Technical guidance on safe installation of a GAC filter used for removing radon from water

Abstract

Publisher Summary A GAC filter may be operational for years. The continuous radioactive decay of radon and its short-lived daughter products in the filter will also result in the accumulation of lead ( 210 Pb) and polonium ( 210 Po). Some ground waters contain radiologically important concentrations of radon ( 222 Rn). During the past few years, the use of granular activated carbon (GAC) filters for removing radon from water has rapidly increased in Finland. However, in many cases the risks related to external gamma radiation originating from the filter during its use are not appropriately considered. In some cases, the filter has caused significant dose rates in the living areas of a home. It was decided to prepare technical guidance on installing a GAC filter in a safe manner. Radiological criteria for gamma dose were established and used for deriving design parameters regarding appropriate shielding and safety distances. Because of the related risks, however, today it is recommended that GAC filters should not be installed in homes. The only exception is installations that do not require any specific considerations concerning external gamma radiation, for example, cases where the filter is placed underground into a well.