The aerosol removal mechanism and capacity related to passive containment cooling system (PCS) for PWR reactors during the severe accident is an important and interesting topic among researchers, which can enhance the natural removal of suspended aerosols, reducing the radioactivity that may leak into the environment. In this study, the heat transfer and aerosol deposition models of a single heat tube of PCS heat exchanger were established. The four natural removal mechanisms (gravity deposition, Brownian diffusion, diffusiophoresis, and thermophoresis) on the tube surface were focused on. The results show that the diffusiophoresis and thermophoresis deposition velocities decease along the flow direction of cooling water inside the heat tube. The maximum total removal coefficient locates at the position that directly above the tube inlet. Aerosol particles with large diameter cannot deposit on the bottom of the heat tube under the certain thermal-hydraulic condition. With the continuing operation of PCS, the total removal coefficient for a PCS heat exchanger decreases rapidly at the beginning and then decreases slowly, while the diffusiophoresis effect is always the dominant for the natural removal.

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