Numerical Simulation And Experiment Investigation On The Radioactive Radionuclide Of Uranic Well Ventilation Exhaust Gas In Atmosphere

Many radioactive radionuclides such as radon and its daughters, uranium dusts and radioactive aerosols, etc. are produced in process of uranic mining, which have caused the 83.3 percent dose of the total nuclear fuel cycle dose. A certain degree of pollution to surroundings is caused by the radionuclides about uranic well ventilation exhaust gas. Radionuclide migration in atmosphere is complicated, and it is concerned with the features of pollution sources, topography and geomorphological features of the migration region, as well as atmospheric wind fields, the climatic characteristics of different regions, precipitation and other factors. The research of radioactive radionuclides about uranic well ventilation exhaust gas is one of emphasis projects of contamination-controlling and environment-administering, which has a great significance to promote sustainable development of the nuclear industry.Supported by National Natural Science Foundation (Research on the forecast method of safety protection distance and radionuclides migration about uranic well ventilation exhaust gas), and based on the radionuclide diffusion characteristics of different wind speed properties and surface roughness degrees, numerical simulation and model experiment investigation on the migration status of radionuclides about uranic well ventilation exhaust gas are accomplished in this dissertation. In addition, the computation method of safety protection distance is discussed, and then the method of numerical computation, prediction and evaluation about uranic well ventilation exhaust gas are put forward finally.In summary, this dissertation includes the following main contents:(1) To investigate systematically the exhaust characteristics and pollution properties about uranic well ventilation, as well as the applicability and shortages of current major research methods about radioactive radionuclides. On that basis, the method of numerical computation, prediction and evaluation about uranic well ventilation exhaust gas are put forward.(2) To analyze systematically the various factors on the migration of radionuclides in atmosphere, and to decide the main factors, which creates the theoretical basis for numerical simulation and model experiment design. (3) Numerical computation methods for the migration of radionuclides in atmosphere under complex terrain are studied. And some basic questions are researched such as the grid division, boundary conditions setting and the selecting of radionuclides computation parameters, etc. Then the computation method of radionuclides phases-separating is brought forward, which creates the basis for the coming numerical simulation research.(4) Based on the source features, wind properties and surface roughness degrees characteristics about uranic well ventilation, the migration impact of wind properties and surface roughness features under complex terrain is researched for radionuclides by numerical simulation. And it is obtained the different factors of radon gas distribution and pollution regions, as well as the migration characteristics of radionuclide particles in atmosphere. And the numerical results are similar to the measurement results on the spot, which creates the basis for prediction and evaluation of radioactive pollution and harm on the surrounding environment about uranic well ventilation exhaust gas.(5) Using the method of small-scaled model water tank experiments, the diffusion of salt liquor in water is used to simulate the diffusion status of radionuclide in atmosphere. In addition, the PIV technology, DIPT technique and flow field visualization technique are used to investigate the diffusion characteristics of radionuclides about uranic well ventilation exhaust gas, and reveal its' rules of migration-diffusion and concentration distribution. At last, the experimental results would be used to verify the numerical results.(6) Based on the above numerical methods and national public dose limit personal standards about uranic mining areas, the evaluation methods for radiation safety protection distance and uranium mine site-selecting are set up. Then the method of exponential smoothing is used to set up pollution prediction model and also it is used to make a ten-year prediction and evaluation on uranic well ventilation exhaust gas radioactive pollution. Finally, some suggestions for preventing and controlling the environmental pollution by radioactive ventilation exhaust gas are put forward.