The Experiment And Simulation Research On The Diffusion Migration Of Nuclide At Uranium Mill-Tailing

The paper has taken a large uranium tailings impoundment in South China as an example studied, focuses on the dynamics coupling mathematical model of migration in the uranium tailings-soil-groundwater system which is in the different conditions. In order to study the effect of the different soil, concentrations and porosity conditions on migration diffusion of the tailings of nuclide U(?) in the further, the diffusion coefficient of soil in uranium tailing is calculated by experiment. The main purpose of the study was to determine diffusion coefficient of U(?) in the uranium tailings where has different soil environments. Compared with the experiment of Chloridion migration in the soil, the effect of contact time,distance, soil texture and porosity on the diffusion of U(?) were also investigated. And then we can obtain the concentration of uranium tailings in migration. The dissertation includes the following contents:(1) The experiment method was used to analyze the clay and sand soil, and the physical and chemical composition of the clay and sand were obtained.(2) In order to study the migration diffusion regularity of the tailings of nuclide U(?),a special self-made container was used. Compared with the experiment of Chloridion migration in the soil.The diffusion coefficient of uranium in different conditions was determined by the method of horizontal soil column infiltration. The diffusion coefficient of chloride and uranium in different soil, time, porosity and other conditions can determined in a device in laboratory as the same time. And it can save more time in the experiment.(3). The diffusion coefficient of uranium and chloride ion was obtained by the laboratory methods under different soil conditions. In the same porosity,the diffusion coefficient of Chlorine ion in the clay was D=0.354×10-3m2/d,while in the sandy soil was D=1.830×10-3m2/d;The diffusion coefficient of Uranium in clay was D=0.950×10-3m2/d,while in the sandy soil was D=1.623×10-3m2/d. The results show that uranium and chloride ion diffused faster in sandy soil than in clay soil(4) When the soil texture is same, the diffusion coefficient of uranium in different porosity is different. And the diffusion coefficient of uranium becomes smaller with the decreases of porosity. The results show that porosity of the soil has a bigger influence on diffusion coefficient. Due to the limitations of the test device, the effect of porosity has no systematic comparison of different porosity influence on the diffusion, it need to be studied in the further.