The Nuclear and Industrial Safety Agency (NISA) on Jan. 18 judged “appropriate” the results of the stress tests of the No. 3 and No. 4 reactors at Kansai Electric Power Co.’s Oi nuclear power plant in Fukui Prefecture. On Jan. 31, an International Atomic Energy Agency team determined that Japan’s stress tests of reactors are “generally consistent” with IAEA safety standards. We beg to disagree; the stress tests are seriously flawed because they do not incorporate the causes and lessons of the disaster at Tokyo Electric Power Co.’s Fukushima No. 1 nuclear power plant. The Fukushima crisis has demonstrated that Japan lacks truly reliable nuclear safety standards.
Of Japan’s 54 reactors, only three remain in operation. When they undergo regular checks in late April, all the nation’s reactors will be offline. The government must be watched closely because it may use the stress test results to justify restarting nuclear power stations without fully disclosing all relevant information.
A stress test is a computer simulation to measure each reactor’s safety margin to prevent severe accidents. Factors such as earthquakes, tsunami, loss of all power sources and loss of cooling functions are taken into account. Test results can vary depending on data fed into computers and the computer programs used. It is impossible for outside parties to determine whether stress tests themselves are appropriate because the data and programs are not disclosed and third-party checks are impossible.
The greatest problem with Japan’s stress tests is that they are being carried out before the causes of and lessons from the Fukushima nuclear crisis are clearly known. It must be remembered that Japan has yet to implement safety standards that incorporate the causes and lessons of the Fukushima crisis.
So far, eight power companies have submitted the results of stress tests on 16 reactors. In the case of the Oi reactors, it was concluded that the reactor cores would not be damaged even if they are hit by an earthquake 1.8 times more powerful or a tsunami four times higher (11.4 meters) than originally anticipated. They would not be damaged for 16 days even with loss of all alternate current (AC) power sources.
But nobody can tell how much of a safety margin in a computer simulation can ensure the prevention of severe accidents. The Nuclear Safety Commission will assess NISA’s report on the Oi stress tests. Since both NISA and the NSC are part of the nuclear power establishment, it would be difficult to convince people if they conclude that the Oi reactors are safe.
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