Japan has put its first nuclear reactor back online since the Fukushima nuclear disaster.
Ohi nuclear plant's Reactor No. 3 was restarted, despite a deep divide in public opinion.
Protests took place outside the plant.
Last month, Prime Minister Yoshihiko Noda ordered the restarts of reactors No. 3 and No. 4, saying living standards can't be maintained without nuclear energy.
All 50 of Japan's working reactors have been turned off.
Last year's earthquake and tsunami sent the Fukushima Dai-ichi plant into multiple meltdowns, setting off the worst nuclear disaster since Chornobyl.
Based on reporting by AP and AFP