包头市天然放射性环境调查与评价

对包头市城区陆地γ辐射空气吸收剂量率和空气中氡、气土及其子体浓度进行了测量。其中γ辐射空气吸收剂量率瞬时测量平均值为62.5 nGy/h,累积测量平均值为100.7 nGy/h,累积剂量扣除宇宙射线响应值后与瞬时剂量结果一致,与包头市2006年航测结果值(60 nGy/h)相当。气溶胶中氡子体α潜能值12.88 nJ/m³,气土子体α潜能值9.55 nJ/m³,两种子体的α潜能值均在标准限值范围内。通过对照射剂量估算,城区外照射年有效剂量为0.58 mSv,内照射年有效剂量为1.29 mSv,数值略高于全国和世界平均水平,在同水平范围内。包头市城区放射性环境有效剂量未超过规定限值,不会对公众健康造成不良影响。

Environmental survey and evaluation of natural radioactivity in Baotou City

This environmental survey for natural radioactivity in Baotou City was conducted with measurement of γ absorbed dose rates in air and with measurement of 222Rn,220Rn and their progenies concentrations.The average value of γ instantaneous dose rates measured in Baotou city was 62.5 nGy/h.The mean cumulative dose rate of γ ray in air was 100.7 nGy/h,which was consistent with both the γ instantaneous dose rate after subtraction of the cumulative dose rate of cosmic rays and the aerial survey value (60 nGy/h) of Baotou City in 2006.The α potential energy concentrations of the 222Rn and 220Rn progenies in aerosol were 12.88 and 9.55 nJ/m3,respectively,and both of them were within the range of standard limits.The annual effective dose in Baotou City was estimated to be 0.58 mSv from external exposure and 1.29 mSv from internal exposure,which are slightly higher than the national average value and the world-wide average.The effective dose from natural radioactivity in Baotou City did not exceed the regulatory limits,and thus,would not pose a threat to public health.