Experimental Study on the Influence of Spray Characteristics and Temperature Control on the Removal Efficiency of Iodine Aerosols

Abstract Radioactive aerosol may be released into the gas and retained in the containment under severe nuclear accidents conditions. Spray system removal is one of the main ways to remove aerosols. Spray droplets and overpressure of primary loop in severe accidents create a complicated high temperature and high humidity environment. A significant portion of radioactive aerosols in nuclear accidents are soluble. These soluble radioactive aerosols (CsOH/CsI) in the containment of the high humidity environment will occur significant hygroscopic growth behavior and may dissolve in droplets. Moreover, if the spray solution is alkaline, changes in particle density, size, shape, and chemical composition of iodine aerosols may occur, significantly influencing the dynamic behavior of aerosol agglomeration, diffusion and deposition, and consequently, the aerosol removal efficiency of the spray system. While extensive research has been conducted on the spray removal of insoluble aerosols (TiO2\SiC), studies on typical soluble iodine aerosol spray removal experiments are largely lacking. In this paper, the experimental study of single nozzle with different spray characteristics on the removal efficiency of iodine aerosol was carried out. This study provides insights into the effects of different spray pressures, flow rates, and pH values on the removal efficiency and influencing patterns of soluble iodine aerosols under various initial particle sizes and different aerosol compositions. Results indicate that, Alkaline spray water with different pH values had no significant effect on the removal efficiency of iodine aerosol. The aerosol removal coefficient in the 0.2μm and 0.5μm particle size ranges of iodine aerosols is the smallest, which is 0.0007s−1–0.0012s−1. Increasing the proportion of soluble aerosols in multi-component aerosols will increase the removal rate of spray aerosols. This study can provide reference for fundamental understanding of the aerosol removal mechanism of soluble iodine aerosols by containment spray droplets and improving the containment spray removal models.