Theoretical model for estimation and control of radon exposure dose considering ventilation pressure drop in ventilation networks.

To minimize the occupational radiation hazards for workers in uranium or associated radioactive underground mines, it is necessary to control the radon exposure dose in each branch of the mine ventilation network. Firstly, a mathematical model of determining potential alpha energy concentration (PAEC) of radon daughters in a single branch was proposed on the basis of the previous radon concentration calculation model in the ventilation network considering ventilation pressure drop. Then, two estimation models of radon exposure dose based on the equilibrium radon concentration and PAEC of radon daughters are introduced. Further, a novel adjustment algorithm and solution procedures were developed to calculate the radon exposure dose of the branches in the ventilation network through two radon exposure dose estimation models, and to regulate the branches that exceeded the limit. Finally, a specific ventilation network in a simulated underground uranium mine with calculation and analysis via MATLAB. The results show that: 1) PAEC of radon daughters and radon exposure dose can be effectively estimated by the method proposed in this paper. 2) The variation of equilibrium factor and deposition of radon daughters have a significant effect on radon exposure dose. 3) To ensure that the radon exposure dose of workers in the mine ventilation network does not exceed the control threshold, the radon exposure dose estimated based on the method proposed in this paper can provide theoretical basis for determining and pre-evaluating appropriate ventilation methods, sufficient air flow rate, and pressure of the main fan.