The first batch of 22 unused fuel assemblies has been successfully removed from a cooling pool in a damaged reactor building at the Fukushima nuclear power plant.
In spite of all the criticism it has received lately for its clumsy handling of the clean-up operations marked with contaminated water leaks,Tokyo Electric Power Company (Tepco) has managed to conduct the first stage of the fuel removal without complications. The process took four days to complete.
As exposing the rods to air could cause them break and release radioactive gas, all the removal operations had to be carried out under water.
Each of the 300kg and 4.5m-long assemblies was pulled out of the cooling pool’s rack on a crane and placed into a heavy steel cask to prevent it releasing radiation.
The cask was then transported to a building housing the station's common pool, which Tepco says wasn't damaged in the quake or tsunami, where the fuel will be deposited.
The fuel was removed from the plant's Unit 4, which was the only one that was off-line when a powerful earthquake struck the facility followed by a destructive tsunami in March 2011 sending the other three reactors into meltdown.
However, the reactor building itself was damaged during a series of hydrogen explosions and would most likely collapse if the area was hit by another earthquake.
Nuclear safety experts therefore decided the fuel rods, stored about 18 metres above ground level in the tilted building pose extreme safety risk.
According to Tepco, it will take a year to remove all 1,500 assemblies, each containing 50-70 fuel rods, from the damaged Unit 4 building. However, some experts have suggested the operation could take even longer, as the engineers don’t know whether any of these assemblies were damaged during the earthquake.
Removing spent fuel from the other three reactors will be even more complicated as their cores melted during the disaster after a cooling system failure. Decommissioning the whole plant is foreseen to take decades and cost billions of dollars.
Tepco said it will review the process before continuing the removal process.