In July 2011, then Prime Minister Naoto Kan ordered stress tests on all Japan's 50 nuclear reactors to assess their safety. By May 2012, they were all idled and for the first time in 40 years the nation was not generating a single kWh from nuclear energy.

Controversially, on June 16, 2012, Kan's successor, Yoshihiko Noda, approved the restart of two reactors. This sparked mass protests that involved a million demonstrators through a summer that saw Japan's largest civil protests since the turbulent 1960s.

Noda faced strong opposition to his plans to hasten the restart of reactors due to widespread safety concerns. Haruki Madarame, chairman of the Nuclear Safety Commission, reinforced those anxieties when he announced in March 2012 that the stress tests were not sufficient to ensure the operational safety of reactors. The government then hastily cobbled together a provisional set of safety guidelines. As it turned out, the two reactors at the Oi nuclear power plant in Fukui Prefecture that had been restarted met only 20 out of the new 30 safety criteria. Furthermore, the power they generated was unnecessary even during one of the hottest summers in memory.