云南省部分地区环境放射性水平调查及居民所受外照射剂量估算

目的 探讨云南省部分地区的环境放射性水平及所致居民外照射剂量。方法 通过对表层土壤、近地面空气气溶胶和水中放射性核素的γ能谱测量分析,利用卫生系统全国土壤调查中选用的模式,估算环境中²³⁸U、²²⁶Ra、²³²Th、⁴⁰K和¹³⁷Cs所致居民的受照剂量。利用美国航空管理局的CARI-6软件,估算了调查地区居民的宇宙辐射剂量。 结果 调查地区近地面空气气溶胶和水样中各核素比活度都低于探测下限。土壤中放射性核素所致居民人均外照射年有效剂量为0.5206 mSv/年,其中,0.52 mSv/年来自土壤中天然放射性核素,0.6 μSv/年来自土壤中¹³⁷Cs。宇宙辐射所致居民剂量为0.61 mSv/年。结论 宇宙辐射和土壤中天然辐射对居民所受外照射剂量贡献为99.95%,人工放射性核素¹³⁷Cs所致居民的外照射剂量贡献仅为0.05%。

Environmental radioactivity investigation and external dose estimation in some districts of Yunnan Province

Objective To measure the current environmental radioactivity levels in some districts of Yunnan Province,and to estimate the external doses to local residents.Methods The surface soil,aerosol and water samples were collected and analyzed by HPGe gamma spectrometry.Based on the estimation model selected by Ministry of Health in the nationwide soil survey,the doses to local residents from 238U,226Ra,232Th,40K and 137Cs in environmental samples were estimated.CARI-6 software issued by FAA (Federal Aviation Administration ) was used to estimate cosmic radiation dose to the local population.Results The external annual dose rate to the local people was 1.13 mSv per year,of which 0.52 mSv per year was contributed by natural radionuclides in soil,0.6 μ Sv per year by 137 Cs in soil and 0.61 mSv per year by cosmic radiation.Conclusions The cosmic radiation and natural radionuclides in soil might contribute 99.95％ of external exposure dose,while artificial radionuclide 137Cs contribute 0.05％ of external exposure dose.