Transient radon diffusion through radon-proof membranes: A new technique for more precise determination of the radon diffusion coefficient

The following paper is focused on the numerical modelling of the transient radon diffusion through radon-proof membranes during the measurement of their radon diffusion coefficient. The major aim of such numerical modelling is to increase the accuracy of radon diffusion coefficients derived from the measured data sets. The developed complex “transient” numerical model is able to calculate the radon diffusion coefficient with sufficient accuracy from almost any data set – even from a short-time measurement with a non-linear course of results. This numerical model can also be used for various analyses of transient radon transfer processes (e.g. for the calculation of radon distribution curves within the membrane). The following paper presents governing equations for the simulation model, together with a brief description of algorithms incorporated in the newly developed software package, which can be used either for the assessment of the radon diffusion coefficient from any data set or for the general analyses of unsteady radon transfer within the measuring device. Several transient model analyses are also presented together with an example of the determination of the radon diffusion coefficient from the measured data.