Abstract
It has been confirmed that, in the measurement of radon-in-water using liquid scintillation counting, the direct method is preferred to the extraction method, since the former is simple technique. With a counting time of 60 minutes, the minimum detectable radon concentration by the extraction method and the direct method were found to be 0.03 Bq/kg and 1 Bq/kg, respectively. The minimum detectable radon concentration of 1 Bq/kg attained by the direct method is sufficient to check the radon concentration in drinking water below the Maximum Contaminant Level (11.1 Bq/L) proposed by the U. S. Environmental Protection Agency. The total net counting rates were estimated by the zero level extrapolating method. The optimized window values of the 3 efficiency tracing points were 50 keV - ∞, 75 keV - ∞ and 100 keV - ∞. The efficiency tracing method has been proved useful with LSCs that are currently available in Japan.
