Japan will allow nuclear reactors to operate for up to 60 years in revised regulations on power plant operators.
The decision marks the first time Japan has set a limit on a reactor's maximum lifespan and comes while it debates an energy strategy that is expected to give a greater role to renewables.
The government said it aims to introduce the 60-year limit a year from now as part of a revision of laws regulating nuclear plant operators after the March 11 earthquake and tsunami crippled reactor cooling systems in the Fukushima Daiichi complex, triggering meltdowns and radiation leaks that led to mass evacuations and widespread contamination.
Public anxiety sparked by the disaster has prevented the restart of many reactors shut for routine checks, and only five of the nation's 54 reactors remain online, prompting utilities to import more fossil fuels to bridge the gap.
Chief Cabinet Secretary Osamu Fujimura said details were still under consideration but the lifespan of a reactor would in principle be 40 years, as suggested by Environment and Nuclear Accident Prevention Minister Goshi Hosono earlier this month. The government will allow plant operators to apply for one extension of up to 20 years for each reactor, in line with US standards.
"There will be no change in the fact that the number of reactors will decline, as will Japan's reliance on them. But we're not talking about the immediate future," Fujimura said at a news conference.
Under the current system, plant operators can apply for an extension after 30 years and are usually granted 10-year extensions with no limit on how often they reapply as long as the nuclear watchdog approves.
The six reactors at the wrecked Fukushima plant are among the oldest, having started operation between 1971 and 1979. Twelve other reactors date back to the 1970s, the two oldest having been operating since 1970.
"Public sentiment is for Japan to end the use of nuclear power. The public wants the country to move away from nuclear power as soon as possible, let alone an extension in the life of nuclear reactors," said Hiroshi Takahashi, a research fellow at the Fujitsu Research Institute.
"But if backed up by safety regulations legally deemed adequate, one has to admit there would be little reason the regulation should not be implemented. What has to be considered is that unlike Germany, which is aiming to shut down all its nuclear plants by 2022, Japan is still discussing the future role of nuclear power, allowing for such logic."
The government plans to submit bills on limiting the length of reactor operations as well as on reorganising nuclear regulators in a parliament session starting later this month. But it is also keen to bring existing reactors back into operation to avert a power crunch and ease the impact on the economy.