Japan ended two months without nuclear power on Thursday when the No. 3 unit at Kansai Electric Power Co's Ohi plant became the first reactor to resume supplying electricity to the grid since a nationwide safety shutdown after the Fukushima disaster.
Japan's last working reactor was idled in early May, leaving the country without nuclear power for the first time since 1970.
The rest of the 50 reactors had already been halted for maintenance and safety checks to see if they could withstand an earthquake and tsunami similar to the disaster that devastated Tokyo Electric Power's Fukushima Daiichi plant in March 2011, causing the worst atomic crisis since Chernobyl in 1986.
The government approved the restart of the No. 3 and No.4 Ohi units in western Japan to avoid a possible summer power crunch. But public safety concerns over nuclear power remain deep, with surveys showing about 70 percent of voters want the country to ditch nuclear eventually.