ANALYSIS OF THE PERFORMANCE OF A RADON MITIGATION SYSTEM BASED ON CHARCOAL BEDS

The performance of a commercially available radon mitigation system based on adsorption of radon onto charcoal beds (RAdsorb system) combined with an electronic air cleaner (EAC) installed in a single family house in Massachusetts has been studied. Semi-continuous measurements were made of the radon ps concentration, potential alpha energy concentration (PAEC), and radon decay product activity-weighted size distribution with and without additional operating aerosol sources. An automated, semi continuous graded screen array (ASC-GSA) system was utilized for the measurement of the activity-weighted size distribution. During the tests without the mitigation system in operation, the conditions in the basement of the house were as follow: the radon concentrations were in the range of 600 to 800 Bq m-3, the Potential Alpha Energy Concentration (PAEC) was 600 to 700 nJ m-3, the particle concentration was below 1000 cm-3, and the fraction of PAEC and Po-218 in the smallest size range, 0.5-1.6 nm were approximately 0.6 and 0.9, respectively. The tests were designed to study the influence on the measured parameters of the combined mitigation system as well as each of the separate components: fan, charcoal bed, and EAC. When all the components of the mitigation system were operating, the radon concentration was below 150 Bq m-3 and the PAEC was below 104 nJ m-3 with the smallest sized fraction of PAEC (0.5-1.6 nm) of about 0.4. The tests showed that under certain conditions, the charcoal bed/EAC mitigation systems can be a potentially valuable technique for reducing a health risk due to indoor radon.