Precipitation washout of tritiated water vapor from a nuclear reactor

Tritiated water vapor from a nuclear power plant is continuously released to the atmosphere and then scavenged by precipitation. Tritium concentrations above the natural level are often observed both in water vapor and in rainwater in the vicinity of a reactor site. In this paper, the washout coefficient of tritium and the validity of the calculation model are studied. The washout coefficient was calculated to be 7.3 × 10−5 s−1 from a rainfall intensity of 2 mm h−1, based on the washout model and concentrations of anthropogenic tritium in water at the Tsuruga site. The validity of the washout coefficient was confirmed by comparing it with the values from two other sites, the Mihama and Ooi sites that have similar meteorological parameters to the Tsuruga site.