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TOKYO (AP) — A remote-controlled robot on Tuesday was used to probe Japan’s toughest nuclear reactor at Japan’s dilapidated Fukushima facility, as officials move forward with delays and controversial cleanup operations.
The 2011 earthquake and tsunami caused a catastrophic meltdown at Fukushima Daiichi’s three reactors, partially burying their radioactive cores in the plant’s concrete foundations, making dismantling extremely difficult.
The operator of the facility, Tokyo Electric Power Company Holdings, said the submersible robot was sent to Unit 1’s primary containment vessel to set up a guideway for the next five robots that will attempt to sample and evaluate the deadly high-radiation molten fuel.
Tuesday’s investigation comes five years after operators sent another robot to the same and heavily damaged reactor, but failed to get any images of the melted fuel.
The robot-led work, delayed from mid-January due to mechanical glitches, is expected to take several days before full-fledged probes begin.
Earlier probes showed that the fuel in Unit 1 was submerged in highly radioactive water to a depth of 2 meters (6.5 feet).
The five other robots, developed jointly by Hitachi-GE Nuclear Energy and the International Nuclear Decommissioning Research Institute, a government-funded consortium, will be sent separately for investigation over the next few months.
Tokyo Electric officials said the probe at Unit 1 aims to measure molten fuel clumps, map them in three dimensions, analyze isotopes and their radioactivity, and collect samples.
These are key to developing equipment and strategy for a safe and efficient molten fuel removal.
About 900 tons of molten nuclear fuel remains in the plant’s three reactors, with about 280 tons in Unit 1, and removing it is a daunting task that officials say will take 30-40 years. Critics say this is overly optimistic.
Remote-controlled robots with cameras provided only a limited view of the melted fuel in areas too dangerous for humans to reach. In 2017, superhigh levels of radiation and structural damage hampered investigation of Unit 1.
Details on how the highly radioactive material can be safely removed, stored and disposed of at the end of the cleanup have yet to be decided.
Tokyo Electric hopes to use a robotic arm to extract the first scoop of melted fuel from Unit 2, where internal robotic probes have made the most progress this year.
Fishermen and residents in Fukushima’s outer districts protested the operator’s plans to dump radioactive water from the reactors into nearby marine radioactive waters after they had reduced them to safely releasable levels.
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