#Fukushima I Nuke Plant: Reactors Shaken Beyond Specs During March 11 Earthquake

TEPCO's little-noticed press release on April 1, 2011 shows the Reactors 2, 3, and 5 at Fukushima I Nuke Plant were shaken horizontally (east-west) beyond their maximum design specs.

The recording time was 130 to 150 seconds, while the earthquake lasted full 3 minutes.

Gal is measured in centimeter/second squared, and it measures the ground motion acceleration. Fore more on the topic, here's a paper from World Nuclear Association.

Here's TEPCO's press release:

Press Release (Apr 01,2011) The record of the earthquake intensity observed at Fukushima Daiichi Nuclear Power Station and Fukushima Daini Nuclear Power Station (Interim Report)

This is the record of the earthquake intensity observed at the lowest basement of the reactor buildings of Fukushima Daiichi Nuclear Power Station and Fukushima Daini Nuclear Power Station when the Tohoku-Taiheiyou-Oki Earthquake occurred approximately at 2:46pm on March 11th, 2011. This report also contains Maximum Response Acceleration based on "Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor Facilities (Revised in 2006)". We will endeavor to keep collecting as much data as possible and examine it in more detail. [Table] The comparison between Basic Earthquake Ground Motion and the record of the earthquake intensity observed at the lowest basement of the reactor buildings of Fukushima Daiichi Nuclear Power Station and Fukushima Daini Nuclear Power Station when the Tohoku-Taiheiyou-Oki Earthquake occurred. 【Reference】 Threshold for reactor scram at each unit(The reactor automatically stops if the intensity of the quake exceeds the threshold.) Glossary · Observed Record of Earthquake Intensity Record that indicates the intensity of an earthquake (Unit: gal) · Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor Facilities Revised in September 2006 based on the newly accumulated knowledge on seismology and earthquake engineering and advanced technologies of seismic design, this is a regulatory guide in reviewing the validity of the seismic design of nuclear power reactor facilities. · Basic Earthquake Ground Motion Ss A basic earthquake ground motion in seismic design of facility, stipulated in Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor Facilities · Maximum Response Acceleration against Basic Earthquake Ground Motion Ss Assuming Basic Earthquake Ground Motion Ss in the evaluation of the earthquake-proof safety, this is the Maximum value of the quake of a building, which is expressed in acceleration.

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