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Q&A Fukushima Treated Water: The Science Explained

With hysteria rampant on Chinese social media following the release of ALPS treated water at Fukushima, we tackle some of the science behind Japan’s decision.



View from a helicopter of the Fukushima Daiichi Power Plant on the day release of treated water into the ocean began (©Kyodo)

Tokyo Electronic Power Company (TEPCO) started releasing treated water from the Fukushima Daiichi Nuclear Power Station on August 24. All of the water released is first treated with the Advanced Liquid Processing System (ALPS) to remove radioactive particles and then further diluted with ocean water. 

On September 4, TEPCO announced that the previous days the levels of tritium were below 10 becquerels per liter. (A becquerel is a unit measure of radioactivity.) That was 150 times lower than the company-designated cutoff point and 1,000 times lower than the international standard. The release is proceeding according to a plan reviewed and monitored by the International Atomic Energy Agency.

China has openly condemned the decision. It has called the water release "extremely irresponsible" and banned the import of all seafood products from Japan. 

Chinese social media circulated many negative messages misinforming the public about the treated water release. One is a video that went viral showing shoppers in China's Hunan province buying salt in bulk. It was dated August 25, the day after the Fukushima water release. 

TEPCO and the Japanese government have been responding to the information war with frequent reports from the release site. On August 31 Japan's prime minister, Fumio Kishida, also pledged to do everything he could to overturn China's ban on seafood imports from Japan. 

What are the issues in the controversy? We tackle some of the main points below and bring them back to the scientific facts.

The July 7 edition of the Global Times, a Chinese newspaper, printed a one-page feature questioning the IAEA report on the plan to release treated water from TEPCO's Fukushima Daiichi Nuclear Power Station. (©Kyodo)

Exactly what took place on August 24? 

Prime Minister Fumio Kishida announced on August 22 that, pending a final testing of the water, TEPCO would start releasing the treated water off Fukushima from August 24.

In turn, TEPCO said on the morning of August 24 that testing for a hydrogen isotope in the water called tritium showed measurements "well below the designated level of 1,500 becquerels per liter." This is also far below the World Health Organization approved standard for drinking water of 10,000 becquerels per liter.  

The ALPS treated and then diluted water originally derives from the cooling process at the nuclear power station following the March 11, 2011 earthquake and tsunami.

Why is there testing for tritium? Is tritium in water safe? 

Tritium is an isotope of hydrogen that cannot be removed from water. 


It is also a substance that is naturally present in small quantities in drinking water and in nature. In this case, the Japanese plan allows for the release of treated water only if tritium levels are a fraction of those approved internationally. 

The International Atomic Energy Agency, an independent body within the United Nations, approved the Fukushima plan. 

IAEA's head Mariano Grossi said in a report released in July 2023 that the discharges of the treated water "would have a negligible radiological impact to people and the environment."  

Frequent testing is carried out to make sure that these substances in the released water are present at or below internationally approved standards. 

IAEA Director-General Grossi (right) visits the TEPCO Fukushima Daiichi Nuclear Power Plant and feeds flounder that are being bred on a trial basis in a tank filled with treated water on the afternoon of July 5, 2023. (©Kyodo)

Does the process remove other radioactive substances? 

Some parties such as Greenpeace Japan have voiced the concern that the process mapped by TEPCO and the Japanese government focuses on tritium. There are other nuclides present even after purification, they argue. 

However, before discharging the water, TEPCO purifies it through a procedure called Advanced Liquid Processing System (ALPS). This process removes most of the 62 nuclides from the water, including strontium-90. 

In 2018, TEPCO acknowledged that another nuclide, carbon-14 is still present in the water, but at very low levels. TEPCO specifically tested for carbon-14 in 2020. The test results revealed the presence of carbon-14 in the ALPS treated water tanks at an average of 42.4 becquerels per liter. 

