Safety containment buildings as barriers against particulate radioactivity release under accident conditions

The role of leak types in various containment designs is discussed relative to the release of particulate radioactivity release from a containment building. It is concluded that the tendency in containment integrity philosophy toward ''leak-before-break'' emphasizes the importance of aerosol deposition in leak paths. Furthermore, the leak paths in cracked concrete containment walls (either primary or secondary) can be regarded to be the most effective locations for such aerosol deposition. The various physical processes of aerosol deposition in leak paths are treated and evaluated. Limited experimental evidence is given of the importance of aerosol deposition in cracks through concrete walls. Inertial deposition in the high flow rate regime and gravitational settling in the low flow rate regime govern this deposition. A preliminary general equation is given describing aerosol penetration through a crack in concrete