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From: edat!brian@uunet.UU.NET (Brian Douglass)
Newsgroups: sci.military
Subject: Re: How is a nuke tested underground?
Message-ID: <1991May10.063806.26071@amd.com>
Date: 9 May 91 17:43:03 GMT
References: <1991May8.034438.11095@amd.com>
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From: edat!brian@uunet.UU.NET (Brian Douglass)


tlijy@cc.curtin.edu.au writes:
>Please bear with my poor knowledge. I am wondering if some one can tell me
>how a nuke is tested underground? Is there any negative impact to the 
>earth crust stability underneath?

A hole is drilled to 1500+ foot range upon which various siesmic
test are run.  Called Well Logging in the oil business.  These
tests detect faults lines, soil composition, water content, etc.
The hole is concreted and eventually a bomb is placed at the
bottom.  An instrument package is placed on top of this (up to 6
stories tall) with realtime recording handled at the surface.
There can easily but 500+ channels of data coming out of the
package back to recorders on the surface.  Those are the trailers
you see in the distance on the surface of ground zero.  The hole is
sealed with concrete and when everything is right, the bomb is set
off.

A typical blast will generate a localized earthquake usually less
that a 4 on the Richter Scale.  People in high buildings are
typically warned in advance on high yield tests.  There has been
well over 200 underground tests, most being operational tests of
tactical and strategic warheads.  In fact, a year or two a
technician found a design flaw, it was confirmed by an actual test,
and a recall was issued.

As far as crust instability, nah.  A caldier (large crater) usually 
sets in some time after the blast as the earth column above the
vaporized blast area collapses inward, but that is actually
designed into the test to happen correctly and is called
containment science.  The only real long term effect is the
irradiation of the ground water table.  A tremendous about of
tritium and yritium (?) is generated.  However, these tables flow
at about 6 feet per year and the Nevada Test Site is ringed with
monitor wells.  The last estimates I saw were 22,000 years for such
contaminated water to reach the Las Vegas water supply.

Hope that answers your question.

Brian Douglass			Voice: 702-361-1510 X311
Electronic Data Technologies	FAX #: 702-361-2545
1085 Palms Airport Drive	brian@edat.uucp
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