Japan moved closer to another period without nuclear power as one of the nation's two operating reactors was set to be taken offline for routine checks late Monday.

Reactor 3 at Kansai Electric Power Co.'s Oi plant in Fukui Prefecture was scheduled to go offline at around 11 p.m., while reactor 4 at the same plant will be taken offline for checks on Sept. 15.

Kansai Electric Power, serving the region centering on Osaka Prefecture, said Friday that the halt of reactor 3 is unlikely to create an energy shortage this week as the high summer temperatures are expected to ease.

Reactors must undergo periodic inspections every 13 months.

Once the two reactors are halted, all of the nation's 50 commercial reactors again will be offline, repeating a situation that only happened previously after the 2011 start of the Fukushima No. 1 disaster.

For two months starting in May 2012, the nation experienced a period of no nuclear power for the first time in more than 40 years.

Kepco has already applied for the restart of reactors 3 and 4 at the Oi plant after their routine checks end.

But it is not clear when or if the two units can restart, because it is necessary to check to determine if they sit atop active faults, a scenario that could render their further operation illegal.