NuFuel & MMSNF 2015

First Workshop on Research into Nuclear Fuel in Europe
and Materials Modeling and Simulation for Nuclear Fuels Workshop
Karlsruhe, Germany, November 16th to 18th, 2015

Updated: Tue 08 Dec 2015, 14:27

Talk 5.6: Modelling the thermomechanical properties of actinide oxides

Conor Galvin, M.W.D. Cooper, M.J.D. Rushton, R.W. Grimes
  • Department of Materials and Centre for Nuclear Engineering, Imperial College London, London. SW7 2AZ.

Abstract

Mixed actinide oxides have been used as nuclear fuel material, furthermore UO2 fuel effectively becomes a mixed oxide during reactor operation due to transmutation and decay. As a result, understanding the behaviour of mixed oxides is of considerable importance. Atomic scale simulations are helpful in understanding the fundamental features governing fuel performance. In the current work, molecular dynamics simulations have been carried out using a new many-bodied potential model to investigate the thermophysical and diffusion properties of actinide oxides at high temperatures. Lattice parameter, enthalpy and specific heat have been calculated for a range of (Thx,Pu1-x)O2 compositions, over a temperature range 300–3200 K. It is difficult to obtain experimental data at higher temperatures for mixed oxides; therefore these simulations provide important insight for systems that are still not sufficiently well understood. In addition to the thermophysical properties, the oxygen diffusivity for (Thx,Pu1-x)O2 was also calculated. The creation of oxygen defects and subsequently a superionic transition causes a ‘bump’ in the lattice parameter, enthalpy and specific heat plots. Enhanced oxygen diffusivity was also observed below this superionic transition.