From: mccauley@vaxr.llnl.gov
Newsgroups: rec.pyrotechnics
Subject: Re: ka-Boom!
Date: 18 Dec 92 18:33:32 GMT
Organization: LLNL_LIS

In article <1gpgr8INNf0i@cronkite.cisco.com>, dstine@cisco.com (David Stine) writes:
> In article <1992Dec16.122727.1@vaxr.llnl.gov> mccauley@vaxr.llnl.gov writes:
>>To everyone in the newsgroup:  Yes, I'm an actual LLNL Mad Bomber, 
>>otherwise known as an MFWBB.  I was personally involved in the Nuclear Test 
>>Program here for many years.  To the extent I can, I'll be happy to comment 
>>on nuclear matters.  Just discovered this newsgroup, and look forward to 
>>further reading.

[stuff deleted]
 
> Well, Bill that's a very generous offer. If I should ask any questions you
> can't answer, simply don't include them in any followup that you might post.
> I know how that clearance thing is... ;-)

Happy to contribute what I can.  After all, someone may come to my aid on a
couple of projects I plan.  In general, questions about nuclear tests are 
answerable.  Questions about bomb design are harder.  
 
> I do have a couple of questions that come to mind...

Only a couple?   Sounds easy!  :)
 
> 1. In an effects test, do you go for the smalled possible yield that will
>    still give you the particular particles/emissions that you want, as 
>    opposed to a yield test, where you pop off a device and measure
>    the effective yield to see how much "bang" you get for your material?

Effects tests are tricky.  The object is to nuke some hardware, observe the
results and hypothesize about the real world effects.  So, you need enough 
bang to do some damage.  But, the bigger the bang in an effects test, the 
greater the cost of containment.  Also, if the bang is bigger, you increase 
the risk of the containment not working and the subsequent harm if the 
containment fails.  (No containment has failed leading to a release to the 
atmosphere in many years now.)
 
> 2. Again, in an effects test, how are the blast boors slammed shut? The
>    write-ups I've seen say that they are driven home by some explosive;
>    I would guess that they are triggered by some timing device which feeds
>    off the same clock as the main detonation, right?

Exactly right.  Although I was never heavily involved in the horizontal 
effects shots, I've at least been in the tunnels and seen the hardware.  
There are usually several blast doors, and they are truly massive 
structures.  Always made me nervous being around 'em.  Plus, I'm highly 
claustrophobic underground in tunnels.

> 3. And the one which has puzzled me for some time: just how is
>    yield measured? After all, if the reaction is perfect, you get the
>    theoretical results. I would assume that theory only goes so far; the
>    actual yield will deviate due errors in theory, material impurity
>    and actual device construction. The stuff we get to hear is that
>    a device is "thus-n-such kilo/mega tons", where it is assumed an 
>    equivalent amount of TNT. I'm curious as to how one compares yields,
>    esp. when you might have produced a contained kiloton explosion of 
>    chemical explosives for a baseline, but then the nukes are possibly
>    1 to 4 orders of magnitude larger in yield; how approximate are
>    yield measurements as a result of this interpolation?

Yield measurements puzzle the people making 'em!  Actually, yield isn't 
that interesting to a bomb designer.  Measurements of the nuclear processes 
involved are what the designers really want.  The expected yield is of 
great interest to the containment scientists and engineers.  The yield 
expected determines how you design and build the containment.  (Lower yield 
and higher yield containments work differently.  Low is harder to contain 
than high, actually.)  Bomb designers want to know how their baby worked 
internally.  Not how big a bang it made.  

Funny, but most of the time, sitting in the control room, we could barely 
feel the results of our labors.  One notable exception set the building 
rocking for some very long seconds, approaching a minute.  We used to use 
"digital accelerometers" on the control consoles to see if we could trap 
the shock wave.  Leaning against the wall of the control point buildings 
was advised, as larger structures rolled better with small amplitude, low 
frequency shocks.  By the way, our digital accelerometers were nickels, 
standing on edge, on tables.  We put the nickels in two axis relative to 
the expected direction of the shock wave.  
 
Amazing what you can find to do when you get bored out in the desert.
 
> thanks muchly, (if you're able to offer any comments)

You're muchly welcome.  Hope this helps.  By the way, I'll be away for a 
couple weeks for the holidays.  You might want to post replies so they'll 
still be around on Monday, 1/4/93 when I'll be back at the computer.

Bill
_______________________________________________________________________________
(Bill McCauley			       |They told me I needed a signature.    )
)Lawrence Livermore National Laboratory|What is a signature?                  (
(P. O. Box 808, L-471		       |Who are "they" anyway?                )
)Livermore, CA   94550		       |I hope this makes "them" happy.       (
((510) 422-1189; BMCCAULEY@LLNL.GOV    |                                      )
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