nuclear-news

Today, the radiation at the Fukushima plant is still so powerful it has proven impossible to get into its bowels to find and remove the extremely dangerous blobs of melted fuel rods, weighing hundreds of tonnes. Five robots sent into the reactors have failed to return.

The plant’s operator, Tokyo Electric Power Co (Tepco) 9501.t, has made some progress, such as removing hundreds of spent fuel roads in one damaged building. But the technology needed to establish the location of 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 in an interview. “The biggest obstacle is the radiation.”

The fuel rods melted through their containment vessels in the reactors, and no one knows exactly where they are now. This part of the plant is so dangerous to humans, Tepco has been developing robots, which can swim under water and negotiate obstacles in damaged tunnels and piping to search for the melted fuel rods.

But as soon as they get close to the reactors, the radiation destroys their wiring and renders them useless, causing long delays, Masuda said.

Each robot has to be custom-built for each building.“It takes two years to develop a single-function robot,” Masuda said.  ………

ICE WALL

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 Gundersen, a former nuclear engineer………..Reporting by Aaron Sheldrick and Minami Funakoshi. Editing by Bill Tarrant http://www.reuters.com/article/us-japan-disaster-decommissioning-idUSKCN0WB2X5