Newsgroups: sci.physics,sci.physics.fusion
Date: Tue, 13 Oct 1992 09:43:49 -0400 
From: Kevin William Ryan <kr0u+@andrew.cmu.edu>
Subject: Re: The H-Bomb secret is out
	<1992Oct7.201848.5499@nmt.edu>

In article <R373RB5w165w@iowegia.uucp> quest@iowegia.uucp (Steve J. Quest) writ
es:
 
>        The actual design of the bomb is simple as I have 
>previously stated.  The only complexity is the procurement of the 
>spent fuel for the jacket, the plutonium for the fissionable core 
>and the tritium for the fusible fuel.  Given the simplicity of 
>reactor design, I for one am suprised that nobody has ever built a 
>small enrichment chamber, enriching natural uranium as 
>hexafluoride gas, and then using this 235 enriched uranium, built 
>a small reactor to breed plutonium for a bomb.  Natural uranium 
>238 absorbs neutrons as well as being split by them- resulting in 
>plutonium 239, which can be extracted chemically.  This plutonium 
>could then be used to build a bomb, or as the core bomb to a much 
>bigger fusion bomb.
>
>        I am actually suprised that nobody has built a "back-yard" 
>nuke in their basement for "neighborhood nuclear 
>superiority"....sq

    One of these days I will have to dig out my old Analog issue where
this sort of thing was discussed. 

    The article (some 10 years ago) gave a quite functional A-bomb
design that could be build by the average plumber. Take an old house,
run a pipe from the third floor 5" gun to the basement which is
otherwise filled with concrete, and fire one fissionable hemisphere down
into the other. If you are using plutonium, add a neutron source half
way down the pipe. The kinetic energy of the gun and the concrete will
hold the fissionables together long enough for a reasonable percentage
to fission. 

    Lousy efficiency, but quite workable. Same principle as the Thin Man bomb. 

    The article then went into the difficulties of the materials
involved. (heh heh heh.) First, machining plutonium without (1) getting
too much together at any one time, (2) using a lead lined wheelchair
with manipulators to handle the machining, and (3) lots of suicidal
volunteers as you will lose several during fuel processing. 

    Or perhaps you want to use U235? It's not generally available, so
you will probably have to process some U238 to enrich to a fissionable
U235 quantity. Obtain a large refinement facility, one with lots of
power and a reasonable stream for cooling, and spend a couple of years
getting up to speed and refining the uranium with the hexafluoride
process. Note that uranium hexafluoride is _nasty_ stuff: it is
literally the reason Teflon was invented. The refinement process is also
very slow: the plants in Oak Ridge are mucking huge for a reason, and
that reason is so that a lot of uranium can be processed at once. 

    Before then, of course, you have to obtain some large quantity of
fissionables. Mining it would be rather obvious, so perhaps you would
like to steal it, say as spent rods from a commercial nuclear reactor?
Bring your multi-ton lead and graphite lined tractor trailer along on
the heist, and be prepared to risk the entire assembly melting through
the floor and leaving a radioactive trail of breadcrumbs to your
hideout: you will have severe problems fitting enough spent rods into
one truck without building a rather poor reactor in the trailer. Oh, and
the driver will have to be one more of those disposable volunteers...

    The article went on in this vein for some length. Basically, the
fission bomb is simple to build (complicated if you want it to be
efficient), but the materials are a beast. The article finished by
recommending that the best way to build a bomb would be to simply steal
one of the ones some government had already made, as the materials
facilities would be a big ticket item for most nations.

                                                    kwr

Internet: kevin.ryan@cmu.edu
Newsgroups: sci.physics