Re: [math-fun] Computational effort
From: Eugene Salamin via math-fun <math-fun@mailman.xmission.com> To: math-fun <math-fun@mailman.xmission.com> Reply-To: Eugene Salamin <gene_salamin@yahoo.com>, math-fun < math-fun@mailman.xmission.com> All methods (that they've told us about) for enriching uranium are slow and require many stages. In this situation, given the U-235 fractions x[F] in the feed, x[P] in the enriched product, and x[W] in the depleted waste (or tails), the SWU is a measure of the amount of effort required to achieve that enrichment. The customer would be charged so many $/SWU. There's lots of Google hits on Separative Work Unit. I found this paper to be quite interesting. arxiv.org/pdf/0906.2505 The usually cited reference book, and one which explains the formula for calculating SWU, is Karl Cohen "The Theory of Isotope Separation", out of print and hard to find, but is in the collection at the King Library at San Jose State University. The gas diffusion and centrifuge methods are so slow because they depend on the mass difference. Fortuitously, natural fluorine consists of the single mass-19 isotope, so UF6 molecules differ only in the uranium. Laser isotope separation offers greater specificity by relying on isotopic differences in electronic spectra of uranium atoms or vibrational spectra in UF6 molecules. So far, laser isotope separation hasn't displaced centrifuges as the preferred technology (at least as far as they're telling us). In principle, i.e. without violating any laws of physics, there could exist a membrane or barrier permeable to only one isotope. This would allow instant single-stage separation. Diffusion of hydrogen through palladium foil is very effective since the D/H mass ratio is 2. The obstacle to its use is the energy required to electrolyse huge amounts of water for the 1/5000 deuterium fraction. If hydrogen sees use as a fuel, isotope separation can piggy-back on it. -- Gene I recall a Manhattan Project documentary where they were debating the feasibility of isotope separation, and someone suggested trying deuterium first. I can't find the quote, but Oppenheimer said something like "Hell, we should be able to do that with our bare hands." --rwg From: rwg <rwg@sdf.org> To: math-fun <math-fun@mailman.xmission.com> Sent: Sunday, March 22, 2015 8:02 PM Subject: Re: [math-fun] Computational effort On 2015-03-22 12:25, Eugene Salamin via math-fun wrote:
There already is a unit for isotope enrichment effort. It is the Separative Work Unit, SWU. -- Gene
Gene, are you saying there's a theoretical proof of no shortcut to enrichment? That sounds like a dangerous assumption.
From: Henry Baker <hbaker1@pipeline.com> To: math-fun <math-fun@mailman.xmission.com> Sent: Sunday, March 22, 2015 12:18 PM Subject: Re: [math-fun] Computational effort
Separating U235 from U238 is a pretty decent "proof of work" system.
"Uraniumcoin" ?
"Isotopecoin" ?
"Hex[a]fluorocoin" ?
"Centricoin" ?
These "coins" put the "rich" into "enriched"...
https://en.wikipedia.org/wiki/Enriched_uranium
Of course, you may only want to use Oralloy certificates in commerce, exchangeable* for the real thing. Who wants to carry around a lead wallet, with even heavier contents?
I've heard of deep pockets, but I can't picture one holding a critical mass of U235coins. If that's a problem, enrich just short of finite critical mass. Short of criticality, the lead would be superfluous. Bcc: Tehran mint --rwg
* (Except by certain not-so-friendly countries.)
At 07:16 AM 3/20/2015, James Propp wrote:
(b) the Manhattan Project,
Henry> Having an upper limit on the # of U235 coins you can have cuts down on inequality; Dr. Piketty would be pleased: https://en.wikipedia.org/wiki/Thomas_Piketty Re lead wallets: I thought that U235 was reasonably radioactive, and the radioactivity increases non-linearly with the amount of material gathered together. :-) Also, lead wallets keep well-heeled friends from exploding with delight from all that hugging. Deep pockets, maybe; heirs, maybe not! ------ Would you disinherit your grandchild merely for having two heads?
