The Transport of Aerosols through Ultrafine Leak Paths

Abstract

The aim of the programme has been to provide generic information to enable a valid assessment to be made of the potential leakage of airborne particles through the seals of containers used to transport nuclear materials in which material in powdered form may be present. A series of experiments has been undertaken using model leak paths based on ultrafine capillaries to quantify the penetration behaviour of a variety of aerosols, varying from spherical calibration standards to irregularly shaped particles more typical of those likely to be encountered under transport conditions. These experiments have been supported by the development of a model that explains the findings and enables aerosol penetration behaviour to be predicted over a much wider range of conditions. These studies lend support to the argument that the current IAEA recommended air leakage rate limit of 10–6 Pa·m³·s⁻¹ is sufficient to prevent the migration of significant particulate-borne radioactivity from a single leak path, although further information is needed about the nature of likely aerosol sources associated with transport movements before a more definitive statement can be made.