The Magnitude 6.8* Chuetsu-oki Earthquake hit Kashiwazaki City and Kariwa Village in Niigata Prefecture at 10:13 am on July 16, 2007. Fifteen people were killed and 2,300 people sustained serious injuries, while thousands of buildings were destroyed, or damaged.

The seven reactors of the Kashiwazaki-Kariwa Nuclear Power Station, the world's largest nuclear power station, were struck by a jolt far greater than they were designed to withstand. It was sheer good fortune that more radioactivity did not escape.**

Niigata Prefecture established two expert subcommittees to consider technical issues relating to the impact of the earthquake on the nuclear power station, one to assess the integrity and seismic safety of the plant and the other to assess the earthquake itself and the ground condition of the site. There are still many unknowns, but gradually more light is being shed on the damage to equipment caused by the earthquake. One important issue raised by the second subcommittee is the danger that another earthquake, even more powerful than the Chuetsu-oki Earthquake, could strike the plant in future.

Under these circumstances, the local people and the people of Niigata Prefecture as a whole cannot feel secure. They must be prepared for the possibility of another disaster.

Nevertheless, before reaching scientific conclusions, hasty engineering judgments were made to restart some of the reactors. Disregarding the concerns of the local people, commercial operations were resumed at Units 6 and 7. Approval was given when debate about the integrity and safety of the plants was still continuing.

Unit 1, the oldest reactor and the one that was most shaken and incurred most damage (based on visual inspections), began start-up tests on May 21. It is now operating at full power and awaiting approval to resume commercial operations. Niigata Prefecture's technical committee (parent committee of the two subcommittees mentioned above) approved start-up tests on May 11, without any substantial discussion and without holding a public hearing. It is likely that at its July 21 meeting it will endorse the resumption of commercial operations. This situation only adds to the residents' concerns.

The subcommittee looking into equipment integrity and seismic safety is now considering Unit 5. At its most recent meeting, held on July 7, the subcommittee was split in its response to a draft report prepared by the secretariat. Questions submitted by eight local groups about penetrating cracks in the wall of the turbine building were also on the agenda. At this stage, the future of Unit 5 is unclear. Debate about Units 2, 3 and 4 has not yet begun. (These three units and Unit 7 were the only reactors operating at the time of the earthquake.) The discussions must not be cut short in the rush to restart.

We sincerely hope that the governor of Niigata Prefecture, the mayors of Kashiwazaki City and Kariwa Village, and Niigata Prefecture's technical committee and its two subcommittees will take the utmost care in their consideration and assessment of the future of the Kashiwazaki-Kariwa Nuclear Power Plant. Top priority should be given to the safety and security of the residents and to ensuring that they can live free of fear and anxiety. To this end, we believe that concerned residents should be given the opportunity to formally participate in the deliberations of the technical committee and its two subcommittees. Issues should be thoroughly debated until they are resolved in a scientific and convincing manner.

The eyes of the world are watching the Kashiwazaki-Kariwa Nuclear Power Plant.

Hideyuki Ban, Baku Nishio and Yukio Yamaguchi
Co-Directors of the Citizens' Nuclear Information Center (CNIC)
July 16, 2010

* Japanese seismic scale

**For articles about the impact of the earthquake on the Kashiwazaki-Kariwa Nuclear Power Station and the road to restart, see CNIC's Earthquakes and Nuclear Power page.

Contact
Philip White, CNIC International Liaison Officer: +81-3-3357-3800 (w)