This paper describes a method for determination of the diffusion coefficient and the solubility of radon in plastics. The method is based on the absorption and desorption of radon in plastics. Firstly, plastic specimens are exposed for controlled time to referent ²²²Rn concentrations. After exposure, the activity of the specimens is followed by HPGe gamma spectrometry. Using the mathematical algorithm described in this report and the decrease of activity as a function of time, the diffusion coefficient can be determined. In addition, if the referent ²²²Rn concentration during the exposure is known, the solubility of radon can be determined. The algorithm has been experimentally applied for different plastics. The results show that this approach allows the specified quantities to be determined with a rather high accuracy—depending on the quality of the counting equipment, it can be better than 10 %.

This work describes an algorithm for automatic counting of alpha tracks in scanned images of electrochemically etched CDs and DVDs. It is demonstrated that the algorithm copes with the specific problems encountered in retrospective ²²²Rn measurements with CDs and DVDs; it reliably separates overlapping tracks and ignores artifacts in the image. The algorithm is validated by comparison to manual counting and a very good correlation is found. The measurement range of ²²²Rn concentrations in dwellings and soil gas is estimated. It is shown that the wide span of track densities that can be covered by the algorithm combined with the specific advantages of the compact disc method can provide reliable measurements in the whole range of ²²²Rn concentrations of practical interest. For retrospective measurements of ²²²Rn in dwellings the estimated range is from 10 Bq/m³ to 100 kBq/m³ for five years exposure time. For ²²²Rn in soil gas the estimated range is from 1 kBq/m³ to 10 MBq/m³ for ten days exposure time.