(679h) Aggregation and Electrostatic Dispersion Characteristics of Radioactive Particles in the Atmosphere
Radioactive decay of radionuclides contained in particles can lead to charge accumulation on the particle surface. Because it can influence interparticle forces, surface charge accumulation may cause interaction of radioactive particles to be different from that of nonradioactive particles. However, aggregation and electrostatic dispersion kinetics of radioactive particles have not yet been fully understood. In this study, aggregation and electrostatic dispersion characteristics of radioactive particles are investigated using a population balance model, an electrostatic dispersion model, and a charge balance model involving mechanisms of radioactivity-induced surface charge accumulation. Because radioactive particles can be bipolarly charged in the atmosphere, a numerical solution of bipolar aggregation has been obtained for the population balance model. Validation tests have shown that results of the numerical solution obtained in this work are in excellent agreement with those of other numerical solutions available in literature. Subsequently, the obtained numerical solution has been coupled with the electrostatic dispersion and charge balance models to simultaneously predict the rates of aggregation, electrostatic dispersion, and surface charge accumulation of radioactive particles. Simulation results have shown that the aggregation and electrostatic dispersion rates of radioactive particles can be significantly different from those of nonradioactive particles because the surface charge accumulated due to radioactive decay can generate strong electrostatic forces between the interacting particle surfaces. A sensitivity analysis has been performed to determine the parameters that influence the aggregation and electrostatic dispersion kinetics of radioactive particles.