Investigation of atmospheric tritiated water vapor level around the Fukushima Daiichi nuclear power plant

Continuous measurement of tritium in the atmosphere is important to evaluate the environmental impact of nuclear facilities and fusion facilities as well as to elucidate tritium behavior in the environment. A passive type sampler is powerful tool to conduct long-term monitoring because this does not require any power supply. This paper demonstrated the effectiveness of the passive type sampler for continuous measurement and characterized temporal variation of atmospheric concentration of tritiated water vapor around the Fukushima Daiichi nuclear power plant. The atmospheric concentrations were successfully obtained at two sampling sites and ranged within the variation in past observation although the concentration at one of the two sites was slightly higher than that of background level in Japan. Additionally, we measured the tritium concentrations of soil pore water and free water in pine needles. These values indicated the validity of the measured atmospheric tritium concentrations.