成都市土壤天然放射性核素的外照射水平估算研究

利用IED22000A便携式微机多道能谱仪对成都市区土壤的天然放射性核素进行了直接就地测量，估算出天然环境放射性核素^238U、^232Th、^40K的比活度范围分别为10.37～77．19Bq／kg、17，85～225．74Bq／kg、284．83～892．67Bq／kg；外照射指数范围为0．16—0．8；离地面1m高的空气吸收剂量率均值为83．23nGy／h；1外照射年有效剂量当量为0．34～0．70mSv；等效镭浓度的变化范围是59．06-386．45Bq／kg，均值为164．15Bq／kg。各项指标均在容许范围之内，因而成都市属于外照射水平的安全区域，人居环境不受影响。

Estimation of Natural Terrestrial External Exposure Levels of Nuclides in Soils in Chengdu

Direct and In situ measurement of natural terrestrial external exposure levels of nuclides from soils in Chengdu was taken using the IED22000A,a portable microcomputer multi -channel spectrometer. It was estimated that the specific activity of radio nuclides ^238 U, 232Th and ^40K was between 10.37 - 77. 19 Bq · kg^-1 ,17.85- 225.74 Bq · kg^-1 and 284.83 -892.67 Bq · kg^-1 ; the external hazard index was between0.16 -0.8. The average air absorbed dose rate measured 1 m above ground, was 83. 23 nGy · h^-1. Yhe annual effective dose in γ external exposure was between 0.34 -0.70mS. The radium equivalent activity was between 59.06 -386, 45 Bq · kg^ - 1, and its averaged value was 164.15 Bq · kg^ - 1. The indicators were in the permissible range. The levels of external exposure in Chengdu stayed in safety range and had no adverse impact on people＇s living environment.