Samarium isotope compositions of uranium ore concentrates: A novel nuclear forensic signature

• Published in: Talanta (Oxford) Vol. 221; p. 121431
• Main Authors: Shollenberger, Quinn R., Borg, Lars E., Ramon, Erick C., Sharp, Michael A., Brennecka, Gregory A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2021
• Subjects: Nuclear forensics; Origin assessment; Samarium isotopes; Thermal neutron capture; Uranium ore concentrate; Samarium isotopes; Thermal neutron capture; Origin assessment; Uranium ore concentrate; Nuclear forensics
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2020.121431

Uranium ore is mined and milled to produce uranium ore concentrate (UOC), a regulated product of the nuclear fuel cycle. Diversion of UOC from the fuel cycle into possible weapons production is a key concern in global nonproliferation efforts. As such, the ability to trace the origin of seized nuclear materials is imperative to law enforcement efforts. Although isotopic signatures of UOCs have proven fruitful to pinpoint sample provenance, new isotopic signatures are needed because most existing isotopic signatures are not indicative of the original ore body from which the U is derived. In this work, we developed a new method to separate samarium (Sm) from a U-rich sample matrix and report the first Sm isotope compositions of 32 UOCs derived from a variety of worldwide uranium mines. Relative to terrestrial standards, approximately half the UOCs have resolved and anticorrelated 149Sm-150Sm isotope compositions, consistent with the capture of thermal neutrons by 149Sm in the ore body. The UOCs with anomalous Sm isotope compositions tend to derive from older (~>1.5Ga) and higher-grade ore bodies, although other factors, such as the presence of neutron moderators like water, also play a role. Nonetheless, the Sm isotope compositions of UOCs directly reflects the neutron fluence over the history of the original ore body and can be used to discern different geologic conditions associated with that ore body. As such, this work demonstrates the potential use of Sm isotopes as a novel nuclear forensics signature for origin assessment of UOCs. [Display omitted] •We present a new method to separate Sm from a U-rich sample matrix.•Developed method was applied to Uranium Ore Concentrate (UOC) samples.•UOCs have anticorrelated 149Sm-150Sm anomalies from neutron capture in U ore bodies.•149Sm-150Sm signatures are indicative of U ore deposit type.•Sm isotope variation in UOCs is a novel nuclear forensic signature.