Report on influence of burst type on physicochemical characteristics. WP9[D9.30] PREDICT – D1.2

The work reported is aimed at increasing the understanding and providing an improved background for modelling of the radiological consequences of atmospheric dispersion of the radioactive cloud from a nuclear bomb detonation. The nearest area to the epicentre would be so badly damaged by the fire and pressure wave that fallout would not be considered a major and immediate concern. At very great distances, the cloud would be so dispersed that resulting contamination levels would be trivial, but at intermediate distances the cloud passage could pose a significant radiological problem. The report describes how characteristics of a nuclear burst event, such as detonation height and weapon yield, influence the formation of the initial stabilized cloud. Particle size distributions and density are important for modelling atmospheric dispersion and various mathematical functions and data are proposed for different burst types and for predictions at different levels of detail. Noble gases considered in the project’s nuclide vector generally decay rather quickly, and their progeny would atmospherically be expected to behave like volatile radionuclides attaching to the surface of particles relatively late after the contaminant particle formation process. A section is dedicated to elucidating the influences of contaminant particle characteristics on their environmental solubility, migration and uptake.