Tuesday, April 5, 2011

#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.

2 comments:

Anonymous said...

http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?_r=2&hp

arevamirpal::laprimavera said...

I'm reading that right now. Thx

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