The Method Study On Groundwate Pollution Risk Assessment Of Uranium Tailings Pond

It is possible that uranium with the waste water enter into groundwater because of uranium mining and uranium tailings' long time of accumulation. Through referring to groundwater pollution risk evaluation models of different pollutants and different forms of pollution domestic and overseas, it taking the structure of the uranium tailings characteristics and the characteristics of nuclide uranium as a starting point, proposed methods of index superposition and process numerical simulation for the groundwater pollution risk assessment.Index of superposition method is through selecting four pollution characteristic indexes may be more impact on groundwater pollution load factor of pollutant of waste liquid leakage, toxic pollution, pollutant migration characteristic indexes and field stacking time, establish the pollution load risk assessment system. Combining with the inherent vulnerability evaluation of groundwater, and at the same time both on the analytic hierarchy process(ahp) to determine weight of objectivity, five grades of groundwater pollution risk are divided through the risk level of superposition method, the pollution load risk assessment system is applied to the evaluation instance finally. The results show that the contamination risk level of groundwater in the area is medium-low.In order to further verify the accuracy of the evaluation results by evaluation method based on the superposition of index, Based on numerical simulation of the diffusion scope of uranium migration and concentration distribution of recent(150 years) and long-term(150 ~ 500 years) pollution risk assessment standards is set up. By generalized research regional hydrogeological model, then established the control equation of solute transport, using MODFLOW and MT3 DMS of uranium migration simulation of up to 500 years, According to the obtained uranium with time migration and diffusion range map and monitoring the concentration changes of map and combined with the established evaluation criteria. Results show that the groundwater pollution risk for low and middle level recently, and this conclusion is consistent with the result based on index method to make the evaluation. Even uranium migrating along with the groundwater for more than 500 years, its pollution diffusion range exceeds the drinking water standard concentration distribution range, and it is also stay away from rivers and human living area basically. According to the established evaluation criteria, it also belongs to medium level of risk.So it shows that the above two kinds of uranium tailings groundwater pollution risk evaluation method are feasible, providing reference models for uranium and other contaminants in groundwater pollution risk assessment, being of great significance to evaluate the risk of groundwater.