The nation’s nuclear watchdog has dismissed the suggestion by seismologist Kunihiko Shimazaki that the maximum impact of a projected earthquake on the Oi nuclear plant could have been underestimated and should be reviewed.
The Nuclear Regulation Authority concluded on July 27 that it will stand by the estimate presented by the operator Kansai Electric Power Co. for the plant in Oi, Fukui Prefecture, calling Shimazaki’s argument “groundless.”
The decision came after Shimazaki, former deputy chairman of the NRA, called for a re-examination in June by pointing out the possibility that the method the utility used significantly underestimated the potential outcome.
He said he had realized that there were problems with the calculating equation adopted by Kansai Electric after scrutinizing data on the movement of the series of earthquakes that have occurred in Kumamoto Prefecture since mid-April.
Shimazaki, professor emeritus at the University of Tokyo, led a team of experts when the NRA examined the fitness of the No. 3 and No. 4 reactors at the plant under the new regulations set in the aftermath of the 2011 Fukushima nuclear disaster.
He was the only seismologist among the NRA’s five members and was in charge of checking utilities’ preparedness for earthquakes and tsunami before he resigned two years ago. Today, no expert on seismic movement sits on the NRA.