One-Group Cross-Sections of High-Threshold Reactions for Precision Neutronics Calculations

Low-concentration nuclides – impurity nuclides – are increasingly in demand in radiochemistry for defining more precisely the neutronic characteristics of the medium. On use in precision calculations, impurity nuclides afford more accurate calculations. This article considers aspects of the calculation of one-group cross sections of the high-threshold reactions (n, nt), (n, 2α), (n, 2p), (n, pα), (n, nd), (n, np), (n, 2nα), and others in extended libraries and their influence on the nuclide composition of irradiated compositions in calculations using the MZK precision program. This program affords guaranteed accuracy of calculated nuclides, including impurities. A procedure is proposed for calculating one-group cross sections as applied to the spectrum in fast reactors.