII.0. ENDF/B-VIII.0 showed improved agreement with experimental k_eff for ⁵⁶Fe, ⁶³Cu, elemental copper, and full library substitution while producing lessened agreement for ¹⁶O and ⁶⁵Cu. With full library and isotope-specific ENDF/B-VIII.0 performance, a best-case ENDF library was formed by excluding underperforming isotopes’ ENDF/B-VIII.0 data, reverting ¹⁶O and ⁶⁵Cu cross sections to ENDF/B-VII.1. This resulted in the average relative deviation between calculated and experimental data improving from 1.45σ for the ENDF/B-VIII.0 library to 1.32σ for the best-case library, relative to benchmark uncertainty.

Keywords:

• Copper
• oxygen
• iron
• criticality safety, validation

View addendum:

ADDENDUM: Validation of Continuous-Energy ENDF/B-VIII.0 16O, 56Fe, and 63,65Cu Cross Sections for Nuclear Criticality Safety Applications

Acknowledgments

This work was supported by the NCSP, funded and managed by the National Nuclear Security Administration for the U.S. Department of Energy.