Japan restarts first nuclear reactor Anti-nuclear activists raise their fists in the air to protest against Japan's approval to resume nuclear plants. Ohi nuclear plant's reactor No.3 has returned to operation Last month, Prime Minister Yoshihiko Noda ordered restarts Tens of thousands of people have gathered in protest DOZENS of protesters have shouted and danced at the gate of the first nuclear power plant to restart since Japan shut down all of its reactors for safety checks following the Fukushima disaster. Ohi nuclear plant's reactor No.3 returned to operation despite a deep division in public opinion. Last month, Prime Minister Yoshihiko Noda ordered the restarts of reactors No.3 and nearby No.4, saying people's living standards can't be maintained without nuclear energy. Many citizens are against a return to nuclear power because of safety fears after the Fukushima accident. Tens of thousands of people have gathered on Friday evenings around Noda's official residence, chanting "Saikado hantai," or "No to nuclear restarts." All 50 of Japan's working reactors were gradually turned off following last year's massive earthquake and tsunami, which sent the Fukushima Dai-ichi plant into multiple meltdowns, setting off the worst nuclear disaster since Chernobyl. But worries about a power crunch over the hot summer months have been growing. Oil imports are soaring. Officials have warned about blackouts in some regions. The government has been carrying out new safety tests on nuclear plants, and says Ohi No.3 and No.4 are safe to restart. Protesters such as Taisuke Kohno, a 41-year-old musician among the 200 people trying to blockade the Ohi plant, aren't so sure. He said protesters were facing off against riot police and planned to stay there day and night. "It's a lie that nuclear energy is clean," he said. After experiencing the nuclear bombing of Hiroshima and Nagasaki, how can Japan possibly want nuclear power? Kansai Electric Power Co, the utility that operates Ohi in central Japan, said on its website that a nuclear reaction restarted at the No.3 reactor, a key step for it to begin producing electricity. Fukushima Dai-ichi, in northeastern Japan, went into meltdowns and exploded after the March 11 tsunami destroyed back-up generators to keep the reactor cores cool. In the latest problem at the crippled plant, Tokyo Electric Power Co, its operator, said the cooling system for the spent nuclear fuel pool at reactor No.4 broke down on Saturday, and a temporary system was set up on Sunday. The cooling system had to be restored within 70 hours, or temperatures would have started to rise, spewing radiation.