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

Abstract

Uranium ore is mined and milled to produce uranium ore concentrate (UOC), a regulated product of the nuclear fuel cycle. Additionally, 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 themore » neutron fluence over the history of the original ore body and can be used to discern different geologic conditions associated with that ore body. Overall, this work demonstrates the potential use of Sm isotopes as a novel nuclear forensics signature for origin assessment of UOCs.« less

Authors:

Shollenberger, Quinn R. ^[1]; Borg, Lars E.  ^[2];

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Ramon, Erick C. ^[2]; Sharp, Michael A. ^[2]; Brennecka, Gregory A. ^[1]

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+ Show Author Affiliations

1. Univ. of Munster (Germany); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Publication Date:

Fri Jul 31 00:00:00 EDT 2020

Research Org.:

Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); German Research Foundation (DFG)

OSTI Identifier:

1668482

Alternate Identifier(s):

OSTI ID: 1810950

Report Number(s):

LLNL-JRNL-811552
Journal ID: ISSN 0039-9140; 1018406

Grant/Contract Number:  

AC52-07NA27344; 440227108

Resource Type:

Accepted Manuscript

Journal Name:

Talanta

Additional Journal Information:

Journal Volume: 221; Journal ID: ISSN 0039-9140

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Nuclear forensics; origin assessment; samarium isotopes; uranium ore concentrate; thermal neutron capture