**4. Conclusions**

In this work, we employ an atomic simulation to investigate the interaction behaviors between a dislocation loop and vacancy-type defects including a vacancy, di-vacancy, and vacancy cluster. The distribution of the binding energies of an 1/2[111] interstitial dislocation loop (IDL) to a vacancy is different from that of a 1/2[111] vacancy dislocation loop (VDL) to a vacancy. When the vacancy is adjacent to the center of the loop, the VDL repulses the vacancy, but the IDL attracts it due to their different stress distributions. The binding energies calculated by elasticity theory (ET) and molecular statics simulations show that they are consistent when they are far away from each other, but it has a large derivation when they are close due to the ET has a difficulty in accurately predicting the stress near the core of the loop. The interaction behaviors between the IDL and a di-vacancy are very similar to that of the IDL and a vacancy. Furthermore, a vacancy cluster (containing 8 vacancies) can hinder the motion of the IDL, which depends on the temperature and their relative position. No matter where the vacancy cluster is, the IDL absorbs a part of the vacancies in the cluster and the unabsorbed vacancies will inhibit the motion of the dislocation loop at low temperatures. While the mobility of IDL is recovered at high temperature by absorbing all vacancies in nanoseconds. Therefore, the temperature and position dependent interaction of the IDL and a vacancy cluster should be taken into account in modeling the microstructure evolution during irradiation. These obtained binding energies and absorption distances provide input parameters for the kinetic Monte Carlo, cluster dynamics, and dislocation dynamics simulations.

**Author Contributions:** Conceptualization, G.-H.L., L.L. (Linyun Liang), H.W., K.X. and L.L. (Linyu Li); methodology, G.-H.L., L.L. (Linyun Liang), X.-C.L., H.W., K.X. and L.L.(Linyu Li); software, L.L. (Linyu Li); validation, L.L. (Linyu Li).; formal analysis, G.-H.L., L.L.(Linyun Liang), X.-C.L., H.W., K.X., B.L., S.J., X.S. and L.L. (Linyu Li); software, L.L. (Linyu Li); investigation, L.L. (Linyu Li); resources, L.L. (Linyu Li); data curation, L.L. (Linyu Li); writing—original draft preparation, L.L. (Linyu Li); writing—review and editing, G.-H.L., L.L.(Linyun Liang), X.-C.L., H.W., K.X., B.L., S.J., X.S. and L.L.(Linyu Li); visualization, L.L. (Linyu Li). All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China, Grant Numbers. 51871007, 12075021, and 12075023, and the National MCF Energy R&D Program of China, Grant Number No. 2018YFE0308103. The APC was funded by Grant Number No. 2018YFE0308103.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author. The data are not publicly available due to technical limitations.

**Acknowledgments:** The authors acknowledge Xinyue Fan for providing inspiration and dealing with technical problems.

**Conflicts of Interest:** The authors declare no conflict of interest.
