Japan has restarted the first nuclear reactor since the meltdown at the Fukushima power plant last year.
Hundreds gathered near the plant in the town of Ohi to protest against the move.
Last month, the prime minister urged support, saying a return to nuclear power was essential for the economy. All 50 of Japan’s nuclear plants were shut after the meltdown at Fukushima, which was triggered by a tsunami and earthquake. The crisis was regarded as the worst nuclear disaster since Chernobyl in 1986.
About 100 of the 650 protesters at the nuclear plant blocked a nearby road overnight, but a Kepco spokesman said the reactivation was not affected.
On June 29, tens of thousands took part in anti-nuclear rallies in Tokyo outside Prime Minister Yoshihiko Noda’s official residence, chanting “Saikado hantai,” or “No to nuclear restarts,” in what correspondents say was a rare show of dissent in Japan. The BBC’s Mariko Oi says it was one of the largest demonstrations seen since the reactors at Fukushima were damaged in March 2011.
Tokyo-based protester Nobuhiko Shudo told the BBC the problem of disposing of radioactive waste was key. “The most important thing for us is sustainability of the Earth for the next generation, so if we have some problems to keep the planet clean and beautiful, then we have to change the industrial structure” to foster alternative energy sources, he said.