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Nuclear Debris Moved out of Reactor Containment Vessel; Removal at Fukushima Plant Accomplished After 3-Year Delay

Yomiuri Shimbun file photo
Tokyo Electric Power Company Holdings, Inc.’s Fukushima No. 1 nuclear power plant is seen on Sept. 10.

The Yomiuri Shimbun

21:00 JST, November 3, 2024

Tokyo Electric Power Company Holdings, Inc. has moved nuclear fuel debris out of a containment vessel in the No. 2 reactor at the Fukushima No. 1 nuclear power plant for the first time since the 2011 accident at the plant.

After its removal on Saturday, the debris was put in a metal enclosure designed to block radiation. TEPCO plans to measure the debris’ radiation level on Tuesday or later, and decide on whether to remove the debris from the plant.

The debris was captured with a claw-like device on Wednesday. According to TEPCO, it was moved into the metal enclosure outside the containment vessel at about 9:50 a.m. on Saturday.

The debris is estimated to be about 5 millimeters in size and weigh less than 3 grams.

If its radiation dose is less than 24 millisieverts per hour, the debris will be transferred to a temporary storage container outside the enclosure. This would effectively complete the trial removal.

The current trial was intended to collect up to 3 grams of melted nuclear fuel and analyze its hardness, composition and other characteristics, to help devise ways to implement full-scale removal. The Japan Atomic Energy Agency’s Oarai research institute in Ibaraki Prefecture will analyze the debris.

The trial removal was initially scheduled for 2021. However, it was postponed for three years due to a delay in the development of equipment and other factors.

TEPCO completed preparations and planned to work on the removal on Aug. 22 this year, but an error was found in the order in which certain pipes, which were used to insert a device, were connected. The company finally launched the work on Sept. 10, but it was suspended on Sept. 17 due to glitch-hit cameras attached to the end of the device.

After replacing the cameras, work resumed on Oct. 28, and the debris was captured two days later.

During the nuclear accident, meltdowns occurred in the Nos. 1 to 3 reactors, generating an estimated about 880 tons of debris when nuclear fuel was mixed with the reactors’ structures. Removing this debris is regarded as the most difficult part of decommissioning the reactors.