(179p) Effects of Radioactivity On Surface Interaction Forces and Aggregation of Aerosols

Explosion of radiological devices is expected to generate radioactive aerosols, which contribute to the transport of radioactivity in the environment. Self-charging of radioactive aerosols is an important characteristic since it affects growth and transport of aerosols in a radioactive plume. Current tests and models of radioactive plumes do not take into consideration the different behavior of radioactive particles, which can become electrostatically charged due to the decay process. The main objective of this study is to investigate effects of self-charging of radioactive aerosols on surface charge, surface forces, and the aggregation rate. Scanning surface potential microscopy (SSPM) is used to measure the surface potential of radioactive surfaces as a function of the decay rate. Atomic force microscopy (AFM) is employed to quantify the adhesion force and force-distance profile between a particle and a planar substrate and to compare measurements with and without the involvement of radioactivity. The mean charge number of radioactive aerosols caused by self-charging is estimated by an approximate model considering particle size and decay rate. Self-charging effects on the collision efficiency of particles in the Brownian regime is calculated as a function of van der Waals, electrostatic, and viscous forces. Results can be incorporated in transport models to accurately predict aerosol transport after nuclear accidents or explosions of radiological devices.