Results from the international evaluation exercise for uranium enrichment measurements

An international evaluation exercise for uranium enrichment measurement was organized by the ESARDA (European Safeguards Research and Development Association) Working Group on Techniques and Standards for Non-Destructive Analysis. The aim of this exercise was to test the different methods and more particularly X- and γ-ray spectrometry methods used in the determination of uranium enrichment. Sets of samples of different uranium enrichments prepared by IRMM (Institute for Reference Materials and Measurements) and BNFL (British Nuclear Fuels) were measured by 15 participants in the IRMM laboratories. A description of this exercise is given here and the final results with their uncertainties are compared to the reference values obtained from mass spectrometry measurements. The main conclusions from this exercise are proposed; in particular, it appears necessary to improve the nuclear data used in the spectral modeling of the XKα region.