Fukushima ready for risky fuel rod removal
Print Edition
Nuclear engineers in Japan are preparing to move uranium and plutonium fuel rods at Fukushima, their most difficult and dangerous task since the plant’s runaway reactors were brought under control two years ago.
Tokyo Electric Power, or TEPCO, will this month begin removing fuel rods from a pool inside a reactor building at the tsunami-hit plant after months of setbacks and glitches.
Experts say the operation is a tricky but essential step in the decades-long decommissioning after the worst atomic accident in a generation.
But it pales in comparison with the much more complex task that awaits engineers who will have to remove the misshapen 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 — must be pulled out of the storage pool where they were kept when a tsunami smashed into Fukushima in March 2011.
The reactor which the pool serves — No. 4 — was not in operation at the time. But hydrogen from Reactor No. 3 got into the building and exploded, tearing the roof off and leaving it at the mercy of earthquakes, storms or another tsunami.
TEPCO says it has not yet found any damage to the assemblies at No. 4, but will be monitoring for abnormalities, such as rust. The removal of fuel is routine at nuclear power plants, but “conditions are different from normal because of the disaster”, company spokeswoman Mayumi Yoshida said.
“It is crucial. It is a first big step towards decommissioning. This is an operation TEPCO cannot afford to bungle,” she said.
A crane has been installed in the building, which is now concealed under a new L-shaped structure.
Reporters were taken to the fourth floor of the plant yesterday, approximately 30 meters up, where they saw the remotely-controlled grabber that will plunge into the pool and hook onto a fuel assembly, placing it inside a fully immersed cask.
The 4.5-meter bundles, weighing 300 kilograms, have to be kept in water during the operation to keep them cool.
“If, for some reason, the water levels dropped, the fuel would quickly heat up,” said Takashi Hara, a TEPCO employee in charge of fuel removal.
The 91-ton cask will then be hauled from the pool — containing as many as 22 fuel assemblies and a lot of water — to be loaded onto a trailer and taken to a different storage pool, where the operation will be reversed.
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