A device to remove debris from a reactor at the damaged Fukushima nuclear power plant shows how to pinch a stone, as unveiled in Kobe, western Japan, on May 28, 2024. Credit: Kyodo News via AP, file
A remote-controlled robot safely returned a small piece of melted fuel collected from inside one of three damaged reactors at the Fukushima Daiichi nuclear power plant that was hit by a tsunami for the first time since the 2011 meltdown.
Tokyo Electric Power Holdings Co., which runs the plant, said on Saturday that the extendable robot, which resembles a fishing rod, successfully clipped pebbles up to 5 millimeters (two inches) in size, the size of a small granola bar, from the top surface of a pebbles. A pile of molten fuel debris at the bottom of the primary containment vessel of reactor No. 2.
The Telesco robot, its front clamps still holding a piece of molten fuel, returned to the sealed container for safe storage after workers in full hazardous materials gear pulled it from a containment vessel earlier Saturday.
The sample return represents the first time that molten fuel is recovered from the containment vessel. But the job will not be finished until it is confirmed that the sample’s radioactivity is below the specified level and it is safely placed in the container.
If the radioactivity exceeds the maximum, the robot must return inside the reactor to find another piece. TEPCO officials said they expect the lot to be small enough to meet requirements.
The mission initially began last August, a trip that was supposed to take two weeks back and forth, but was put on hold twice due to mishaps.
Tokyo Electric Power Holdings, also known as TEPCO, operator of the wrecked Fukushima Daiichi nuclear power plant in Japan, unveils a robot that will be used to recover debris at the power plant in Kobe, western Japan, on May 28, 2024. Credit: Kyodo News via AP, file
The first was a procedural error at the beginning that led to a halt in work for about three weeks, and then the robot’s two cameras designed to transmit views of the target areas to its operators in the remote control room malfunctioned. The camera problem required the entire robot to be pulled out to be replaced before the mission resumed on Monday.
The Fukushima Daiichi plant lost key cooling systems during the 2011 earthquake and tsunami, causing meltdowns in its three reactors. An estimated 880 tons of deadly radioactive molten fuel remain inside, and Tepco has implemented a number of robotic probes to figure out how to take the plant out of service.
Tepco said Wednesday that Telesco successfully cut off a piece that supposedly weighed less than 3 grams (0.1 ounces) from the planned area directly below the Unit 2 reactor core, from which large amounts of molten fuel fell during the meltdown 13 years ago.
The plant’s president, Akira Ono, said that only small specifications could provide basic data for planning a decommissioning strategy, developing the necessary technology and robotics, and knowing retrospectively how the accident developed.
The government and TEPCO have set a target of 30 to 40 years for the cleanup, which experts say is overly optimistic and should be updated.
No specific plans have been identified to completely remove or dispose of the fuel debris.
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