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通过对我国五个地区的37个地下工程的空气离子环境和氡水平的测试及试验研究表明;投入正常使用的地下工程,特别是人员较多的掩土工程空气离子环境较差,空气负离子浓度的均值只有201个/cm~3,单极性系数均值高达2.0。大气尘,水分子团等空气中悬浮的凝结核均是空气离子的消失因素,通风空调系统与设备也消耗大量的空气离子。地下工程中氧及其子体虽然是空气离子的产生因素,但由于较高的氡水平对人体有害,必须按“放射卫生标准”使之保持在一定的水平之下。文中给出了空气负离子浓度、氧浓度和含尘量间关系的回归曲线,提出了改善地下工程空气离子环境的有效措施是:降低空气中含尘量和湿度,并适当安装空气负离子发生器。地下工程中氧水平一般比地面室内高一个数量级以上,地下工程中工作人员因吸入氡子体所致剂量限值应为3msv,氡子体导出空气浓度应为93Bq/m~3,在所测使用地下工程中超出此标准的工程占54%,工作人员因吸入氡子体所致年有效剂量均值为3.92msv,是限值(3msv)的131%。地下工程中降低氡水平的经济有效措施是通风换气,文中给出了估算氡平均析出率和防氡通风率的简单、易行、实用的方法,并编制了地下工程防氡通风率估算表。
Through testing and experiment on air ion environment and radon level in 37 underground projects in five regions of our country, it shows that underground engineering with normal use, especially with more personnel, has worse air ion environment, negative air ion concentration The average value of only 201 / cm ~ 3, unipolar coefficient average up to 2.0. Atmospheric dust, water molecules and other suspended nucleus in the air are the disappearance of air ions, ventilation and air conditioning systems and equipment also consume large amounts of air ions. Although the oxygen and its daughters in the underground project are the production factors of air ions, they must be kept under a certain level according to the “Radiation Health Standard” due to the high radon level being harmful to the human body. In this paper, the regression curves of the relationship between air anion concentration, oxygen concentration and dust content are given, and the effective measures to improve the air ion environment in underground engineering are: to reduce the dust content and humidity in the air, and to properly install the air anion generator. The level of oxygen in underground engineering is generally more than one order of magnitude higher than that in the ground. The dose limit for underground engineering due to inhalation of radon progeny should be 3 Gy. The concentration of radon-derived air should be 93 Bq / m 3. 54% of the projects using underground engineering exceeded this standard, and the annual effective dose due to inhalation of radon progeny was 3.92msv, which is 131% of the limit (3msv). The cost-effective measure to reduce the level of radon in underground works is ventilation. The simple, easy and practical method to estimate radon average radon rate and radon radon rate is given in this paper. .