Study on the real-time radon release pattern of granite under temperature-pressure coupling

Uranium ore, as an important energy mineral, is accompanied by the release of radioactive gas, radon, during the mining process. In order to study the release law of radon gas and its daughters inside granite under the state of temperature-pressure coupling in the deep stratum, the experiment uses uniaxial compression experiments under different temperature gradients (25 °C, 50 °C, 75 °C, 100 °C, 150 °C, 200 °C, 250 °C, and 300 °C) and real-time monitoring of radon release changes, to explore the effect of different temperatures on the behavior of radon release inside granite. The experimental results show that: with the increase of strain, the radon release of granite as a whole shows the trend of increasing, then decreasing, and then increasing again, and reaches the peak in the unstable propagation stage of cracks. The radon exhalation decreases by 28.45 % in the stage of compression and densification at 100–150 °C, and increases by 29.33 % in the stage of expansion of cracks at 150–200 °C. The temperature-pressure coupling effect significantly affects the radon release behavior of granite, and the high temperature. The temperature-pressure coupling significantly affects the radon release behavior of granite, with high temperatures leading to a decrease in the mechanical properties of granite and accelerating the evaporation of water between mineral crystals and within the crystals and the thermal expansion of minerals, which in turn promotes the release of radon gas; in addition, the generation of thermal damages and microcracks provides new channels for radon gas migration. This study provides an important basis for the in-depth understanding of the radon release law of granite under temperature-pressure coupling conditions and the formulation of scientific prevention and control strategies.