Fukushima plant readies for dangerous fuel rod removal

Nuclear engineers in Japan are readying to move uranium and plutonium fuel rods at Fukushima, in their most difficult and dangerous task since the plant's runaway reactors were brought under control two years ago.
Tokyo Electric Power (TEPCO) is expected this month to begin taking out fuel rods from a pool inside a reactor building at the tsunami-hit plant, in a technically challenging operation that will test the utility's know-how after months of setbacks and glitches.
Experts say the operation is a tricky but essential step in the decades-long decommissioning process after the worst atomic accident in a generation.
But, they add, it pales in comparison with the much more complex task that awaits engineers who will have to remove the mis-shapen cores of three reactors that went into meltdown, probably relying on technology that has not yet been invented.

More than 1,500 nuclear fuel assemblies -- bundles of rods -- need to be pulled out of the storage pool where they were being kept when the tsunami smashed into Fukushima in March 2011.
The reactor the pool serves -- No 4 -- was not in operation at the time but hydrogen from Reactor No 3 escaped into the building and exploded, tearing the roof off and leaving it at the mercy of natural hazards like earthquakes, storms or another tsunami.

TEPCO says it has not yet found any damage to the assemblies at No 4, which contain a mixture of uranium and plutonium, but will be monitoring for abnormalities.

The removal of fuel is part of regular work at any nuclear power plant, but "conditions are different from normal because of the disaster," said company spokeswoman Mayumi Yoshida.
"It is crucial. It is a first big step towards decommissioning the reactors," she said. "Being fully aware of risks, we are determined to go ahead with operations cautiously and securely."
"This is an operation TEPCO cannot afford to bungle"
Chunks of debris that were sent flying into the pool by explosions have largely been removed and a crane has been installed. A protective hood has been erected over the building's skeleton to contain any radioactive leaks.

A remotely-controlled grabber will sink into the pool and hook onto a fuel assembly, which it will pull up and place inside a fully immersed cask.
The 4.5-metre bundles weighing 300 kilogramme have to be kept in water throughout the operation to keep them cool.