The Nuclear Regulation Authority will conduct an onsite inspection June 15 of the only nuclear reactors now operating in Japan to check whether they are safe enough to be allowed to continue operating beyond July when new safety requirements take effect, sources close to the matter said Saturday.

About 20 inspectors, including NRA Commissioner Toyoshi Fuketa, will examine equipment such as an air-cooled power generator for emergency use and water pump newly installed at the No. 3 and 4 reactors at the Oi nuclear plant in Fukui Prefecture to respond to a severe accident.

The new requirements have been compiled to enhance nuclear regulation in the wake of the devastating accident at Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant in 2011, triggered by a massive earthquake and tsunami in March that year.