I. The Fukushima accident: reminders about a nuclear tragedy in Japan
On March 11, 2011, a magnitude 9.1 earthquake triggered a wave that reached a height of 30 meters on parts of Japan's eastern coast and spread up to ten kilometers inland. The wave reached the Fukushima-Daiichi nuclear power plant on the coast. At a height of 15 meters, it disables the cooling systems of the reactors and spent fuel storage pools. This led to nuclear fuel degradation and core meltdowns in 3 reactors, followed by hydrogen explosions. This was the second nuclear power plant disaster in history to be classified at level 7, the highest on the international scale of nuclear events. The Fukushima-Daiichi nuclear accident is at the same level of severity as the Chernobyl disaster in terms of radioactive releases, according to IRSN (Institut de Radioprotection et de Sûreté Nucléaire).
Since the accident, almost a million m3 of water contaminated with radioactive substances has been stored in a thousand tanks. This water comes from rain, groundwater or injections needed to cool the cores of the reactors that melted down after the tsunami. In 2020, the Japanese authorities announced that the storage capacity for this water would soon be saturated, and that it had to be disposed of. Moreover, this step is mandatory before the plant can be safely decontaminated and dismantled. But how to dispose of this radioactive and dangerous water with the least possible risk to the health and safety of the environment and the population?
II. The solution of discharging the water into the ocean
Among the solutions evaluated by the experts commissioned by the government, the choice of discharging the water into the sea was preferred to letting it evaporate or burying the tanks. As a result, over 1.3 million tonnes of radioactive water (equivalent to the contents of 500,000 Olympic-sized swimming pools) will be discharged into the Pacific Ocean. The water will be gradually released (maximum 500,000 liters per day) via an underwater tunnel 1km from the coast. Before being discharged into the sea, the contaminated water would be filtered, treated by a decontamination system that eliminates all radioactive elements except tritium, and diluted. Nevertheless, several fishermen, local farmers and NGOs opposed the decision, fearing the consequences for marine biodiversity and human populations. Some of Japan's neighbors, notably China and South Korea, also expressed reservations, concern and even condemnation of this solution, given its impact on the environment. But the Japanese authorities confirmed the plan in 2021. Then, on July 4, 2023, the solution received the green light from the International Atomic Energy Agency (IAEA), the United Nations' nuclear watchdog. The IAEA found that, despite the concerns it raised, the plan met international standards and that the impact on the population and the environment was "negligible". On Tuesday August 22, 2023, Japanese Prime Minister Fumio Kishida announced that the discharge of radioactive water into the ocean would begin on Thursday August 24, 2023. The government had declared the previous day that it had obtained a "certain degree of understanding" from fishermen. But some of them still fear the economic consequences of a possible boycott of their products by worried consumers.
III. International reactions to the Japanese plan
Japan once again tried to reassure its citizens and international opinion, especially its neighbors, that its solution would have less impact. Tests would be carried out on seawater after the spill. A Japanese official said that the first results could be available in early September. The country will also test fish in waters close to the plant and publish test results on the Ministry of Agriculture website. For its part, the IAEA has pledged to publish monitoring data "in real time and near real-time".
However, all these assurances were not enough to erase the doubts of neighboring countries. China, fiercely opposed to the plan, banned seafood imports from ten Japanese prefectures, including Fukushima and Tokyo, in July 2023. Products from other prefectures had to be tested for radioactivity. For Wang Wenbin, spokesman for Chinese diplomacy, "The ocean is the property of all mankind; it is not a place where Japan can arbitrarily dump contaminated water". John Lee, Hong Kong's Chief Executive, also announced on Tuesday that the territory would "immediately" apply restrictions on foodstuffs from Japan. On the South Korean side, the government had conducted a study which concluded, in July, that the release of water would have a negligible impact on its waters. It therefore declared that it would respect the IAEA's assessment. However, South Korean activists disagreed with this position and protested twice (on July 7 after the IAEA report, then on August 22, 2023 after Japan's announcement). Lastly, the Pacific island states are divided on the issue, fluctuating between concern and confidence in the IAEA report. Fiji's Prime Minister, for example, has publicly supported the report, while acknowledging that the issue is controversial.
Moreover, Japan's decision comes on the heels of the adoption of the International Treaty on the Protection of the High Seas. Adopted on June 19, 2023, this treaty aims to "ensure the conservation and sustainable use of marine biological diversity in international waters". The aim of the treaty is to achieve the objectives and targets relating to the oceans of the United Nations 2030 Agenda for Sustainable Development and the global framework for biodiversity set out in the Kunming-Montreal Convention, which came out of COP15. The question of whether Japan's actions are in line with these commitments and objectives could arise at an early stage. Japan is also a signatory to the 1994 Montego Bay Convention, which regulates international maritime law and makes the high seas a common heritage of mankind. It also contains provisions for the protection of biodiversity and biological resources, notably in article 119. Litigation before the International Tribunal for the Law of the Sea, a body created by the Convention, cannot be ruled out in the years to come.