A continuing review of the impact of a strong earthquake that led to the shutdown of the Kashiwazaki-Kariwa nuclear power plant in Japan is likely to influence approaches to the seismic safety of nuclear power plants worldwide, a report by a second IAEA fact finding mission investigating the event said today.
The team confirmed there was no significant damage to the parts of the plant important to safety after its mission in late January 2008. However, its 68-page findings, published today, said that "no international regulation or experience" is readily available to precisely characterise the effects of the 18 July 2007 earthquake.
"The IAEA is in a position to provide international expertise to apply to the event and in so doing international nuclear power safety standards will benefit," Philippe Jamet, head of the IAEA´s Division of Installation Safety and leader of the mission said today.
The Niigataken Chuetsu-oki earthquake "very significantly exceeded"" the level of seismic activity for which the plant, in the coastal prefecture of Niigata, north-west of Tokyo, was designed, the report said.
The four reactors in operation at the time in the seven unit complex - the world´s largest nuclear power plant - shut down safely and there was a very small radioactive release well below public health and environmental safety limits.
In order to understand the earthquake and to assess the possibility of future earthquakes that may affect the nuclear power plant, the report said, a large amount of "high quality" work has been performed by Japanese experts. They will now have to assemble all the data within a coherent framework to produce an appropriately conservative seismic evaluation, said the report.
The 12-member IAEA-led team of international experts who compiled the report was invited to Japan by the Japanese Nuclear and Industrial Safety Agency (NISA). The mission was tasked with focusing on seismic safety, the integrity of the plant and fire safety. The team held meetings with regulators, geologists, seismologists and the operators of the plant, the Tokyo Electric Power Company (TEPCO). It also visited the plant.