Thermophysical properties of urania-zirconia (U,Zr)O2 mixed oxides by molecular dynamics

JOURNAL OF NUCLEAR MATERIALS

卷:528

Article

Frost, D. G.^1,2  Galvin, C. O. T.¹  Cooper, M. W. D.³  Obbard, E. G.^1,2  Burr, P. A.^1,2 

[1] Univ New South Wales, Sch Mech & Mfg Engn, Sydney, NSW, Australia

[2] Australian Nucl Sci & Technol Org ANSTO, Sydney, NSW, Australia

[3] Los Alamos Natl Lab, Los Alamos, NM USA

关键词: UO2;    ZrO2;    Thermal expansion;    Thermal conductivity;    Nuclear fuel;   

DOI  :  10.1016/j.jnucmat.2019.151876

来源: Elsevier

【 摘 要 】

Molecular dynamics simulations were used to investigate the thermophysical properties of (U,Zr)O-2 between 300 K and 3500 K. For compositions with <25% UO2 the tetragonal phase is stable and 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 becomes insignificant beyond 1000 K. Thermal expansion of (U,Zr)O-2 mixtures with >25% UO2, which are in the cubic fluorite phase, is similar to that of UO2. A superionic transition is observed in cubic (U,Zr)O-2 at temperatures between 1500 K and 3000 K, occurring at progressively lower temperatures with increasing ZrO2 content. 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 temperature increase in fuels with a significant pellet-clad bonding layer. (C) 2019 Elsevier B.V. All rights reserved.

【 授权许可】

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