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Shield machine to dig undersea tunnel to discharge ‘treated water’ has not yet been approved nor has the local government… Preparations are steadily underway at TEPCO’s Fukushima Daiichi Nuclear Power Plant.

A shield machine is carried by a cart and installed at the bottom of a shaft at TEPCO’s Fukushima Daiichi Nuclear Power Plant on April 25 (courtesy of TEPCO).

April 25, 2022
 On April 25, TEPCO installed a “shield machine” at the launch site to dig an undersea tunnel to the discharge port 1 km offshore over plans to discharge contaminated water from the Fukushima Daiichi Nuclear Power Plant (Okuma and Futaba towns, Fukushima Prefecture) into the sea after purification treatment. The plan for the facilities to discharge the contaminated water has not been approved by the Nuclear Regulation Authority, and the local government has not yet given its approval for the start of construction. However, TEPCO explained at a press conference on the same day, “We are preparing for the construction work, and we will move ahead to the extent that there are no problems.

Contaminated water generated when cooling water injected into the reactors of Units 1-3 came into contact with nuclear fuel debris melted down in the accident and mixed with groundwater and rainwater that entered the buildings. Tritium, a radioactive substance that cannot be removed, remains in concentrations exceeding the national discharge standard. The government and TEPCO have been working on a plan to use large amounts of seawater to dilute the tritium concentration to less than 1/40th of the discharge standard and discharge the water into the sea.

 TEPCO began preparatory work on the 24th, bringing a shield machine (about 3 meters in diameter and 7 meters in length) to the port of the power plant, and on the 25th, placed it at the bottom of a shaft (16 meters deep) where they will begin digging an undersea tunnel built in the port area. The tunnel is now ready for construction to begin immediately. The tunnel will connect the shaft, which will temporarily store water to be discharged, with the offshore water discharge port.
 Preparations for the construction of the water discharge outlet will begin on the 25th, and excavation of the seafloor will begin on the 29th.

Although the regulatory commission has completed its review of the facility plan, TEPCO has yet to submit a revised plan to the regulatory commission based on the content of the review. The approval is expected to come after June, when the public will be invited to comment on the plan. The approval of Fukushima Prefecture and the towns of Okuma and Futaba must also be obtained before tunnel excavation can begin. (Kenta Onozawa)


May 1, 2022 - Posted by | Fuk 2022 | , , ,

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