The Nuclear and Industrial Safety Agency said Monday it has endorsed stress test results on an idled reactor at Shikoku Electric Power Co.'s Ikata power plant, making it the third reactor to have cleared a key step for resuming operation.

NISA said it submitted a report validating the test results on reactor 3 of the plant in Ehime Prefecture to the Nuclear Safety Commission to have the adequacy of the agency's evaluation checked.

But the prospects for subsequent procedures are uncertain as the commission's chairman, Haruki Madarame, has said it would be difficult for the body to check the stress test results because the commission is planned to be incorporated with a new nuclear regulatory agency soon.

The new agency was originally scheduled to be set up April 1, but given a delay in Diet deliberations in a related bill on its establishment, the agency is unlikely to be set up as planned and the commission is expected to remain in existence for a while.

NISA said in the report it has confirmed through the test that Shikoku Electric has taken sufficient measures to prevent the Ikata reactor from getting into a situation similar to those at the Fukushima No. 1 power plant, even if it is hit by an earthquake and tsunami bigger than assumed levels when the reactor was designed.

The government mandated the two-stage stress test because of the crisis at the Tokyo Electric Power Co.'s Fukushima complex. Clearing the first stage of the computer simulation-based test is a precondition for restarting reactors that have been idled for regular checks.