This is a fraction of the national regulatory standard of 2,000 becquerels per liter. In other words, the quantity is very low to begin with. After further dilution with seawater of at least 100 times, the water is then again checked for tritium. 

TEPCO has also promised to conduct continuous testing to check the levels of nuclides in the water prior to release. This explanation is published on its website. Test results, including comparisons to pre-release levels and international standards, can be found on the company's interactive page.  

An IAEA Task Force is inspecting the treated water tanks on June 2 (©TEPCO)

Was releasing the water in the sea the only option? 

Since 2011, water that came into contact with radioactive material in the cooling process has been stored in special drums. These are lined up at the Fukushima site. 

However, TEPCO and the Japanese government say that storage space for these drums is running out. With that in mind, options for safely disposing of the water have been explored since 2013. Reducing the stored material and releasing the treated water is a "fundamental step towards decommissioning the nuclear power station," highlighted Prime Minister Kishida on August 21.

In total, the Japanese government and TEPCO considered five options for the disposal of the wastewater. 


These options were narrowed down to two following discussion in a special committee on the issue in 2020. One was releasing the treated water as vapor in the atmosphere. The other was by diluting and releasing the treated water into the ocean. 

Both methods are consistent with internationally recognized protocols. They have historical precedents and were approved by the IAEA. Ultimately, the government of Japan chose the option of releasing treated water into the ocean. The government says that this option yields more predictable results. It is also the option more commonly used by other countries. 

Why not mix the water with cement?

A briefing at the Pacific Islands Forum in July 2023, raised another option. A few experts asked whether the Japanese government had considered using the diluted treated water in cement construction. 

The Japanese side said it had considered and rejected the proposal in the past. Heat is generated during the mixing of concrete. It feared the heat would cause evaporation into the atmosphere of the ALPS-treated water. That would therefore make measuring tritium levels more difficult, among other technical and legal reasons. 

Fishermen in Soma, Fukushima, take care of their fishing gear on August 22. They are the biggest victims of China's misinformation campaign and economic coercion. (©Kyodo)

Is it true that the price of seafood has gone down in Japan due to the treated water controversy? 

As of August 31, this does not appear to be the case. On that day, the local NHK broadcast from Fukushima reported that seafood prices had not changed at the Iwaki market, a location famous for high-quality seafood. 

It's useful to remember that Fukushima has gone to great lengths to measure food safety with a thorough contamination testing system. This system was put in place in the aftermath of the 2011 tsunami and earthquake. The locals are used to having their food tested and certified as safe by the authorities. Moreover, the process has demonstrated its reliability for over a decade. 

Why is China condemning the treated water release?

China is the only foreign country that has openly criticized Japan's release of ALPS treated water in Fukushima. In addition, when its demand was rejected and the treated water release moved forward, China announced a blanket ban on all seafood coming from Japan. 

TEPCO and the Japanese government have ensured timely public access to all testing data from the sea around the release site. Since China releases tritium from its own nuclear power stations at much higher levels, its reasons for opposing Japan's release of ALPS treated water can only be speculated. 

The sushi section of a supermarket in Beijing has a sign saying: "It is not imported from Japan." On August 29. (©Kyodo)

What about other countries?

Although the South Korean government had initially opposed the plan, it later received the IAEA's independent report on the plan and observed the IAEA inspections. Subsequently, after meeting with the IAEA, the government in Seoul said it accepts the IAEA-approved plan. In addition, South Korea accepted the invitation to conduct independent testing to check the safety of the process. 

Embassy representatives from other countries, such as Australia and Italy, have posted messages on X, formerly known as Twitter, showing "support for Japan's scientifically based methodology." The United States ambassador visited Fukushima, ate sushi there, and talked with fishermen in support of the Japanese plan. 


In a statement released by the embassy, he also said, "The United States stands firmly with Japan, especially when contrasted with China’s overtly political decision to ban all Japanese seafood imports and past failures in openness and scientific cooperation."


Author: Arielle Busetto

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