Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!att!cbnews!cbnews!military
From: ke4zv!gary@gatech.edu (Gary Coffman)
Newsgroups: sci.military
Subject: Re: Question about Nuclear Weapons
Message-ID: <1990Oct29.032829.10296@cbnews.att.com>
Date: 29 Oct 90 03:28:29 GMT
References: <1990Oct23.190943.7623@cbnews.att.com> <1990Oct26.021043.27122@cbnews.att.com>
Sender: military@cbnews.att.com (William B. Thacker)
Organization: Gannett Technologies Group
Lines: 32
Approved: military@att.att.com



From: ke4zv!gary@gatech.edu (Gary Coffman)

In article <1990Oct26.021043.27122@cbnews.att.com> cr2r+@andrew.cmu.edu (Christian M. Restifo) writes:
>
>
>From: "Christian M. Restifo" <cr2r+@andrew.cmu.edu>
>
>Anyway, I'm sure if some rocket scientist sat down, he could calculate
>the theoretical depth at which the material would go critical.  Most
>nuclear weapons, nowadays, are actually two nuclear weapons in one.  A
>fission explosion causes the radioactive material to go critical and
>start a fusion reaction.  I don't think any known depth could implode
>the material enough (at the same level of a fission explosion) to
>initiate a fusion reaction.

I'm not a rocket scientist, but I play one on the net. :-)
The basic problem with detonating a fission bomb to to achieve super 
criticality quickly enough to prevent the weapon from "squibbing"
when it becomes merely critical. If everything is not done just right,
the weapon squibs and blows the nuclear material apart before a
significant reaction takes place. When everything is done just right,
the inertia of the pieces holds the core together in super critical
conditions long enough to let the nuclear reaction really heat up.
Even then the weapon explodes long before fission reaches completion.
One of the quests of nuclear bomb designers is to find ways to hold
the core super critical longer thus getting more yield from a given
size device. The very deepest ocean trenches have insufficent pressure
to prevent squib fire.

Gary