[ RadSafe ] Centifuges

andrewa at alder.ws andrewa at alder.ws
Mon Sep 19 14:51:20 CDT 2011

> From: JPreisig at aol.com

> Hmmmm, actually, I think
> a small nation or a handful of  scientists/engineers (nowadays)
> could
> do some pretty severe
> U235 or Pu enrichment with 5-10 centrifuges  or less.  Probably one
> could have fewer centrifuges
> and round the clock shifts of people running  the centrifuges.
> Let's
> be careful out there.

Let's indeed be careful. Even a small centrifuge cascade takes several
days to start or stop. The assumption that one would ever be run other
than "round the clock" is, I'm sorry to say, ridiculous but not uncommon.

> From: "Brennan, Mike  (DOH)" <Mike.Brennan at DOH.WA.GOV>

> To the best of my knowledge, centrifuges aren't used when making a
> plutonium based nuclear device.

Exactly. AFAIK, Pu enrichment has never been proposed as a serious
proliferation risk. One problem is that the mass difference between the
Pu239 and Pu241 is even less than that between U235 and U238.

It's generally believed to be far quicker and cheaper to make bomb quality
plute directly, through low burnup, than to enrich the plute from high
burnup fuel. It also seems far more productive to use enrichment capacity
to produce bomb quality uranium than to use the same capacity to enrich
plute, for many reasons. Either way, nobody is likely to use the plute
enrichment route, barring the future discovery of a breakthough isotope
separation technology that can be used to enrich plute but not uranium.

Even the most speculative journalists have yet to propose any such
possible technology, although many do seem to suppose one exists. The
smart money is on these journos simply being ignorant of the facts.

Again, let's be careful.

Andrew Alder

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