Ground Water Pollution Risk In The Rejected Uranium Tailing Reservior Based On AHP-unknown Measure-SPA

Once a large amount of toxic and hazardous substances in the seepage of the tailing of the rejected uranium tailing reservoir,which make the reservoir to be a source of low-level radioactive contamination,are vertically migrated to the groundwater in the reservoir area and break through the depletion and the ability to recover itself of the groundwater system,the groundwater in this area must be polluted.Therefore,the risk assessment of groundwater pollution in this area is one of the important measures for environmental monitoring of uranium tailing reservoir.At present,there is not only an unified and systematic groundwater pollution risk assessment system for the rejected uranium tailing reservoir,but there is a certain degree of uncertainty in the groundwater system and the pollution risk assessment for the this reservoir.Now,in order to reduce the uncertainty in the system,this paper create a risk assessment model based on the pollution process and a risk assessment method based on the AHP-unknown measure-SPA for the rejected uranium tailing reservoir and finally obtains a comprehensive and systematic groundwater pollution risk assessment system for the rejected uranium tailing reservoir.The main contents of this paper are as follows:(1)According to the pollution process,the scope of the groundwater contamination risk analysis of the decommissioned uranium tailings reservoir is divided into the whole process consisting of tailings seepage,porous media(saturated zone and non-saturated zone),and risk receptor(groundwater),meanwhile the three ideal concept layer,including contaminants layer,porous medium layer,and groundwater layer is used to construct a groundwater contamination risk analysis model for the rejected uranium tailing reservoir.For the risk analysis of the reservoir area,the analysis of anti-fouling performance of non-saturated zones,the analysis of pollution transmission of the saturated water zone,and the analysis of the hazards of pollution are carried out layer by layer,a total of 15 pollution risk factors,such as current storage capacity,are finally obtained to construct a risk assessment model of groundwater pollution of the rejected uranium tailing reservoir.(2)A hierarchical model has been constructed based on the established groundwater pollution risk assessment model and using the Analytic Hierarchy Process(AHP)to obtain weight vectors for system level B and index level C.Using the product of the weight vector and the unknown measure evaluation matrix to replace the same,different,and opposite membership degree matrix of contact number of the set pair analysis(SPA)optimizes the set pair analysis and evaluation process,and set the trend analysis to present the system pollution situation.While the number of assessments of the unknown measure,the degree of connection,and the number of levels of groundwater pollution risk assessment are the same,the average value of the contact number range corresponds to the groundwater pollution risk assessment grade of the rejected uranium tailing reservoir.All this constructs a risk assessment method for groundwater pollution of rejected uranium tailing reservoir based on AHP-unknown measure-SPA.(3)A large rejected uranium tailing reservoir in Hunan is used as an evaluation example to verify the feasibility of the established risk assessment of groundwater pollution in the rejected uranium tailing reservoir,the result is that the risk of groundwater pollution in this reservoir belongs to the medium pollution risk and has a relatively low pollution situation.