Explained | Japan’s decision to flush Fukushima wastewater into the ocean Premium

Japan plans to start flushing 1.2 million tonnes of water from the embattled nuclear power plant into the Pacific Ocean from this year.

Japan is expected to start flushing 1.25 million tonnes of wastewater from the embattled Fukushima nuclear power plant into the Pacific Ocean this year, as part of a $76-billion project to decommission the facility. The project received the Japanese cabinet’s approval in 2021 and could take three decades to complete. The idea, which experts and officials in Japan had floated in 2016, has been controversial for its suspected impact on the water, marine life, fishers’ livelihoods and other countries in the area. It has also received flak within Japan for sidelining other options and stoked concerns about the government’s sincerity.

In March 2011, after a magnitude 9 earthquake, a tsunami flooded the Fukushima Daiichi nuclear power plant in Okuma and damaged its diesel generators. The loss of power suspended coolant supply to reactors at the facility; the tsunami also disabled backup systems.

Soon, radioactive materials leaked from reactor pressure vessels, exploded in the facility’s upper levels, and exposed themselves to the ambient air, water, soil, and local population. Winds also carried radioactive material thrown up into the air into the Pacific. Since then, the power plant and its surrounding land have been uninhabitable.

The water that the Japanese government wants to flush from the plant was used to cool the reactors, plus rainwater and groundwater. It contains radioactive isotopes from the damaged reactors and is thus itself radioactive. Japan has said that it will release this water into the Pacific Ocean over the next 30 years.

The Tokyo Electric Power Company (TEPCO), which operates the Fukushima facility, has said it has treated the water to remove most radioactive isotopes; former Prime Minister Yoshihide Suga added in 2021 that the water will be “far above safety standards”. His government required the water to have 1/40th as much tritium as the permitted limit.

Officials have defended the plan saying TEPCO is running out of room for the water-tanks and that nuclear plants around the world regularly release water containing trace amounts of radionuclides into large waterbodies.

However: “There is no known threshold below which radiation can be considered safe,” M.V. Ramana, the Simons Chair in Disarmament, Global and Human Security at the University of British Columbia, Vancouver, told The Hindu. “[A]ny discharge of radioactive materials will increase the risk of cancer and other known health impacts to those who are exposed.”