Tepco decided in July 2019 that it would permanently close the facility, which means all 10 nuclear reactor units in the northeastern prefecture of Fukushima, including the six at Fukushima-Daiichi, will be decommissioned.
The company presented the outline of decommissioning plans to the municipal assembly of Tomioka, one of the two host towns of the nuclear station.
The utility estimated the cost of decommissioning Fukushima-Daini at 280 billion yen ($2.59bn).
According to the outline, the decommissioning process for Fukushima-Daini will have four stages, taking 10 years for the first stage, 12 years for the second stage and 11 years each for the third and fourth stages.
Tepco will survey radioactive contamination at the facility in the first stage, clear equipment around nuclear reactors in the second, remove the reactors in the third and demolish the reactor buildings in the fourth.
Tepco said it will transfer a total of 9,532 spent nuclear fuel units at the facility to a fuel reprocessing company by the end of the decommissioning process, and 544 unused fuel units to a processing firm by the start of the third stage.
The company will submit its finalised decommissioning plans for Fukushima-Daini to the Nuclear Regulation Authority after gaining approval from the municipal governments of Tomioka and the other host town, Naraha, and the Fukushima prefectural government.
Fukushima-Daini has four 1,067-MW boiling water reactors that began commercial operation between April 1982 and August 1987.
All four units have been shut down since the March 2011 earthquake and tsunami which resulted in a series of equipment failures, fuel meltdowns, and releases of radioactive materials at nearby Fukushima-Daiichi.
Twenty-seven of Japan’s 42 commercial nuclear units have been designated for decommissioning and plans for the decommissioning of 11 have now been approved by the regulator.
Japan has a total of 62 nuclear power units, but shut down all 42 reactors that were operating at the time after the Fukushima-Daiichi accident. Thirty-three units have a licence to operate although before units return to service they need to meet stricter safety standards introduced following Fukushima-Daiichi.