Kyushu Electric Power Co. restarted a nuclear reactor in Kagoshima Prefecture on Thursday after the prefectural governor, who is opposed to nuclear power, effectively permitted the move last week.

Reactor No. 1 at the Sendai nuclear power complex is one of five reactors to have been reactivated under stricter safety regulations adopted in the wake of the 2011 Fukushima reactor meltdowns. Following resumption in August 2015, its operation had been suspended for a regular checkup since Oct. 6.

The utility pulled out control rods from the reactor at around 9:30 p.m. The reactor is expected to achieve criticality by Friday morning and to start power generation from Sunday. Commercial operation is set to resume from Jan. 6.

Kyushu Electric on Tuesday notified Kagoshima Gov. Satoshi Mitazono of the planned restart of the reactor and was not requested to suspend it this time, it said.

Mitazono, who was elected in July on an anti-nuclear platform, asked the utility in August and September to immediately suspend operation of the plant. Reactor No. 1 came to a halt in October for a regular checkup.

The Sendai complex's reactor No. 2 is scheduled to be suspended for regular checks from Dec. 16 to Feb. 27.

Mitazono had told the prefectural assembly earlier this month that he had no legal power to decide whether to restart the reactor, paving the way for the latest move.

On Thursday, however, Mitazono said that he will take "strong action, regardless of the reactor's operation," if an experts' committee, which he plans to set up to examine safety at the plant, finds any safety problems.

Some 30 local residents and anti-nuclear group members gathered in front of the Sendai plant Thursday morning to protest the reactivation.