Important Report from TEPCO

The Tokyo Electric Power Company, Incorporated, would like to make comments on subjects that are reported by the newspapers, TV or websites.

Reactor buildings will not collapse even if earthquake with the same scale as that of Tohoku - Pacific Ocean Earthquake occurs again.

April 5, 2012

At 11:04 pm on April 1, a 5.9-magnitude earthquake centered in the coast of Fukushima Prefecture occurred. Hama-dori of Fukusihma Prefecture registerd intensity 5 lower on the Japanese seismic (intensity) scale of 7. No abnormalities were detected at facilities for water injection into the reactors, nitrogen gas injection, cooling of spent fuel pool, and the treatment of highly contaminated water at Fukushima Daiichi Nuclear Power Station. They all operate normally after the quake. As for the degree of the shake of the reactor buildings, Unit 6's reactor building's foundation registered 40.7 gal in horizontal direction and 19.4 gal in vertical direction.

We, TEPCO, evaluates earthquake-proof safety by developing Design Basis Earthquake Ground Motion Ss as large-scale quake which would possibly occur in future. For example, the degree of shake of Unit 6's reactor building's foundation against the Design Basis Earthquake Ground Motion is 448 gal in horizont al direction and 415 gal in vertical direction (, which is around 10 times large in horizontal way and around 20 times large in vertical way compared with the quake occurred on April 1, 2012). We assess that the level of this Design Basis Earthquake Ground Motion is almost same as the one recorded for the Tohoku - Pacific Ocean Earthquake. Based on the Motion, we simulated the damaged situation of the current reactor buildings of Unit 1 to 4, having implemented quake response analysis for the reactor buildings as well as equipments and pipes which are important in terms of safety. As a result, we confirmed that there are no negative signal, such as shear/ twist of quake-proof walls of buildings, the fact that the stress of facilities/ piping lowers the standard value, and the fact that buildings collapse and facilities/ piping lose their functions.

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