Title: Trace Impurities Identified as Forensic Signatures in CMX-5 Fuel Pellets Using X-ray Spectroscopic Techniques

Abstract

We report that small-particle analysis is a highly promising emerging forensic tool for analysis of interdicted special nuclear materials. Integration of microstructural, morphological, compositional, and molecular impurity signatures could provide significant advancements in forensic capabilities. We have applied rapid, high-sensitivity, hard X-ray synchrotron chemical imaging to analyze impurity signatures in two differently fabricated fuel pellets from the 5th Collaborative Materials Exercise (CMX5) of the IAEA Nuclear Forensics International Working Group. The spatial distributions, chemical compositions, and morphological and molecular characteristics of impurities were evaluated using X-ray absorption near-edge structure (XANES) and X-ray fluorescence chemical imaging to discover principal impurities, their granularity, particle sizes, modes of occurrence (distinct grains vs incorporation in the UO₂ lattice), and sources and mechanisms of incorporation. Differences in UO_2+x stoichiometry were detected at the microscale in nominally identical UO₂ ceramics (CMX5-A and CMX5-B), implying the presence of multiple UO₂ host phases with characteristic microstructures and feedstock compositions. Al, Fe, Ni, W, and Zr impurities and integrated impurity signature analysis identified distinctly different pellet synthesis and processing methods. For example, two different Al, W, and Zr populations in the CMX5-B sample indicated a more complex processing history than the CMX5-A sample. K-edge XANES measurements reveal both metallicmore » and oxide forms of Fe and Ni but with different proportions between each sample. Altogether, these observations suggest multiple sources of impurities, including fabrication (e.g., force-sieving) and feedstock (mineral oxides). This study demonstrates the potential of synchrotron techniques to integrate different signatures across length scales (angstrom to micrometer) to detect and differentiate between contrasting UO₂ fuel fabrication techniques.« less

Authors:

van Veelen, Arjen  ^[1];

• Search DOE PAGES for author "van Veelen, Arjen"
• Search DOE PAGES for ORCID "0000-0002-8176-3645"

Hickam, Sarah M. ^[1]; Edwards, Nicholas P. ^[2]; Webb, Samuel M. ^[2]; Clark, David L. ^[1]; Wilkerson, Marianne P.  ^[1];

• Search DOE PAGES for author "Wilkerson, Marianne P."
• Search DOE PAGES for ORCID "0000-0001-8540-0465"

Pugmire, Alison L. ^[1]; Bargar, John R.  ^[2]

• Search DOE PAGES for author "Bargar, John R."
• Search DOE PAGES for ORCID "0000-0001-9303-4901"

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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. SLAC National Accelerator Lab., Menlo Park, CA (United States)

Publication Date:

Thu May 05 00:00:00 EDT 2022

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program; G. T. Seaborg Institute; USDOE Office of Science (SC), Basic Energy Sciences (BES); National Institutes of Health (NIH)

OSTI Identifier:

1869625

Report Number(s):

LA-UR-22-20968
Journal ID: ISSN 0003-2700

Grant/Contract Number:  

89233218CNA000001; AC02-76SF00515; P30GM133894

Resource Type:

Accepted Manuscript

Journal Name:

Analytical Chemistry

Additional Journal Information:

Journal Volume: 94; Journal Issue: 19; Journal ID: ISSN 0003-2700

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; fuels; impurities; materials; uranium; x-ray absorption near edge spectroscopy