• Kyodo


The Nuclear and Industrial Safety Agency said Wednesday it will soon finalize a draft report endorsing the results of stress tests on two idled reactors at Kansai Electric’s Oi power plant in Fukui Prefecture — the first time such tests will be approved.

NISA made the decision after presenting and hearing opinions on the draft report at a meeting the same day with experts. The final version will then be submitted to the Nuclear Safety Commission of Japan for checking.

At the meeting, however, experts questioned NISA’s endorsement of Kepco’s stress tests.

Masashi Goto, a former nuclear power plant design engineer, said the stress tests are “totally meaningless” as a tool to check the safety of reactors, as NISA has yet to decide how much leeway the reactors should have to withstand earthquakes and tsunami.

The government introduced stress tests for nuclear reactors amid the Fukushima nuclear crisis, and made them a prerequisite for restarting reactors idled for scheduled checks.

If the commission approves the report, NISA plans to explain the test results to residents in Fukui Prefecture.

The government would then have to decide whether to authorize the restart of the reactors, weighing the stress test results against the local community’s concerns over the safety of nuclear power. The Fukui Prefectural Government is cautious about restarting the two reactors.

Ten of the 11 reactors Kepco operates are currently offline for inspections, leading to fears of electricity shortages in its service area. The utility’s only operating reactor, the No. 3 unit at the Takahama power plant in Fukui Prefecture, is set to undergo periodic maintenance later this month.

In its draft report, NISA endorsed Kansai Electric’s evaluation that reactors 3 and 4 at the Oi plant are capable of withstanding an earthquake 1.8 times stronger than the most powerful quake projected to hit the area, and tsunami up to 11.4 meters high, four times higher than the maximum level predicted.

But NISA also said it needs to confirm the utility’s investigation of previous tsunami that occurred in nearby areas, as well as the connectivity of active faults.

Overall, NISA said sufficient measures have been taken over the two reactors to prevent a disaster similar to the meltdowns at the Fukushima No. 1 nuclear plant, even if they were hit by a quake and tsunami of the size that ravaged the Fukushima facility.

Only three of Japan’s 54 commercial reactors are currently in operation, as they have to undergo regular checks every 13 months and now need to pass the government’s stress tests before resuming operations. If none are approved for a restart, all will be offline by May.

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