| As an important strategic resource related to national security,uranium is of great significance to industry,national defense and other fields.At present,the main way of uranium mining industry is in-situ uranium mining,but in the process of mining,uranium will decay and release radon gas,which will produce radon pollution and discharge to the surface with holes and crevices in pipes and houses.Therefore,reducing radon concentration and exhalation rate in uranium mining environment is the goal of radon protection in China's occupational health work,and it is also the necessary condition to realize the sustainable development of China's uranium mining industry.In this paper,based on the previous researches on radon-proof materials,the research and development of the radon-proof sealing materials for the uranium pool in Bayan Ullah uranium mine is carried out with the aim of putting them into field use,the purpose is to reduce the radon exhalation rate of the collecting pool and to protect the health of the workers and the surrounding environment.In this paper,the principles of Radon diffusion,seepage and diffusion-seepage transport are studied.A physical model of radon diffusion and transport in single-layer non-radon source media is proposed,and the formula of radon concentration and radon exhalation rate under stable condition are deduced by using the physical model.According to the expression of Radon exhalation rate on the surface of the medium,the best thickness interval of the material is calculated.In the experimental part,6 kinds of anti-radon sealing materials were selected according to the field diffusion and migration law and the principle of anti-radon.Polyurethane sealant,one component polysulfide sealant,neutral silicone structural adhesive,epoxy resin coating,acrylate coating and acid alcohol resin coating were introduced from the aspects of physicochemical properties,functions,advantages and disadvantages,and 6 kinds of anti-radon sealing materials were prepared according to the sample preparation principle Radon samples.The radon prevention performance test device and experimental steps are designed to test the samples.According to the test data,qualitative and quantitative analysis is carried out.The radon concentration diffusion coefficient and radon resistance rate are compared and calculated.The advantages and disadvantages of sealant and film-forming paint are comprehensively analyzed.The weathering resistance,volume expansion rate,adhesion,flexibility and thawing resistance of radon proof materials were tested.Combined with site environment design and construction scheme,polyurethane and coating technology is selected for one site construction.The radon leakage rate and the exhalation rate of the collecting pool before and after the blockage are calculated.The radon leakage rate and exhalation rate are calculated.The leakage rate of the collecting pool is 2.94×10-4s-1,and the average radon-reducing efficiency is 44.37%,which has not reached the expected radon-preventing effect,and the problems of dry-cracking and peeling of the materials have not reached the field radon-preventing requirement.Changing the research material and improving the construction technology,the polyurethane and Sealant double-layer coating technology was determined to construct the holes and crevices of the collecting tank.The final selection of polyurethane sealant,one-component polysulfide sealant and epoxy coating for secondary field application.By measuring the effect of the second field construction,the leakage rate of the collecting pool after the closure decreased from 2.94×10-4s-1 to 4.57×10-5s-1 after the first construction,and the resistance rate of radon increased to 84.4%,the requirement of preventing radon rate above 70%has been achieved.Finally,some suggestions are put forward for the problems existing in the field of Bayan Ullah collecting tank,and the research and development of the sealing material for preventing radon leakage and its field application are completed. |
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