Japan to be without nuclear power after May 5

Trade Minister Yukio Edano signaled it would take at least several weeks before the government, keen to avoid a power crunch, can give a final go-ahead to restarts, meaning Japan is set on May 6 to mark its first nuclear power-free day since 1970.

"If we thoroughly go through the procedure, it would be (on or) after May 6 even if we could restart them," Edano told a news conference, adding that whether they can actually be brought back online is still up to ongoing discussions.

The crisis at the Fukushima Daiichi nuclear plant, where a huge earthquake and tsunami in March 2011 triggered radiation leaks, has hammered public faith in nuclear power and prevented the restart of reactors shut down for regular maintenance checks, with all but one of 54 reactors now offline.

Nuclear power accounted for about 30 percent of Japan's electricity demand before the Fukushima crisis.

In discussing restarts of the No.3 and No.4 reactors at Kansai Electric's Ohi nuclear power plant, in western Japan, the first to clear the government's technical review on resilience against a severe event, Tokyo has said it wants local backing even though it is not legally required.

The hosts of the Ohi plant - the governor of Fukui prefecture and mayor of Ohi town, some 360 km (225 miles) southwest of Tokyo - told Edano on Saturday that some conditions should be met before they can make a decision.

These included a safety review by an expert panel formed by the prefecture and backing from areas neighboring Fukui that are becoming increasingly vocal about possible radiation damage in the event of an accident at any of the 13 reactors in Fukui.

Exactly when Fukui Governor Issei Nishikawa and Ohi Mayor Shinobu Tokioka will make decisions is unclear.

Members of the expert panel will be visiting the Ohi plant on Wednesday and are likely to meet several more times before they reach a conclusion, while the Fukui assembly may meet as early as next week to discuss whether they can back the restarts, Masao Sato, a member of the assembly, told Reuters.

Ohi town told Reuters in March that it conditionally backed the restart. Fukui governor Nishikawa told Edano on Saturday that, while the government has addressed some of Fukui's concerns, more discussions were needed on safety.

While a looming summertime power crunch is a headache throughout Japan, Kansai Electric's service region, including Japan's second biggest metropolitan area of Osaka, is particularly vulnerable as nuclear power met more than 40 percent of power needs prior to the Fukushima crisis.

Electricity generated by the Ohi No.3 and 4 reactors accounted for around 1.8 percent of the total amount of electricity generated in Japan in the business year 2009/10, data from the trade ministry and the Federation of Electric Power Companies in Japan showed.

Edano said that the government may have to protectively come up with plans for rolling blackouts.

"We absolutely cannot let power go out suddenly," he said.

The governors of Shiga and Kyoto prefectures, bordering Fukui, on Tuesday outlined recommendations for the central government on restarting reactors, including publicizing views from independent organizations on reactor safety.

The last time Japan saw a nuclear power-free period was the five days ended on May 4, 1970, when the two reactors then existing were both shut for maintenance, according to the Federation of Electric Power Companies of Japan.

(Additional reporting by Yoshiyuki Osada in Kyoto; Editing by Alex Richardson)