Consideration on the earthquake-resistant margin of equipment base-bolts receiving the shearing load during seismic movements

Sakaguchi, Shinobu; Tachibana, Ikuya; Koshino, Katsuhiko; Shirozu, Hidetomo ; Shirai, Nobutoshi ; Imamoto, Nobuo ; Tomita, Tsuneo; Tobita, Hiroo; Yamanaka, Atsushi ; Kobayashi, Daisuke; Kishi, Yoshiyuki; Isobe, Hiroyasu; Nemoto, Masahiro; Ishizaki, Kazuma; Tanaka, Hitoshi; Seno, Shigeo

In the Niigataken Chuetsu-oki Earthquake on 2007, observed earthquake motion exceeded design base at the Kashiwazaki Kariwa nuclear plant. However, there was no earthquake damage in safety important equipments to stop reactor, to cool reactor, and to contain radioactive materials. One of this reason is said that many safety margin are included in the design and the permissible value. To know more accurate safety margin, shearing force examinations for the base bolts were conducted. In examinations, delegate test-bolts were made; the test bolts were selected from heavier equipment in Tokai Reprocessing Plant. In this report, the shearing strength obtained from the examinations shows more accurate safety margin.