Progress of fuel removal from the spent fuel pool

Spent fuel used to generate electricity etc. is stored in the spent fuel pool located at the top of reactor building.In order to minimize risks associated with such spent fuel etc., we are preparing to remove them from the reactor building where the accident occurred.

About spent fuel

Nuclear fuel is replaced with unused one after it is used in a reactor. Spent fuel is the fuel removed for replacement. Since spent fuel generates heat, it is cooled in order to be stored stably.

Progress of fuel removal

Unit 1

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

Unit 2

A fuel removal work platform (work platform/anticum) will be constructed on the south side of the building in preparation for spent fuel removal.

Unit 3

Fuel removal started in April, 2019.

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.

  • *

    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

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.

Steps for fuel removal

  • (1)

    Fuel assemblies stored in the spent fuel pool are put into a transport container (cask) one by one in the water using a fuel handling machine.

  • (2)

    Lid is attached to the cask, which is then cleaned. After that it is lowered to the ground floor using a crane and loaded onto a trailer.

  • (3)

    The cask is transported to the common pool located on-site.

  • (4) Fuel in the cask is stored in the common pool.

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