Jun 15, 2017 (Japan Times) - Toshiba Corp. unveiled on Thursday a submersible robot to take live video of reactor 3 at the Fukushima No. 1 power plant to confirm whether fuel debris is sitting at the bottom of a pool of radioactive water inside.
The location and condition of the fuel in the three reactors hit by core meltdowns is critical information for Tokyo Electric Power Company Holdings Inc., which runs the plant. Removing the fuel debris is considered the most difficult part of decommissioning the complex.
Unit 3 has the highest level of water inside at 6 meters. The fuel debris inside is presumed to have melted through its pressure vessel and settled at the bottom of its primary containment vessel.
"Until today, no one has seen the situation inside reactor 3," said Tsutomu Takeuchi, senior manager at Toshiba's Fukushima Restoration and Fuel Cycle Project Engineering Department.
"If we can observe the situation inside the reactor, that would be a huge leap in our ongoing effort to extract the debris" and eventually shut down the wrecked plant, he said during a demonstration of the robot at the Port and Airport Research Institute in Yokosuka, Kanagawa Prefecture.
Co-developed with the International Research Institute for Nuclear Decommissioning, the cylindrical 30-cm robot, dubbed the "mini manbo" (miniature sunfish), has a camera that can move 180 degrees vertically on its front and a fixed camera on its rear, allowing it to crawl through the water while capturing images.
Tepco plans to send the remotely controlled robot into the reactor as early as mid-July. A camera inserted into the reactor in October 2015 was unable to reach the bottom of the containment vessel.
Source: ANNnewsCH
