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

The performance of a commercially available radon mitigation system ba sed on adsorption of radon onto charcoal beds (RAdsorb system) combine d with an electronic air cleaner (EAC) installed in a single family ho use in Massachusetts has been studied. Semi-continuous measurements we re made of the radon ps concentration, potential alpha energy concentr ation (PAEC), and radon decay product activity-weighted size distribut ion with and without additional operating aerosol sources. An automate d, semi continuous graded screen array (ASC-GSA) system was utilized f or the measurement of the activity-weighted size distribution. During the tests without the mitigation system in operation, the conditions i n the basement of the house were as follow: the radon concentrations w ere in the range of 600 to 800 Bq m-3, the Potential Alpha Energy Conc entration (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. T he tests were designed to study the influence on the measured paramete rs of the combined mitigation system as well as each of the separate c omponents: fan, charcoal bed, and EAC. When all the components of the mitigation system were operating, the radon concentration was below 15 0 Bq m-3 and the PAEC was below 104 nJ m-3 with the smallest sized fra ction of PAEC (0.5-1.6 nm) of about 0.4. The tests showed that under c ertain conditions, the charcoal bed/EAC mitigation systems can be a po tentially valuable technique for reducing a health risk due to indoor radon.