The Model Of Radon Migration In Porous Emanation Mediaand The Calculation

Nuclear energy is a kind of high efficient and clean power,the exploration of nuclear resource has a bright foreground, how to explore the uranium mine safely and properly has become a significant subject in the development of nuclear industrial in China. However, the personal dose level of uranium mine workers in China is 3 to 5 times higher than the world average level, leaching uranium ore heap and uranium tailings are the main source of radon in air, because of the changing weather, the moisture of leaching uranium ore heap and uranium tailings vary, and the distribution of radon and radon release on media surface are influenced by the moisture transfering, therefore, in order to keep our country's nuclear industry developing continuously, the study on the model of radon migration in porous emanation media and the calculation methods has significant meanings both in theory and engineering practice for the explosion.This dissertation was supported by the National Natural Science Foundation of China project “Study on radon migration behavior of particle packed dual porous emanation media under the effects of heat and moisture transferring”(No. 11575080). With the study of radon migration model in porous media under moisture transfer, the numerical simulation of the model and the application in certain uranium mineral heap, the main innovative achievements gained are as follows:(1) Based on the Richards equation and the radon diffusive-seepage model, the radon migration model in porous emanation media undermoisture transfer was derived. With the Richards equation, the variation laws of hydraulic parameters in porous emanation media were obtained.According to the relationships between the physical and hydraulic parameters in porous emanation media, the influence of hydraulic parameters on each physical parameters of the media were analyzed, and the radon distribution of radon concentration in gas and liquid phase under the two phase balance was studied.(2)With the pde function and the finite difference methods,compiling a program named RnFDM, the distributions of radon of unsteady state in porous media under different time and space were simulated, and either were the media surface release rate of radon in gas and water phases. Meanwhile, the influence of hydraulic parameters on each physical parameters of the media were simulated.(3)Applying the model and simulation into practical uranium mineral leap, according to the hydraulic parameters and physical parameters in actual situations, the radon concentration in the media and release rate on the surface of the media were both simulated, which can provide theoretical and design advice for radon prevention and radon control for leaching uranium ore heap and uranium tailings. The simulated results shows:1) The effective diffusive coefficient between gas and liquid in porous emanation media decreases with the increment of the time; the effective diffusive coefficient in porous emanation media firstly increases and then decreases with the increment of the media depth, finally reaches the minimum value at the bottom.2) The emanation coefficient in porous emanation media decreases with the increment of the time; The emanation coefficient in porous emanation media firstly decreases and then increases with the incrementof the media depth, finally reaches the maximum value at the bottom.3) The direction of gaseous seepage velocity is upwards, and the direction of liquidus seepage velocity is downwards. Both of the two kind of velocity decrease with increment of time; the gaseous seepage velocity firstly increases and then decreases with the increment of the media depth,the liquidus seepage velocity decreases with the increment of the media depth.4) The radon concentration in porous emanation media increases with the increment of the media depth; the concentration of the porous media firstly increases and then decreases in the shallow depth of the media, increases with the increment of depth in deeper place.5) The direction of the gaseous radon release rate is upwards, the release rate increases with time, the speed of release rate becomes slower with the time.