Background radiation in the production area of hokutolite in Taiwan

In this study, measurements were carried out for gross α/β activities, radium-isotope and tritium activities in water, major naturally occurring radionuclides in soil, sludge and plants, and radon-isotope activities in air. The ambient dose rate, effective dose rate, direct radiation dose from surface of the ground as well as the annual effective dose to the public was estimated. Gross α/β activities detected in hot spring water indicated that the hot spring water is undrinkable in this area. Gamma activity in water was mainly from daughters of 228Ra and 226Ra, which decreased downstream the Beitou Creek. The activity of 3H was lower than the minimum detectable activity (MDA) at the sampling sites. The 7Be and 137Cs were rare in soil. Potassium-40 was measured in sludge, and 7Be and 4 K were found in plants. Cobalt-60 was <MDA in soil, sludge and plants in this area. The derived absorbed dose rate and estimated effective dose rate were similar to average global levels. Activity concentrations of 238U and 232Th in soil were both maximum in the production region of hokutolite due to precipitation of these radionuclides. Sludge activity for 238U and 232Th were both highest in the Geothermal Valley. The contribution of terrestrial sources to effective dose rate was highest around the production region of hokutolite. Direct radiation dose was around the level of 10−10 μSv/h. Annual effective dose was estimated lower than 0.088 ± 0.013 mSv/year. Directly measure...
Source: Radiation Physics and Chemistry - Category: Physics Source Type: research