A molecular dynamics framework to simulate the irradiation-induced helium generation in nickel-based alloys

In this study, we have developed a molecular dynamics (MD) framework to simulate the combined effects of the irradiation-induced defects production, their accumulation, and the generation of helium in metals and alloys. This framework is applied to alloy 800H, a candidate structural material for various advanced reactor designs, to evaluate the combined effects of irradiation-induced damage and helium generation in the microstructure. Our results show a strong impact of He on the accumulation of Frenkel pairs (FP), and on the nucleation and growth of nanocavities. In particular, the higher the generation rate of He, the larger the population of accumulated FPs and the higher the density and size of nanocavities at a given irradiation dose. Inversely, the importance of irradiation damage on the nucleation and growth of He bubbles is highlighted, indicating the strong correlation between both phenomena. This MD framework offers a clearer path towards a more detailed atomistic simulation of the evolution of the microstructure under irradiation but also can consider the generation of fission products and transmutations.