Thermophysical properties of urania-zirconia (U,Zr)O2 mixed oxides by molecular dynamics
Molecular dynamics simulations were used to investigate the thermophysical properties of (U,Zr)O2 between 300 K and 3500 K. For compositions with <25% UO2 the tetragonal phase is stable but beyond 25% the cubic fluorite phase becomes stable for all temperatures. Thermal expansion, heat capacity and thermal conductivity have been predicted. The addition of ZrO2 to UO2 causes a reduction in thermal conductivity however this effect decreases with increased temperature and, beyond 1000 K, becomes insignificant. Thermal expansion of (U,Zr)O2 mixtures with >25% UO2, which are in the cubic fluorite phase, is similar to that of the pure UO2 end member. A superionic transition is observed in cubic (U,Zr)O2 at temperatures between 1500 K and 3000 K, occurring at progressively lower temperatures with increasing ZrO2 content. Here, the heat capacity of these mixed oxides increases from 80 J/mol.K up to 130 J/mol.K at temperatures relevant to accident conditions, possibly retarding heating in fuels with a significant pellet-clad bonding layer.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE); USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- 89233218CNA000001
- OSTI ID:
- 1574000
- Alternate ID(s):
- OSTI ID: 1693656
- Report Number(s):
- LA-UR-19-25917; TRN: US2001315
- Journal Information:
- Journal of Nuclear Materials, Vol. 528; ISSN 0022-3115
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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