Uncertainty propagation from n+56Fe nuclear reaction model parameters to neutron multiplication factor

Abstract Nuclear data are the main uncertainty sources for modern neutron transport calculations. However, complete correlation matrices among different nuclear data are not presented in the current evaluations. In order to completely consider that correlation between nuclear data, the present work propagates the covariance matrix of continuum n+56Fe reaction model parameters to the effective neutron multiplication factor (keff) of a thermal neutron spectrum benchmark and a fast neutron spectrum benchmark. Results show that the uncertainty propagated from angular distribution is not negligible. The general correlations between angular distributions and cross sections of 56Fe for neutron energies above 850 keV are respectively −0.39 ± 0.05 and −1.02 ± 0.02 for keff calculation in the thermal and fast benchmarks, respectively. These correlations reveal the importance of a complete correlation matrix of nuclear data for propagating uncertainties to neutronic calculations.