A method for measuring accurate radon concentration in water by means of γ-ray spectrometry

Simple and accurate methods for the determination of radon concentration in water have been developed. Sample water collected in a 100 ml Teflon vial was directly measured with a low-background Ge spectrometer and the radon concentration was derived from the γ-ray measurement of radon daughter nuclides on the assumption that radon and daughter nuclides were in a radioactive equilibrium. γ-ray spectrometry incorporated with a solvent extraction method was applied to water with low-level radon concentration. The lower detection limits (3σ) were 1.3 Bql−1 for the γ-direct method, and 0.25 Bql−1 for the extraction method. Applications to the ground water and tap water are given.