Evaluation of the 235U prompt fission neutron spectrum including a detailed analysis of experimental data and improved model information

Denise Neudecker, Patrick Talou, Albert C. Kahler, Morgan C. White, Toshihiko Kawano, A. Plompen, F.-J. Hambsch, P. Schillebeeckx, W. Mondelaers, J. Heyse, S. Kopecky, P. Siegler (+1 others)
2017 EPJ Web of Conferences  
We present an evaluation of the 235 U prompt fission neutron spectrum (PFNS) induced by thermal to 20-MeV neutrons. Experimental data and associated covariances were analyzed in detail. The incident energy dependence of the PFNS was modeled with an extended Los Alamos model combined with the Hauser-Feshbach and the exciton models. These models describe prompt fission, pre-fission compound nucleus and pre-equilibrium neutron emissions. The evaluated PFNS agree well with the experimental data
more » ... perimental data included in this evaluation, preliminary data of the LANL and LLNL Chi-Nu measurement and recent evaluations by Capote et al. and Rising et al. However, they are softer than the ENDF/B-VII.1 (VII.1) and JENDL-4.0 PFNS for incident neutron energies up to 2 MeV. Simulated effective multiplication factors k eff of the Godiva and Flattop-25 critical assemblies are further from the measured k eff if the current data are used within VII.1 compared to using only VII.1 data. However, if this work is used with ENDF/B-VIII.0β2 data, simulated values of k eff agree well with the measured ones.
doi:10.1051/epjconf/201714604012 fatcat:mhwjo43dyzdn3kqyu255a2o2si