Influence of nuclear data on uranium enrichment results obtained by XKalpha spectral region analysis

During the recent international uranium exercise organized by the ESARDA NDA Working Group, several participants determined the uranium enrichment of samples using methods based on analysis of the XKalpha region of the uranium spectrum. For these methods, no calibration with known enrichment standards is required but accurate knowledge of nuclear data is needed. Despite this requirement, it appeared that during the exercise, four different sets of nuclear data were used by the participants. In view of this fact, it was decided to introduce these nuclear data sets into some computer codes in order to check their effects on the enrichment results. Two participants agreed to cooperate, and the main results of this test are presented here. It can be seen that three nuclear data sets, although different, give satisfactory results with no significant bias. Nevertheless, a more accurate characterization of X- and gamma-ray emission from 235U, 235U and their daughters appears necessary.