Measurement Of Radon Concentrations And Etimation Of Its Emissions Of Coal-fired Plants

This dissertation was designed to make a detailed investigation of the present situation about the measurement of the level of radon concentration and its emission in coal-fired power plants,take field trips to investigate the production process of coal-fired power plants. monitor radon concentration levels on critical points of production process in three typical coal-fired power plants, which are located in Hunan, Hubei and Jiangxi provinces. The measurement equipment is RAD7, a multi-functional electronic radon monitor detect. At the same time, gathering the coal samples of the three coal-fired power plants for the measurements of radionuclide 226 Ra activity concentration. What’s more, using the research and experimental data, and two different radon emissions estimation methods established, to preliminary estimated radon emissions and normalized emission of coal-fired power plants. Specific studies are as follows:(1) Investigation of the present situation about the measurement of the level of radon concentration and its emission estimation methods of coal-fired power plants at home and abroad. The investigation shows that studies on effects of radiation environment of coal-fired power plants are mainly concentrated in Shanghai, Beijing, Jiangsu, Xi’an and Hong Kong eastern regions, but the data on radon concentration and emissions are scarce. Currently a Jiangxi coal-fired plant, which has a good ventilation condition, is known to have a low radon concentration in coal-fired boiler, turbine, electrical, workshop and living areas. Parts of India coal-fired power plants radon concentration levels are higher than China, Jiangxi, but still below or between(1993) recommended action level 200~600 Bq/m3.(2) Monitoring radon concentration levels on critical points of selected typical coal-fired power plants in Hunan, Hubei, Jiangxi provinces. Because of coal combustion, massive radon gas are released,the radon concentration in flue gas system is higher than intake radon concentrations, and denigration entrance has the highest radon concentration. Chimney radon concentration is lower than desulfurization inlet because of the air from desulfurization inlet.(3) Establishment of radon emissions estimation method from coal-fired plants. Estimated radon emissions from three typically coal-fired power plants based on 226Ra-222 Rn balance principle, the additional presupposition is all 222 Rn gas released after combustion. The results shows: 4#630MW unit of Hunan has a minimum annual radon emission theoretical estimate 5.0×1010Bq, and its maximum emission is 14.2× 1010 Bq. So the actual measurements of annual radon emissions is 6.7×1010Bq, between 5.0×1010~14.2×1010Bq. The annual radon emission of 1#330MW turbine and 3# 680 MW turbine in Jiangxi is 6.5×1010Bq and 6.8×1010Bq. While the annual radon emission of 5#350MW turbine and 7#660MW turbine in Jiangxi is 1.9×1010Bq and 5.5 × 1010 Bq. According to power generation and coal consumption of China’s coal-fired power plants, different 226 Ra activity concentrations in coals, a typical value of radon emissions from coal-fired plants is calculated,and the result is 121 GBq / GWa.