The 10 Biggest Nuclear Reactors



  • Net Capacity: 4,494 megawatts
  • Location: Fukui, Japan
  • Number of Reactors: 4
  • Output (2010): 27,298.28 gigawatt-hours

Located 220 miles (350 kilometers) west of Tokyo, the Ohi power plant comes a close second to Fukushima Daini in churning out electricity for Japan. The facility generated 27,298.28 gigawatt-hours of energy in 2010 -- that would have been enough to provide all the homes in Maryland electricity in 2009 [sources: IAEA PRIS, KU Institute for Policy & Social Research].

Although the earthquake of March 2011 didn't directly affect the Ohi power station, Unit 3 has been offline since the disaster struck. In the aftermath of the quake, the Japanese government ordered all 35 nuclear reactors that had been shut down for regular safety inspections to remain offline until they completed a two-step stress test.

The test is designed to determine a reactor's ability to withstand large earthquakes and tsunamis. In October 2011, Ohi Unit 3 passed the first phase. Step two is a comprehensive stress test similar to those that have been proposed by the European Union. The test results will be sent to Japan's Nuclear and Industrial Safety Agency (NISA) and Nuclear Safety Commission (NSC) before an additional panel of government officials will decide whether Ohi 3 can resume operating. All of the reactors that were stopped after the quake will go through this process. As you can imagine, it will take time to get Japan's nuclear power stations back to full capacity.