Abstract: In the high-energy irradiation environment, the structural materials of nuclear power plant could produce internal defects, which will affect the service performance. In this paper, molecular dynamics method is used to simulate the cascade collision process of Fe in irradiation environment and the effect of PKA (Primary Knock-on Atom) energy on irradiation damage defects. The results show that the cascade collision process of Fe is divided into three stages, the number of Frenkel defect pairs first reaches the peak and then recombines, resulting in a rapid decrease in the number of defect pairs and finally a tend to be stable. With the increase of PKA energy, the higher the number of Frenkel defect pairs in peak and stable states, the higher the defect recombination ratio. Meanwhile, with the increase of PKA energy, the larger the cluster size of interstitial clusters and vacancy clusters, the more the number of corresponding clusters. Therefore, the radiation damage process of Fe can be used to predict the radiation damage of materials under high-energy radiation environment and provide theoretical guidance for the service life of materials.

Key words: Fe, irradiation damage, molecular dynamics, Frenkel pairs, PKA energy