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Title: Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy

Abstract

Uranium ores mined for industrial use are typically acid-leached to produce yellowcake and then converted into uranium halides for enrichment and purification. These anthropogenic chemical forms of uranium are distinct from their mineral counterparts. The purpose of this study is to use soft X-ray absorption spectroscopy to characterize several common anthropogenic uranium compounds important to the nuclear fuel cycle. Non-destructive chemical analyses of these compounds is important for process and environmental monitoring and X-ray absorption techniques have several advantages in this regard, including element-specificity, chemical sensitivity, and high spectral resolution. Oxygen K-edge spectra were collected for uranyl nitrate, uranyl fluoride, and uranyl chloride, and fluorine K-edge spectra were collected for uranyl fluoride and uranium tetrafluoride. Interpretation of the data is aided by comparisons to calculated spectra. These compounds have unique spectral signatures that can be used to identify unknown samples.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1344048
Report Number(s):
PNNL-SA-115752
Journal ID: ISSN 0584-8547; 47772
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Spectrochimica Acta. Part B, Atomic Spectroscopy; Journal Volume: 127; Journal Issue: C
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; uranium; x-ray; nuclear forensics; anthropogenic uranium; x-ray absorption spectroscopy; Environmental Molecular Sciences Laboratory

Citation Formats

Ward, Jesse D., Bowden, Mark, Tom Resch, C., Eiden, Gregory C., Pemmaraju, C. D., Prendergast, David, and Duffin, Andrew M.. Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy. United States: N. p., 2017. Web. doi:10.1016/j.sab.2016.11.008.
Ward, Jesse D., Bowden, Mark, Tom Resch, C., Eiden, Gregory C., Pemmaraju, C. D., Prendergast, David, & Duffin, Andrew M.. Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy. United States. doi:10.1016/j.sab.2016.11.008.
Ward, Jesse D., Bowden, Mark, Tom Resch, C., Eiden, Gregory C., Pemmaraju, C. D., Prendergast, David, and Duffin, Andrew M.. 2017. "Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy". United States. doi:10.1016/j.sab.2016.11.008.
@article{osti_1344048,
title = {Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy},
author = {Ward, Jesse D. and Bowden, Mark and Tom Resch, C. and Eiden, Gregory C. and Pemmaraju, C. D. and Prendergast, David and Duffin, Andrew M.},
abstractNote = {Uranium ores mined for industrial use are typically acid-leached to produce yellowcake and then converted into uranium halides for enrichment and purification. These anthropogenic chemical forms of uranium are distinct from their mineral counterparts. The purpose of this study is to use soft X-ray absorption spectroscopy to characterize several common anthropogenic uranium compounds important to the nuclear fuel cycle. Non-destructive chemical analyses of these compounds is important for process and environmental monitoring and X-ray absorption techniques have several advantages in this regard, including element-specificity, chemical sensitivity, and high spectral resolution. Oxygen K-edge spectra were collected for uranyl nitrate, uranyl fluoride, and uranyl chloride, and fluorine K-edge spectra were collected for uranyl fluoride and uranium tetrafluoride. Interpretation of the data is aided by comparisons to calculated spectra. These compounds have unique spectral signatures that can be used to identify unknown samples.},
doi = {10.1016/j.sab.2016.11.008},
journal = {Spectrochimica Acta. Part B, Atomic Spectroscopy},
number = C,
volume = 127,
place = {United States},
year = 2017,
month = 1
}
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  • For a number of metallic and nonmetallic U systems as well as a few Th compounds, the near-edge x-ray-absorption fine-structure spectra, taken by transmission and total-electron-yield techniques, are reported at the L/sub 3/, M/sub 3/, M/sub 4,5/, N/sub 4,5/, and O/sub 4,5/, thresholds. At L/sub 3/ and M/sub 3/, similar spectra with analogous information are observed. While in the metallic U systems, the white lines at L/sub 3/ and M/sub 3/ show only minor variations in position and relative peak height, a shift of approx. =4 eV is observed between UCl/sub 3/ and UF/sub 4/, representing mainly the difference inmore » Coulomb interaction between a 2p/sub 3/2/ core hole and the 5f configurations. The spectra at the M/sub 4,5/ and N/sub 4,5/ thresholds are dominated by intense absorption peaks due to 3d-5f and 4d-5f transitions probing directly the unoccupied 5f states. No multiplet structure due to 3d-5f or 4d-5f exchange interaction is resolved, but the linewidths of the M/sub 4,5/ peaks in the metallic U systems are found to decrease by approx. =20% with increasing U-U distance, reflecting a narrowing of the unoccupied 5f bands. The spectra at the O/sub 4,5/ thresholds, on the other hand, show well-resolved structures, which are atomiclike for ThF/sub 4/ and UF/sub 4/ and may be described by spin-orbit and exchange splitting of the 5d/sup 9/5f/sup 1/ and 5d/sup 9/5f/sup 3/ final states, respectively. In metallic U systems, the O/sub 4,5/ structures are broadened and partly lost, presumably due to the more itinerant nature of the 5f states.« less