Experimental study on permeability characteristics and radon exhalation law of overburden soil in uranium tailings pond.

The permeability characteristics of overburden soil have a significant effect on radon exhalation in uranium tailings pond. To understand this change, the effects of dry density, particle size range, and moisture content on the gas permeability and radon exhalation were studied by correlation analysis method. According to the mechanism of radon generation, the permeability characteristics of overburden, and the weather conditions, a theoretical model of radon exhalation was constructed and an experimental setup was designed. A series of tests on different properties of overburden soil were conducted by uranium tailings permeameter, and the radon exhalation rate of corresponding overburden surface was measured by local static method. Results show that the permeability of overburden decreased, which led to the decrease of radon exhalation: (1) At the same moisture content, with the increase of dry density, both the gas permeability and radon exhalation rate decrease. (2) At the same moisture content, with the increase of the particle size range, both the gas permeability and radon exhalation rate increase. (3) At the same dry density, with the increase of moisture content, the gas permeability decreases, while the radon exhalation rate increases slightly at first and then decreases.