235U capture cross-section adjustment in criticality benchmarks using ENDF/B-VII.1 evaluation

ABSTRACT This present study aims to evaluate the nuclear data uncertainty on the neutron multiplication factor (keff) in order to adjust the 235U capture multigroup cross sections and the covariance matrix of the ENDF/B-VII.1 evaluation. For this purpose, the generalized linear-least squares method is applied. The 44 multigroup cross sections and the covariance matrix are processed with NJOY99 nuclear software, while MCNP6.1 nuclear code is used for the keff and sensitivity profile calculations. The obtained results show that the 235U capture cross sections require an adjustment of approximately ？1% in 0–6 eV, ？0.5% in 6 eV to 3 keV, 2% in 3 keV to 0.4 MeV, and ？10% in 0.4–20 MeV