The Importance of the Uranium-238 Inelastic Transfer Matrix for Fast-Reactor Analysis

The ²³⁸U inelastic scattering was modified to reflect the recently recommended larger values for the 45-keV (2⁺) and 146-keV (4⁺) levels. The partial inelastic cross sections for the other levels given in ENDF/B-IV between 0.8 and 3.7MeV were accordingly decreased such as to keep the total inelastic cross section unchanged. To investigate the consequences of these modifications three fast-neutron assemblies have been analyzed. The above modifications result in a general improvement between calculated and measured fast-reactor parameters.