湖南省煤渣砖建筑物内及含镭量较高矿区周围室内、外氡浓度的调查研究

INVESTIGATION ON LEVELS OF RADON IN BUILDINGS MADE OF CINDER BRICKS OR IN MINERAL REGIONS

用 CSR 固体径迹探测器调查了湖南省典型煤渣砖建筑物内及铀矿和含镭量较高的煤矿周围居民点室内、外的年平均氡浓度。用驻极体收集积分测氡法测量了建筑物内不同位置和室外离地面不同高度处的氡浓度。估算了湖南省煤渣砖建筑物对居民产生的附加剂量。本文主要介绍这些调查研究的方法和结果,所得主要结果如下:(1)普通建筑物内氡年平均浓度 C_(Rn)为15.6Bq·m^(-3);A、B 和 C三类煤渣砖建筑物内 C_(Rn)分别为28.5、31.6和71.1Bq·m^(-3);辰溪煤矿(包括电厂)和二铀矿周围居民点室内 C_(Rn)依次为36.1和43.4、85.6Bq·m^(-3)。(2)室外氡浓度随离地面高度 h 增加而下降,h=1.5m 处(呼吸带高度)的氡浓度约为3m 高处的1.6倍;室内中央氡浓度亦随 h 增加而下降,通常人们睡觉时头部位置的氡浓度较高。(3)居住在普通建筑物的居民,室内、外年有效剂量当量之和为1.6mSv,其中吸入氡子体所致1.1mSv,为γ外照射所致0.5mSv 的2.2倍;居住在煤渣砖房居民吸入氡子体所致附加年有效剂量当量平均为1.6mSv,为γ外照射所致1.0mSv的1.6倍。湖南省14家煤渣砖厂和24家石煤碳化砖厂每年生产的砖和投产以来所生产的砖对居民产生的附加年集体有效剂量当量分别为45和360人·Sv。

Concentrations of radon and its daughters in typical houses made of different kinds of bricksand in uranium or coal mining regions in Hunan province were investigated with CSR track detector.The measured annual average concentration C_(Rn) in normal houses was 15.6Bqm^(-3),in A,B and Ccategory cinder brick made buildings 28.5,31.6 and 71.1Bqm^(-3) respectively,in dwellings aroundChenxi coal mine(including power plant)and two uranium mines 36.1,43.4 and 85.6Bqm^(-3),respectively.Outdoor radon concentration decreased with increasing height,h,from the ground.TheRn concentration at h=1.5m was 1.6 times of that at h=3m.The Rn concentration at the centre ofa room was also decreasing with increasing height from the ground.The Rn concentration at theposition of heads of sleeping people(near the wall)was 1.6—2.9 times of that just below the ceiling.The annual effective dose to residents of normal houses was 1.6mSv, of which 1.1mSv was frominhalation of Rn daughters,2.2 times of that from γ external exposure(0.5mSv).The additionalaverage annual effective dose equivalent to residents in cinder brick made buildings from inhalation ofRn daughters was 1.6mSv,1.6 times of that from γ external exposure(1.0mSv).The annualproducts of 38 coal cinder brick mills in Hunan caused a additional effective dose equivalent of 45man·Sv,and their total products from commissioning 360 man·Sv.