Japan has started to discharge treated radioactive water from its crippled Fukushima nuclear plant into the Pacific Ocean, despite strong opposition from neighboring countries and environmental groups.
The move comes 12 years after a massive earthquake and tsunami triggered a nuclear meltdown at the plant, which resulted in large amounts of contaminated water being stored in tanks.

Japan says it has no choice but to release the water, which has been treated to remove most of the radioactive elements, except for tritium, a form of hydrogen that is hard to separate.
The International Atomic Energy Agency (IAEA) has endorsed Japan’s plan and said the water poses no significant risk to human health or the environment.
However, China, South Korea and Taiwan have condemned the decision and imposed bans on Japanese seafood imports, while local fishermen and activists have staged protests in Japan.
What is in the water and how is it treated?
The Fukushima Daiichi nuclear power plant suffered a triple meltdown in March 2011, when a 9.0-magnitude earthquake and a 15-meter tsunami knocked out its cooling systems.
Since then, the plant operator, Tokyo Electric Power Company (Tepco), has been pumping in water to cool down the reactors’ fuel rods, which are still hot and radioactive.
This water becomes contaminated with radioactive material and needs to be stored in tanks on site. The plant currently has more than 1,000 tanks, holding enough water to fill over 500 Olympic-sized swimming pools.
Tepco says it will run out of space for the tanks by next year, and that it needs the land to build new facilities to decommission the plant safely.
The water is treated by a system called ALPS (Advanced Liquid Processing System), which removes 62 types of radioactive elements, including cesium, strontium and plutonium.
However, it cannot remove tritium, a radioactive isotope of hydrogen that is produced naturally in the environment and also by nuclear reactors.
Tritium is considered to be relatively harmless because it emits very weak radiation and does not accumulate in the body. It is also diluted to meet international standards before being released into the ocean.
What are the risks and impacts of releasing the water?
According to the IAEA, the release of the water will have “negligible” radiological impact on people and the environment, as long as it is done in a controlled manner and under strict monitoring.
The agency says that tritium is routinely discharged from nuclear facilities around the world, including in China and South Korea, without causing harm to marine life or human health.
It also says that the concentration of tritium in the water discharged from Fukushima will be far below the operational limit of 1,500 becquerels per liter (Bq/L), which is six times lower than the World Health Organization’s limit for drinking water at 10,000 Bq/L.
However, some experts and activists disagree with this assessment and argue that more studies are needed to understand the long-term effects of tritium on marine ecosystems and human health.
They say that tritium can cause DNA damage and increase the risk of cancer, especially for children and pregnant women. They also worry that tritium can accumulate in fish and shellfish over time, posing a threat to food safety and consumer confidence.
Some critics also point out that Japan has not been transparent about the amount and quality of the water it plans to release, and that it has not consulted adequately with neighboring countries and stakeholders.
How will Japan carry out the release and what are the reactions?
Japan plans to release about 1.25 million tons of water into the ocean over several years, starting from 2023. The first release is one of four scheduled between now and March 2024.
The water will be pumped out of the tanks through pipes that extend about 1 kilometer offshore. The discharge rate will be adjusted according to the tide, weather and fishing activities.
The process will be supervised by an independent panel of experts and monitored by both Japanese authorities and the IAEA. The data will be made public online for transparency.
Japan says it has taken various measures to address the concerns of local fishermen, who fear that their livelihoods will be ruined by the stigma attached to Fukushima seafood.
These include providing financial compensation, promoting local products domestically and internationally, and installing underwater cameras to show that there is no visible difference between the treated water and seawater.
Japan has also tried to reassure its neighbors and the international community that the release is safe and necessary. It has held bilateral talks with China and South Korea, as well as multilateral meetings with other countries in the region.
However, these efforts have not been enough to ease the tensions and mistrust that have arisen from Japan’s decision.
China has called Japan’s move “extremely irresponsible” and “unilateral”, saying it violates international law and poses a serious threat to the global marine environment and human health.
China has also announced a ban on all seafood imports from Japan, and urged Japan to revoke its decision and consult with other countries.
South Korea has expressed “strong regret” and “grave concern” over Japan’s plan, saying it poses a risk to the safety of its people and the marine ecosystem of the Korean Peninsula.
South Korea has also banned Japanese seafood from the Fukushima region, and said it will step up its radiation monitoring and inspections of Japanese food products.
Taiwan has also voiced its opposition to Japan’s plan, and said it will ban the import of Japanese seafood from areas near Fukushima.
Meanwhile, local fishermen and activists in Japan have staged protests and filed lawsuits against the government and Tepco, demanding them to stop the release of the water.
They say they have not been consulted or informed properly about the plan, and that they have not been given enough evidence or guarantees that the water is safe.
They also say they have already suffered enough from the nuclear disaster, which has devastated their industry and reputation.