Measurement of uranium, radium and radon concentration in ground water sampled over Hiroshima prefecture, Japan

A new method to measure the concentration of uranium and radium in ground water has been developed. One-liter of ground water was evaporated on a Teflon sheet and measured with a low background Ge detector. According to the decay of 238U, radio equilibrium has been achieved between 238U and progeny 234Th after about 150 days. 238U concentration can be determined from the gamma-ray measurement of the dry up sample. Ground water samples were collected from 58 locations in Hiroshima prefecture. Radon concentration was measured directly from the 250 mL water sample. It has been shown that dependence of uranium, radium and radon concentration on the geological map in Hiroshima prefecture. A clear correlation was observed between uranium and radium concentration, but not between uranium and radon concentration. (author)