Isotopic and Compositional Variations in Single Nuclear Fuel Pellet Particles Analyzed by Nanoscale Secondary Ion Mass Spectrometry

Connaugh M. Fallon, William R. Bower, Ian C. Lyon, Francis R. Livens, Paul Thompson, Matthew Higginson, Jane Collins, Sarah L. Heath, Gareth T. W. Law

Research output: Contribution to journalArticleScientificpeer-review


The Collaborative Materials Exercise (CMX) is organized by
the Nuclear Forensics International Technical Working Group, with the aim
of advancing the analytical capabilities of the participating organizations and
providing feedback on the best approaches to a nuclear forensic
investigation. Here, model nuclear fuel materials from the 5th CMX iteration
were analyzed using a NanoSIMS 50L (CAMECA) in order to examine
inhomogeneities in the 235U/238U ratio and trace element abundance within
individual, micrometer scale particles. Two fuel pellets were manufactured
for the exercise and labelled CMX-5A and CMX-5B. These pellets were
created using different processing techniques, but both had a target enrichment value of 235U/238U = 0.01. Particles from these pellets were isolated for isotopic and trace element analysis. Fifteen CMX-5A particles and 20 CMX-5B particles were analyzed, with both sample types displaying inhomogeneities in the U isotopic composition at a sub-micrometer scale within individual particles. Typical particle diameters were ∼1.5 to 41 μm for CMX-5A and ∼1 to 61 μm for CMX-5B. The CMX-5A particles were shown to be more isotopically homogeneous, with a mean 235U/238U atom ratio of 0.0130 ± 0.0066. The CMX-5B particles showed a predominantly depleted mean 235U/238U atom ratio of 0.0063 ± 0.0094, which is significantly different to the target enrichment value of the pellet and highlights the potential variation of 235U/238U in U fuel pellets at the micrometer scale. This study details the successful application of the NanoSIMS 50L in a mock nuclear forensic investigation by optimizing high- resolution imaging for uranium isotopics.
Original languageEnglish
JournalACS Omega
Issue number1
Pages (from-to)296-303
Number of pages8
Publication statusPublished - 14 Jan 2020
MoE publication typeA1 Journal article-refereed

Bibliographical note

Article published under an ACS AuthorChoice License

Fields of Science

  • 116 Chemical sciences

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