Photo/Illutration A Tokyo Electric Power Co. official shows a facility for diluting radioactive water with seawater at the Fukushima No. 1 nuclear power plant on June 26. (Pool)

Tokyo Electric Power Co. has completed all the facilities required for the controversial release of treated radioactive water from the crippled Fukushima No. 1 nuclear power plant into the ocean, including an undersea tunnel.

The Nuclear Regulation Authority will begin inspections on June 28 to confirm the performances of the facilities.

The government is expected to decide on the timing of the start of the water release after the International Atomic Energy Agency, which studied the safety of the treated water, releases a report.

TEPCO, the plant’s operator, raised a tunnel boring machine around 9:30 a.m. on June 26 after the tunnel, which will release water 1 kilometer off the Pacific coast, was completed.

The utility also placed a cover on the discharge outlet of the tunnel to prevent sand from flowing inside it.

On the same day, equipment was shown to media representatives including piping for mixing radioactive water with seawater, with a diameter of about 2 meters, and valves for suspending water releases during an emergency.

TEPCO officials also demonstrated how they will operate facilities and release water and how they would respond in the event of an emergency.

Under the plan, radioactive water processed by the Advanced Liquid Processing System (ALPS), which removes radioactive substances other than tritium, will be diluted with seawater.

After tritium levels are lowered under one-40th of government standards, or 1,500 becquerels per liter, the water will be released into the ocean.

TEPCO officials said the water release will be suspended when tritium levels in the seawater exceed 700 becquerels per liter around the discharge outlet or 30 becquerels per liter within a 10-km radius from the plant.

Radioactive water continues to be generated at the Fukushima No. 1 plant as rainwater and groundwater flows into reactor buildings where melted nuclear fuel remains and other facilities. The daily amount totaled about 90 tons in fiscal 2022.

The water processed by the ALPS equipment is stored on the plant premises, but tanks are expected to be filled around February to June next year. As of June 15, about 1.34 million tons, or 97 percent of capacity, are stored.

The government decided to release treated water into the sea in April 2021, but opposition remains strong among local fishermen and some countries in the region.

In a document handed to the Fukushima prefectural fisheries cooperative association in 2015, the government and TEPCO promised that they “will not dispose of (treated water) without gaining the understanding of those concerned.”

China has expressed strong opposition, among other countries.

The Hong Kong government has said it will halt imports of Japanese foods that could be affected if Japan releases treated water into the sea.

(This article was written by Keitaro Fukuchi and Ryo Sasaki.)

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