The Nuclear Regulation Authority found no critical problems during an on-site inspection Saturday of Kansai Electric Power Co.'s Oi nuclear plant, while assessing whether its two reactors can meet new safety requirements coming into force in July.

"We did not come away with any impression that something is definitively insufficient or needs an emergency response," NRA Commissioner Toyoshi Fuketa said after his team examined reactors 3 and 4, the nation's sole operating units, in Fukui Prefecture.

The NRA set up an investigative panel after an outline of the new standards was compiled in April to check if Kepco is sufficiently prepared for potential dangers like quakes and tsunami.

While the panel will formally report the outcome of its assessment to the NRA later this month, the watchdog is now expected to allow the reactors to stay online through September — which will be followed by shutdowns for mandatory checkups.

All of Japan's reactors were temporarily taken offline in the wake of the nuclear crisis at the Fukushima No. 1 power plant in March 2011. But the two reactors at the Oi plant were reactivated in July last year because they cleared a set of provisional safety standards introduced by the government at that time.

As for the nation's other reactors, utilities are expected to apply for permission to restart them after the new requirements enter into force next month.