Leakage of aerosols from containment buildings.

Experimental data on the plugging of ducts by aerosols are reviewed and compared with a simple model. The model predicts that the mass of the aerosol entering the duct prior to plugging is proportional to the cube of the duct diameter. This relation has been used to correlate experimental data on a variety of aerosols over a range of duct diameters from 100 micrometers to 30 cm. The proportionality constant appears to be a function of the effective density of the aerosol deposit and of the location of the plug. In the process of plugging leak paths, aerosols attach to the walls or to previously deposited aerosols. Some of these agglomerates break off and are resuspended in the airstream so that the sizes of aerosols exiting from short length leaks are substantially increased. When all of these effects are considered, it appears that less than 1 mg of respirable aerosol can leak from a typical Reactor Containment Building operating at the design pressure and gas leak rate (0.1 vol% per day). This is a reduction of more than four orders of magnitude from the case where the aerosol is assumed to leak as a gas.