Even robots are 'dying' at Fukushima's ground zero: High levels of radiation destroy their wiring rendering them useless 

The robots sent in to find highly radioactive fuel at Fukushima's nuclear reactors, and to spare humans from having to enter the highly radiated area, have 'died'.

As soon the specially-designed machines get close to the reactors the radiation destroys their wiring and it renders the expensive pieces of kit all but useless. 

As a result, authorities still do not know how to dispose of highly radioactive water stored in an ever-mounting number of tanks around the site. 

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Five years ago, one of the worst earthquakes in history triggered a 32ft-high (10 metre) tsunami that crashed into the Fukushima Daiichi nuclear power station causing multiple meltdowns. A lone tree sits on the tsunami scarred landscape, inside the exclusion zone, which was decimated by the tide of water

Five years ago, one of the worst earthquakes in history triggered a 32ft (10 metre) high tsunami that crashed into the Fukushima Daiichi nuclear power station, causing multiple meltdowns.

Nearly 19,000 people were killed or left missing and 160,000 lost their homes and livelihoods.

Today the radiation at the Fukushima plant is still so powerful it has proven impossible to get into the reactors to find and remove the extremely dangerous melted fuel rods.

The plant's operator, Tokyo Electric Power Co (Tepco) has managed to remove hundreds of fuel roads in one damaged building.

The inside of the plant is unsafe for humans so Tepco has been developing robots to search for the melted fuel rods, pictured. The robots can swim under water and negotiate obstacles in damaged tunnels and piping. But as soon as they get close to the reactors, the radiation destroys their wiring and renders them useless

The disaster forced all of Japan's dozens of reactors offline for about two years in the face of public worries over safety and fears of radiation exposure

But the technology needed to find the melted fuel rods in the other three reactors at the plant has not been developed.

'It is extremely difficult to access the inside of the nuclear plant,' Naohiro Masuda, Tepco's head of decommissioning said. 

'The biggest obstacle is the radiation.'

The fuel rods melted through their containment vessels in the reactors so no one knows exactly where they are now.

This part of the plant is unsafe for humans so Tepco has been developing robots to search for the melted fuel rods. 

The robots can swim under water and negotiate obstacles in damaged tunnels and piping.

But as soon as they get close to the reactors, the radiation destroys their wiring and renders them useless.

This causes long delays, Masuda said. Each robot has to be custom-built for each of the four buildings, and it takestwo years to develop a single-function robot.

Tepco added that conditions at the Fukushima power station have improved dramatically since the disaster. 

A worker wearing a protective suit and a mask levels ground at Tokyo Electric Power Co's (Tepco) tsunami-crippled Fukushima Daiichi nuclear power plant in Okuma town, Fukushima prefecture, Japan

Radiation levels in many places at the site are now as low as those in Tokyo.

More than 8,000 workers are at the plant at any time, according to officials on a recent tour. 

Traffic is constant as they spread across the site, removing debris, building storage tanks, laying piping and preparing to dismantle parts of the plant.

Much of the work involves pumping a steady torrent of water into the wrecked and highly radiated reactors to cool them down.

Afterward, the radiated water is then pumped out of the plant and stored in tanks that are proliferating around the site.

Five years after the nuclear disaster emptied much of Japan's northeastern coast, tourism is giving locals of the abandoned town a chance to exorcise the horrors of the past

What to do with the nearly million tonnes of radioactive water is one of the biggest challenges, said Akira Ono, the site manager. 

Ono said he is 'deeply worried' the storage tanks will leak radioactive water in the sea, as they have done several times before, prompting strong criticism for the government.

The utility has so far failed to get the backing of local fishermen to release water it has treated into the ocean.

Ono estimates that Tepco has completed around 10 per cent of the work to clear the site up - the decommissioning process could take 30 to 40 years. 

But until the company locates the fuel, it won't be able to assess progress and final costs, experts say.

Use of X-ray like muon rays has yielded little information about the location of the melted fuel and the last robot inserted into one of the reactors sent only grainy images before breaking down.

Tepco is building the world's biggest ice wall to keep groundwater from flowing into the basements of the damaged reactors and getting contaminated.

First suggested in 2013 and strongly backed by the government, the wall was completed in February, after months of delays and questions surrounding its effectiveness. 

Later this year, Tepco plans to pump water into the wall - which looks a bit like the piping behind a refrigerator - to start the freezing process.

Stopping the ground water intrusion into the plant is critical, said Arnie Gunderson, a former nuclear engineer.

'The reactors continue to bleed radiation into the ground water and thence into the Pacific Ocean,' Gunderson said. 'When Tepco finally stops the groundwater, that will be the end of the beginning.'

While he would not rule out the possibility that small amounts of radiation are reaching the ocean, Masuda, the head of decommissioning, said the leaks have ended after the company built a wall along the shoreline near the reactors whose depth goes to below the seabed.

'I am not about to say that it is absolutely zero, but because of this wall the amount of release has dramatically dropped,' he said.