Abstract:The contents of natural radionuclide such as 238U, 232Th and 40K on the ground surface of Dalian City, Liaoning Province, are surveyed with the ARD γ-ray spectrometer. The results show that the average specific radioactivity of 238U is 23.09 Bq/kg (ranging from 1.24 to 151.91), 232Th 18.99 Bq/kg (0.41-92.57), and 40K 386.39 Bq/kg(31.30-1095.50), which are all significantly lower than the national and world averages. On the basis of measured radionuclide concentration, the parameters including the absorbed dose rate of γ radiation(Dr) at 1 m above the ground, external exposure index (Ir), internal exposure index (IRa) and annual effective dose (Daed) are calculated, and then the natural radioactivity level are evaluated. The average Dr of 39.04 nGy/h is far lower than the national average (81.5 nGy/h) and world average (80 nGy/h). The average values of Ir and IRa are 0.23 and 0.12 respectively, much less than the national limit (1) for external exposure index of building materials. The Daed of 0.048 mSv is far below the world average annual effective dose (0.46 mSv) and limit of annual effective dose for external public exposure (1.0 mSv). The evaluation results show that the natural radioactive radiation of surface in Dalian urban area is at a safe level.
韩志滨, 马宏伟, 杜广仁. 大连市区地表天然放射性水平调查[J]. 地质与资源, 2020, 29(5): 483-489.
HAN Zhi-bin, MA Hong-wei, DU Guang-ren. INVESTIGATION ON THE NATURAL RADIOACTIVITY LEVEL OF GROUND SURFACE IN DALIAN URBAN AREA. GEOLOGY AND RESOURCES, 2020, 29(5): 483-489.
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