It has been more than eight years since the Tōhoku earthquake struck Japan, resulting in a devastating tsunami and damage to the Fukushima nuclear power plant. Several reactors at the plant went into meltdown, causing widespread contamination of the region. Tokyo Electric Power Company Holdings (Tepco) has just taken a major step toward cleaning up the site by removing the first spent-fuel assembly from reactor 3. Of course, they did it with a robot after figuring out how to keep them from dying.
The March 11, 2011 earthquake caused a 49-foot (15-meter) tsunami to come crashing down on the Fukushima plant. The water flowed easily over the sea wall protecting the facility, flooding the turbine buildings. Reactors 1, 2, and 3 all overheated and melted down. The build-up of hydrogen gas caused explosions that scattered radioactive debris across the landscape. It was a horrific accident that could have been even worse if not for the fact that the three other reactors were offline for inspections.
Tepco expects it will take decades to completely clean up the site, and the first major step in that process is removing the radioactive fuel rods from the melted-down reactors. Previously, Tepco removed all the fuel rods from reactor 4, which did not experience a meltdown. The company was supposed to begin removing fuel from reactors 1-3 in 2014, but technical issues and continued high levels of radiation delayed plans.
Fukushima Daiichi following the meltdown.
Earlier this year, Tepco started testing the technology employed in the new operation. It used a small remote-controlled probe to scoop up radioactive debris from the bottom of reactor 2. This week, Tepco used a remote operated crane to grab one of the fuel rods and remove it from its rack. The crane carefully lowered the rod into a storage cask that will eventually house many more rods. Once sealed, Tepco plans to move the casks to an on-site storage pool.
Reactor Unit 3 holds 514 spent-fuel assemblies and a further 52 unpent-fuel assemblies. Removing all of them is not an overnight task. Tepco hopes to have seven more low-risk fuel assemblies removed by June. It will take until at least March 2021 to have reactor 3 cleaned out. Work to remove the fuel rods from reactors 1 and 2 will start in 2023. The ruined Fukushima plant has 1,573 spent and unspent-fuel rods across all its reactors. Even when the operation is complete, it could be years before people are allowed back inside the core exclusion zone.
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