Neutron thermalizatíon in heavy water-Measurement and calculation of spectra

Abstract

Spatially dependent neutron spectra have been measured in nonpoisoned heavy w ater (99.53 mol %), using the time-of-flight technique. From a critical review of the available scattering kernels, the ENDF/CASKET model was selected; this model in conjunction with a modified version of the DTF-IV transport code in Sg and P approximations, proved to be satisfactory for the cases studied. Also calculations were perform ed by the THERMOS and NYRESE codes. For the spectra studied the largest discrepancies between theory and measurement were 15%, a substantial improvement over prior studies.