Suitability evaluation of measurement method for radon exhalation rate of porous medium containing radon adsorbing materials.

In radon pollution control, materials with radon adsorbing characteristics will significantly affect the migration and release of radon. In this paper, radon adsorbing medium (activated carbon particles) is proposed to be added to the building foundation granular filling layer as a radon adsorbing layer to alleviate indoor radon pollution. Radon exhalation rate is an important physical quantity used to evaluate the radon exhalation capacity of materials. This study compared the measurement results of radon exhalation rate on the radon adsorbing media surface by the traditional Closed-loop Method (CLM) and the Activated Carbon Purification Closed-loop Method (ACPCM) through experiments. The results show that the surface radon exhalation rate decrease rapidly due to the back diffusion effect of CLM, which seriously affects the measurement results. ACPCM can avoid the interference of back diffusion effect on the adsorption amount of radon adsorbing medium, obtaining reliable measurement results. In addition, the migration process of radon in the gas-solid medium and its interface during the measurement was simulated by computational fluid dynamics (CFD), and the measurement mechanism of the two methods was revealed. The research results can provide reference for the determination of radon exhalation rate on the radon adsorbing medium surface.