Next month marks the fifth anniversary of the magnitude-9.0 earthquake and tsunami that decimated northern Japan. Aside from the over 17,000 dead and missing people the catastrophe’s worst legacy was the near-destruction of the Fukushima Dai-ichi nuclear power plant. The tsunami’s waves knocked out its cooling and power systems, initiating a fuel meltdown, and operator Tokyo Electric Power Co. has struggled to contain radiation ever since.
Too radioactive for humans, many parts of the plant have been under the watchful eye of robots — first U.S. military machines and then a succession of Japanese devices that have been modified or specially built.
One of the former is Quince, a simple crawling rescue droid that was equipped with a camera and dosimeter to gather imagery of the upper floors of the complex in the summer of 2011.
Veolia buys Kurion for $350M
Veolia Environnement SA, a provider of water, waste, and energy management services, this month acquired Kurion Inc., which provides systems for accessing, separating, and stabilizing hazardous materials. U.S. regulatory approval for the $350 million deal is pending.
In 2013, Paris-based Veolia signed an agreement with the French Alternative Energies and Atomic Energy Commission and formed Asteralis, a subsidiary focused on characterizing waste and assessing nuclear facilities.
Kurion was started with just $5 million from investors including Lux Capital and has tested its Modular Vitrification System at the Pacific Northwest National Laboratory.
“Bringing Kurion and its employees into Veolia is going to enable us to develop a world-class integrated offer in nuclear facility cleanup and treatment of low-level radioactive waste around the world,” said Antoine Frerot, chairman and CEO of Veolia.
Veolia will also provide Kurion the opportunity to expand into new markets, said William Gallo, CEO of Irvine, Calif.-based Kurion, which has about 200 employees. According to Reuters, there are about 400 nuclear plants in operation worldwide, and about 100 to 150 will be decommissioned by 2050.
An example of the latter kind — purpose-built robots — is Toshiba Corp.’s new submersible grappling arm, the Fuel Removal System (FRS). Like many of the other robots used at Fukushima Dai-ichi, it was designed for one task, in this case removal of debris and fuel rods at the fuel pool in the Unit 3 reactor building, where radiation remains too high for workers.
The pool contains 566 fuel-rod assemblies that must be moved to a secure, quakeproof facility. Blocking the way, however, is rebar and other rubble from a hydrogen explosion that damaged the upper part of the building.
The FRS looks a bit like a deep-sea submersible robot. Suspended from an overhead gantry, the 74-ton Fuel Handling Machine unit can descend into the pool to grapple and cut debris into pieces with two multi-jointed arms while another arm can pick up the fuel-rod assemblies.
Depending on the job required, the cutting or gripping jigs can be switched out via remote control. The fuel is then placed in a transfer vessel for secure transport.
Cameras on the remote-controlled FRS provide operators with a detailed view of what’s going on, and they are designed to be easily replaced when radiation wears them down.
“The most difficult part of the operation to retrieve fuel is positioning [cameras] properly, then positioning the robot at the right angle in non-routine work only by carefully monitoring multiple views,” said Toshiba spokesman Motohiro Ajioka. “Routine work such as grabbing and removing fuel is not that difficult.”
Installation of the remote-controlled device will begin this year, with the removal work continuing through April 2018. But it won’t be the first time that fuel rods have been removed at Fukushima Dai-ichi since the quake.
Exercise in teleoperation
Tokyo Electric Power Co. (TEPCO) removed over 1,500 rods from a storage pool in the damaged Unit 4 building in a delicate operation that lasted over a year. Since radiation there was relatively low, however, workers could supervise the extraction from within the precarious structure. The Unit 3 job will be a long exercise in teleoperation.
Toshiba is a member of a nuclear plant services consortium called the International Research Institute for Nuclear Decommissioning (IRID), which is helping in the 40-year, ¥986 billion ($8.7 billion) effort to dismantle the toxic power station.
The company has developed a number of other robots for the task, including machines that can vacuum radioactive dust, decontaminate surfaces by blasting dry ice, and inspect the inside of primary containment vessels surrounding the reactors, where radiation can exceed 10 Sv/h.
More on Japanese and Reactor Robots:
“It is essential to use robots for investigation or decontamination in a high-dose environment,” said TEPCO spokeswoman Yukako Handa. “Since a high level of technological development is necessary to develop robots for debris removal, the government took the initiative, and we continue with development, not only with domestic manufacturers and research institutes, but also with related overseas institutes.”
The University of Manchester is among those working on underwater robots to assess radiation in submerged parts of the damaged reactor.