By Aaron Sheldrick and Minami Funakoshi
(Reuters) – The robots sent in to find highly radioactive fuel at Fukushima’s nuclear reactors have “died”; a subterranean “ice wall” around the crippled plant meant to stop groundwater from becoming contaminated has yet to be finished. And authorities still don’t how to dispose of highly radioactive water stored in an ever mounting number of tanks around the site.
Five years ago, one of the worst earthquakes in history triggered a 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 its bowels to find and remove the extremely dangerous blobs of melted fuel rods.
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,” Naohero 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.