中国部分地区^(220)Rn浓度的测量

Detction of ^(220)Rn and Its Progency Concentrations in Some Areas in China

目的 了解我国不同地区室内外^(220)Rn及其子体的水平及对居民所产生的有效剂量。方法 采用日本名古屋大学提供人的Rn-Tn固体径迹探测器和子体潜能法测量了室内外^(222)Rn、^(220)Rn及其子体的浓度,用UNSCEAR 1996年报告给出的^(222)Rn、^(220)Rn剂量转换系数估算了吸入^(222)Rn和^(220)Rn子体产生的年均有效剂量。对土壤中^(232)Th含量与^(220)Rn浓度的相关性及其影响因素进行了探讨。结果 北京、广州、珠海、平凉等地室内^(220)Rn及其子体的浓度分别是<LLD～1326Bq·m^(-3)和<LLD～4.7EEC Bq·m^(-3);室外^(220)Rn子体的浓度是<LLD～2.2EEC Bq·m^(-3)。^(220)Rn及其子体所致的年均有效剂量为0.18～0.60mSv,占^(222)Rn、^(220)Rn及其子体总有效剂量当量的13.1％～55.6％。室外^(220)Rn及子体的浓度取决于土壤中^(232)Th的含量。影响室内^(220)Rn浓度的主要原因是建筑材料中^(232)Th的含量及^(220)Rn的面析出率。结论 我国室内外^(220)Rn浓度普遍高于世界平均值,这与我国土壤中^(220)Rn的母体核素^(232)Th含量偏高有关。

Objective To realize the level of 220Rn and its progeny concentrations and annual effective dose from 220Rn in different areas in China.Methods Rn and its progeny concentrations, outdoors and indoors, were obtained by using Rn - Tn solid state nuclear track detectors developed by Nagoya University, Japan, and potential energy analysis method.The annual effective dose from Rn and its progenies were calculated using the conversion coefficient from UNSCEAR 1996 report. Results Rn and its progeny concentrations in Beijing, Guangzhou, Zhuhai and Pingliang are < LLD - 1326 Bq-m-3, < LID - 4.7 EEC Bq-m-3 (indoors), and < LLD - 2.2 EEC Bq-m-3 (outdoors) , respectively. The annual effective dose from 220Rn and its progenies calculated using preliminary measurement results is 0.18 - 0.60mSv/a, being about 13.1 % - 55.6% of the total annual effective dose from 222Rn,220 Rn and their progenies. Rn and its progeny concentrations depend on the content of Th in soil.The main factors affecting Rn indoors arc the content of 232Th in the building materials and the 220Rn emanation rates. Conclusions 220Rn concentrations indoors and outdoors in China are higher than the average of the world which correlated with Th content in soil.