Studies on radioactivity in hot spring water by in-situ γ spectrometry

A new method was developed to determine the radioactive nuclides in hot spring water. A high-resolution gamma-ray spectrometry can be made by dipping a Ge (Li) detector covered with a long neck probe into the water sample. From the height variations of some special peaks in γ spectra with time, informations as to radioactive disequilibrium in the sample could be obtained as shown in the experimental data for ''Tatsunokuchi'' hot spring water. Even in the background γ radiation from surface soil and others, the content of radon in water sample could be estimated from the γ ray peaks of the daughter nuclides of radon in a radioactive equilibrium. This could be made either by plotting various data in a figure (two methods was proposed) or by the calculation based on the selfabsorption and the geometrical counting efficiency of each γ ray. The application of this method was made for several hot springs and other natural water samples, and the results are reported in this paper. (auth.)