The once-promising, shape-shifting robot designed specifically to assess the status of the No. 1 Fukushima Daiichi power plant has stalled and likely broken down completely, leaving officials at the Tokyo Electric Power Co. (TEPCO) to figure out a different strategy for shutting down the facility.
The robot stalled just a few hours after entering the containment vessel on April 10. Two days later, the power utility said it had given up plans even to retrieve, let alone repair, the device, and had decided to postpone sending in a second robot on April 13 as originally planned. So technicians began cutting the cable that the first robot used to send data to the accident investigators.
Still, the 2-foot-long robot accomplished some of its mission. TEPCO officials said that before it stalled, it managed to photograph and record temperature and radiation levels at 14 of the 18 target locations inside the containment vessel.
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But no evidence has been found of what caused the robot to malfunction, and radiation levels inside the reactor remain too high for human beings to be sent inside to investigate.
The Fukushima Daiichi power plant, situated on Japan’s Pacific coast, was struck by an earthquake and tsunami in March 2011 and suffered meltdowns in three of its six nuclear reactors. The accident released nearly 30 percent more radioactive material than the Soviet Union’s Chernobyl disaster in 1986.
The remotely controlled robot was developed by Hitachi and its affiliate, Hitachi-GE Nuclear Energy.
It crawls on small treads, moving like a snake, but is also capable of changing to a U-shape, allowing it to move backward and forward like a wheeled vehicle.
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TEPCO said the robot was sent into one of the containment vessels at the No. 1 reactor at 9:25 a.m. on April 10. Shortly after 2 p.m., however, technicians directing the robot lost control of it, and spent the next two days trying to coax a response from it.
The utility was stoical about the failure, acknowledging that sending the robot into the reactor was “an unprecedented experiment,” and expressing some relief that it was able to obtain some crucial information on its aborted mission.
The shape-shifting robot that failed wasn’t the first to be used to assess damage at the crippled nuclear power plant. Fifteen other robots have been used and retrieved without incident. They include Packbot and Warrior, military robots built by the US company iRobot, both used to remove obstacles in the buildings. Another was Raccoon, which decontaminated parts of the reactor buildings.
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TEPCO had hoped that the snakelike robots would help determine the state and location of the reactors’ damaged fuel and help it develop a strategy for its safe removal. Another impediment from the high levels of radiation is that the utility and the Japanese central government had to delay by five years – until 2025 – the previously scheduled start of removing the melted fuel.
Because of the intense radiation, the only answer is uniquely new technology, according to Dale Klein, a former chairman of the US Nuclear Regulatory Commission who is now a TEPCO adviser.
“This is a challenge that has never been faced before in the world,” Klein said, “and there will have to be new equipment developed to make that happen. … Those tools and equipment do not exist today, but [Japan’s] fundamental knowledge of robotic, remotely controlled devices will, I think, be sufficient.”
By Andy Tully Of Oilprice.com
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Andy Tully is a veteran news reporter who is now the news editor for Oilprice.com