Determination of the radon diffusion length in building materials using electrets and activated carbon.

This work presents a technique for determining the radon (222Rn) diffusion length in porous materials. A mathematical model that describes the process of radon diffusion in a closed chamber, divided into two sections by a porous building material, is proposed. The derived relations allow evaluating the radon diffusion length in the material from measurements of the radon concentrations in the two sections. Preliminary experimental results are presented for the diffusion lengths of concrete and gypsum obtained by measuring the radon concentration via two standard passive detection methods: electrostatic electret chambers and activated charcoal canisters. The electret measurements were checked by a solid state continuous radon monitor.