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Title: Measurement of UO 2 surface oxidation using grazing-incidence x-ray diffraction: Implications for nuclear forensics

Abstract

Nuclear forensics involves determination of the origin and history of interdicted nuclear materials based on the detection of signatures associated with their production and trafficking. The surface oxidation undergone by UO 2 when exposed to air is a potential signature of its atmospheric exposure during handling and transport. To assess the sensitivity of this oxidation to atmospheric parameters, surface sensitive grazing-incidence x-ray diffraction (GIXRD) measurements were performed on UO 2 samples exposed to air of varying relative humidity (34%, 56%, and 95% RH) and temperature (room temperature, 50 °C, and 100 °C). Near-surface unit cell contraction was observed following exposure, indicating oxidation of the surface and accompanying reduction of the uranium cation ionic radii. The extent of unit cell contraction provides a measure of the extent of oxidation, allowing for comparison of the effects of various exposure conditions. No clear influence of relative humidity on the extent of oxidation was observed, with samples exhibiting similar degrees of unit cell contraction at all relative humidities investigated. In contrast, the thickness of the oxidized layers increased substantially with increasing temperature, such that differences on the order of 10 °C yielded readily observable crystallographic signatures of the exposure conditions.

Authors:
 [1];  [2]; ORCiD logo [2];  [3];  [2]
  1. Stanford Univ., CA (United States). Dept. of Geological Sciences and Center for International Security and Cooperation
  2. Stanford Univ., CA (United States). Dept. of Geological Sciences
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Sciences Directorate
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
OSTI Identifier:
1513109
Alternate Identifier(s):
OSTI ID: 1505855
Report Number(s):
LLNL-JRNL-757741
Journal ID: ISSN 0022-3115; 945687
Grant/Contract Number:  
AC52-07NA27344; SC0001089; DMR-1332208
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 502; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
Chemistry, Nuclear science and engineering

Citation Formats

Tracy, Cameron L., Chen, Chien-Hung, Park, Sulgiye, Davisson, M. Lee, and Ewing, Rodney C. Measurement of UO2 surface oxidation using grazing-incidence x-ray diffraction: Implications for nuclear forensics. United States: N. p., 2018. Web. doi:10.1016/j.jnucmat.2018.01.052.
Tracy, Cameron L., Chen, Chien-Hung, Park, Sulgiye, Davisson, M. Lee, & Ewing, Rodney C. Measurement of UO2 surface oxidation using grazing-incidence x-ray diffraction: Implications for nuclear forensics. United States. doi:10.1016/j.jnucmat.2018.01.052.
Tracy, Cameron L., Chen, Chien-Hung, Park, Sulgiye, Davisson, M. Lee, and Ewing, Rodney C. Wed . "Measurement of UO2 surface oxidation using grazing-incidence x-ray diffraction: Implications for nuclear forensics". United States. doi:10.1016/j.jnucmat.2018.01.052. https://www.osti.gov/servlets/purl/1513109.
@article{osti_1513109,
title = {Measurement of UO2 surface oxidation using grazing-incidence x-ray diffraction: Implications for nuclear forensics},
author = {Tracy, Cameron L. and Chen, Chien-Hung and Park, Sulgiye and Davisson, M. Lee and Ewing, Rodney C.},
abstractNote = {Nuclear forensics involves determination of the origin and history of interdicted nuclear materials based on the detection of signatures associated with their production and trafficking. The surface oxidation undergone by UO2 when exposed to air is a potential signature of its atmospheric exposure during handling and transport. To assess the sensitivity of this oxidation to atmospheric parameters, surface sensitive grazing-incidence x-ray diffraction (GIXRD) measurements were performed on UO2 samples exposed to air of varying relative humidity (34%, 56%, and 95% RH) and temperature (room temperature, 50 °C, and 100 °C). Near-surface unit cell contraction was observed following exposure, indicating oxidation of the surface and accompanying reduction of the uranium cation ionic radii. The extent of unit cell contraction provides a measure of the extent of oxidation, allowing for comparison of the effects of various exposure conditions. No clear influence of relative humidity on the extent of oxidation was observed, with samples exhibiting similar degrees of unit cell contraction at all relative humidities investigated. In contrast, the thickness of the oxidized layers increased substantially with increasing temperature, such that differences on the order of 10 °C yielded readily observable crystallographic signatures of the exposure conditions.},
doi = {10.1016/j.jnucmat.2018.01.052},
journal = {Journal of Nuclear Materials},
issn = {0022-3115},
number = C,
volume = 502,
place = {United States},
year = {2018},
month = {1}
}

Journal Article:
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