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Post by davidm on May 4, 2012 15:28:59 GMT 9.5
Since I'm at the nuclear for dummies stage I try to defer to folks who have studied these matters. Here's a fellow who seems to have some background in these matters who has thought about plutonium production and sees it as raising serious proliferation concerns. He doesn't seem to think building a primitive nuclear bomb from plutonium is that hard, even if it is reactor grade. Given that breeder reactors breed plutonium my guess is he would be wary of them. MODERATOR Pasting large slabs of text in a comment violates BNC Comments Policy. Anecdotal remarks are not scientific. For more information please check the BNC Comments Policy before posting again.
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Post by davidm on May 4, 2012 15:55:42 GMT 9.5
(Comment deleted - violation of the BNC Comments Policy)
MODERATOR Please read the section of the comments policy regarding the posting of refs/links. Thankyou.
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Post by Christine Brook on May 4, 2012 16:13:41 GMT 9.5
David M and others wanting to know more on the topic of proliferation should read: IFR FaD 9 – Summary of non-proliferation advantages of the Integral Fast Reactor BNC has dealt with this at some length.
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Post by anonposter on May 4, 2012 17:29:17 GMT 9.5
There's also depletedcranium.com/why-you-cant-build-a-bomb-from-spent-fuel/There are also plenty of other people equally knowledgeable who say you can't do it with what comes out of normally operated civilian power reactors. At the present time there is no evidence that anyone has actually built a working nuclear bomb using spent PWR fuel (reactor grade plutonium tends to get very hot as well, that's also going to be an issue). The US claimed to have detonated a bomb using reactor grade plutonium, but eventually admitted that the material came from a British Magnox and so may have been almost weapons grade and not anything like what modern electricity production optimised reactors would produce (and they haven't even said how well it worked or what advanced design features it had). The British also did a couple of tests and didn't get very good results (they worked, but the yield was low). As far as I'm concerned unless someone actually detonates a working bomb made using spent fuel from a normally operated PWR or BWR this is a made up threat. Of course the fact that the details are classified (and with good reason) means that it's hard to actually verify (the same with any design a student came up, no one who actually would be qualified to judge whether it'd work would comment on it, though I doubt your room-mate knew how to safely handle high explosives (I heard of one design where an explosives expert thought the builder would die trying to make it)). Besides, if reactor grade plutonium were any good for weapons why go to the expense of operating separate reactors on a shorter fuel cycle which in many cases never generated a watt of electricity when you could just use the by-products of the power industry (and why does everyone who wants the bomb either develop uranium enrichment (or buy it of A. Q. Khan) or research reactors running on natural Uranium?)? It may make sense not to sell Plutonium breeder reactors and plutonium reprocessing technology to countries which don't have a history of stable democracy though (Thorium reactors (basically useless for those who want the bomb) are probably going to end up better at making electricity and removing salt from seawater anyway so reserving the types where there's more proliferation risk to stable democracies doesn't seem like a bad idea). Still, if a country wants the bomb badly enough they'll get it unless we use force to stop them, removing the reasons for countries to seek nuclear bombs is a better long term strategy than trying to keep civilian reactors away from them.
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Post by Janne M. Korhonen on May 4, 2012 22:05:43 GMT 9.5
In addition to above statement by Richard Garwin, the former director of Theoretical Division at Los Alamos - J. Carson Mark - has also pointed out that reactor-grade Pu (RGPu) is indeed usable for nuclear explosive devices. As I haven't seen any actual nuclear weapon designer dispute this claim, I'm willing to accept it.
What Depleted Cranium and several others argue is that RGPu is not a good material for military weapons. This is absolutely correct: a bomb made from RGPu is unreliable, clumsy and inefficient from a military requirements standpoint. But what they fail to say is that even RGPu from modern LWRs, if used in a Nagasaki-level bomb design, would reliably yield an explosion of 1-5 kilotons, with a possibility for full 20 kt yield. Even a 0,5 kt explosion - the equivalent of 500 very large truck bombs going off at once - would undoubtedly wreak havoc in any modern metropolis.
HOWEVER, it does not follow that nuclear reactors - even breeders - are "bomb factories." For one thing, a would-be proliferator would usually need a processing facility for separating the said plutonium; the only major stocks of separated plutonium are in countries that already have nuclear weapons. If one has access to the processing facility, it is very difficult to find a reason why one wouldn't have access to a dedicated plutonium breeding pile.
