From: houle@nmt.edu (Paul Houle)
Newsgroups: sci.physics.fusion
Subject: Re: The H-Bomb secret is out
Date: 11 Oct 92 20:41:22 GMT
Article-I.D.: nmt.1992Oct11.204122.14733
Organization: New Mexico Tech

In article <1992Oct11.070033.4704@murdoch.acc.Virginia.EDU> crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:

>     Au contraire mon ami.  Enriching *one ounce* to weapons grade
>     by gaseous diffusion takes a plant the size of a small town.  
>     You don't do better by only having to do a little.  Also,
>     the natural abundance of U-235 is about 0.7%.  Even if you
>     only want 3 kilos of product, you're talking many tons of feedstock.
>     You might want to invest in a calutron.  The only problem is that 
>     you'll need a rather large electrical substation nearby since those
>     babies really draw the juice, and you'll have to wait quite a 
>     while for your 3 kilos.
>
>     I don't think that you seem to recognize that you are talking about
>     *industrial* processes.  These are things that cannot, by their
>     very nature, fit in your basement.  Do you think that you could
>     cast and build a tractor in your basement?  How about your vaunted
>     transmission?
>
>                               dale bass

	For once I'll have to agree with you.  Fission energy technology
has poor scalability down to the basement-operation size.  Assuming that
this guy wants to make 3 kilos (and I think that he will actually want
quite a bit more.  He will either need about 35 kg to actually construct
a gun-type device,  or he will need to manufacture 5-10 kg of plutonium;
which if I remember correctly will require that he actually burns up
about that mass in uranium (and will need much more to keep the mass
critical all the way through).  Then again,  it might be possible to make
a ~very~ efficient reactor that uses moderation that needs only 3 kg of
highly enriched uranium.  Might be good for a swimming pool heater or
neighborhood cogeneration system (both! :-)

	Probably the only isotope separation technology that should scale
down well is laser isotope separation,  but that is still kinda blue-skyish.
Yet,  if it could be made to work,  there is no reason why one couldn't
build a rather small isotope separation system that might even scale to
basement operation size.  Now,  it might take you forever to make enough
high-enriched U235 to do anything interesting with it.  If we assume that
35 kg is "enough",  and that U235 is about %1 by weight,  then we would
need something like 3.5 metric tons of uranium to get it.  I suppose that
you could fit all that in a basement,  but it would be hard.  A really
high-tech laser enrichment system might continuously process metallic
natural U (most efficient for storage) into UF6,  run one-pass separation
to ~90% U235,  and then recycle the F at the end of the cycle which
might barely make this into something you could run at home.  Building
it in your basement might be harder;  and it all depends on developments
in technology which are certainly not known to the public...  Although it
is almost certain that somebody has done classified work on it.

	Then again,  laser isotope separation might become very handy
for other elements.  Diamonds that contain isotopically pure C12 have
about an order of magnitude better heat conductivity than regular
diamonds...  And C13 diamonds should be harder.


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