The Nuclear Regulation Authority formally kicked off the process Friday for determining whether the No. 3 and No. 4 reactors at the Oi power plant in Fukui Prefecture, the nation's only operating reactors, are safe enough to stay online after new safety requirements take effect in July.
The NRA compiled the new regulations to improve safety following the 2011 Fukushima crisis.
Operators of reactors that are still offline will have to wait for the requirements to come into force before applying to restart them.