Measurement of radon-222 in aqueous samples by decay product filtration

An apparatus has been developed for measuring 222Rn content in aqueous samples based on the filtration of the radon decay products from a flow of helium gas circulating through the water sample in a closed cycle. This system has an advantage over the current method of measuring 222Rn in its ease of operation: no sample preparation is necessary; operators require no special training; and the apparatus is compact and portable. Although the sensitivity of the method cannot compete with those predominantly in use, it is sufficient to measure concentrations encountered in inland waters and coastal oceanic areas. Some preliminary measurements from the Sea of Galilee and the Dead Sea are presented. (author)