Fabrication and thermophysical property characterization of UN/U3Si2 composite fuel forms

J. T. White, A. W. Travis, J. T. Dunwoody, A. T. Nelson

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42 Scopus citations

Abstract

High uranium density composite fuels composed of UN and U3Si2 have been fabricated using a liquid phase sintering route at temperatures between 1873 K and 1973 K and spanning compositions of 10 vol% to 40 vol% U3Si2. Microstructural analysis and phase characterization revealed the formation of an U-Si-N phase of unknown structure. Microcracking was observed in the U-Si portion of the composite microstructure that likely originates from the mismatched coefficient of thermal expansion between the UN and U3Si2 leading to stresses on heating and cooling of the composite. Thermal expansion coefficient, thermal diffusivity, and thermal conductivity were characterized for each of the compositions as a function of temperature to 1673 K. Hysteresis is observed in the thermal diffusivity for the 20 vol% through 40 vol% specimens between room temperature and 1273 K, which is attributed to the microcracking in the U-Si phase. Thermal conductivity of the composites was modeled using the MOOSE framework based on the collected microstructure data. The impact of irradiation on thermal conductivity was also simulated for this class of composite materials.

Original languageEnglish
Pages (from-to)463-474
Number of pages12
JournalJournal of Nuclear Materials
Volume495
DOIs
StatePublished - Nov 2017
Externally publishedYes

Funding

U 3 Si 2 button fabrication by D. Byler along with assistance in specimen preparation by S. Voit is greatly appreciated. The authors wish to thank D.A. Andersson for the critical review of the manuscript. Work was in part supported by U.S. Department of Energy, Office of Nuclear Energy Nuclear Technology Research and Development program under contract DE-AC52-06NA25396 . This research was also partially supported using funding received from the DOE Office of Nuclear Energy's Nuclear Energy University Programs under contract DE-NE0000711 .

FundersFunder number
DOE Office of Nuclear Energy
Nuclear Energy University ProgramsDE-NE0000711
U.S. Department of Energy
Office of Nuclear EnergyDE-AC52-06NA25396

    Keywords

    • Accident tolerant fuels
    • Composite nuclear fuel
    • Uranium mononitride
    • Uranium silicide

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