Control Study Of Radon Exhalation On The Surface Of The Water-immersing Fragmented Emanation Media

At present, the environmental problems such as hazy weather and global warming are seriously effecting people’s normal life, so people hope to use some kinds of clean energy. The nuclear power having the advantages of high energy and no pollution has been taken as the fourth generation energy after the fossil oil. And the uranium is one of the main raw materials of the nuclear power. However, while using the uranium, we should not ignore the the radon exposure risk brought by the uranium industry to people’s health. The heap-leaching uranium ore heaps and the uranium tailings are the main sources of the atmosphere radon of the uranium mine. In the process of uranium ore’s heap-leaching, there is a level of liquid stockpiled in the bottom of the uranium ore heap. The operating uranium tailings are mostly in the open in our country. Once the rainfall capacity is quite large, there is a level of rain water stockpiled in the tailings. The water stockpiled in these pile bodies will effect the surface radon exhalation of these pile bodies. Besides, the soil cover method is the main way to deal with the decommissioned uranium tailings in our country, and there are few studies and practices on the water cover method. The above two aspects can be boiled down to one problem of the surface radon exhalation of the water-immersing fragmented emanation media.Therefore, this paper intends to provide a computing method for the surface radon exhalation rate of the water-immersing fragmented emanation media, and then a certain basis for controlling the radon exhalation on the surface of the water-immersing fragmented emanation media, through the study of the problem of the radon exhalation on the surface of the water-immersing fragmented emanation media. First, the one-dimensional steady-state mathematical models of radon diffusion transfer in the water-immersing fragmented emanation media are built and simulated numerically. Then, this paper chooses the uranium tailings from a southern uranium mine in our country as the studied object. By using the homemade one-dimensional water-immersing experimental apparatus, the surface radon exhalation rates of media under different water levers are measured. According to the parameters obtained by experiments, the theoretical values of the established mathematical models are calculated. And the theoretical values are compared with the experimental measured values. Finally, the data of reducing radon efficiency of the water cover obtained in the experiment are discussed.The research results are as follows:1. The one-dimensional steady-state mathematical models of radon diffusion transfer in the water-immersing fragmented emanation media are built. As the results of the numerical simulation of these models show, for the fragmented emanation media of a certain height, the surface radon exhalation rate of the media decreases with the water level in the media increasing; the surface radon exhalation rate of the water stabilizes 0 Bq·m-2·s-1, when the water cover thickness exceeds a certain value;2. The one-dimensional water-immersing experimental apparatus for simulating the radon diffusion transfer in the water-immersing fragmented emanation media is designed and made, and the experiments of the measurement of the surface radon exhalation rate of the water-immersing fragmented emanation media under different water levers are conducted. As the results has shown, with the water level increasing, the surface radon exhalation rate decreases; when there exists a water cover, the surface radon exhalation rate value is less than the limiting value of the surface radon exhalation rate regulated by the related rules and regulations of our country;3. According to the parameters obtained by the experiments, the theoretical values of the established mathematical models are calculated. And the experimental measured values are well matched with the theoretical values;4. Through the comparative study on the literatures, the feasibility of engineering practice of the water cover method to make the decommissioned uranium tailings to realize the reducing and control radon criterion is preliminarily discussed.