LEARNING FROM THE HANSHIN-AWAJI EARTHQUAKE

摘要

The Hanshin-Awaji earthquake, which struck the southern part of Hyogo Prefecture early on 17 January 1995, shocked both Japan and the world. Kobe City and its vicinity in particular, suffered critical damage. Some 5500 people were killed, 40 000 were injured and 200 000 buildings were heavily damaged. Many Kansai Electric Power facilities were also damaged. Ten of 21 thermal power plants and 50 of 861 substations were damaged. Kansai Electric's total loss from the earthquake amounts to more than 220 billion Japanese yen (2.3 billion US$). However, none of Kansai Electric's nuclear power plants, about 100 km northeast of the epicentre, were affected by the earthquake, though eight of its 11 NPPs were operating at the time. Although all Japanese NPPs are equipped with automatic trip circuits that respond to earthquake movement, the measured acceleration values were far below the set points of reactor automatic shutdown. After the earthquake, the NPPs were checked to make sure that they were not damaged, and continued operation. Since Japan often suffers big earthquakes, Japanese power utilities apply strict aseismic measures in their NPPs, and Kansai Electric reconfirmed that its NPPs would have been safe if struck by an earthquake of the same scale as the Hanshin-Awaji quake. Kansai Electric also published the results of the review. However, as local people around nuclear sites are concerned about the safety of NPPs, Japan's Nuclear Safety Commission (NSC) set up a task force to examine whether the current aseismic guidelines were appropriate. Power utilities also re-examined their present measures against earthquakes. Besides the safety issue, the utilities have also decided to strengthen measures to secure lifelines, transport of materials and staff, and communication between utilities and organizations concerned, including the media.