Out of scientific curiosity, I once sent a request for quotations for reactor-grade graphite required in Pu piles resembling Hanford's original design. I got answer to my RFQ in ten hours; a Chinese company was more than willing to deliver up to spec stuff, pre-cut and ready for assembly, for $4022/metric ton, one month from order to delivery. No export requirements or special paperwork needed. (One reactor requires maybe 1000 tons of the stuff.)
Such a pile would be far easier to hide and operate than any current or proposed commercial reactor. It would also be about order of magnitude cheaper.
In any case, it seems that would-be proliferators are abandoning the Pu approach altogether in favor of enriched uranium. As efficient centrifuge enrichment is now widespread, the uranium approach has many advantages - in fact, it's so desirable that there appear to be proposals for any future U.S. nuclear weapons to rely solely on uranium.
It should also be noted that there is absolutely no way - short of full-scale occupation - to prevent any state from developing nuclear weapons if the determination to do so exists. It does not matter how much we self-flagellate ourselves or how much we shut down nuclear reactors: even the plutonium route is so easy that a determined proliferator will be capable of navigating it in a decade or two at most.
But fortunately, more and more states have realized that nuclear weapons are absurdly expensive and have little to no actual value for anything. There are now far fewer nuclear weapons programs in the world than there were just in the 1980s, not to mention 1960s when even Sweden had its own (and very serious) bomb program.
Nukes are essentially a political problem, and must be solved politically, not by trying to restrict beneficial technology just because it could - in theory - be useful for a malefactor. One would equally argue that ammonium nitrate based fertilizers should be totally forbidden, because they have been used in a variety of terrorist bombs, or that breweries should be smashed because they could be used as bioweapon factories. (As an example, four U.S. Army scientists manufactured huge quantities of weaponized anthrax as far back as in 1942, using old brewery equipment and with a total budget that would have kept the Manhattan project running for a day at most. If that anthrax had been spread over Japan - as was discussed - large areas of the island would be uninhabitable even today, due to anthrax spores.)
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Post by grlcowan on May 4, 2012 23:52:01 GMT 9.5
Arguing that it is hard or impossible is a misstep, I think. It is like arguing that car engines are hard, or impossible, to make into multibarrel cannons.
If there were no other, easier, better way to get much better guns, the impossibility of guaranteeing that no car engine will ever be thus weaponized would indeed be a genuine argument against them.
In this world, it isn't; only if there were a market for anti-car casuistry would it ever be heard.
Because of governments' fossil fuel interest, there is just such a market for anti-nuclear-power casuistry, and the attempt to link any kind of power reactor to proliferation is exactly this.
MODERATOR Some of the text has been edited to remove inflammatory remarks.
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Post by davidm on May 5, 2012 2:31:53 GMT 9.5
MODERATOR The remark to which you refer has been edited to comply with BNC Comments Policy.
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Post by grlcowan on May 5, 2012 5:01:58 GMT 9.5
MODERATOR The remark to which you refer has been deleted as it no longer pertinent thus your follow up comment no longer applies.
