Tokyo Electric Power Company (TEPCO) released its plans on August 25, 2021, to construct a roughly 1 km-long undersea tunnel to release treated radioactive water from the Fukushima Daiichi Nuclear Power Station.[1] Since the accident in 2011, more than 1 million tons of treated water has accumulated at the complex. The water was contaminated when it was pumped into the ruined reactors to cool the melted fuel and is being treated using an advanced liquid processing system. While the process removes most radioactive materials, it leaves behind tritium, which is considered low risk at low concentrations. On August 24, 2021, the Japanese government announced that it will buy marine products to support the fishing industry in case the release of treated water from the plant hurts their sales.[2] Prior to this, in April 2021, the government decided to start discharging treated water in the spring of 2023. However, the plan has been opposed by fishermen, citizens, and nearby countries.

TEPCO will construct the undersea tunnel by hollowing out bedrock on the seabed near the plant’s No. 5 reactor. The tunnel will stretch 1 km east and release the water into an area where there are no fishing rights in place. The company will dilute the treated water with seawater to reduce the tritium concentration to less than 1,500 becquerels per liter. Because the seawater in the port in front of the Fukushima Daiichi Nuclear Power Plant contains radioactive materials, the seawater will be taken from elsewhere. TEPCO plans to apply to the Nuclear Regulation Authority for a review of the construction plans and begin preparatory work soon. The company hopes to start construction in early 2022 and begin operations in spring 2023 in line with government policy.

[1] https://www.tepco.co.jp/en/hd/newsroom/press/archives/2021/20210825_01.html

[2] https://www.japantimes.co.jp/news/2021/08/24/national/fukushima-water-tunnel/