Japan will make nuclear "stress tests" a mandatory part of safety checks following the Fukushima Daiichi disaster.
Japan will make new "stress tests" for nuclear reactors, ordered after the Fukushima disaster, a routine part of safety checks to determine how long plants can remain in operation, Japan's
Nuclear crisis minister Goshi Hosono said the tests would help to determine how long nuclear plants could remain in operation, adding that it was inevitable that nuclear power will decline as a share of Japan's energy supply as older plants are decommissioned.
"Construction of new nuclear plants would be extremely difficult," Hosono said.
"The question of whether Japan reduces its dependence on nuclear power is not a question of policy - it's just an observation of the reality we face."
The stress tests are being developed to assess how well Japan's nuclear plants could withstand future disasters, which Hosono called necessary to "make a judgment about how we define safe nuclear power".
This highlights the stricter terms that nuclear plant operators such as Tokyo Electric Power Co will face in both restarting idled plants and extending their operating life after the Fukushima incident.
It could add uncertainty to Japan's energy outlook since many had assumed that the stress tests, loosely modelled on tests developed by the European Union, would be a one-time event.
Thirteen of Japan's reactors are older than 30 years, excluding the six at the crippled Fukushima Daiichi plant.
Currently nuclear plant operating licences have no set expiration but utilities are required to get a 10-year extension after three decades of operation.
Hosono said the stress tests results would be key to determining reactor operating spans, and that some could be allowed to keep operating while others could be ordered closed well before the 30-year mark.
Before the Fukushima crisis, Japanese utilities had been pushing toward technology they argued could allow existing plants to operate 60 years or longer.
By the end of next week, Japan will be operating only 17 of the 54 reactors it had available before the March 11 earthquake tipped the Fukushima Daiichi plant into the world's worst atomic crisis since Chernobyl in 1986.
Japan's trade ministry has said that, without approvals to restart reactors after they go off-line for maintenance, all of Japan's reactors could be shut by next April, raising the prospect of a deepening power shortage into next year.
The first stage of the new nuclear safety tests will assess how much margin a plant has above current safety standards.
Hosono said the Japanese government will take responsibility for long-term monitoring of radiation exposure and health of workers at the Fukushima plant, which has so far been left in the hands of the operator Tepco
Tepco had failed to provide enough key equipment like dosimeters and to screen contract workers for radiation exposure in the first weeks of the crisis, he added.
"There is the possibility of a lot of problems down the road so we are making this the responsibility of the government," Hosono said.
Japan's nuclear industry has been criticised for its heavy reliance on contract workers and day laborers without a system for screening for potential health problems like cancer, and Hosono said the government had to "take the lead" on this area.