Work proceeds on building tunnel to discharge treated water at Fukushima N-plant
September 7, 2022
FUKUSHIMA — Tokyo Electric Power Company Holdings, Inc. held a press viewing of the construction site of an underwater tunnel leading to the ocean for discharging treated water from the Fukushima No. 1 nuclear power plant in Fukushima Prefecture.
The treated water is to be piped to an offshore discharge site through the tunnel, which is about 1-kilometer long.
On the seaward side of reactor Nos. 5 and 6, there is a shaft about 18 meters deep that leads to a tunnel with a diameter of 3.1 meters that extends toward the sea.
The walls of the tunnel are covered with reinforced concrete to prevent leakage.
A shield machine with many pipes and cables has been used to dig about 80 meters since Aug. 4.
A worker was monitoring the excavation amid the loud sound of the motor.
“Once the tunnel is excavated to 150 meters, the pace of excavation will be several times faster from that point forward,” said a TEPCO official. “We’ll proceed with safety as our top priority.”
The excavation is proceeding smoothly, but rough seas have prevented the installation of the discharge port at the end of the tunnel, which was scheduled to be done in August.
The ocean is expected to be even rougher in the winter. The failure to install the outlet before then could delay the construction work and possibly push back the start of water discharge, which is scheduled in the spring, to around summer.
Source: https://japannews.yomiuri.co.jp/society/general-news/20220907-56640/
Operator shows digging of tunnel to release treated water from Fukushima Daiichi
Sept. 6, 2022
The operator of the crippled Fukushima Daiichi nuclear power plant has shown to media work to dig an underwater tunnel for releasing treated water from the facility into the ocean.
Tokyo Electric Power Company began building the tunnel in early August to release the water about one kilometer offshore, after diluting it.
The operator gained approval for the work from the Nuclear Regulation Authority and local authorities. The project is in line with the Japanese government’s policy.
On Tuesday, media were allowed to view the construction site, where workers used a huge excavator called a shield machine under the seabed.
The tunnel starts about 16 meters underground near a quay wall of the plant’s No.5 and 6 reactor buildings.
TEPCO officials say the tunnel is being dug at a pace of five to six meters a day, and is so far 80 meters long.
The firm aims to complete the work next spring, but has suggested it may take until next summer, depending on weather.
Local fishery workers have expressed concern about possible reputational damage from the release. Fukushima Prefecture and other local authorities say the plan has yet to gain public understanding.
Reactors at the plant suffered meltdowns in the March 2011 earthquake and tsunami.
Water used to cool molten fuel at the facility mixes with rain and groundwater. Accumulated water is treated to remove most radioactive materials and stored in tanks on the plant’s premises.
The filtered water still contains tritium. The government plans to dilute the water to bring the concentration of tritium well below the percentage permitted by national regulations.
The amount of tritium in the diluted water is also ‘expected’ to be below World Health Organization guidance levels for drinking water quality.
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