Experimental Study on Aerosol Penetration Through Concrete Cracks Under Inertial Collision and Steam Condensation

Estimation of aerosol penetration through the cracked concrete wall with a submillimeter height has attracted more attention for radioactivity optimization evaluation of containment, which emphasizes the aerosol deposition inside the cracks without catastrophic destruction of containment. While, no deposition has been considered in current radiological assessments and the penetration of aerosol is simply assumed to be released as the leakage of gas. Therefore, the results of assessment are too conservation for the leakage of radioactive aerosol without considering any deposition. In this work, an experimental facility is set up to study the penetration of particles through cracked concrete walls with different geometric dimensions. Titanium dioxide powder is chosen due to its density and nontoxicity. A sampling system is designed for the measurement of aerosol concentration under high temperature and containing condensable steam. One regular concrete crack in the shape of a straight rectangular slot and one irregular concrete crack with different streamwise tortuosities, τ, which is defined as the radio of the actual length of a crack pathway and the thickness of concrete structure, have been used in the tests of gas leakage and aerosol exposure. The height of cracks can be calculated from the consequences of gas leakage characteristic, based on the Suzuki’s flow model. Research results of aerosol exposure tests indicate that increasing the flow rate, particle diameter and tortuosity all can enhance the aerosol penetration, and micron particles cannot penetrate concrete cracks, compared with submicron particles. The aerosol penetration through the straight concrete crack is in good agreement with the prediction by the correlation proposed by Van De Vate, but no agreement is reached for the irregular crack with some tortuosity. Meantime, the effect of steam condensation on aerosol penetration is also been discussed preliminarily.