Abstract: The most prominent radioactive occupational hazard factor in non-uranium mines such as coal mines is excessive exposure to radon underground. To obtain the overall radon concentration data of the coal mine ventilation network and ensure that the underground radon concentration is within a safe level, a method for calculating the underground radon concentration based on the principle of node air volume balance and the mathematical model of radon concentration distribution, as well as the regulation method when the radon concentration in a branch exceeds the limit, was studied. Taking a certain mine in Shaanxi as the research object, through the combination of numerical calculation and on-site testing, radon measurement points were first set up at the return air outlet, intake air outlet and main passage of the fully mechanized mining face according to the ventilation network structure of the mine, and the radon exhalation rate was calculated based on the measurement results. Then, combined with the air volume, cross-sectional size and length of each branch, the radon concentration data for each branch in the ventilation network were calculated. When the radon concentration in a certain branch exceeded the limit, the ventilation demand to meet the safety threshold was calculated by reverse calculation in the concentration-exceeding area, and the regulation was carried out according to the calculation to bring the radon concentration in the branch back to a safe range. Verified by on-site measurements at 5 nodes, the absolute deviation between the radon concentration calculation results and the measured data is within 11%, and the regulation measures taken based on the calculation results successfully reached the expected level, verifying the reliability of the calculation results. The research results can provide theoretical reference for the prevention and control of radon gas in mines.

Key words: coal mine, radon concentration, ventilation network, concentration solution