The “Little Sunfish,” the swimming robot that TEPCO is using to capture images of the containment vessel in the Unit 3 reactor of the ruined Fukushima power plant, has brought back the goods.
A trove of new images captured in the past few days show what is likely to be melted nuclear fuel from inside the reactor, what Bloomberg describes as a “potential milestone” in the cleanup of one of the worst atomic disasters in history.
The pictures show what looks to be the melted nuclear fuel that caused the worst-ever nuclear disaster when northeastern Japan was hit by a massive earthquake and tsunami in March 2011. If confirmed, these would be the first discovery of the fuel, which is being sought by TEPCO as part of the cleanup effort.
“Tokyo Electric Power Co. Holdings Inc., Japan’s biggest utility, released images on Saturday of mounds of black rock and sand-like substances at the bottom of the No. 3 reactor containment vessel at Fukushima, which is likely to contain melted fuel, according to Takahiro Kimoto, an official at the company. A survey on Friday found black icicles hanging from the above pressure vessel, which was “highly likely” to contain melted fuel. Kimoto noted it would take time to confirm whether this debris contains melted fuel.
‘The pictures that we have gained will assist us in devising a plan for removing the melted fuel,’ Kimoto told reporters Saturday night in Tokyo. ‘Taking pictures of how debris scattered inside of the reactor was a big accomplishment.’
If confirmed, these pictures would be the first discovery of the fuel that melted during the triple reactor accident at Fukushima six years ago. For Tokyo Electric, which bears most of the cleanup costs, the discovery would help the utility design a way to remove the highly-radioactive material.”
The pictures were taken by the “Little Sunfish,” the Toshiba-designed robot the company sent into the destroyed reactors to explore the inside of the reactor for the first time from July 19. The robot, 30 centimeters (12 inches) long that can swim in the flooded unit, was tasked with surveying the damage inside and also finding the location of corium, which is a mixture of the atomic fuel rods and other structural materials that forms after a meltdown.
“It is important to know the exact locations and the physical, chemical, radiological forms of the corium to develop the necessary engineering defueling plans for the safe removal of the radioactive materials,” said Lake Barrett, a former official at the U.S. Nuclear Regulatory Commission who was involved with the cleanup at the Three Mile Island nuclear power plant in the U.S.
“The recent investigation results are significant early signs of progress on the long road ahead.”