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Title: Corium lavas: structure and properties of molten UO 2-ZrO 2 under meltdown conditions

Abstract

In the exceedingly rare event of nuclear reactor core meltdown, uranium dioxide fuel reacts with Zircaloy cladding to produce eutectic melts which can subsequently be oxidized by coolant/moderator water. Oxidized corium liquids in the xUO 2·(100 – x)ZrO 2 system were produced via laser melting of UO 2-ZrO 2 mixtures to temperatures in excess of 3000 K. Contamination was avoided by floating the droplets on a gas stream within an aerodynamic levitator and in-situ high-energy x-ray diffraction experiments allowed structural details to be elucidated. Molecular dynamics simulations well reproduced diffraction and density data, and show less compositional variation in thermal expansion and viscosity than suggested by existing measurements. As such, corium liquids maintain their highly penetrating nature irrespective of the amount of oxidized cladding dissolved in the molten fuel. Metal-oxygen coordination numbers vary with both composition and temperature. The former is due to mismatch in native values, n UO(x = 100) ≈ 7 and n ZrO(x = 0) ≈ 6, and the requirement for oxygen site stabilization. Furthermore, the latter provides a thermal expansion mechanism.

Authors:
 [1];  [2];  [1]; ORCiD logo [3];  [4];  [4];  [2];  [2]
  1. Materials Development, Inc., Arlington Heights, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); Stony Brook Univ., Stony Brook, NY (United States)
  4. Materials Development, Inc., Arlington Heights, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR)
OSTI Identifier:
1481173
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS

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. Corium lavas: structure and properties of molten UO2-ZrO2 under meltdown conditions. United States: N. p., 2018. Web. doi:10.1038/s41598-018-20817-z.
Alderman, O. L. G., Benmore, C. J., Weber, J. K. R., Skinner, L. B., Tamalonis, A. J., Sendelbach, S., Hebden, A., & Williamson, M. A. Corium lavas: structure and properties of molten UO2-ZrO2 under meltdown conditions. United States. doi:10.1038/s41598-018-20817-z.
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. Mon . "Corium lavas: structure and properties of molten UO2-ZrO2 under meltdown conditions". United States. doi:10.1038/s41598-018-20817-z. https://www.osti.gov/servlets/purl/1481173.
@article{osti_1481173,
title = {Corium lavas: structure and properties of molten UO2-ZrO2 under meltdown conditions},
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 = {In the exceedingly rare event of nuclear reactor core meltdown, uranium dioxide fuel reacts with Zircaloy cladding to produce eutectic melts which can subsequently be oxidized by coolant/moderator water. Oxidized corium liquids in the xUO2·(100 – x)ZrO2 system were produced via laser melting of UO2-ZrO2 mixtures to temperatures in excess of 3000 K. Contamination was avoided by floating the droplets on a gas stream within an aerodynamic levitator and in-situ high-energy x-ray diffraction experiments allowed structural details to be elucidated. Molecular dynamics simulations well reproduced diffraction and density data, and show less compositional variation in thermal expansion and viscosity than suggested by existing measurements. As such, corium liquids maintain their highly penetrating nature irrespective of the amount of oxidized cladding dissolved in the molten fuel. Metal-oxygen coordination numbers vary with both composition and temperature. The former is due to mismatch in native values, nUO(x = 100) ≈ 7 and nZrO(x = 0) ≈ 6, and the requirement for oxygen site stabilization. Furthermore, the latter provides a thermal expansion mechanism.},
doi = {10.1038/s41598-018-20817-z},
journal = {Scientific Reports},
issn = {2045-2322},
number = 1,
volume = 8,
place = {United States},
year = {2018},
month = {2}
}

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Works referenced in this record:

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


DL_POLY_2.0: A general-purpose parallel molecular dynamics simulation package
journal, June 1996