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Robot Inside Fukushima Reactor Discovers Source of Water Leaks

June 5 (Bloomberg) -- Tokyo Electric Power Co. said a robot sent inside Unit 1 of the wrecked Fukushima nuclear power station has discovered the source of water leaks plaguing decommissioning work.

A robot designed by Hitachi-GE Nuclear energy, a venture between Hitachi Ltd. and General Electric Co., for the first time took clear pictures showing water drips from the reactor containment vessel into the building’s basement via an elastic pipe joint, the company known as Tepco said.

With radiation inside the Fukushima Dai-Ichi reactors still at deadly levels, the plant operator has struggled to determine how water dumped on the units for cooling is leaking.

Until Tepco can plug the leaks, it must keep pumping out contaminated water, which it must then store and filter to remove radioactivity.

Large pools of water prevent Tepco from beginning work to remove melted fuel from Fukushima’s reactors, the company said.

As much as 1.5 metric tons of water is leaking from Unit 1 every hour or almost 10,000 gallons a day, according to Tepco estimates.

The robot was lowered into the Unit 1 suppression chamber on May 27 and maneuvered inside for three days, Tepco said. The machine took still and video images while being controlled from hundreds of meters away, the company said.

Radiation inside Unit 1 measured as high as 10 sieverts per hour -- the highest equipment could handle -- months after the disaster, according to Tepco data. That’s enough to kill a person “within a few weeks” from a single exposure, according to the World Nuclear Association.

Last November Tepco placed a remote-controlled boat inside Unit 1’s basement in an effort to find the source of the leaks. The vessel couldn’t provide enough precision to identify the source, Tepco said.

To contact the reporter on this story: Yuriy Humber in Tokyo at

To contact the editors responsible for this story: Jason Rogers at Iain Wilson, Indranil Ghosh

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