Effects of the Niigata-Chuetsu-Oki Earthquake on Kashiwazaki-Kariwa Nuclear Power Plants and actions to safe plants

The Niigata-Chuetsu-Oki Earthquake occurred in Niigata prefecture of Japan, 2007. All of reactor units 2, 3, 4 and 7 of Kashiwazaki-Kariwa Nuclear Power Plants automatically powered down safely in response to the quake, while units 1, 5 and 6 were already shut down for inspection at the time. A fire broke out in a transformer at reactor units 3. This report included the state of Niigata-Chuetsu-Oki Earthquake, securing safety of reactor, damage of the plant and its effects on the public. Reported were fire of transformer and a leak of radioactive gases, aseismic plans and disaster measures including a policy, evaluation and inspection of facilities, evaluation of analysis, investigation of mechanism of earthquake, and public use and offering of information. Illustrated are conditions of safety of reactor (example of BWR5), estimation of fire causes, joint of transformer 3B after the fire, improvement of joint of transformer, outline of discharge of radioactive water into sea, flow of inspection and evaluation, analyses of shear strain of reactor building, analytical results of Units 7, surveying of land and sea area, difference of active faults, and fire fighting activities. (S.Y.)