Unit 4

At the time of the accident, although a hydrogen explosion occurred, all of the fuel rods of Unit 4 had been transferred to and were stored in the spent fuel pool as part of the periodic inspection, and they therefore received no major damage. The fuel rods were removed from the spent fuel pool and transferred to the common pool starting on November 18, 2013, and the transfer work was completed on December 22, 2014.

  • *

    "1533" is the number of fuel assemblies removed, except for two new fuel assemblies which were removed before in 2012.

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    Breakdown of transferred assemblies by type
    Spent fuel: 1,331 assemblies/1,331 assemblies
    Unirradiated (New) fuel: 202 assemblies/202 assemblies

  • *

    Number of times of cask transportation: 71

As of December 22, 2014

Overview of Fuel Removal from the Spent Fuel Pool

The fuel assemblies stored in the fuel rack inside the Unit 4 spent fuel pool were taken out and transferred to the common pool located within the station site for centralized storage.
This fuel removal operation started on November 18, 2013 and conducted with the following steps. Its completion date was December 22, 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 by using a fuel handling machine.

  • (2)

    Lift up the cask from the spent fuel pool by using a crane.

  • (3)

    Works such as closing the lid of and decontaminating the cask are performed on a floor as high as the operating floor.

  • (4)

    Lower the cask back down toward the ground using the crane to lay it on a trailer.

  • (5)

    Transport the cask to the common pool by using the trailer.

Other Units

Unit 1

The debris removal work in the upper part of the Unit 1 reactor building is underway.

Unit 2

Preparations are being made to demolish the upper part of the reactor building.

Unit 3

The fuel removal cover in the Unit 3 reactor building and other facilities are currently being installed.

Units 5 and 6

The decision to decommission these units was taken in December 2013. They are being 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 is being carried out in cooperation with research institutes including the International Research Institute for Nuclear Decommissioning (IRID) and related manufacturers.

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