An Activated Charcoal-based, Liquid Scintillation - Analyzed Airborne Rn Detector

Abstract

An inexpensive, easy-to-use detector for measuring airborne 222Rn based on 222Rn diffusion and absorption in activated charcoal is presented. The detector uses chemical extraction and liquid scintillation for measurement of the 222Rn concentration, is designed to be insensitive to temperature and humidity effects, and obtains sensitivity levels of 675 CPM (Bq L-1)-1 [25 CPM (pCi L-1)-1] at room temperature.

Application of activated charcoal radon collectors in high humidity environments

“…In other words, the moisture take-up by activated charcoal has been shown to result in the displacement of radon and a lowered count rate (Schroeder et al, 1989). In order to overcome this problem, ST-100 installs a few grams of desiccant with the granular activated charcoal in the vial.…”

“…A user of the ST-100 needs to decide whether a specific level of estimation error based on a reduction of sensitivity would be acceptable for specific research purposes; this should be done by comparing it with other levels of estimation errors. For example, a change in sensitivity of ACRC could be caused by a large difference in environmental temperature (George and Weber, 1990;Schroeder et al, 1989).…”

“…In this range of environmental conditions, this collection method shows sufficient reliability for the estimation of the radon concentration. However when ACRC are used in extremely high humidity environments, the adsorption of radon changes significantly (Wilson, 1989;Schroeder et al, 1989;Scarpitta, 1990). Therefore, in some cases, data correction would be necessary.…”

Temperature calibration formula for activated charcoal radon collectors

“…PicoRad detectors are simple commercially available activated charcoal radon collectors that are particularly suitable for short-term radon assessment in dwellings and workplaces (WHO, 2009). In contrast with previous charcoal canisters (George, 1984;Cohen and Cohen, 1986) which required g-spectroscopy measurements, PicoRad detectors make use of the liquid scintillation counting method (Prichard and Marien, 1985;Schoreder et al, 1989) to estimate the adsorbed radon activity. It offers numerous advantages such as less charcoal needed (3 g), a lower determination limit (<5 Bq m À3 ) (Bem et al, 1999), a shorter collection time (<48 h), and possibilities for repeated and automatized scintillation measurements.…”

Development of a technique for the measurement of the radon exhalation rate using an activated charcoal collector

“…A combination of an activated charcoal tool and a liquid scintillation counting system (Schroeder et al, 1989) has also been used for radon measurements in air. The internal radon concentration in the cuvette could be evaluated by this combination.…”