Researchers say they have discovered melted fuel inside a second of Fukushima’s three damaged reactors, an important step towards cleaning up the plant in Japan.

Last week, engineers sent a long telescopic probe into Unit 2 and took images of what looks like melted fuel. The Tokyo Electric Power Company (TEPCO), who operated the rod, said it looked like the fuel had breached through the reactor’s core and fallen to the floor.

"There is so much that we still haven't seen," TEPCO spokesperson Takahiro Kimoto told reporters on Friday, January 19.

"But we were able to obtain important information that we need in order to determine the right method for removing the melted fuel debris."

Three of Fukushima’s six reactors went into meltdown in March 2011 following a deadly tsunami. About 160,000 people were evacuated from nearby, with little prospect of ever returning.

In order to begin the clean-up process, engineers need to locate that melted fuel from those reactors. The radiation levels at the reactors are too high for humans, though, so robots have been used – with varying success so far.

It wasn’t until July last year that the first melted fuel was found, thanks to a robot called Little Sunfish, at one of the reactors – Unit 3. Now that fuel has also been found at Unit 2, just one reactor remains. The plan is to start removing fuel by 2021.

On Friday, images were released showing the fuel in the shape of pebbles and clay.

 

Another image showed a bundle of fuel rods, which suggests they melted and breached out through the bottom of the reactor core.

To capture the images, TEPCO engineers inserted a pole 13 meters (43 feet) long into a small utility hole, 12 centimeters (4.7 inches) across. They spotted a handle for the fuel rod assembly, which means there must have been a pretty big hole in the reactor.

"This next effort at Unit 2 illustrates our commitment to developing technologies that will enable decommissioning at Fukushima Daiichi and also become useful elsewhere," said Chief Decommissioning Officer Naohiro Masuda in a statement from TEPCO.

"Even with the new approach this will be a challenging mission, but we will persevere because obtaining this information is important to developing the ability to eventually remove the fuel debris."

Once the fuel debris is found, the decommissioning process is expected to take four decades at a cost of $188 billion. This latest news, however, is an important step towards that beginning.