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| Estimation of Doses to the Residents Arising from Inhalation of Rn-222, Rn-220 and Their Decay Products in High Background Radiation Area of Yangjiang |
| YUAN Yong-ling1, H. Morishima2, SHEN Hong2, et al |
| Labor Hygiene Institute of Hunan province, Changsha 410007, China |
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Abstract Objective This paper reports on the estimate of average annual effective dose of the residents and absorbed dose in some human tissues and organs arising from inhalation of Rn-222, Rn-220 and their decay products in investigated areas.Methods In order to calculate equilibrium factor F for Rn-222 and equilibrium equivalent concentration of Rn-220, we measure concentration of Rn-222 and Rn-220 by discrete sampling.Meanwhile, we measure the concentration of decay products of Rn-222 and Rn-220.Based on the equilibrium factor F of Rn-222 and equilibrium equivalent concentration of Rn-220, and the occupancy factor, writer estimated average annual effective doses and absorbed doses in some tissues and organs to the residents arising from inhalation of Rn-222, Rn-220 and their decay products in investigated areas.Results The data based upon the results of integrated measurements on the concentration of Rn-222 and Rn-220 in investigated areas.The average indoor and outdoor concentrations of Rn-222 are 49.61 Bq·m-3 and 17.30 Bq·m-3 in HBRA, respectively, and 18.1 and 11.7 Bq·m-3 in CA, respectively.The average indoor and outdoor concentrations of Rn-220 are 95.16 Bq·m-3 and 9.3 Bq·m-3 in HBRA, respectively, and 12.4 and 8.1 Bq·m-3 in CA, respectively.The averages of equilibrium factors of Rn-222 for indoors and outdoors in HBRA are 0.46 and 0.53, respectively.The values in CA are 0.62 for indoors and 0.63 for outdoors, respectively.The value of equilibrium equivalent concentration of Rn-220 for indoors and outdoors in HBRA are 6.51 Bq·m-3 and 0.79 Bq·m-3, respectively, and the values for CA are 0.66 Bq·m-3 and 0.33 Bq·m-3, respectively.Conclusion The estimate of average annual effective dose to the residents arising from inhalation of Rn-222, Rn-220 and their decay products was 3.28 mSv·a-1 in HBRA, while that in CA was 1.03 mSv·a-1.The trachea-bronchial tree has the maximum absorbed dose in HBRA, the value is 5.40 mGy·a-1;lung has the second absorbed dose, the value is 1.08 mGy·a-1.These two values are about 4.0 times in CA.The estimate of average annual effective dose to the residents arising from inhalation of Rn-220 and its decay products was 1.75 mSv·a-1 in HBRA.We noted that Rn-220 and its decay products are very important component of effective dose for the inhabitants living in the HBRA.
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Received: 21 September 2001
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ZHENG Senxing, ZHANG Yan, HUANG Lihua, ZHENG Qishan, LIU Pan, GUO Huozhong, ZOU Tianlu, YAN Jianming. Investigation and analysis of the application frequency of medical X-CT and the dose in Fujian Province in 2016[J]. , 2018, 27(6): 543-546,561. |
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