Effective diffusion coefficient of radon in concrete, theory and method for field measurements

A linear diffusion model serves as the basis for determination of an effective radon diffusion coefficient in concrete. The coefficient was needed to later allow quantitative prediction of radon accumulation within and behind concrete walls after application of an impervious radon barrier. A resolution of certain discrepancies noted in the literature in the use of an effective diffusion coefficient to model diffusion of a radioactive gas through a porous medium is suggested. An outline of factors expected to affect the concrete physical structure and the effective diffusion coefficient of radon through it is also presented. Finally, a field method for evaluating effective radon diffusion coefficients in concrete is proposed and results of measurements performed on a concrete foundation wall are compared with similar published values of gas diffusion coefficients in concrete. (author)