| Coal has made great contribution for the socio-economic development but also brought serious environmental pollution problems. Combustion of coal in the course of the radionuclides in coal ash and cinder in the enrichment of the residue, then with ash, the ash into the soil, affecting the level of radioactive soil. The resource of coal is abundant in Shaanxi Province. There are a lot of coal-fired power plants, which have brought a mass of solid waste every year, but the study about the radioactive influence of solid waste is extremely deficient. This research has great theoretical and practical significance in the radioactive radiation monitoring and protection.In this paper, two coal-fired power plants in Xi'an for the study, application of the low end of gamma spectroscopy analysis the coal, the ash, the slag of coal-fired thermal power plant and the soil around coal-fired power plants. It has studied the process of transfer and enrichment of radionuclides, researched the environmental radioactive influence of the two coal-fired power plants and the solid waste that using as structural material.The results showed that in the long-term production process of power plant, due to the release of fly ash deposition, contents of natural radioactive nuclides increased obviously in the surface soil around coal-fired power plant. We should bring additional attention to the radiation of solid waste that using as structural material to prevent the health of denizen was affected. The main conclusions were listed below:1. In the residue of Xijiao coal-fired power plant, the average of radionuclide concentration is 16.2 Bq/kg for 226Ra, 28.0 Bq/kg for 232Th, 49.6 Bq/kg for 40K in the coal and 59.2 Bq/kg for 226Ra, 72.0 Bq/kg for 232Th, 250.1 Bq/kg for 40K in the ash and 53.5 Bq/kg for 226Ra, 49.7 Bq/kg for232Th, 214.4 Bq/kg for 40K. After the coal is burnt, the mean concentration of 226Ra, 232Th and 40K in the ash is 3.7, 2.6 and 5.0 times of the coal and in the residue is 3.3, 1.8 and 4.3 times of the coal. The enrichment factor of 226Ra, 232Th is 0.761 and 0.707. The absorb dose rate increase 0.458×10-8 Gy/h while using the ash of Xijiao coal-fired power plant as architectural material. The effective dose rate is 0.074 mSv every year.2. The mean natural radionuclide concentration is 31.46 Bq/kg for 226Ra in horizon A, 24.85 Bq/kg for 226Ra in horizon B, 25.70 Bq/kg for 226Ra in horizon C and the background of 226Ra is 25±1 Bq/kg in soil around Xijiao coal-fired plant. The total gamma dose rate in air at 1 m above the ground is 56.4 nGyh-1; the average radium equivalent activity is 128.74 Bq/kg around Xijiao coal-fired plant; the average annual effective dose rate is 0.550 mSv.3. The mean natural radionuclide concentration is 36.56 Bq/kg for 226Ra, 36.08 Bq/kg for 232Th, 88.55 Bq/kg for 40K in the coal and 55.18 Bq/kg for 226Ra, 65.15 Bq/kg for 232Th, 242.84 Bq/kg for 40K in the ash and residue of Baqiao coal-fired power plant. After the coal is burnt, the mean concentration of 226Ra, 232Th and 40K in the ash is 1.5, 1.8 and 2.7 times of the coal and in the residue is 3.3, 1.8 and 4.3 times of the coal. The enrichment factor of 226Ra, 232Th is 0.550 and 0.658. The absorb dose rate increase 0.423×10-8 Gy/h while using the ash of Baqiao coal-fired power plant as architectural material. The effective dose rate is 0.060 mSv every year.4. The mean natural radionuclide concentration is 36.57 Bq/kg for 226Ra in horizon A and the background of Ra is 26±1 Bq/kg in soil around Baqiao coal-fired plant. The total gamma dose rate in air at 1 m above the ground is 58.3 nGyh-1; the average radium equivalent activity is 133.82 Bq/kg around Baqiao coal-fired plant; the average annual effective dose rate is 0.552 mSv.5. The mean natural radionuclide concentration is 42.83 Bq/kg for 226Ra in horizon A and the background of 226Ra is 26±1 Bq/kg in soil around Baqiao coal-fired plant. The total gamma dose rate in air at 1m above the ground is 58.3 nGyh-1; the average radium equivalent activity is 136.70 Bq/kg around Baqiao coal-fired plant; the average annual effective dose rate is 0.552 mSv.
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