New Gaussian Plume Equation for the Impacts of Dust Storms on Radionuclide Transport

Abstract

ABSTRACT Potential impacts of dust storms on radionuclide atmospheric dispersion have been the focus of great attention lately by countries that opted to build nuclear power plants in arid regions. The Gaussian point source dispersion equations have been modified to incorporate the rate of scavenging of gaseous radioactive plumes emitted from nuclear power plants due to adsorption by nanoaerosols that come from dust storms. The radionuclide-nanoaerosol interaction has been built based on the flux-matching theory assumptions: the size of a particle has the same order of magnitude of the mean free path of the molecules of air, and the adsorption coefficient is time-dependent. A correction factor (λr) has been introduced to the Gaussian plume equation to represent the fraction of the remaining radionuclides in the atmosphere at any distance downwind. A case study involving iodine-131 was used to apply the modified equations and to estimate the correction factor for different dust storms. The fraction of the adsorbed radionuclides on the atmospheric nanoaerosols (1 – λr) varies from less than 0.1 during a dust storm that has a density of 10 µg m–3 to more than 0.9 during a heavy dust storm of 1000 µg m–3 of density. Therefore, 90 percent of the transported radionuclide plume can be adsorbed by the atmospheric nanoparticles during the heavy dust events, while less than 10 percent can be adsorbed on the atmospheric nanoaerosols in normal days. These findings pose new challenges since radionuclides can be carried by nanoaerosols to farther distances than what is normally expected.