Radiological Health Engineering Laboratory, Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109-2104, USA.
Health Phys. 2011 Feb;100(2):138-47. doi: 10.1097/HP.0b013e3181edb807.
Radon in indoor air is often measured using activated charcoal in canisters. These are generally calibrated using large, humidity- and temperature-controlled radon chambers capable of maintaining a constant radon concentration over several days. Reliable and reproducible chambers are expensive and may be difficult to create and maintain. This study characterizes a small radon chamber in which Rn gas is allowed to build up over a period of several days for use in charcoal canister calibration and educational demonstrations, as well as various radon experiments using charcoal canisters. Predictive models have been developed that accurately describe radon gas kinetics in the charcoal canisters. Three models are available for kinetics in the small chamber with and without radon-adsorbing charcoal canisters. Presented here are both theoretical and semi-empirical applications of this equilibrium-based model of radon adsorption as applied to canisters in the small chamber. Several charcoal canister experiments in the small chamber with an equilibrium-based model of radon adsorption applied are reported. Results show that it is necessary to include a continuous radon monitor in the chamber during canister exposures, as the radon removal rate is highly variable. Furthermore, the presence of the canisters significantly decreases the amount of radon in the small chamber, especially when several canisters are present. It was found that canister response in the small chamber is largely consistent with the equilibrium-based model for both applications, with average errors of 1% for the theoretical application and -4% for the semi-empirical approach.
室内空气中的氡通常使用活性炭罐进行测量。这些通常使用大型、湿度和温度控制的氡室进行校准，这些氡室能够在几天内保持恒定的氡浓度。可靠且可重复的室昂贵，并且可能难以创建和维护。本研究描述了一个小型氡室，其中 Rn 气体允许在几天的时间内积累，用于活性炭罐校准和教育演示，以及使用活性炭罐进行各种氡实验。已经开发了预测模型，可以准确描述活性炭罐中的氡气体动力学。有三种模型可用于带有和不带有氡吸附活性炭罐的小型室中的动力学。本文介绍了这种基于平衡的氡吸附模型在小型室中应用于罐的理论和半经验应用。报道了在应用基于平衡的氡吸附模型的小型室中进行的几个活性炭罐实验。结果表明，在罐暴露期间，必须在室内连续监测氡，因为氡去除率变化很大。此外，罐的存在大大降低了小型室中的氡含量，尤其是当存在多个罐时。结果发现，小型室中罐的响应在两种应用中均与基于平衡的模型基本一致，理论应用的平均误差为 1%，半经验方法的平均误差为-4%。
