An underwater robot is investigating the site of the Fukushima nuclear plant which was destroyed by an earthquake and tsunami that hit the coast of Japan in 2011. The “swimming robot” is called “the little sunfish” and is about the size of a loaf of bread. (Photo via irid.or.jp )
In March 2011, the northeastern coast of Japan was hit by a massive earthquake and tsunami that destroyed the Fukushima nuclear plant and caused the most devastating nuclear incident of its kind since the crisis at Chernobyl in 1986. Over 18,000 people were killed as a result of the 2011 earthquake and tsunami. As of December, the Japanese government estimates the total cost of cleaning up the Fukushima plant, including compensation, decommissioning, and decontamination, will reach £150bn (approximately $175 billion). The project is expected to last for decades due to the extensive damage sustained, as well as the high levels of radiation that necessitate the initial use of robots to investigate the site.
The little sunfish, which was co-developed by Toshiba Corp. and the International Research Institute for Nuclear Decommissioning (a government-funded consortium), represents the third attempt to examine the site with robotic instruments after the first “scorpion-shaped robot” and second “snake-shaped robot” failed in the first two reactors. According to Mari Yamaguchi of the Associated Press, the scorpion bot was left inside the plant’s Unit 2 containment vessel after its crawling function failed, and the subsequent snake-shaped robot, which was designed to clear debris for the scorpion probe, “...was removed after two hours when its cameras failed due to radiation levels five times higher than anticipated.” Finally, on the third attempt, the loaf-of-bread-sized robot has succeeded where the others failed, in that it has provided the first images of the damaged reactors, and in those, what is believed to be melted nuclear fuel. In Yamaguchi’s article, a spokesman for the plant’s operator, Toyota Electrical Production Company’s Takahiro Kimoto, is quoted as saying that, “...debris has apparently fallen from somewhere higher above. We believe it is highly likely to be melted fuel or something mixed with it,” and that it would take some time to analyze which portions of the rocks were fuel.
Yamaguchi reports that ‘the little sunfish’ is remotely controlled by a group of four operators, and it houses lights, two cameras, a dosimeter (a device used to measure radiation levels), five propellers, and can withstand radiation levels up to 200 Sieverts; a dose that would kill a human instantly. The bread-sized robot appears capable of probing the dangerous nuclear ruins, which is reassuring given the expectation of a decades-long cleanup project. The efficacy of the little sunfish is also very promising when considering Yamaguchi’s suggestion that, “Scientists need to know the fuel’s exact location and understand the structural damage in each of the three wrecked reactors to work out the safest and most efficient ways to remove the fuel.” At the moment, it seems that the small-but-mighty instrument will enable the organizations charged with the responsibility of cleaning up the plant to develop the strategies and technologies necessary to restore the plant to its original condition. Surely it’s a daunting mission, but every journey must begin somewhere, and in this case, it begins with the little sunfish.
Watch the video below for the first footage of the nuclear reactor and the little sunfish at work: