Several more reactors have since shut for regular maintenance, slashing Japan's nuclear generating capacity to just 7,580 megawatts, or only 36 percent of its registered nuclear capacity.
In May, Japan's average nuclear run rate fell to 40.9 percent, the lowest in at least a decade and well below 62.1 percent a year earlier.
Before the quake and tsunami, which forced the closure of three other power plants in addition to Tokyo Electric Power Co's Fukushima Daiichi facility, nuclear power supplied about 30 percent of Japan's electricity.
Although a reactor is legally cleared for restart once it receives approval from the Nuclear and Industrial Safety Agency (NISA), a trade ministry watchdog, nuclear operators always seek local government approvals as well, in recognition of the importance of support from the community around the plant.
If no reactors that shut for regular maintenance after the disaster are restarted, it would cost an extra 2.4 trillion yen ($30 billion) to make up lost power generation during the financial year to next March, a trade ministry estimate showed.
If all of Japan's reactors end up offline without any restarts, the extra cost would escalate to 3 trillion yen a year, reflecting the need to buy more fossil fuels from abroad while the use of renewable energy remains limited.
Among the 19 Japanese reactors that remain online, the last due to be shut for inspections -- on April 9, 2012 -- is the 1,356 megawatt No.6 reactor at Tokyo Electric's Kashiwazaki-Kariwa plant in northwestern Japan a NISA official said. The reactor came out of its last maintenance period just two days before the March 11 disaster.
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http://www.reuters.com/article/2011/06/08/us-japan-nuclear-reactors-idUSTRE7572P920110608
