Temperature calibration formula for activated charcoal radon collectors

• Published in: Journal of environmental radioactivity 2011, Vol.102 (1), p.60-63
• Main Authors: Cooper, Alexandre, Le, Thiem Ngoc, Iimoto, Takeshi, Kosako, Toshiso
• Format: Article
• Language: English
• Subjects: Accumulators; Activated carbon; Activated charcoal collectors; Adsorption; Algorithms; Analysis methods; Applied sciences; Atmospheric pollution; Calibration; Calibration experiment; Charcoal - chemistry; Collectors; Conversion factor; Exact sciences and technology; Mathematical models; PicoRad detectors; Pollution; Radiation Monitoring; Radioactivity; Radon; Radon - analysis; Radon - chemistry; Radon gas; Relative humidity; Temperature; Temperature effect
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/j.jenvrad.2010.09.004

Radon adsorption by activated charcoal collectors such as PicoRad radon detectors is known to be largely affected by temperature and relative humidity. Quantitative models are, however, still needed for accurate radon estimation in a variable environment. Here we introduce a temperature calibration formula based on the gas adsorption theory to evaluate the radon concentration in air from the average temperature, collection time, and liquid scintillation count rate. On the basis of calibration experiments done by using the 25 m 3 radon chamber available at the National Institute of Radiological Sciences in Japan, we found that the radon adsorption efficiency may vary up to a factor of two for temperatures typical of indoor conditions. We expect our results to be useful for establishing standardized protocols for optimized radon assessment in dwellings and workplaces. ► The temperature effect on radon adsorption is proportional to α e β / T . ► The calibration formula is C F ( T , t ) = 3.1 × 10 − 5 e 2887 ( T + 273 ) [ 1 − e − 0.080 t ] . ► The radon adsorption efficiency varies up to a factor of two for T = 8.5–31 °C. ► The average temperature is suitable for estimating CF(T,t) in a fluctuating environment.