TOKYO (AP) — Japanese nuclear regulators inspected ground structures at the country’s only operating nuclear plant to examine if an existing fault line is active.

The inspection Friday determines whether the Ohi plant in western Japan should close. Its No. 3 and No. 4 reactors went back online in July, becoming Japan’s only operating reactors after all 50 Japanese reactors went offline for inspection following the March 11, 2011, crisis at Fukushima Dai-ichi. 

A five-member team will meet Sunday in Tokyo to discuss the findings. 

If the fault that cuts across the Ohi plant is determined to be active, the plant must be closed.

Government’s safety guidelines ban a nuclear plant directly above an active fault.

Active faults are also thought to be under several other plants across Japan and are under investigation.