US-Japan nuclear forensics analysis to identify the origins and process history of UOCs

Shollenberger, Q. R.*; 木村 祥紀; Inglis, J. D.*; Lindvall, R.*; 西脇 大貴; 山中 澪奈; 海野 勇次*; 細井 雅春*; Marks, N.*; Kips, R.*; et al.

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Uranium ore concentrate (UOC), or yellowcake, is a precursor material for nuclear fuel and is formed when uranium ore has been mined and milled (chemically processed). UOC is a commercially and internationally traded product, and several cases have been reported where UOC was found outside regulatory control or interdicted as part of a law enforcement investigation. Consequently, we need to advance our understanding of nuclear forensic signatures to identify the origins and process history of UOCs. Such signatures include the concentration of uranium (U), other minor and trace-level constituents, and isotopic composition of U or strontium (Sr). However, the interpretation of these nuclear forensic signatures can be difficult due to various types of uranium mining techniques, as well as the processing of U ores to UOCs. Therefore, multiple nuclear forensics signatures are necessary to determine material origin with high confidence. Through the Office of Nuclear Smuggling Detection and Deterrence (NNSA/US DOE/NSDD), we present the analysis of seven UOCs provided by the Japan Atomic Energy Agency (JAEA). Nuclear forensic measurements were performed on these UOCs at four different laboratories located in both the US and Japan. This study will focus on the signatures of uranium concentration, trace elements, and U and Sr isotopic compositions. We will discuss the results from the different laboratories and evaluate the importance of these signatures in the context of nuclear forensics.