Abstract: There are risks of radioactive pollution diffusion and external radiation exposure during the salvage process of foreign objects in the primary circuit of nuclear power plants, especially for metal foreign objects activated by neutrons. There may be risks of over-dose exposure of personnel during the salvage process. This paper mainly discusses the radiation risk control of foreign objects emerging from primary circuit. This paper also analyzes the source, classification, and emerging risk of foreign objects in primary circuit, and calculates the impact of primary circuit foreign objects emerging with different radiation levels on the workplace through related software modeling. Corresponding radiation risk protection and control measures according to the degree of impact are formulated, which could provide a protection plan for conducting related work.

Key words: Foreign body, Salvage, Radiation risk, Control