Survey of the natural radionuclides concentrations using a car-borne survey method

摘要

In 1992-1996, we estimated the environmental radiation dose rates and the natural radionuclides concentrations in soil Tokai area in central Japan using a car-borne survey method. In this paper, the distribution and the variation of natural radionuclides (potassium, uranium and thorium) concentrations were described, because the natural radiation dose rates were reported in the former paper. In this survey, all concentrations of potassium, uranium and thorium were highest in Gifu Prefecture, followed by Mie Prefecture and Aichi Prefecture, and the variation of radionuclide concentration due to region was observed. And, from the correlation analysis between concentration of natural radionuclides and absorbed dose rates in air due to γ-ray, it was shown that potassium and thorium have greatly contributed to dose rates in air, and among concentrations of potassium, uranium and thorium, strong correlation was shown between potassium and thorium. Lastly, we showed results of correlation analysis between terrestrial γ-ray dose rates obtained from this survey and annual mean radon concentration obtained by other researchers.