A study on natural absorbed dose rate in air (using TLDs) and concentration of natural radionuclides in soil in all area of the Osaka Pref

Absorbed dose rates in air at 40 sites throughout Osaka Pref. were measured by TLDs and a relationship between the dose rates and the rates estimated from concentrations of natural radionuclides in the surface soils collected at the sites was studied. The highest and lowest values of air absorbed dose rates obtained in Osaka Pref. were 114.1±1.0, 66.3±2.3 nGy/h, respectively, and the former value was obtained at granite zone and the latter at andesite zone. It was found that soil particles smaller than 10 mesh contribute to the dose rate more significantly than those larger than 10 mesh. We found a fairly good correlation between the dose rates and the concentrations of 40K in the surface at the sites. (author)