Built for Tough Work
Cleaning up after a nuclear disaster is no easy task. Decommissioning one reactor is tough enough, but doing it for six, three of which suffered core meltdowns — the situation following the Fukushima disaster more than six years ago — can seem downright impossible. However, Japanese technology firm Hitachi and American company General Electric (GE) may have found a way through a joint partnership.
The two companies have been working on a robotic clean-up crew to dispose of nuclear fuel debris left at the Fukushima Daiichi nuclear power plant. Dubbed "muscle robots," these special machines — five types in total — have arms equipped with hydraulic springs that work like human muscles.
The hydraulics are necessary because electronics aren't able to withstand the environment inside these reactors. "The robots are based on a concept completely different from those of conventional robots," Hitachi-GE Nuclear Energy, Ltd. senior engineer Koichi Kurosawa explained to The Nikkei Asian Review.
The robots are currently undergoing tests at a plant owned by Hiroshima-based engineering service company Chugai Technos. There, the "muscle robots" are operating in a life-sized replica of the primary containment vessel (PCV) of Fukushima's reactor No. 1. The goal is to have the robots ready for actual debris removal by 2021.
Where No Human Can Go
Back in March 2011, the Fukushima Daiichi nuclear power plant suffered a catastrophic meltdown due to an earthquake and a resulting tsunami. The meltdown produced solid nuclear fuel wastes containing highly radioactive plutonium and uranium.
Human removal of these fuel wastes just simply isn't a viable option. Not only are they very heavy— an estimated 800 tons in total — the radiation in the nuclear PCVs is strong enough to kill a person after just a few minutes of exposure.
The only option left is to employ non-human help, and to that end, several companies have been working on robotic nuclear waste cleaners.
Toshiba has a scorpion-like swimming robot with a camera at its tail that has helped assess the extent of the Fukushima reactors' damage. This robot is also meant to locate the melted fuel rods lost during the disaster. Another set of robots were also employed by the Tokyo Electric Power Co. previously, but they broke down due to the radiation's intensity.
The Hitachi-GE "muscle robots" are designed to work well in highly radioactive environments, assured Kurosawa. However, they might not be such great helpers elsewhere. "Asked if the robots are applicable to other nuclear power plants, I would say the possibility is low," he admitted.
Nevertheless, decommission work for Fukushima's damaged reactors seems well underway. Finishing the process may take some 30 to 40 years, but thanks to technological innovations like these "muscle robots," human lives needn't be lost during the process.