Effect of Simulation Technique on the High-Dose Irradiation Response of Nuclear Materials

For decades computer simulations have been used to understand the primary damage in materials, produced by energetic particles. These simulations have revealed a number of quantities, such as the number of defects produced, their structures and the spatial distribution of the produced defects. However, most work has been carried out on single cascades, reaching only very small doses. More recently, overlapping cascade simulations have been used to investigate the evolution of the system in the high-dose regime. In this work, we have studied the response and evolution of the system, while applying different simulations techniques. In this study we focused on tungsten, which is highly relevant for fusion applications. The techniques include; full-Molecular Dynamics (MD) cascades; Frenkel-pair insertion methods; a combination of MD simulations and FP insertion. Additionally, so-called cascade annealing simulations of the obtained damaged structures with the previous mentioned methods were used. The different methods revealed differences in many of the observed quantities, both at low and high doses. We found that cascade annealing is a very effective technique to obtain representative high-dose simulation cells, with a much lower computational cost than conventional methods.