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Title: The structure of liquid UO2-x in reducing gas atmospheres

Abstract

High energy X-ray diffraction experiments performed on hypostoichiometric UO2-x liquids in reducing gas mixtures of 95%Ar:5%CO and 95%Ar:5%H2 are compared to that conducted in a pure Ar atmosphere [Skinner et al., Science 346, 984 (2014)]. The measurements are pertinent to severe accident scenarios at nuclear reactors, where core melts can encounter reducing conditions and further shed light on the oxide chemistry of the low valence states of uranium, particularly U(III), which become stable only at very high temperatures and low oxygen potentials. The radioactive samples were melted by floating small spheres of material using an aerodynamic levitator and heating with a laser beam. In the more reducing environments, a 1.7% shift to lower Q-values is observed in the position of the principal peak of the measured X-ray structure factors, compared to the more oxidizing Ar environment. This corresponds to an equivalent elongation in the U-U nearest neighbor distances and the U-U periodicity. The U-O peak (modal) bond-length, as measured from the real-space total correlation functions, is also observed to expand by 0.9–1.6% under reducing conditions, consistent with the presence of 15–27% U3+ cations, assuming constant U-O coordination number. The slightly larger U-U elongation, as compared to the U-O elongation, ismore » interpreted as a slight increase in U-O-U bond angles. Difficulties concerning the determination of the hypostoichiometry, x, are discussed, along with the future directions for related research.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [1]; ORCiD logo [3];  [4];  [5];  [6];  [6]
  1. Materials Development Inc., Arlington Heights, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States). X-ray Science Division
  2. Argonne National Lab. (ANL), Argonne, IL (United States). X-ray Science Division
  3. Argonne National Lab. (ANL), Argonne, IL (United States). X-ray Science Division; Stony Brook Univ., NY (United States). Mineral Physics Inst.
  4. Materials Development Inc., Arlington Heights, IL (United States)
  5. Materials Development Inc., Arlington Heights, IL (United States)A
  6. Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1389313
Alternate Identifier(s):
OSTI ID: 1349361
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 110; Journal Issue: 8; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; X-ray diffraction; Liquid metals; X-ray absorption near edge structure; Uranium; Atmospheric temperature

Citation Formats

Alderman, O. L. G., Benmore, C. J., Weber, J. K. R., Skinner, L. B., Tamalonis, A. J., Sendelbach, S., Hebden, A., and Williamson, M. A. The structure of liquid UO2-x in reducing gas atmospheres. United States: N. p., 2017. Web. doi:10.1063/1.4977035.
Alderman, O. L. G., Benmore, C. J., Weber, J. K. R., Skinner, L. B., Tamalonis, A. J., Sendelbach, S., Hebden, A., & Williamson, M. A. The structure of liquid UO2-x in reducing gas atmospheres. United States. doi:10.1063/1.4977035.
Alderman, O. L. G., Benmore, C. J., Weber, J. K. R., Skinner, L. B., Tamalonis, A. J., Sendelbach, S., Hebden, A., and Williamson, M. A. Wed . "The structure of liquid UO2-x in reducing gas atmospheres". United States. doi:10.1063/1.4977035. https://www.osti.gov/servlets/purl/1389313.
@article{osti_1389313,
title = {The structure of liquid UO2-x in reducing gas atmospheres},
author = {Alderman, O. L. G. and Benmore, C. J. and Weber, J. K. R. and Skinner, L. B. and Tamalonis, A. J. and Sendelbach, S. and Hebden, A. and Williamson, M. A.},
abstractNote = {High energy X-ray diffraction experiments performed on hypostoichiometric UO2-x liquids in reducing gas mixtures of 95%Ar:5%CO and 95%Ar:5%H2 are compared to that conducted in a pure Ar atmosphere [Skinner et al., Science 346, 984 (2014)]. The measurements are pertinent to severe accident scenarios at nuclear reactors, where core melts can encounter reducing conditions and further shed light on the oxide chemistry of the low valence states of uranium, particularly U(III), which become stable only at very high temperatures and low oxygen potentials. The radioactive samples were melted by floating small spheres of material using an aerodynamic levitator and heating with a laser beam. In the more reducing environments, a 1.7% shift to lower Q-values is observed in the position of the principal peak of the measured X-ray structure factors, compared to the more oxidizing Ar environment. This corresponds to an equivalent elongation in the U-U nearest neighbor distances and the U-U periodicity. The U-O peak (modal) bond-length, as measured from the real-space total correlation functions, is also observed to expand by 0.9–1.6% under reducing conditions, consistent with the presence of 15–27% U3+ cations, assuming constant U-O coordination number. The slightly larger U-U elongation, as compared to the U-O elongation, is interpreted as a slight increase in U-O-U bond angles. Difficulties concerning the determination of the hypostoichiometry, x, are discussed, along with the future directions for related research.},
doi = {10.1063/1.4977035},
journal = {Applied Physics Letters},
number = 8,
volume = 110,
place = {United States},
year = {2017},
month = {2}
}

