Abstract: Based on CFD method, this paper studied the indoor air flow and particle movement after the radioactive powder material scattering accident in a closed workshop, and analyzed the influence of particle size, scattering speed and scattering height. The results show that the particle movement is mainly affected by the gas circulation inside the confined space. Most of the particles are deposited on the ground or attached to the wall and captured, and a small part of the particles will be floating and suspended indoors in the later period and move with the airflow. There is little difference in aerosol motion and distribution caused by different scattering velocities. Particles with small particle size are more likely to be separated from the mainstream area and form scattered dust under the influence of the drag force of the surrounding gas. Therefore, the smaller the particle size is, the larger the deposition range caused by the spraying lag is.

Key words: CFD method, falling accident, aerosol particle