Radiation safety assurance for the population of the Far Eastern regions of the Russian Federation under conditions of long-term discharge of water from the Fukushima–1 NPP

In connection with the planned prolonged discharge of tritium-containing water from the Fukushima Daiichi Nuclear Power Plant, a gradual increase in tritium concentrations is expected in the coastal waters of the Far Eastern regions of the Russian Federation. The aim of this study is to improve the methods for ensuring the radiation safety of the population under conditions of long-term discharge of radioactive water from the Fukushima Daiichi Nuclear Power Plant based on numerical modeling of ocean current circulation. Materials and Methods : Seawater samples from the coastal areas of Kamchatka, Primorsky, and Khabarovsk Krais, Magadan and Sakhalin Oblasts, and the Chukotka Autonomous Okrug for the period 2023–2025 were used for the analysis of tritium content. Lagrangian models accounting for the spatiotemporal structure of oceanic circulation and currents were employed to describe tritium transport processes. Results and Discussion : The mean values of tritium specific activity in samples collected at distances of up to 1000 m from the shore were shown to range from less than 1.0 Bq/kg to 5.5 Bq/kg. Numerical modeling revealed potential accumulation zones for tritium discharged with treated water from the Fukushima Daiichi Nuclear Power Plant: the Southern Kuril Islands, Sakhalin Island, the southern tip of the Kamchatka Peninsula, and Bering Island. The East Kamchatka Current forms a dynamic barrier along the eastern coast of Kamchatka, limiting the intrusion of contaminated waters into coastal areas. Conclusion : To organize effective long-term monitoring of tritium in seawater and, subsequently, in seafood, it is necessary to refine the areas of the most likely tritium accumulation in the waters of the Russian Far East.