International Wrongfulness of Japan's NCW Sea Discharge

When the Fukushima nuclear power plant in Japan experienced a significant accident in 2011, a significant volume of nuclear-contaminated water (NCW) was produced throughout the accident treatment procedure. The Japanese government decided to release 1.25 million tons of NCW into the ocean from storage tanks on April 13, 2021. On August 4, 2023, Japan formally initiated the discharge of NCW into the sea. Japan's discharge of NCW is closely related to the protection of marine ecology and human health and safety, and this move has triggered major concerns and strong dissatisfaction among various stakeholder countries. In terms of the details of the decision process related to TEPCO's discharge program announced by the Japanese government, the Japanese government is suspected of violating relevant international law obligations. In this paper, we will identify the international treaties, principles of international law, and international customary law that can regulate Japan's discharge of NCW from the sources of international law, and analyze the jurisprudence of international law related to nuclear accidents to determine the illegality of Japan's discharge of NCW into the sea.