Toshiba Corp. on Monday demonstrated a device it anticipates will be used to remove fuel-rod assemblies from the spent fuel pool in the reactor 3 building at the crippled Fukushima No. 1 nuclear plant.
Scheduled to begin extracting 566 fuel-rod assemblies sometime in fiscal 2017, Toshiba, the builder of reactor 3, showed how the gigantic remote-control crane-like device will work during a demonstration at a company factory in Yokohama.
Tokyo Electric Power Co. has said that although it is working to reduce the radiation level inside the reactor 3 building, it remains impossible for humans to safely monitor the removal of the fuel-rod assemblies.
It was this hurdle that prompted Toshiba to create the remotely controlled device to clear debris and remove rods from the cooling pool.
The crane consists of two parts, including two robotic arms that can pick up and cut debris, and another arm that is designed to grab the assemblies.
The machine is equipped with a number of cameras, allowing workers to see from multiple angles and enabling them to better control it from a distance.
In December 2014, Tepco finished removing 1,535 fuel rod assemblies from the pool in the reactor 4 building.
For that job, low radiation levels allowed workers to stand at the pool to directly monitor the removal process.
Compared with that job, the removal of the fuel-rod assemblies from the reactor 3 pool will be “more difficult since it will have to be done completely remotely,” Tepco official Isao Shirai said.
Unlike reactor 4, which had been shut down and unfueled at the time of the March 11, 2011, disasters, reactor 3 was damaged by a hydrogen explosion and meltdown in the days that followed released radioactive materials into the area.
Tepco said it hopes to eventually bring radiation levels down to 1 millisievert per hour — a rate still too high for long-term work at the reactor 3 site.
The utility plans to install a cover over the pool and begin setting up the Toshiba device this year. Training for workers to master the intricacies of the remote-control system is expected to begin next year.
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