[ RadSafe ] [Nuclear News] Japan quake not seenslowingU.S.nuclear revi.val

[Jaro]

If you work in the nuclear industry, you may get media inquiries about
earthquake resistance of nuclear plants -- either specific ones in your
area, or in general -- and how they compare to Kashiwazaki-Kariwa, and the
earthquake it endured last Monday, 16 July 2007.

This is a tricky question to answer, because most of us don't work in this
specialty field, and may therefore be ignorant of such basics as the
difference between an earthquake *magnitude* (usually quoted in the media as
a "Richter Scale" number), and the *intensity* of physical effects like
horizontal acceleration, that structures are designed to cope with.

While the earthquake *magnitude* is a single number, the *intensity* of
physical effects is a variable that depends on such things as distance from
the earthquake epicenter, the geological depth of the epicenter, the type of
geology at the plant site, etc.

There is NO simple way of converting a given earthquake *magnitude* number
to the acceleration experienced as a result, at a given location, and
therefore no instant answer to the question of equivalence between different
plant sites, and plant design suitability.

Fortunately, there are internet resources that provide useful information,
that can be used to get an approximate idea of the actual physical effects.

One such resource is the USGS ShakeMap facility, which automatically
generates shaking and intensity maps throughout a geographic area, for each
significant earthquake event.
For background info on ShakeMap, see
http://earthquake.usgs.gov/eqcenter/shakemap/background.php
The continuously updated list of ShakeMap results is posted at
http://earthquake.usgs.gov/eqcenter/shakemap/list.php?y=2007&n=global

Specifically, Monday's earthquake near the Kashiwazaki-Kariwa plant is the
listing with Event ID "2007ewac" titled "NEAR THE WEST COAST OF HONSHU,
JAPAN" posted at
http://earthquake.usgs.gov/eqcenter/shakemap/global/shake/2007ewac/
A Peak Ground Acceleration map is likewise available at the same web site,
at
http://earthquake.usgs.gov/eqcenter/shakemap/global/shake/2007ewac/#Peak_Gro
und_Acceleration

The Kashiwazaki-Kariwa plant is located on the west coast, directly opposite
the location of the epicenter (indicated with a star on the above linked
maps).
The ShakeMap contours indicate a Peak Ground Acceleration of 20%g (ie. 20%
of gravitational acceleration) at that location.
Typical nuclear plant critical structure and equipment design is for 20%g or
more (depending on the plant site location, of course), so its not
surprising that the Kashiwazaki-Kariwa plant survived with relatively minor
damage, involving only non-critical equipment like the transformer that
caught fire.

Anyway, I hope this helps.

 Jaro
^^^^^^^^^^^^^^^^^^^^^



-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl]On
Behalf Of Sandy Perle
Sent: Friday, July 20, 2007 8:32 PM
To: John R Johnson; radsafe-bounces at radlab.nl; LNMolino at aol.com;
radsafe at radlab.nl
Subject: Re: [ RadSafe ] [Nuclear News] Japan quake not
seenslowingU.S.nuclear revi.val


I agree with John. The earthquake had significant coverage in both written
as well as TV/Cable/Internet form.

Be sure that the anti-nuclear plant forces will attempt to focus on the
earthquake as reason not to build other plants.

Sandy Perle
Sent via BlackBerry by AT&T
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