The Nuclear and Industrial Safety Agency instructed all electric power companies on July 22 to report by Aug. 22 any errors in data on the earthquake resistance of nuclear power plants and on any problems in systems to check data errors.
The Nuclear and Industrial Safety Agency instructed all electric power companies on July 22 to report by Aug. 22 any errors in data on the earthquake resistance of nuclear power plants and on any problems in systems to check data errors.
The instructions came after a discovery, which NISA disclosed the same day, that data used in the anti-seismic diagnosis of the Genkai nuclear power plant No. 3 reactor contained errors.
The diagnosis results are expected to be used in stress tests, on which decisions will be made on whether to authorize the restart of nuclear reactors currently suspended.
NISA instructed Kyushu Electric Power Co., the operator of the Genkai plant, to report on recurrence prevention measures by the end of July and to submit a recalculation of the erroneous report by the end of October.
NISA said the recalculation would require about three months because the errors in the data also affect equipment and piping systems within the buildings.
Meanwhile, NISA also instructed electric power companies to conduct stress tests, consisting of two phases, for all nuclear power plants in Japan. These stress tests assess the plants' margin of safety with respect to accidents and natural disasters.
The first phase of stress tests will be used as a precondition for the restart of nuclear power plants that have been suspended. The second phase of stress tests will involve all 44 commercial nuclear reactors in Japan, except those at Tokyo Electric Power Co.'s Fukushima No. 1 and No. 2 nuclear plants.
However, the latest discovery of errors in earthquake resistance diagnosis data for the Genkai plant has compromised the tests' reliability. Some part of the tests do not rely on the anti-seismic diagnosis data, but NISA said it will not analyze reports on the first phase of the stress tests before the electric power companies finish checking the data and file reports with NISA.