Key changes in nuclear data in the transition from ENDF/B-V to ENDF/B- VI

摘要

Major changes were made in the evaluated nuclear data base in going from ENDF/B-V to ENDF/B-VI. A complete revision of all the cross sections standards was implemented using results from a simultaneous analysis of all standard reactions; energy-angle correlated secondary distributions for emitted particles and gamma rays were introduced; many natural element evaluations were replaced by isotopic data; vastly expanded fission-product yield and decay data files were included; and altogether some 74 general purpose data evaluations were either completely replaced or significantly revised. Applications that will utilize nuclear data from the recently issued ENDF/B-VI library are varied in scope, and a number of the improvements and changes that have occurred relative to the previous library are significant for certain of the application areas. The purpose of this paper is to examine the changes in data that have occurred in a selection of nuclear reactions important for applications, emphasizing several that influence results in key data testing calculations. In particular, the paper highlights revisions in neutron-induced reactions from (sup 14)N and (sup 16)O that are important in calculating neutron transport and/or reflection in air, and some of the changes in data for (sup 235)U, (sup 238)U, and (sup 239)Pu that are significant in fast reactor applications.