基于土壤氡源的湿度可调控的氡室系统

摘要/Abstract

摘要： 氡是构成天然辐射本底的主要成分,是辐射环境监测的重要内容之一。利用已知标准氡活度浓度的氡室对氡测量仪器进行刻度校正和性能检验,是氡测量中质量保证的重要环节。氡室通常由标准镭源以及氡活度浓度和湿度可以稳定调控的箱体构成,其中放射性镭源的获取及安全管理,常常给氡室的制造和推广使用带来困难。本研究依据地表深层土壤中氡活度浓度高且长时间稳定的特性,研制出了一种基于土壤氡源的湿度可调控的简易氡室系统。该系统利用不同比例的土壤气体和空气混合,调节氡活度浓度;利用电除湿,在一定范围内调节湿度。实验结果表明,该套氡室系统氡活度浓度能够在826～5 852 Bq/m³范围内稳定调节,相对湿度能够在30.8%RH～70.6%RH范围内调节,氡活度浓度和湿度的稳定时间都能超过40小时。该氡室系统摆脱了镭源的限制,简单且易于实现,能够应用于测氡仪标定或检验实验,服务于教学和科研,有望推广应用于测氡仪的比对和质量控制。

关键词: 氡室, 氡气体, 土壤氡, 湿度调控, 氡活度浓度调控

Abstract: Radon is the major components of the natural radiation background, and radon measurement is important for radiation environmental monitoring. Radon chamber, used for the calibration and performance check of radon monitors, plays an important role during the procedure of quality control for radon measurement. Conventional radon chamber generally consists of standard radium sources and volume for controlling radon concentration and humidity. While permission and safety management of standard radium source make conventional radon chambers difficult to develop and widely use. On the basis of the characteristics of soil gas which has high and stable radon concentration, a humidity controllable radon chamber system based on soil-radon is designed and constructed. This radon chamber system realizes the control of radon concentration by mixing air with soil gas in different fraction, and that of humidity by refrigeration type dryer. The research of radon chamber system made by Peking University shows the radon concentration and relative humidity can be controlled from 826-5 852 Bq/m³, and 30.8%-70.6%, respectively, and both of them can be stable for over 40 hours. This radon system gets rid of the limitation of radium sources, and is easy to be constructed and realized. It provides a possible way for in-situ calibration for radon monitors and can be widely used on quality control for radon measurement.

Key words: radon chamber, radon gas, radon in soil, humidity control, radon concentration control

中图分类号:

X859

茅钰才, 王云祥, 张磊, 郭秋菊. 基于土壤氡源的湿度可调控的氡室系统[J]. 辐射防护, 2020, 40(5): 402-407.

MAO Yucai, WANG Yunxiang, ZHANG Lei, GUO Qiuju. Study on a humidity controllable radon chamber system based on soil-radon[J]. RADIATION PROTECTION, 2020, 40(5): 402-407.

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