Natural radioactivity in soil around Baqiao coal - fired power plant had been measured by using a Nal ( Tl) γ - ray spectrometry. The results show that the specific activity of 226Ra,232Th and 40K in soil samples ranges from 27.60 to 48.78, 44. 39 to 61. 39 and 640.19 to 992. 25 Bq/kg with an average of 36.07 , 51. 13 and 733.91 Bq/kg, respectively. The average activity of 226Ra in soil around the power plant is greater than the average of Shaanxi soil, while slightly less than the average of Chinese soil. The average activity of Th and K in the studied soil samples are higher than the average level of Shaanxi soil and Chinese soil. The concentrations of 226Ra and 232Th in soil samples collected within 1000 m sites to coal - fired power plant boundary show no significantly spatial differences, whereas K concentration in soil samples collected from 100 m sites is less than from 400 m and 1 000 m sampling sites. The evaluation results of radium equivalent activity, air absorbed dose rate and annual effective dose rate show that coal - fired power plant affected the natural radioactivity level of surrounding soil, but natural radioactivity of soil is in normal level.%应用低本底多道γ能谱仪测定了燃煤电厂周围土壤中天然放射性核素226 Ra、232Th和40K的比活度,评价了其辐射危害.测定结果表明,土壤中226 Ra、232Th和40K的比活度分别为27.60～ 48.78、44.39～ 61.39和640.19～ 992.25 Bq/kg,平均值分别为36.07、51.13和733.91 Bq/kg.电厂周围土壤中226Ra比活度大于陕西土壤平均水平,稍小于全国土壤平均值；232 Th和40K比活度均大于陕西省土壤和全国土壤平均水平.在距离电厂1 000 m范围内,土壤中226Ra和232Th无明显空间差异,而40K比活度在距电厂100 m处土壤中明显低于400 m和1000m处.等效镭活度、空气吸收剂量率和年有效剂量率评价结果表明,燃煤发电对灞桥电厂周围土壤放射性有一定影响,但放射性水平处于正常.
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