The remote-controlled robots that were sent into the site of the 2011 meltdown at the Fukushima Daiichi nuclear power plant in Japan have reportedly 'died', thanks to incredibly high amounts of leaked radioactive materials destroying their wiring.

The robots - which take years to manufacture - were designed to swim through the underwater tunnels of the now-defunct cooling pools, and remove hundreds of extremely dangerous blobs of melted fuel rods. But it looks like that’s not going to happen any time soon.

In 2011, one of the most severe earthquakes in recorded history triggered a 10-metre-high tsunami that killed nearly 19,000 people and destroyed the homes and jobs of 160,000, and crashed into Japan’s Fukushima nuclear power plant, leading to several meltdowns.

Five years on, and researchers from the Tokyo Electric Power Company (Tepco) - the Japanese utility that maintains the site - still can’t figure out how to clean up the highly dangerous radioactive materials in the water and melted fuel rods that remain on the site.

"Efforts to clean up Fukushima, which is considered the largest nuclear disaster since the Chernobyl accident in 1986, are under continued scrutiny after a series of blunders and Tepco's admission that efforts in the short term to contain contamination may take as long as 30-40 years," Peter Dockrill reported for us back in January, when the robots were first deployed.

It’s estimated that the team has so far only addressed 10 percent of the mess left behind by the meltdowns, and the pressure to get a move-on is certainly not going to go away any time soon, with news last December that the damaged plant is continuing to leak small amounts of radioactive materials into the Pacific Ocean. Radioactive material has even been showing up on the west coast of the US.

One approach Tepco has taken is to build the world’s biggest 'ice wall' around the plant to stop the nearby groundwater being contaminated, but that’s yet to be completed, and it only stems the damage - it doesn’t clean up the mess that’s still sitting in there.

"It is extremely difficult to access the inside of the nuclear plant," Naohiro Masuda, Tepco's head of decommissioning, told Reuters. "The biggest obstacle is the radiation."

"The reactors continue to bleed radiation into the ground water and thence into the Pacific Ocean," added Artie Gunderson, a former nuclear engineer who is not involved in the project. "When Tepco finally stops the groundwater, that will be the end of the beginning."

As we reported in January, Tepco successfully removed 1,535 spent fuel-rod assemblies from the cooling pool in the reactor 4 building, which was a relatively easy job because that reactor had lower radiation levels, so human workers could oversee the retrieval process more closely.

Reactor 3, which is where our poor, recently deceased robots had been sent, contains far higher levels of radiation, and humans can’t get near it. It’s estimated that there are 566 fuel-rod assemblies that need to be removed from just this one reactor.

"The fuel rods melted through their containment vessels in the reactors, and no one knows exactly where they are now," Reuters reports.

As soon as the robots got close to the reactors, the radiation destroyed their wiring and rendered them useless, causing long delays, Masuda told the press organisation, adding that because each robot has to be custom-built for each building, it takes two years to develop every single one.

Meanwhile, the Fukushima site manager, Akiro Ono, admitted that he was "deeply worried" that the storage tanks will leak radioactive water into the sea if they can’t figure out how to get everything cleaned up in time.

It’s not yet clear if better, stronger robots are the answer to cleaning up the Reactor 3 building, it could be that the technology to build robots that are resistant to such high levels of radiation doesn’t actually exist, and the Tepco researchers will have to come up with some other solution.

What we do know is this problem isn’t going away any time soon, and if leakages occur, it will affect us all, so all we can do is hope that the science will come through. In the meantime, you can watch the robots below - in happier times before they were destroyed - and marvel at how freaking cool they once were: