Treatment of nuclear data for transport problems containing detailed temperature distributions

摘要

This paper considers the problem of accurately representing the temperature dependence of neutron cross-section data in neutron transport problems when there are many nuclides and when the temperature distributions vary significantly with both space and time. An approach involving interpolation between nuclear data libraries at various reference temperatures is investigated. Reference nuclear data libraries are obtained by Doppler broadening cross sections to the desired temperatures using the NJOY code system. Several interpolation schemes over various temperature intervals are studied. Interpolated values at intermediate temperatures are compared to NJOY Doppler-broadened results for the same temperature. Differences relative to the Doppler-broadened results are calculated in order to judge the suitability of the interpolation scheme and temperature interval. The total, elastic scattering, capture, and fission (if applicable) reactions for U-238, U-235, natural Zr, O-16, B-10, and H-1 are considered in this study, over a temperature range of 294 to 811 K (similar to 70 to similar to 1000 degrees F). The nuclides and temperature range are selected to best represent typical light water reactor calculations.