Fukushima Daiichi water to be discharged into sea

13 April 2021

The Japanese government today announced its formal decision that the treated water stored at the Fukushima Daiichi site will be discharged into the sea. Tokyo Electric Power Company (Tepco) is expected to start discharging the mildly-radioactive water in 2023 in line with international standards and regulations.

Tanks of treated water at the Fukushima Daiichi site (Image: Tepco)

At the Fukushima Daiichi site, contaminated water is treated by the Advanced Liquid Processing System (ALPS), which removes most of the radioactive contamination, with the exception of tritium. This treated water is currently stored in tanks on-site. The total tank storage capacity amounts to about 1.37 million cubic metres and all the tanks are expected to be full around the summer of 2022.

Japan's Ministry for Economy, Trade and Industry today released a basic policy for disposing of the stored treated water.

"Regarding the tanks installed on the site of Fukushima Daiichi nuclear power plant, it has been pointed out that the existence of the tanks themselves is a cause of the adverse impacts on reputation, and that the risk of leakage and other risks due to deterioration or disaster may increase along with long-term storage," the document says. "Moreover, building additional tanks in surrounding areas outside the Fukushima Daiichi plant for additional storage would require more land and result in an additional burden on the people who are working diligently toward reconstruction."

The basic policy calls for the ALPS-treated water to be discharged into the sea "on the condition that full compliance with the laws and regulations is observed, and measures to minimise adverse impacts on reputation are thoroughly implemented".

Prior to discharging the stored water, Tepco is required to obtain approval from Nuclear Regulation Authority for its detailed plan for doing this, as well as for the construction of the necessary facilities.

The start of the discharge of ALPS-treated water into the sea is expected to be in about two years' time. A small amount of water will be released initially, with its impacts on the surrounding environment assessed.

Tritium levels

According to the policy document, the tritium will be diluted to 1500 becquerels per litre, which is one-40th of the concentration permitted under Japanese safety standards and one-seventh of the World Health Organisation's guideline for drinking water. The total annual amount of tritium to be discharged "will be at a level below the operational target value for tritium discharge of the Fukushima Daiichi plant before the accident (22 trillion becquerels per year)". The amount will be reviewed periodically. "This operational value for tritium discharge is within the range of the amount of discharge from each nuclear power station inside and outside the county."

"Disposal of the treated water is an unavoidable challenge for the decommissioning of the plant," Prime Minister Yoshihide Suga was quoted as saying by Jiji Press. "The government concluded that the ocean release is a realistic method."

Under the basic policy, the government will provide support to various industries such as the fisheries industry in Fukushima prefecture, its neighbouring prefectures and others. This support will include setting up and developing sales channels both in local areas and areas of major consumption, including overseas.

In a statement, Tepco said it takes the government's decision to discharge the water "very seriously". It said it will "strictly comply with all laws and regulations, such as nuclear safety regulations which are in line with international standards, while also thoroughly implementing measures to minimise the adverse impacts on reputation."

"Tepco shall immediately notify the public after it has formulated our response that is based on the government's basic policy," the company said.

International cooperation

The decision to discharge the water into the sea was welcomed by International Atomic Energy Agency (IAEA) Director General Rafael Mariano Grossi. He said the IAEA stands ready to provide technical support in monitoring and reviewing the plan's safe and transparent implementation.

"Today's decision by the Government of Japan is a milestone that will help pave the way for continued progress in the decommissioning of the Fukushima Daiichi nuclear power plant," Grossi said. "Tanks with the water occupy large areas of the site, and water management, including the disposal of the treated water in a safe and transparent manner involving all stakeholders, is of key importance for the sustainability of these decommissioning activities."

He added: "The Japanese government's decision is in line with practice globally, even though the large amount of water at the Fukushima plant makes it a unique and complex case."

The IAEA noted that Japan has requested its cooperation in the disposal of the water by the IAEA dispatching international expert missions to review the country's plans and activities against IAEA safety standards, and supporting and being present at environmental monitoring operations there.

"We will work closely with Japan before, during and after the discharge of the water," said Grossi. "Our cooperation and our presence will help build confidence - in Japan and beyond - that the water disposal is carried out without an adverse impact on human health and the environment."

Researched and written by World Nuclear News