Fukushima's ground zero: No place for man or robot

The robots sent in to find highlyradioactive fuel at Fukushima's nuclear reactors have "died." Asubterranean "ice wall" around the crippled plant meant to stopgroundwater from becoming contaminated has yet to be finished.And authorities still don't know how to dispose of highlyradioactive water stored in an ever-mounting number of tanksaround the site.

Five years ago, one of the worst earthquakes in historytriggered a 10-metre high tsunami that crashed into theFukushima Daiichi nuclear power station causing multiplemeltdowns. Nearly 19,000 people were killed or left missing and160,000 lost their homes and livelihoods.

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Today, the radiation at the Fukushima plant is still sopowerful it has proven impossible to get into its bowels to findand remove the extremely dangerous blobs of melted fuel rods.

The plant's operator, Tokyo Electric Power Co (Tepco), has made some progress, such as removing hundreds ofspent fuel rodsin one damaged building. But the technologyneeded to establish the location of the melted fuel rods in theother three reactors at the plant has not been developed.

"It is extremely difficult to access the inside of thenuclear plant," Naohiro Masuda, Tepco's head of decommissioningsaid in an interview. "The biggest obstacle is the radiation."

The fuel rods melted through their containment vessels inthe reactors, and no one knows exactly where they are now. Thispart of the plant is so dangerous to humans, Tepco has beendeveloping robots, which can swim under water and negotiateobstacles in damaged tunnels and piping to search for the meltedfuel rods.

But as soon as they get close to the reactors, the radiationdestroys their wiring and renders them useless, causing longdelays, Masuda said.

Each robot has to be custom-built for each building."Ittakes two years to develop a single-function robot," Masudasaid.

Irradiated water

Tepco, which was fiercely criticised for its handling of thedisaster, says conditions at the Fukushima power station, siteof the worst nuclear disaster since Chernobyl in Ukraine 30years ago, have improved dramatically. Radiation levels in manyplaces at the site are now as low as those in Tokyo.

Watch "Fukushima: A Nuclear Story" onThe Passionate Eye onMarch 13 at 10p.m.ETon CBC News Network

More than 8,000 workers are at the plant at any one time,according to officials on a recent tour. Traffic is constant asthey spread across the site, removing debris, building storagetanks, laying piping and preparing to dismantle parts of theplant.

Much of the work involves pumping a steady torrent of waterinto the wrecked and highly radiated reactors to cool them down.Afterward, the radiated water is then pumped out of the plantand stored in tanks that are proliferating around the site.

What to do with the nearly million tonnes of radioactivewater is one of the biggest challenges, said Akira Ono, the sitemanager. Ono said he is "deeply worried" the storage tanks willleak radioactive water in the sea as they have done severaltimes before prompting strong criticism for the government.

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

Ono estimates that Tepco has completed around 10 per cent ofthe work to clear the site up the decommissioning processcould take 30 to 40 years. But until the company locates thefuel, it won't be able to assess progress and final costs,experts say.

The much-touted use of X-ray-like muon rays has yieldedlittle information about the location of the melted fuel and thelast robot inserted into one of the reactors sent only grainyimages before breaking down.

Ice wall to containgroundwater

Tepco is building the world's biggest ice wall to keepgroundwater from flowing into the basements of the damagedreactors and getting contaminated.

First suggested in 2013 and strongly backed by thegovernment, the wall was completed in February, after months ofdelays and questions surrounding its effectiveness. Later thisyear, Tepco plans to pump water into the wall which looks abit like the piping behind a refrigerator to start thefreezing process.

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

"The reactors continue to bleed radiation into the groundwater and thence into the Pacific Ocean," Gunderson said. "WhenTepco finally stops the groundwater, that will be the end of thebeginning."

While he would not rule out the possibility that smallamounts of radiation are reaching the ocean, Masuda, the head ofdecommissioning, said the leaks have ended after the companybuilt a wall along the shoreline near the reactors whose depthgoes to below the seabed.

"I am not about to say that it is absolutely zero, butbecause of this wall the amount of release has dramaticallydropped," he said.