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Works referenced in this record:

Development and operating experience of a short-period superconducting undulator at the Advanced Photon Source
journal, April 2015

  • Ivanyushenkov, Y.; Harkay, K.; Abliz, M.
  • Physical Review Special Topics - Accelerators and Beams, Vol. 18, Issue 4
  • DOI: 10.1103/PhysRevSTAB.18.040703

Area detector corrections for high quality synchrotron X-ray structure factor measurements
journal, January 2012

  • Skinner, Lawrie B.; Benmore, Chris J.; Parise, John B.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 662, Issue 1
  • DOI: 10.1016/j.nima.2011.09.031

Accident tolerant fuels for LWRs: A perspective
journal, May 2014


Molecular-dynamic simulation of the thermophysical properties of liquid uranium
journal, June 2010


Molecular Dynamics study of the effects of non-stoichiometry and oxygen Frenkel pairs on the thermal conductivity of uranium dioxide
journal, February 2013


Ab initio investigation on oxygen defect clusters in UO2+x
journal, November 2008

  • Geng, Hua Y.; Chen, Ying; Kaneta, Yasunori
  • Applied Physics Letters, Vol. 93, Issue 20
  • DOI: 10.1063/1.3035846

Thermophysical properties of uranium dioxide
journal, March 2000


Continuous Structural Transition in Glass-Forming Molten Titanate BaTi 2 O 5
journal, November 2016

  • Alderman, O. L. G.; Benmore, C. J.; Tamalonis, A.
  • The Journal of Physical Chemistry C, Vol. 120, Issue 47
  • DOI: 10.1021/acs.jpcc.6b08248

Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides
journal, September 1976


Experimental evidence of Xe incorporation in Schottky defects in UO 2
journal, March 2015

  • Bès, René; Martin, Philippe; Vathonne, Emerson
  • Applied Physics Letters, Vol. 106, Issue 11
  • DOI: 10.1063/1.4914300

Aerodynamic levitator for in situ x-ray structure measurements on high temperature and molten nuclear fuel materials
journal, July 2016

  • Weber, J. K. R.; Tamalonis, A.; Benmore, C. J.
  • Review of Scientific Instruments, Vol. 87, Issue 7
  • DOI: 10.1063/1.4955210

Determination of solidus-liquidus temperatures in the uo2 + x system (−0.50<x<0.20)
journal, May 1970


Melting of stoichiometric and hyperstoichiometric uranium dioxide
journal, June 2005


High-temperature studies of UO2 and ThO2 using neutron scattering techniques
journal, January 1987

  • Hutchings, Michael T.
  • Journal of the Chemical Society, Faraday Transactions 2, Vol. 83, Issue 7
  • DOI: 10.1039/f29878301083

Taking the measure of molten uranium oxide
journal, November 2014


Thermal Transport in Off-Stoichiometric Uranium Dioxide by Atomic Level Simulation
journal, April 2009

  • Watanabe, Taku; Srivilliputhur, Srinivasan G.; Schelling, Patrick K.
  • Journal of the American Ceramic Society, Vol. 92, Issue 4
  • DOI: 10.1111/j.1551-2916.2009.02966.x

Neutron diffraction by germania, silica and radiation-damaged silica glasses
journal, February 1969


Progress in the thermodynamic modelling of the O–U binary system
journal, May 2002


Iron K-edge X-ray absorption near-edge structure spectroscopy of aerodynamically levitated silicate melts and glasses
journal, March 2017


Current knowledge on core degradation phenomena, a review
journal, April 1999


Low Cation Coordination in Oxide Melts
journal, April 2014


Chemical thermodynamic representation of
journal, February 1985


Premelting transition in uranium dioxide
journal, March 1993

  • Hiernaut, J. P.; Hyland, G. J.; Ronchi, C.
  • International Journal of Thermophysics, Vol. 14, Issue 2
  • DOI: 10.1007/BF00507813

Local structural variation with oxygen fugacity in Fe2SiO4+ fayalitic iron silicate melts
journal, April 2017


Extracting the pair distribution function from white-beam X-ray total scattering data
journal, June 2011


Molten uranium dioxide structure and dynamics
journal, November 2014


Molecular dynamics simulation of premelting and melting phase transitions in stoichiometric uranium dioxide
journal, September 2007

  • Yakub, Eugene; Ronchi, Claudio; Staicu, Dragos
  • The Journal of Chemical Physics, Vol. 127, Issue 9
  • DOI: 10.1063/1.2764484

Two-dimensional detector software: From real detector to idealised image or two-theta scan
journal, January 1996

  • Hammersley, A. P.; Svensson, S. O.; Hanfland, M.
  • High Pressure Research, Vol. 14, Issue 4-6, p. 235-248
  • DOI: 10.1080/08957959608201408