Common Pool & Cask Storage
TEPCO began emptying common pool fuel to the cask storage field and unit 4 spent fuel to the common pool in late 2013. This work was completed in 2014.
Common Pool Total Space: 6840 assemblies
Common Pool Current Inventory: 6089 assemblies*
Permanent Cask Storage: 1412 assemblies
Temporary Cask Bunkers: number unknown
Cask Sizes: 52 and 37 assembly-sized casks used. TEPCO is using a 22 assembly-sized transportation cask to move fuel from the reactor building spent fuel pools to the common pool.
*TEPCO has been removing fuel from the pool to a cask storage facility built up on the hill.
A spent fuel assembly can have 7,500 trillion becquerels of radioactivity within it 3 years after being removed from the reactor. This is why spent fuel is always handled underwater or stored in casks
The common or shared pool and current cask storage are part of TEPCO’s pre-disaster fuel management plan. The common pool holds much of the overflow spent fuel inventory from units 1-6 at Fukushima Daiichi. As part of TEPCO’s roadmap, they intend to make changes to the common pool so damaged fuel may be inspected and stored separately from intact fuel assemblies. (This will include adding a bulkhead wall to separate the two.) The bulkhead plan was scrapped in 2012-2013 in favor of removing fuel from the common pool to cask storage to make room.
Units 1-4 Spent Fuel Being Moved To Common Pool
By September 2014 most of the spent fuel had been removed from unit 4. The remaining fuel consists of mostly unused fuel assemblies and damaged assemblies. At least some of these will be stored in the spent fuel pool of unit 6 for the time being. As of November 2013, TEPCO began moving fuel from the unit 4 spent fuel pool to the common pool. TEPCO announced prior to this that they were moving current fuel from the common pool to cask storage bunkers up on the hill to make room. The transport cask being used for the process of removal from unit 4 is an NFT-22B model transport cask (aka CASTOR). TEPCO originally planned to remove spent fuel from units 1-4 on this schedule:
Cask Storage Bunkers
TEPCO began moving fuel into the cask bunkers in 2012. They have not been clear about how many of the casks will be transferred to the bunkers in total. The current capacity is 6840 fuel assemblies. Fuel from the common pool has been loaded into casks and sent to the bunkers up on the hill. As they need to make room in the common pool older fuel can be put into casks and moved to new bunker storage.
Cask Storage Building
This building (pictured on the right) holds a small number of casks. As of 2014, the Cask Storage Building has been emptied of all casks. The cask storage building resides near the docks. Casks stored here are intended to be shipped out to France or the UK for reprocessing rather than for long-term storage. With the disaster at the plant and Japan’s fuel reprocessing plan now up in the air, no fuel is being shipped out of Fukushima Daiichi.
An interim fuel storage center at Rokkasho has been in the works but was dependent on the completion of a fuel reprocessing facility there. Local agreements tied the two together. Considerable local backlash resulted when the central government suggested ending the reprocessing facility but keeping the fuel storage in Rokkasho. Locals demanded all the fuel casks be sent back to their original location but that has not happened to date.
Fuel Location Status
As of April 2014, this was the count of spent fuel in each reactor unit spent fuel pool, the bottom table lists the cask facility on the hill, then the common pool. The line in the top table with all zeros is the emptied old cask storage building.
An updated version of the spent fuel chart from 11.2021