Modification to Fissile Element Cross Sections and Their Influence on the Calculated Parameters of Fast Critical Assemblies

摘要

Fast cross section sets are prepared for the analysis of fast critical assemblies to test the agreement of calculated and measured integral parameters. Modifications are brought to fissile element cross sections making use of recently measured cross section data, and these updated cross section data are utilized to compare the calculated integral parameters of these assemblies, and to determine the effect brought to the calculated results by the differences between the data. The results are presented for the eigenvalue, central fission ratios and central sample reactivity in the 239Pu fueled assemblies ZPR-3-48, 49, 50 and ZEBRA-6A, whose spectra simulate those of large fast reactors. In addition, for ZPR-6-7 and ZPPR-2, which are large fast critical assemblies intended for testing the calculational procedures of practical demonstration reactor design, the results of analysis obtained with the updated cross section set are compared with experiments. It is found that the cross section for 241Pu recommended here satisfactorily agrees with the experimental reactivity worth.