- At the time of the accident, although a hydrogen explosion occurred, all of the fuel rods had been transferred into and stored in the spent fuel pool as part of the periodic inspection. Therefore, they survived relatively undamaged.
- Fuel removal started on November 18, 2013 and is scheduled to be completed within year 2014.
Completion status of transfer from Unit 4 to Common Pool
- ◯Breakdown of transferred assemblies by kind
Spent fuel1,331 assemblies/1,331 assemblies
Unirradiated (New) fuel176 assemblies/ 202 assemblies
- ◯Number of times of cask transportation:
as of December 15, 2014
*The removal of the spent fuel assemblies was completed on November 5th,2014.
The removal operation will continue to be performed in a safe and measured manner until the last fuel assembly has been removed and transferred to the common pool.
*The radiation dose from new (unirradiated) fuel is small enough to handle by hand.
Outline of the fuel removal from the spent fuel pool
The fuel assemblies stored in the fuel rack inside the Unit 4 spent fuel pool are to be taken out and transferred to the common pool located within the station site for centralized storage. This fuel removal operation starts on November 18, 2013 and will be conducted with the following steps. Its completion is scheduled for the end of 2014.
- (1)Relocate the fuel assemblies stored in the fuel rack inside the spent fuel pool, one by one, into a transportation container (cask) underwater using a fuel handling machine.
- (2)Lift up the cask from the spent fuel pool using a crane.
- (3)Conduct, on the floor as high as the operating floor, such works as closing the lid of the cask and decontaminating the cask.
- (4)Lift down the cask toward the ground using the crane to lay it on a trailer.
- (5)Transport the cask to the common pool using the trailer.
Summarized explanation (3:42)
Actual work (3:42)
Photos and videos
On-premise transportation container landing on the water and fuel removal
Video taken underwater
Work at the common pool
Extraction of spent fuel
Video taken underwater: extraction of spent fuel
Cask transfer at common pool
Frequently asked questions
For frequently asked questions, please click here.
- Since the fuel melted into a state called debris, it became difficult to apply conventional measures to remove it.
- To deal with this situation, we are planning to conduct the task in parallel with the development of tools and devices for removal, etc. during the decommissioning process, over the next 30 to 40 years.
- Having been spared from the worst effects of the earthquake and tsunami, these units’ fuel remains stored in a stable condition under a cooling system in the nuclear reactors and spent fuel pools.
- The decision to decommission these units was taken in December 2013. They will be utilized for full scale mock-up tests (demonstrations using actual equipment) for research and development in the areas of remote-controlled decontamination of reactor buildings, investigation of the inside of primary containment vessels, and devices to remove fuel debris. The work will be carried out in cooperation with research institutes including the International Research Institute for Nuclear Decommissioning (IRID) and manufacturers.