U235 (and U238) are 'just' alpha emitters; a bit of plastic will suffice (and would actually be better, limiting Bremsstrahlung production compared to lead or other heavy elements -- U plus a bit of lead foil makes X-rays). There's no real radioactivity danger as long as it's external, though it's very hazardous if inhaled. (If you carry it long enough you'd eventually get burned, but you'd probably be chemically poisoned long beforehand.) Charles Greathouse Analyst/Programmer Case Western Reserve University On Mon, Mar 23, 2015 at 8:08 PM, Bill Gosper <billgosper@gmail.com> wrote:
From: Eugene Salamin via math-fun <math-fun@mailman.xmission.com> To: math-fun <math-fun@mailman.xmission.com> Reply-To: Eugene Salamin <gene_salamin@yahoo.com>, math-fun < math-fun@mailman.xmission.com>
All methods (that they've told us about) for enriching uranium are slow and require many stages. In this situation, given the U-235 fractions x[F] in the feed, x[P] in the enriched product, and x[W] in the depleted waste (or tails), the SWU is a measure of the amount of effort required to achieve that enrichment. The customer would be charged so many $/SWU. There's lots of Google hits on Separative Work Unit. I found this paper to be quite interesting. arxiv.org/pdf/0906.2505 The usually cited reference book, and one which explains the formula for calculating SWU, is Karl Cohen "The Theory of Isotope Separation", out of print and hard to find, but is in the collection at the King Library at San Jose State University. The gas diffusion and centrifuge methods are so slow because they depend on the mass difference. Fortuitously, natural fluorine consists of the single mass-19 isotope, so UF6 molecules differ only in the uranium. Laser isotope separation offers greater specificity by relying on isotopic differences in electronic spectra of uranium atoms or vibrational spectra in UF6 molecules. So far, laser isotope separation hasn't displaced centrifuges as the preferred technology (at least as far as they're telling us). In principle, i.e. without violating any laws of physics, there could exist a membrane or barrier permeable to only one isotope. This would allow instant single-stage separation. Diffusion of hydrogen through palladium foil is very effective since the D/H mass ratio is 2. The obstacle to its use is the energy required to electrolyse huge amounts of water for the 1/5000 deuterium fraction. If hydrogen sees use as a fuel, isotope separation can piggy-back on it.
-- Gene
I recall a Manhattan Project documentary where they were debating the feasibility of isotope separation, and someone suggested trying deuterium first. I can't find the quote, but Oppenheimer said something like "Hell, we should be able to do that with our bare hands." --rwg
From: rwg <rwg@sdf.org> To: math-fun <math-fun@mailman.xmission.com> Sent: Sunday, March 22, 2015 8:02 PM Subject: Re: [math-fun] Computational effort
On 2015-03-22 12:25, Eugene Salamin via math-fun wrote:
There already is a unit for isotope enrichment effort. It is the Separative Work Unit, SWU. -- Gene
Gene, are you saying there's a theoretical proof of no shortcut to enrichment? That sounds like a dangerous assumption.
From: Henry Baker <hbaker1@pipeline.com> To: math-fun <math-fun@mailman.xmission.com> Sent: Sunday, March 22, 2015 12:18 PM Subject: Re: [math-fun] Computational effort
Separating U235 from U238 is a pretty decent "proof of work" system.
"Uraniumcoin" ?
"Isotopecoin" ?
"Hex[a]fluorocoin" ?
"Centricoin" ?
These "coins" put the "rich" into "enriched"...
https://en.wikipedia.org/wiki/Enriched_uranium
Of course, you may only want to use Oralloy certificates in commerce, exchangeable* for the real thing. Who wants to carry around a lead wallet, with even heavier contents?
I've heard of deep pockets, but I can't picture one holding a critical mass of U235coins. If that's a problem, enrich just short of finite critical mass. Short of criticality, the lead would be superfluous.
Bcc: Tehran mint --rwg
* (Except by certain not-so-friendly countries.)
At 07:16 AM 3/20/2015, James Propp wrote:
(b) the Manhattan Project,
Henry>
Having an upper limit on the # of U235 coins you can have cuts down on inequality; Dr. Piketty would be pleased: https://en.wikipedia.org/wiki/Thomas_Piketty
Re lead wallets: I thought that U235 was reasonably radioactive, and the radioactivity increases non-linearly with the amount of material gathered together. :-)
Also, lead wallets keep well-heeled friends from exploding with delight from all that hugging.
Deep pockets, maybe; heirs, maybe not! ------
Would you disinherit your grandchild merely for having two heads? _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
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