Measurement and Analysis of Leakage Neutron Spectra from Spherical Assemblies of Chromium, Manganese and Copper with 14 MeV Neutrons

Abstract

In order to make benchmark validation of the nuclear data for Cr, Mn and Cu in existing modern evaluated nuclear data files, leakage neutron spectra in the energy range from 0.1 to 15 MeV from spherical sample piles were measured by a time-of-flight technique using intense 14 MeV neutron source, OKTAVIAN. To make a qualitative understanding of the dependence of the spectra on individual partial cross sections, a trial calculation was performed by Monte Carlo neutron transport code MCNP-4A along with several kinds of modified cross sections for Mn. The measured spectra were compared with those by theoretical calculation using MCNP-4A with the evaluated nuclear data files. The comparison was made by the spectrum shape and by the C/E values in four energy regions. The calculations for Cr, Mn and Cu using JENDL-3.2, JENDL Fusion File, FENDL-1.0 and EFF-2 give satisfactory predictions with a few exceptions. By checking the result of the trial calculation, it is considered that these disagreement is caused by improper evaluation either of inelastic scattering cross section values and/or energy distribution of secondary neutrons.