Uncovering uranium isotopic heterogeneity of fuel pellets from the fifth collaborative materials exercise of The Nuclear Forensics International Technical Working Group

In 2017, the Nuclear Forensics International Technical Working Group organized their fifth Collaborative Materials Exercise (CMX-5). The exercise samples were two uranium dioxide fuel pellets manufactured from the same starting materials by different processes to have similar bulk isotopic composition, but different spatial uranium isotopic distributions. Sets of identical materials were sent to all participating laboratories, who then utilized their existing nuclear forensic capabilities to independently analyse fuel pellets and identify similarities and differences of the materials’ characteristics. Here we present and compare the ability of different analytical techniques to spatially resolve uranium isotopic heterogeneity in the uranium oxide fuel pellets.