About this Abstract |
Meeting |
2020 TMS Annual Meeting & Exhibition
|
Symposium
|
Computational Materials Science and Engineering of Materials in Nuclear Reactors
|
Presentation Title |
Atypical Melting Behaviour of (Th,U)O2, (Th,Pu)O2 and (Pu,U)O2 Mixed Oxides |
Author(s) |
Conor OT Galvin, Patrick A. Burr, Michael WD Cooper, Paul CM Fossati, Robin W Grimes |
On-Site Speaker (Planned) |
Patrick A. Burr |
Abstract Scope |
Numerous discrepancies and anomalies have been reported in the melting behaviour of the ternary UO2–ThO2–PuO2 system, sometimes attributed to limitations of the experimental set-up. Here we use molecular dynamics to shed light on the peculiar melting behaviour of the mixed oxides. We show that minima in solidus and liquidus are indeed observed at ∼5% additions of the oxide with higher melting point, as proposed in some experiments, and that this is an inherent property of the solid solutions, not an artefact of experimental procedures. We propose that the root cause for this reduction in melting point is the enhanced formation of Frenkel pairs. The energy of Frenkel pairs is observed to reduced at low solute concentrations due to the presence of small amounts of cations of larger ionic radius, causing local distortion in the lattice. These defects may act as nucleation sites for early-onset melting. |
Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |