Japan will be able to avoid power cuts this summer even if the nation's last few nuclear reactors cease operating.
Until the March 11 earthquake and tsunami, nuclear energy provided a third of Japan's power. But public anxiety since the disaster, which triggered a radiation crisis at Fukushima Daiichi nuclear plant, has prevented the restart of reactors shut for routine checks.
Only three of the nation's 54 reactors remain in use and all are due to go off-line by the spring, despite government efforts to regain public trust in the industry. The loss of nuclear power has raised fears of forced power rationing and temporary blackouts in the summer peak demand period, when air conditioning puts extra strains on supply.
But Trade Minister Yukio Edano said there was a good chance of coping without such mandatory cuts on electricity usage even if all the reactors were shut.
"We don't know how much electricity will be available this summer because it depends on the separate matter of reaching a conclusion about safety concerns," Edano told a news conference.
"We would have to call for conservation of electricity, but there's an excellent chance (the power lost if all nuclear plants are shut this summer) can be overcome without placing curbs on electricity consumption," he added.
The government, worried about a power crunch, is pushing for reactors to resume operations, even as it reviews the role of nuclear power in the resource-poor country's energy mix in a new mid- to long-term programme to be decided in coming months.
Japan has abandoned its plan to boost nuclear power to more than half of its electricity supply by 2030, but proponents argue that atomic power is vital to prevent more Japanese companies from moving abroad in search of lower costs, and to provide a stable electricity supply.
Last summer, Tokyo Electric Power Co, the operator of the Fukushima plant, struggled to meet power demand, sparking government-mandated power savings by big industrial users.
This winter the government urged users to reduce electricity use during peak hours in Osaka and surrounding areas of western Japan, covered by Kansai Electric Power Co, and on the southern main island of Kyushu, covered by Kyushu Electric Power Co.
Kansai Electric and Kyushu Electric are two of Japan's most nuclear-reliant utilities.
Officials are now reviewing results of stress tests that use computer simulations to show if reactors can withstand extreme events like last year's quake and tsunami.
Experts from the U.N. atomic watchdog visited the Ohi nuclear plant in central Japan on Thursday after Japan's nuclear safety agency said tests on two Ohi reactors showed they were capable of withstanding a severe shock. The U.N. experts will hold a briefing next week.
A panel of Japanese experts will review the tests, with local governments also required to approve reactor restarts before cabinet ministers give the final go-ahead.
The mayor of Ohi, however, said further clarification on safety standards and stress tests was needed. "We can't determine whether the reactors can be restarted at this phase. What needs to be clarified are regulations that could prevent severe accidents and the necessary safety standards, then we can move on to the issue of restarts," Ohi mayor Shinobu Tokioka said.
"The stress tests gave ratings but the town of Ohi cannot use this to decide whether to restart the reactors or not, as no pass or fail threshold has been set at this stage."
A tough choice faces many local governments that host nuclear power plants - not allowing their restarts may help soothe safety concerns but the facilities also create employment and budget revenue.