Experimental Model to Study Characteristics of Radon Cover in Waste Landfills

Waste from resource extraction industries contains uranium and thorium decay chain radionuclides. One important radiological impact of these wastes is the release of radon into the atmosphere. Therefore, the prediction/evaluation of radon flux and the effectiveness of different covers are the major elements in radiation protection, long-term safety aspects, and the modeling of radon release into the environment for a final assessment of radiological impacts and required remediation actions. A measurement system has been designed based on the transient-diffusion method to evaluate radon exhalation by the short-time accumulation technique. The validity of the laboratory model to quickly estimate the radon release from soils, the diffusion coefficient, and the effect of covers was investigated. From the results obtained from the experimental model, it was observed that after a 0.5-m(1-m) cover layer, the radon flux reduction factor increases from 1.3(2.1) for sand to about 2(3) for clay. The results show that the effectiveness of the cover layer studied is 3, which is similar to theoretical and experimental results in uranium tailings ponds.