International law obligations for the disposal of Fukushima nuclear-contaminated water under the principles of nuclear safety

The disposal of contaminated water from Japan's Fukushima nuclear power plant is a significant international nuclear safety issue with considerable cross-border implications. This matter requires compliance not only with the law of the sea but also with the principles of nuclear safety under international law. These principles serve as the overarching tenet of international and China's domestic nuclear laws, applicable to nuclear facilities and activities. The principle of safety in nuclear activities is fully recognized in international and domestic laws, carrying broad legal binding force. Japan's discharge of nuclear-contaminated water into the sea violates its obligations under the principle of safety in nuclear activities, including commitments to optimum protection, as low as reasonably practicable, and prevention. The Japanese government and the International Atomic Energy Agency (IAEA) have breached the obligation of optimum protection by restricting the scope of assessments, substituting core concepts, and shielding dissenting views. In the absence of clear radiation standards, they have acted unilaterally without fulfilling the obligation as low as reasonably practicable principle. The discharge of Fukushima nuclear-contaminated water poses an imminent and unpredictable risk to all countries worldwide, including Japanese residents. Japan and the IAEA should fulfill their obligations under international law regarding disposal, adhering to the principles of nuclear safety, including optimum protection, the obligation as low as reasonably practicable, and prevention through multilateral cooperation. Specifically, the obligation to provide optimum protection should be implemented by re-evaluating the most reliable disposal technologies and methods currently available and comprehensively assessing various options. The standard of the obligation as low as reasonably practicable requires that the minimization of negative impacts on human health, livelihoods, and the environment should not be subordinated to considerations of cutting costs and expenses. Multilateral cooperation should be promoted through the establishment of sound multilateral long-term monitoring mechanisms for the discharge of nuclear-contaminated water, notification and consultation obligations, and periodic assessments. These obligations under international law were fulfilled after the accidents at the Three Mile Island and Chernobyl nuclear power plants. The implications of the principles of nuclear safety align with the concept of building a community of shared future for nuclear safety advocated by China. In cases of violations of international law regarding the disposal of nuclear-contaminated water that jeopardize the concept of a community of a shared future for nuclear safety, China can also rely on its own strength to promote the implementation of due obligations through self-help.