THE COMPUTER SIMULATION OF URANIUM DIOXIDE

We describe how molecular dynamics simulation has been used to study the properties of the nuclear fuel UO2 and other materials having the same (fluorite) crystal structure. These materials become highly disordered and the anions become very mobile in the high temperature solid. Molecular dynamics has allowed us to investigate the nature of the disorder and to analyze the diffusion process in terms of vacancy and interstitial defects. The simulations have successfully reproduced the ion disordering observed experimentally in UO2. We discuss the prospects for extending the simulations to include the effects of electronic excitations and electronic polarizability which arc known to be important in UO2