某铀矿环境空气中^(220)Rn水平调查

Investigation of ^(220)Rn activity concentration in the surrounding region of a uranium mine

为了解某铀矿环境中^(220)Rn活度浓度水平及特征,采用RAD7测氡仪对该铀矿区周边环境空气中^(222)Rn和^(220)Rn活度浓度水平进行了调查,对土壤中^(232)Th比活度与空气中^(220)Rn活度浓度的相关性及其影响因素进行了探讨,并对公众受照剂量进行了估算。调查结果表明,调查区环境空气中^(220)Rn活度浓度属正常天然本底水平,其频数分布类型为偏态,且近八成测量点处^(220)Rn活度浓度大于^(222)Rn活度浓度;野外环境空气中^(220)Rn及子体活度浓度主要受土壤中^(232)Th比活度和季节因素影响;调查区环境空气中^(220)Rn及子体所致剂量占总氡剂量的比例为近20%,应给予关注。

To investigate the level of thoron（220Rn）concentration and its characteristics,the concentration of radon（222 Rn）and 220 Rn outdoor were measured using radon monitor named RAD7 in the surrounding region of a uranium mine.The main factors affecting the concentration of 220 Rn and its progeny at outdoor were discussed,and the annual effective dose from 222 Rn and 220 Rn to the residents living around the uranium mine was estimated too.The findings show that the 220 Rn concentration in the survey areas is at natural background leve1,its frequency distribution type shows skewness,and 220 Rn concentration is greater than 222 Rn concentration at nearly eighty per cent monitoring sites.The concentration of 220 Rn and its progeny at outdoor is mainly affected by the specific activity of the natural radionuclide 232 Th in soil and the seasonal factors.The annual effective dose from 220 Rn and its progeny accounts for about 20%of that from 222 Rn,220 Rn and their progenies in the survey areas,and so effective dose from220 Rn can not be ignored.