Using molecular dynamics to predict the solidus and liquidus of mixed oxides (Th, U)O-2, (Th, Pu)O-2 and (Pu, U)O-2

COT Galvin and PA Burr and MWD Cooper and PCM Fossati and RW Grimes, JOURNAL OF NUCLEAR MATERIALS, 534, 152127 (2020).

DOI: 10.1016/j.jnucmat.2020.152127

Molecular dynamics (MD) was used to establish a mechanistic basis for the experimentally observed reduction in liquidus and solidus temperatures below the melting point of the end-members for the mixed oxides (Th, U)O-2, (Th, Pu)O-2 and (Pu, U)O-2. This dip is found at similar to 5% additions of the oxide with higher melting point to the oxide with the lower melting point. There are many causes suggested for the dip; here the distribution of the cation Frenkel energy for the mixed oxides caused by the local environment is proposed as a contributor. Furthermore, a variant of the moving interface method which yields information on the position of the solidus and liquidus boundaries, is used to predict the phase diagrams of these systems. (C) 2020 Elsevier B.V. All rights reserved.

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