An aerial view shows No 4 (front L), No 3 (front R), No 2 (rear L) and No 1 reactor buildings at Kansai Electric Power Co.'s Takahama nuclear power plant in Takahama town, Fukui prefecture, in this file photo taken by Kyodo November 27, 2014. [Photo/Agencies]

TOKYO - Japan restarted a nuclear complex on Friday in Fukui Prefecture, western Japan, marking the second complex since the 2011 Fukushima disaster to be brought back online.

It is also the first of the fast-breeder type of reactors that run on uranium-plutonium mixed oxide fuel to become operational.

Kansai Electric Power Co. confirmed that it had reactivated the No 3 reactor at its Takahama plant in Fukui Prefecture.

The restart came a year after the utility was first granted approval to reboot the reactor after gaining approval from Japan's Nuclear Regulation Authority (NRA) under its new, stricter safety guidelines.

The reactor is expected to reach criticality within half a day and generate electricity in around four days, its operator said.

There are now three reactors operational in the wake of the Fukushima disaster, the worst in commercial nuclear history, including two reactors at Kyushu Electric Power Co.'s Sendai plant in Kagoshima Prefecture. They were brought back online last year in August and October.

The Japanese government is looking to bring all of the nation's 48 reactors idled for safety checks and in the wake of the Fukushima multiple meltdowns back online and aims to produce 20 percent of the country's electricity from nuclear power by 2030, despite public opposition.