Four utilities are planning to apply for permission to restart 12 reactors at six nuclear power plants across Japan as soon as a set of new safety requirements, approved June 19 by the Nuclear Regulation Authority, enter into force on July 8.
Ten of the 12 reactors are idle. The other two are running, but are expected to go offline for regular inspections in September.
With the Nuclear Regulation Authority expected to need about six months for screening the restart applications, the first of their kind, it appears unlikely any of the reactors will be brought back online by the end of this year.
The applications are being prepared for reactivating the No. 1, No. 2 and No. 3 reactors at Hokkaido Electric Power Co.'s Tomari nuclear plant; the No. 3 and No. 4 reactors at Kansai Electric Power Co.'s Oi nuclear plant in Fukui Prefecture; the No. 3 and No. 4 reactors at Kansai Electric's Takahama nuclear plant, also in Fukui Prefecture; the No. 3 reactor at Shikoku Electric Power Co.'s Ikata nuclear plant in Ehime Prefecture; the No. 3 and No. 4 reactors at Kyushu Electric Power Co.'s Genkai nuclear plant in Saga Prefecture; and the No. 1 and No. 2 reactors at Kyushu Electric's Sendai nuclear plant in Kagoshima Prefecture.
They are all pressurized water reactors, different in type from the crippled boiling water reactors at Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant. Pressurized water reactors have been granted a five-year grace period for installing filtered venting equipment for suppressing the discharge of radioactive substances during a severe accident.
They are all relatively new, being in service for less than 30 years, which makes it easier for them to meet the revised safety requirements.
Some experts have argued that a geological fault line running across the premises of the Oi plant may be active. The debate could protract the safety screenings for the No. 3 and No. 4 reactors at Oi, which are the only two of Japan's 50 nuclear reactors that are currently up and running.
Once the two Oi reactors go offline in September, there will be no active nuclear reactors in Japan, as was the case between May through July 2012. That was the first time since 1970 that such a situation had occurred.
Kyushu Electric could delay the restart applications for the No. 3 and No. 4 reactors at Genkai, where retrofitting work is expected to last through September. Observers say the No. 3 reactor at Ikata faces the fewest technical hurdles to a restart of all 12 reactors being considered for reactivation.
Leaders of local governments that host reactors being considered for early restarts have hailed the official endorsement of the reinforced safety requirements.
"Rigorous safety standards have been set on the basis of up-to-date knowledge and the lessons learned from the Fukushima nuclear disaster," said Kazuhiko Yamashita, mayor of Ikata, where the Ikata nuclear plant is located.
"We are one step higher on a flight of steps to a restart," said Hideo Iwakiri, mayor of Satsumasendai, home to the Sendai nuclear plant.
But critics have said the new safety requirements are not enough.
"I can hardly believe lessons were learned from the Fukushima nuclear disaster," said Hirohiko Izumida, governor of Niigata Prefecture, which hosts Tokyo Electric's Kashiwazaki-Kariwa nuclear plant. He pointed out the new regulation standards do not clearly define who should make decisions to deal with a potential nuclear accident, such as whether to pump in seawater to cool down an overheating reactor.
"The central government has to make up for the shortcomings, including by amending laws and regulations," Izumida added.
The Citizens' Commission on Nuclear Energy, which organizes researchers and civil advocacy groups, submitted a 10-item emergency recommendation to the Cabinet Office and the Nuclear Regulation Authority on June 19.
"The new regulations have been pushed through under political pressure, and are questionable in so many points," said Harutoshi Funabashi, a Hosei University sociology professor who chairs the organization.
(Ryuta Koike and Jin Nishikawa contributed to this article.)