| Abstract:With the Environmental Protection Department of the radiation environment monitoring program carried out, it’s monitoring of objects including NORM industries (including coal-fired power plants, iron and steel making plants, cement plants etc.) in Hunan, Hubei and Jiangxi provinces along the Yangtze River. This paper is to preliminary consummates our country NORM enterprise in the source term of cement production; to provide basic data support which the radioactive emission levels research in NORM industries; and to evaluate the radiation influence around the staff, the public and the environment to lay the foundation.The cement plants in Jiangxi and Hubei province along the Yangtze River are chosen as object, expressed in A plant and B plant. The contents and analysis of the survey mainly contained as follows.(1) Source term data analysis:The results showed that the activity concentration of 226Ra,232Th and 40K in cement production produced by A plant and B plant were below the mean by the report of UNSCEAR1993. The radium equivalent activity (Raeq≤370Bq/kg) varied from 63.4Bqkg to 102.4Bqkg, the internal exposure index (IRa≤1) were between 0.15 and 0.23, and the external exposure index (Iγ≤1) varied from 0.22 to 0.36; Similar to A plant, the parameter Raeq varied from 58.1Bqkg to 88.6Bqkg, the internal exposure index IRa were between 0.13 and 0.21, and the external exposure index Iγ varied from 0.16 to 0.24 in plant B. The radioactivity parameters Raeq, IRa, Iγ in A plant and B plant were both below the safe use limits according to UNSCEAR2000 report and GB6566-2010.(2) 210Po emission analysis:210Po emissions were estimated to be7.32×10’Bq/a in A plant combined with business operating parameters, and the normalized emission was 5.50×10’Bq/Mt,The same as A plant, the emission of 210Po was calculated to be 7.26×106 Bq/a and the normalized emission was 2.34×106 Bq/Mt.On one hand, data showed that the emission in A plant was one orders of magnitude higher than B plant. Both A plant and plant B was there to four orders of magnitude lower than the results reported abroad (7.8×1010Bq/a); the other hand, both two plant were within the level of clearance prescribed by Dutch Radiation Protection decree.(3) 222Rn emission analysis:The result showed that 222Rn emission was calculated to be 8.66×1010Bq/a combined with business operating parameters and the normalized emission was 3.61×1010Bq/Mt in A plant; similar to A plant,222Rn emission was calculated to be 7.94×1010Bq/a and the normalized emission was 2.56×1010Bq/Mt in B plant. From the calculation results we know,222Rn emission in A Plant was approaching to B, but was lower than foreign reports (1.57×10uBq/a).(4) Effective doses received by workers:The measurement results showed that annual effective dose received by workers due to y external irradiation ranged from 0.078mSv/a to 0.222 mSv/a in A plant, with an average of 0.143 mSv/a; while workers in B plant got an average annual effective dose of 0.161 mSv/a due to y external irradiation, with range from 0.106 mSv/a to 0.298 mSv/a. The effective dose in B plant was slightly higher than that of A plantDue to the way inhalation of uranium and thorium series radionuclides, workers in A plant got an effective dose varying from 0.00956 mSv/a to 0.00959 mSv/a and with a mean of 0.00957 mSv/a, the annual effective dose was approaching to foreign reports (0.0011mSv/a～ 0.0173mSv/a) and B plant with results of 0.00959mSv/a. |
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