Uranium assay and trace element analysis of the fourth collaborative material exercise samples by the modified Davies-Gray method and the ICP-MS/OES techniques

An international group of laboratories participating in CMX-4 subjected three samples to comparative nuclear forensic analysis using uranium assay and trace element analysis techniques to determine if the samples had similar or different origins. Uranium assay indicated that two pellet samples (ES-2 and ES-3) were nearly pure UO₂ while the black powder sample ES-1 was primarily UO₂ with UO₃ and/or U₃O₈ forms present as impurities. Trace element analysis by five of the six participating laboratories reported molybdenum concentrations below 10 µg/g U in all of the exercise samples, suggesting the same likely facility of origin for all three samples. (author)