重庆雪玉洞氡浓度变化特征及其危害防护

Variation characteristics of the radon's concentration and protection to the harm in the Xueyu cave,Chongqing

利用PRM-2100氡子体监测仪对重庆市丰都县雪玉洞氡子体平衡当量浓度进行连续12个月的监测。研究表明:(1)雪玉洞洞内氡子体平均平衡当量浓度为2 135.7Bq/m3;取平衡因子为0.5,则其平均氡浓度为4 271.4Bq/m3;(2)氡子体平衡当量浓度总体呈现出夏季高、冬季低及洞层越高,浓度越高的特点,而且氡子体平衡当量浓度变化与洞内温度变化相关性不明显,但与洞外的相关性则较强;(3)雪玉洞游客因吸入氡子体所致的年均有效剂量当量为0.02mSv/a,只是联合国原子辐射效应科学委员会(UNSCEAR)估计的氡子体对公众产生危害的年有效剂量界限值(1.30mSv/a)的1.54%,因此短时间游览对游客的健康不会产生影响。但是,由于洞穴讲解员、保安、拍照人员在洞内工作时间较长,接受氡子体照射的年均有效剂量当量分别为7.69mSv/a、11.96mSv/a、59.48mSv/a,均高于UNSCEAR的年有效剂量。因此,需要合理安排洞穴内工作人员工作时间和科学地制订出他们的年工作时间上限;加强氡危害相关知识的普及与洞穴工作人员的个人防护;在高氡浓度析出区域进行屏蔽防护或在适当位置安装空气净化器;与此同时,还要加强氡及其子体浓度的分析和监测等。

PRM-2100 （Radon RAE Progeny）is used to measure the equivalently effective concentration （EECRn ）of radon’s daughter in the Xueyu cave for 12 months.The average EECRn is 2 135.7 Bq/m3 .Take the balance factor as 0.5,the average concentration of radon in the Xueyu cave is 4 271.4 Bq/m3 .The EECRn is higher in summer and lower in winter.The EECRn in each layer is different,the higher the layer,the high-er the EECRn .The outside temperature can affect the EECRn ’s distribution in cave environment.The effec-tive dose there to tourists is only 0.02 mSv/a,only amount to 1.54 % of the threshold value （1.30 mSv/a） estimated by the United Nations Scientific Committee on the Effects of Atomic Radiation （UNSCEAR）,so it is unharmful dose to the public and will not affect the health of tourists.The effective dose for tourist guides,security guards and photographer is 7.69 mSv/a,1 1.96 mSv/a,59.48 mSv/a respectively,which are higher than the UNSCEAR estimated annual effective dose to the public.These effective doses should be received sufficient attention.The protection measures for tourism caves include reasonable arrangement for staff working hours and annual maximum working hours in the cave,popularization the knowledge about ra-don hazards and enhance the awareness of self-protection for the cave staff.In the high radon concentration area,shield protection or air purifier at appropriate position should be installed,and at the same time the a-nalysis and monitor to the concentration of radon and its progeny should be strengthened.