铀矿井排风放射性尾气在大气中扩散的数值模拟及实验研究

Numerical modeling and experimental research on the radioactive exhaust gas from the ventilation outlet of the uranium mining well

对某铀矿山排风尾气中核素氡在大气中的扩散进行数值模拟,同时建立了物理实验模型,在水槽中进行PIV实验。将数值模拟结果与实验结果进行了对比,发现两者能较好地吻合。结果表明,在排风井下风向200m以内核素氡浓度衰减较快;随着下风向距离的增大,地面浓度不断降低,到了300m的位置氡浓度变化缓慢;继续增大距离,地面浓度变化不大。研究方法及结论可以为铀矿区安全防护距离的科学制定提供一定的参考。

The paper is inclined to present our research progress on numerical modeling and experimental determination of the radioactive exhaust gas diffusion from the ventilation outlet of the uranium mining well, especially, the diffusion of radionuclide in the atmosphere. As is known, due to the radioactive risk caused by the radionuclide, it seems extremely complex to clarify the problem and its multifaceted complexity. To make things worse, it is impossible to repeat the status quo of the research objects because of its random nature. Thus, it seems too costly and consumable to conduct the experiments in terms of the manpower and material resources, whereas the numerical simulation can serve as one of the most popular ways to predict the pollution for the test conditions are easy to get control. For, as a matter of fact, numerical modeling was just found to be one of the earlier users in simulating the radionuclide radon migration from the uranium mining-well in some uranium mining areas. Then physical experiment model was set up and PIV （Particle Image Velocity ） experiments were conducted in a water tank to investigate the radionuelide radon diffusion mechanism as well as the airflow pattern on uranie ventilation outlet over complex terrains. Furthermore, various water flow velocities were used to denote the different wind speeds, whereas graphs and curves indicating the velocity vectors and streamlines were used to explain the diffusion of radionuclide radon with PIV technique in the tank. Finally, the result of simulation could be akin to compare the results of experiments, which prove to be coincided to a great extent. All in all, our research shows that the concentration attenuation rate of radionuclide radon can be found going on rapidly in the range of 200 m, with the ground concentration dropping along the downwind-ward distance. Then, with the increase of the distance from uranic ventilation outlet, the ground concentration would be getting lower and lower. However, when the downwind-ward distance reaches 300 m, the ground concentration variety would be slower in the direction. On the other hand, with the increase of the distance from uranic ventilation outlet, the ground concentration would change noticeably. Thus, it can be seen that the numerical modeling and experimental research methods suggested in this paper and its results are expected to be of great significance and help to lay a foundation to determining the safety protection distance in a scientific and theoretical sense.