Atomistic modelling of materials is typically achieved by using Molecular Dynamics (MD). However, due to the fact that MD needs to resolve atomic vibrations, a very large number of small time steps are needed and the total simulation time is therefore often limited to less than one microsecond. The timescale limitation can be overcome by using Adaptive Kinetic Monte Carlo (AKMC) methods. Kinetic Monte Carlo methods exploit the fact that over longer time periods the dynamics of atomic systems typically consist of diffusive jumps from state to state.
We have used the Daresbury laboratory AKMC code (DL-AKMC) to explore the possible atomic transitions (and associated energies) of a 30% Pu MOX structure with five different types of cation Frenkel Pair defects at 1020K, 1600K and 2170K. The Potashnikov interatomic potential was used throughout this work. The software package Ovito has also been used to visualise and map atom movement. We present a statistical analysis of the atomic transitions and discuss how these can be used as a starting point for understanding the evolution of radiation damage in MOX fuel.