15 Apr (NucNet): The operator of the Fukushima-Daiichi nuclear power station has begun removing fuel from a cooling pool at one of three reactors that melted down following the March 2011 earthquake and tsunami.
Tokyo Electric Power Company said today that workers started removing the first of 566 used and unused fuel rods stored in the pool at Unit 3.
The measure marks a milestone in efforts to decommission the plant, although the more critical removal of melted fuel from inside the three damaged reactors, Units 1, 2 and 3, will prove more difficult.
Tepco said fuel rod removal from Unit 3 will take two years, followed by Units 1 and 2 where about 1,000 fuel rods remain in storage pools. In 2017 Tepco said it expected fuel removal at Units 1 and 2 to begin between 2020 and 2023.
The fuel rods stored in Unit 3’s cooling pool were not damaged in the 2011 disaster, when a powerful earthquake and tsunami knocked out Fukushima-Daiichi’s backup power supply and triggered the world’s worst nuclear accident since Chernobyl, 25 years earlier. Transferring them to safer ground would better protect them in the event of another catastrophic earthquake.
Workers are remotely operating a crane to raise the fuel from a storage rack in the pool and place it into a protective cask. The whole process occurs underwater to prevent radiation leaks. The utility plans to repeat the procedure in the two other reactors that suffered meltdowns.
In 2014, Tepco removed all 1,533 fuel rods from the storage pool at Unit 4, which was idle and had no fuel loaded when the earthquake and tsunami occurred. All fuel rods have been removed from storage pools at Units 5 and 6, which were offline but still fuelled..
Units 4, 5 and 6 did not suffer any fuel damage during the earthquake and tsunami. Unit 4 was offline and was not loaded with fuel, but the reactor building was severely damaged by a hydrogen explosion. Units 5 and 6 were offline, but were still fuelled.
Fuel from Units 5 and 6 was unloaded into the reactors’ storage pools and from there into a central fuel storage pool onsite.
Tepco said in 2018 that the fuel in the central storage pool will be transferred into dry storage casks which will temporarily stay onsite. At a later stage, these casks will be shipped to central dry-storage facilities at Rokkasho and Mutsu.