Experimental Study on Aerosol Resuspension Induced by Erosion and Denudation in Containment

摘要: When a severe accident occurs in a nuclear reactor core, a large amount of radioactive aerosols exist within the containment. Aerosols deposited on containment walls can resuspend under airflow, becoming a persistent radioactive source term. This phenomenon increases aerosol concentration within the containment and heightens the risk of radioactive material leakage. This study utilizes a visualization experiment system to investigate the effects of humidity, gas velocity, and deposition surface orientation on aerosol resuspension characteristics. The results demonstrate that under the denudation mechanism in a high humidity condition (RH = 98%), capillary forces significantly suppress aerosol resuspension, with a resuspension fraction of only 13.5%, compared to 93.5% under dry condition (RH=30%). On vertical walls, aerosol deposition is lower, and compact structures
are harder to form; consequently, the resuspension fraction under the erosion mechanism is only 50% of that on horizontal walls. In erosion cases, low-velocity airflow (10 m/s) primarily resuspends small aerosols downstream, while larger clusters roll and separate, reducing the median particle size of resuspended aerosols. Under denudation cases, high-velocity transient airflow (60 m/s) causes multilayer aerosols to resuspend simultaneously, with clusters entrained in the flow, leading to a bimodal particle size distribution. Compared to erosion, denudations transient airflow produces higher acceleration and additional aerodynamic removal forces (Bassettforce), resulting in significantly higher resuspension fractions. This study provides critical data on the resuspension characteristics driven by erosion and denudation mechanisms, offering an experimental foundation for the management of radioactive aerosols in containment.