中国核动力院外围空气中7Be、40K、60Co、131I、137Cs分布特征及所致公众年有效剂量评价

基于2015—2017年中国核动力院外围空气中⁷Be、⁴⁰K、⁶⁰Co、¹³¹I、¹³⁷Cs监督性监测数据,对综合楼、南坝工会和木城水厂监测点附近居民组三种途径的有效剂量进行了粗略估算。结果表明:随距核设施距离增加,⁶⁰Co、¹³¹I、¹³⁷Cs平均年摄入量和所致年有效剂量减小;综合楼附近居民组中成人、青少年、儿童、幼儿、婴儿经吸入⁷Be、⁴⁰K、⁶⁰Co、¹³¹I、¹³⁷Cs平均年摄入量分别为29.25、26.48、20.16、11.49、6.79 Bq/a;综合楼附近居民组中青少年、儿童、成人、幼儿、婴儿,经吸入、浸没和地面沉积途径⁶⁰Co、¹³¹I、¹³⁷Cs所致年有效剂量分别为133.58、130.98、128.61、120.20、118.61 nSv/a,⁶⁰Co所致剂量分数达到95.6%,其次是¹³⁷Cs;地面沉积途径所致剂量分数达到54%,其次是吸入;综合楼附近居民组中青少年组成员⁶⁰Co、¹³¹I、¹³⁷Cs所致有效剂量最大为133.58 nSv/a,但此有效剂量也仅占评价剂量目标值(0.25 mSv)的1‰以下。由此可以得出,核基地核设施正常运行工况下,⁶⁰Co、¹³¹I、¹³⁷Cs对核基地外围空气的影响很小。

Distribution characteristics of 7Be, 40K, 60Co, 131I and 137Cs in the ambient air of China Nuclear Power Institute and annual effective dose evaluation for the public

Based on monitoring data of ⁷Be, ⁴⁰K, ⁶⁰Co, ¹³¹I and ¹³⁷Cs in the ambient air around the China Nuclear Power Institute from 2015 to 2017, the effective doses of residents near the monitoring points of comprehensive building, Nanba Trade Union and Mucheng water plant were roughly estimated. The results showed that the average annual intake of ⁶⁰Co, ¹³¹I and ¹³⁷Cs as well as the induced annual effective doses decreased with the increase of the distance from the nuclear facilities; the average annual intakes of adults, teenagers, children, infants and newborns of residents near the comprehensive building by inhalation of ⁷Be, ⁴⁰K, ⁶⁰Co, ¹³¹I and ¹³⁷Cs are 29.25, 26.48, 20.16, 11.49 and 6.79 Bq/a, respectively; the annual effective doses of teenagers, children, adults, infants and newborns of residents near the comprehensive building caused by inhalation, immersion in the air and ground deposition of ⁶⁰Co, ¹³¹I and ¹³⁷Cs are 133.58, 130.98, 128.61, 120.20 and 118.61 nSv/a, respectively; the dose fraction caused by ⁶⁰Co reached 95.6%, followed by ¹³⁷Cs; the dose fraction caused by surface deposition reached 54%, followed by inhalation; the maximum effective dose caused by ⁶⁰Co, ¹³¹I and ¹³⁷Cs in the youth group of residents near the comprehensive building is 133.58 nSv/a, but this effective dose is only less than 1‰ of the target value of the evaluation dose (0.25 mSv).It can be concluded that ⁶⁰Co, ¹³¹I and ¹³⁷Cs have little influence on the ambient air of the nuclear base under normal operating conditions.