TEPCO has started removing fuel from the Unit 4 spent fuel pool at Fukushima Daiichi nuclear power station. Four un-used fuel assemblies were loaded into a cask during the first day of work on 18 November.
Once filled, the cask will be sealed, decontaminated, transported across site and unloaded in a common pool storage facility, serving all six reactors. This process is expected to take "approximately one week," according to TEPCO.
Preparation work started at 09:50am. Workers first opened the lid of the fuel transport container and it was transported to the spent fuel pool using the main crane. The container reached the bottom of the spent fuel pool at 12:30pm.
The fuel removal operation began at 3:18pm. Workers used the smaller refuelling crane to move fuel assemblies one by one from their vertical storage racks to the container. Loading of the first fuel assembly was completed at 3:27pm, according to TEPCO.
Once the transport container is full it will be sealed, lifted from the water by the main crane and placed on the service floor for decontamination. After decontamination it will be transported across the site and unloaded at a shared pool storage facility. This process will be repeated until the pool is empty.
It will take "approximately one week" from placing the first 22 fuel assemblies into the cask at the unit 4 spent fuel pool to storing it in the common pool, TEPCO said.
The Nuclear Regulatory Authority granted its approval for the security and radiological protection aspects of the work on 12 November. TEPCO engineers and workers completed final functional checks of the cranes using non-radioactive dummy fuel the following day.
The unit 4 spent fuel pool contains a total of 1533 fuel assemblies (1331 used, 202 unused). Work to remove the fuel assemblies is expected to last until the end of 2014.
Photo: Transport container is lowered into the unit 4 spent fuel pool (Source: TEPCO)