Tokyo Electric Power Co. shows its installation work to cover the upper part of the No. 3 nuclear reactor building that was blown off by the March 2011 hydrogen explosion at the Fukushima No. 1 nuclear power plant. (Masashi Nishimura)

OKUMA, Fukushima Prefecture--Tokyo Electric Power Co. showed reporters its progress in installing a new roof above Fukushima No. 1 nuclear plant’s No. 3 reactor building on Aug. 2, ahead of work to remove spent nuclear fuel from a storage pool.

The company demonstrated how it is carrying out the work, which is necessary because the upper section of the reactor building was blown off in a hydrogen explosion in the nuclear disaster at the plant in March 2011.

The roof project marks a step toward removing nuclear fuel assemblies in the spent nuclear fuel storage pool in the building.

To prevent the spread of radioactive material, TEPCO started to set up the half-tubular shaped cover to shield the damaged reactor building at the end of last month.

The 566 nuclear fuel assemblies currently lying in the pool will become a significant risk if another major disaster strikes the area.

TEPCO is expected to start removing the fuel from around mid-fiscal 2018.

Early on Aug. 2, part of the roof measuring around 17 meters high and weighing 37 tons was lifted to the top floor of the reactor building with a large crane.

Workers connected the new part of the cover to another section that had been installed at the end of July, completing one eighth of the roof. When finished, it will be about 60 meters long.

Dedicated removal machines are needed to retrieve the fuel from the storage pool. The machines that had been used at the plant prior to the accident were removed because they were severely damaged by the hydrogen explosion.