The President of Fukushima Dai-ichi Decommissioning Naohiro Masuda has put out the call for better robots which would be deployed for inspection and debris removal tasks at the three damaged reactors that suffered meltdowns in March 2011.
"We should think out of the box so we can examine the bottom of the core and how melted fuel debris spread out," Masuda said, as quoted by the AP wire service.
Masuda spoke to reporters on Thursday at a news conference in Tokyo. He said the approach for robotics required more creativity.
The history of exploratory robots in use at the damaged plant appears discouraging at a glance. It has taken years to develop some of the probes sent into highly radioactive ares of the three damaged units. But the robots have all failed within one or two hours of use, their wiring quickly deteriorating from the intense radioactivity.
The primary task is to locate where the melted fuel might be in congealed masses at the bottom of the containment vessels, so that the next series of robots can remove debris that stands in the way of removal, then to retrieve the melted fuel.
This year, Tepco sent a debris clearing robot through a pipe to explore the damaged Unit 2. It found some fuel-like debris at the bottom of the reactor vessel, siting on or melted into a grating known as the pedestal But the debris-clearing robot could not get close enough to confirm the finding. Instead, it was retrieved before it failed completely, so it would not block the path of the next probe. Its total time in active service was about two hours, much shorter than the 10 hours technicians were hoping to get out of it before it failed.
It was followed by a Scorpion-style probe – narrow and flexible in the middle. That, too, failed quickly, this time too quickly for technicians to retrieve it.
The next probe planned for exploring the damage is a very small waterproof robot that is being designed for Unit 1 and will be deployed in March or April.
Toshiba has already designed a robot that will be lowered into Unit 1 to remove debris, including fuel rods. This robot has two arms, one of which can grasp and the other of which can cut. The report is expected to be deployed in 2017 as a tool that can remove 566 fuel rods from the cooling pool of Unit 1.
This clip shows the Toshiba robot developed for Unit 1.
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