2015 Volume 64 Issue 9 Pages 553-561
Hydrogen explosion occurred at Fukushima Dai-ichi nuclear power plants in Japan on 12―15th March, 2011. At the same time, lots of radioactive materials have been released including tritium(T), and caused serious environmental impacts. In order to investigate the effect of the accident of Fukushima Dai-ichi nuclear power plant on environment, we collected the short precipitation(hourly collected precipitation) and spring water for several years after the accident. As to the precipitation collected, T and radiocaesium were measured by using liquid scintillation counter and high-purity germanium detector, respectively. Furthermore, we also measured the concentration of ions(Na＋, Cl－, Ca2＋, and SO42－) in spring water. From the above-mentioned matters, the following points have been obtained:(1)The variation of T concentration in recent three years(2012, 2013 and 2014) can be clarified. (2)The effect of the accident on spring water in mountains around the Fukushima prefecture is so small. (3)As to the short precipitation on 15th March, 2011, the activity of radiocaesium was not detected, but the activity of T was detected significantly.