Tokyo: Japan`s idled nuclear reactors could be turned on again if they pass the first stage of two-step post-Fukushima safety checks, the government said on Monday.
Still, without a timeframe for the tests, concerns remain about summer power shortages that could hurt the economy.
Last week`s surprise announcement that the government would conduct stress tests alarmed corporate Japan and outraged some local authorities, who had been prepared to approve reactor restarts after receiving safety assurances from the government.
The first stage of the stress tests will target reactors which have already completed routine checks and are ready for restart. The checks will assess tolerance of severe phenomena exceeding those for which they were designed.
A second stage of tests will assess all of Japan`s 54 reactors and involve a comprehensive safety assessment of all Japan`s nuclear plants, the government added in its statement.
Four months after the Fukushima Daiichi plant was smashed by a tsunami and began leaking radiation, only 19 of the country`s 54 reactors are running and if some do not resume operations, Japan could be without nuclear power by next April.
The disaster has also sparked a broader public debate about the role of nuclear energy in earthquake-prone, resource-poor Japan, which relied on atomic power for almost 30 percent of its electricity before the crisis.
"Safety and a sense of security are the top priority," Chief Cabinet Secretary Yukio Edano told a news conference.
"On the other hand, the government must fulfill its responsibility for a stable supply of electricity and is coordinating on this with relevant ministries ... and will make every effort to secure (supply) in the medium and long term," he added.
Edano gave no precise timeframe for completing either of the two stages, but said they should be carried out speedily.
In a sudden shift in policy last week, Prime Minister Naoto Kan -- under fire for his handling of the nuclear crisis -- said Japan would administer stress tests for nuclear plants modeled on those conducted by the EU after the meltdowns at the tsunami-crippled Fukushima Daiichi atomic power plant.
The move was welcomed by critics who charge that Japan`s safety regulations have been too lax, but it also raised the risk of power shortages that would stretch into the summer of 2012 and could hurt industrial production.
The government had been pushing for early restarts of facilities that have completed regular checks to avoid a power crunch, but some local authorities whose approval is required by custom were outraged by the policy shift, and said they could not give their OK until the government clarified its stance.
Kan has ordered a blank-slate review of Japan`s energy policy, which before the March 11 disasters had aimed to boost nuclear energy`s share of electricity supply to more than 50 percent by 2030.
He also wants to raise the share of renewable energy sources such as solar and wind power to more than 20 percent by the 2020s and has made passage of a bill to promote such energy sources a condition for keeping a promise to resign.