Radon release behavior of uranium ore submerged in water under different temperatures

Radon (Rn-222) released by the decay of Ra-226 in uranium ores may cause potential radiation risks in the water environment. However, the migration behaviour characterised by the low diffusion coefficient of radon in water and the slow change in concentration is still lacking systematic research. This study investigates the radon release behavior of uranium ore in water under different temperature conditions (20-32 °C). A closed-loop measurement system combined with a bubbling method was established, utilizing a RAD7 radon detector. A nonlinear model was developed to describe the time-dependent measured radon concentration, and the radon release rate was obtained through nonlinear fitting. Experiments were conducted under five temperature conditions ranging from 20 °C to 32 °C. The Results showed that the proposed model achieved high fitting accuracy (R² > 0.95) across all conditions. The radon release rate increased significantly with temperature, rising from 0.210 ± 0.006 mBq s^-1 to 0.391 ± 0.019 mBq s^-1 within the range of 20 °C-32 °C, an increase of 86 %. Further analysis shows that the radon release rate of uranium ore in water has a good linear relationship with temperature, indicating that temperature is an important factor affecting the radon release behavior. The methods and models proposed in this paper can effectively depict the radon release behavior of uranium ores in water environments and are suitable for related experimental designs to assess environmental radiation risks.