Anaiysis On Current Situation Of Pollution And Water Quality Comprehensive Assessment Of Seepage Of Decommissioning Uranium Tailings Impoundment Based On The Cloud Model

Uranium tailings pollutes the groundwater through the tailings leakage, which is the main way of diffusion of radionuclide from the uranium tailings impoundment to surrounding enviroment. With the increase of reservoir age of decommissioning uranium tailings impoundment, the possibility of infiltration to groundwater of radionuclide and intake will greatly increase, causing the environmental pollution of groundwater and damaging the ecological environment seriously by spread to various biological. This kind of harm has the characteristics of protracted nature, concealment, great harm and difficult restoration. Therefore, it is necessary for analysis on current situation of pollution and water quality assessment of seepage. It can make clear the present water quality of seepage, investigate the main pollutants in seepage and possible pollution situation of groundwater, and provide evidence for water environment treatment and reatment engineering of decommissioning uranium tailings impoundment.This paper first introduced the environment survey of decommissioning uranium tailings impoundment and analyzed the each pollutants in seepage. On this basis, the water quality evaluation index system of seepage was established by the method of index screening combining principal components analysis with correlation analysis. Then,the combination assigning method combining AHP and CRITIC was used to evaluate weight of the indexes. And the water quality comprehensive assessment based on cloud model was built by applying cloud model to improve water pollution index method. Finally, the given method was applied in the seepage water quality comprehensive evaluation of decommissioning uranium tailings impoundment and compared with original water pollution index method. The main research work and achieved results of this dissertation are as follows:(1) Through analysis of pollutants in seepage, the main pollutants were determined including pH, U, ??, NH4-N, Mn, Zn, F-. The water quality evaluation index system of seepage was established by the method of index screening combining principal components analysis with correlation analysis, determining the final evaluation indexes including pH, U, Ra, ??, NH4-N, Mn, F-, Zn. The screening result and the analysis result of main pollutants were basically in agreement, which was proved rationality of seepage water quality evaluation index system.(2) Combining the advantages of AHP and CRITIC, the combinationassigning method based on AHP-CRITIC was proposed and used to evaluate weight of indexes of seepage water quality evaluation. The analysis process and result was more objective and reasonable than single weighting method. It can provide data support for water quality comprehensive evaluation.(3) According to the defect and deficiency of water pollution index method, the water quality comprehensive assessment based on cloud model was built by applying cloud model to improve water pollution index method. On the basis of WPI classification standard, the WPI evaluate cloud was generated by using normal cloud generator. The WPI of each evaluation factor was computed using the measured data.Combining the single factor WPI cloud generated by backward cloud generator and combined weight, the integrated WPI cloud was obtained through integrated cloud algorithm and compared with the WPI evaluate cloud, determining water quality grade.(4) With the example application, the water quality comprehensive assessment result of each dam seepage was obtained. Comparing with original water pollution index method, the comparison showed that the model is objective and reliable. It can reflect the present water quality of seepage very well and remedy defect and deficiency of water pollution index method effectively, providing new idea for the study of water quality evaluation method.