From: Mike Lorrey (mlorrey@yahoo.com)
Date: Mon Oct 14 2002 - 16:59:24 MDT
--- "Robert J. Bradbury" <bradbury@aeiveos.com> wrote:
> Red Mercury seems to be an urban legend without much
> substance to it:
>
>
http://www.eng-tips.com/gviewthread.cfm/lev2/19/lev3/64/pid/466/qid/26894
>
> Interestingly it does beg an answer to my earlier question
> as to whether there is a material other than U-235 or Pu-239
> that can make a nuclear weapon with less material. U-235
> decays releasing an alpha particle with ~4.7 MeV while
> Pu-239 decays with an alpha particle with 5.2 MeV. Other
> isotopes like Am-241;-2433 (alpha, 5.4-6 MeV) and Cm-242/3/4/5/6/7,
> alpha, 5.3-6.2 MeV) would seem to be likely candidates.
>
> Some of those isotopes seem to be much nicer choices as they
> have half lives in the days to years time frame rather than
> the tens of thousands to millions of years. So I suspect
> they would go "poof" with quite a bit less material involved.
>
> Anyone enough of a nuclear engineer to know what the critical
> parameters are? Is it rate of alpha particle production?
> Or perhaps neutron capture rates (thermal neutron cross section???).
> Also -- nuclear reactions as I was taught them were based on
> an exponential rate in the increase of neutron production
> (alpha particles shouldn't be able to enter a nucleus) --
> how does the release of an alpha particle get translated into
> neutrons? (Does the alpha particle itself decay very quickly?).
As demonstrated in a previous list posting on using Americium in
spacecraft propulsion, it is highly unstable, with criticality masses
in the fraction of a gram level, as I recall. To make a bomb, you'd
have to have small amounts of Americium embedded within small BB type
shells of frangible neutron mediating material. Use a conventional
explosive to fragment the shells, thus exposing the Americium cores to
each other and reaching supercritical levels. Scale the amount of
Americium used to the kiloton yield desired. Beware of rapid
decomposition of the Am material, given it's short half life, your bomb
would quickly go stale and inert. THis might be useful from a land mine
application, where you'd want your mines to go inert after a set
period, though this is just for the nuclear stage of the explosive. THe
chemical explosive would remain volatile, though I imagine that in such
a case, the inert BB's would then be useful for shrapnel as in a
standard US Claymore type mine.
If you have an automatic expiration circuit built in, you could have
the mine self detonate after the Am stage has gone inert.
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