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Post by BNC Moderator on May 5, 2012 11:37:03 GMT 9.5
A reminder to all of BNC's Citation rule:Citing literature and other sources — appropriate and interesting citations and links within comments are welcomed, but please DO NOT cite material that you have not yourself read, digested and understood. As a general rule, please introduce any and every link or reference with a short description of the material, your judgement on its quality, and the specific reason you are including it (i.e. how it is relevant to the discussion).Please do not post large slabs of copied text. Read more: bravenewclimate.proboards.com/index.cgi?action=display&board=bncforumabout&thread=31&page=1#ixzz1txNxMKIe
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Post by Luke Weston on May 7, 2012 23:08:36 GMT 9.5
This is well worth reading if you want an interesting peer-reviewed scientific paper to cite which deals with this subject in scientifically-literate detail. You'll have to deal with the "Big Journal" subscription paywall, but unfortunately that's the price we often have to pay these days for good quality peer-reviewed credible scientific publications. www.sciencedirect.com/science/article/pii/S0029549308003750I believe there are some other published papers out there on similar subjects by the same authors, or some of the author(s), which are also worth reading. If the pit is so thermally hot that the weapon cannot be assembled at all without melting, degrading, decomposing or igniting the HE assembly, then there's absolutely no point talking about spontaneous fission neutron emission, pre-detonation, assembly velocity or fizzle yields, it's all moot. I never did understand what J. Carson Mark meant by his proposed "thermal bridge". Was he talking about something like sticking copper heatsink fins through the inside of the HE lens assembly or something like that, to conduct the heat out from the pit? Well that's one way to make an already extremely complicated problem in explosive hydrodynamics much, much, much harder. It's probably essentially impossible to insert any kind of heatsink plate or "thermal bridge" through the explosive lens assembly without completely wrecking the already very complicated design of the explosive lens assembly in an implosion bomb. Maybe the experts at LANL, or similar national nuclear weapons experts, with decades of experience, actual working weapons designs, designs and data that have been validated through extensive nuclear weapons testing, large budgets, hydrodynamic radiography expertise and very strong HPC capability can probably pull it off. But that's irrelevant. We're not talking about the experts from the nuclear weapons states doing it, we're talking about the "N'th country" doing it, we're talking about terrorists doing it, rogue states doing it. For anyone other than the nuclear weapons state's weapons engineering experts with extensive experience with implosion radiography, high performance computing, explosive hydrodynamics experimentation and actual nuclear weapons testing, it's going to be basically impossible. And anyway, where do they get the reactor-grade plutonium from in the first place? Break into the local nuclear power plant and sneak off with some sort of 55 gallon drum or something labelled as "reactor grade plutonium"? Not exactly.
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Post by davidm on May 8, 2012 9:05:07 GMT 9.5
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Post by Luke Weston on May 8, 2012 10:47:47 GMT 9.5
To make a plutonium bomb, you need to set up and operate a nuclear reactor (which could be a very simple natural uranium graphite pile) in such a way that plutonium is formed with a suitable isotopic composition with very low levels of 238Pu and 240Pu and mostly consisting of 239Pu.
Not all plutonium is created equal. Which plutonium nuclide(s) you've got matters a great deal.
You then take the highly radioactive irradiated uranium and subject it to plutonium-selective solvent extraction chemistry such as the PUREX process.
A plutonium-selective separation (which usually means an aqueous solvent extraction sort of thing) is not intrinsically associated with all nuclear fuel processing, and it is certainly not intrinsically needed for the efficient recycling and utilisation of nuclear fuel for abundant energy generation.
And then, after that radiochemical separation of plutonium, you've got your solution of plutonium nitrate or something like that, which then requires further chemical processing to reduce it into plutonium metal, and alloying with gallium to stabilise it in the delta phase.
And then, after all that is done, you've still got the design and engineering of the nuclear weapon, which is seriously non trivial, ahead of you.
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Post by anonposter on May 8, 2012 12:50:09 GMT 9.5
The device which the Carter administration claimed was made of reactor-grade plutonium was most likely made of Plutonium with ≈90% 239Pu which is not what comes out of civilian reactors, thus it is not proof that it is possible to make a bomb out of spent LWR fuel (the US still hasn't actually admitted exactly what the composition of the plutonium they used for that device was, though have admitted it came from a British Magnox).
It's also worth noting that Carter didn't actually complete his nuclear engineering education (deleted potentially libelous anecdotal implication) and he most likely never operated a nuclear reactor.
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Post by Janne M. Korhonen on May 8, 2012 18:52:32 GMT 9.5
This is well worth reading if you want an interesting peer-reviewed scientific paper to cite which deals with this subject in scientifically-literate detail. <snip> If the pit is so thermally hot that the weapon cannot be assembled at all without melting, degrading, decomposing or igniting the HE assembly, then there's absolutely no point talking about spontaneous fission neutron emission, pre-detonation, assembly velocity or fizzle yields, it's all moot. Luke, I believe the authors made a major error in the paper. They totally ignored well-known in-flight insertion technique, which means the insertion of Pu "pit" just moments before detonation. The original reason for IFI was safety, but it would also work very well for this purpose. The separated Pu pit is quite simple to cool with e.g. thermal bridges, after all. IFI is not at all difficult: even the Nagasaki bomb was not stored or transported with the pit. If you look at any detailed drawings or read the memoirs, you'll note the "apple core" used to insert the pit before take-off. Furthermore, automated IFI mechanisms were introduced IIRC in Mk 5 nuclear bombs. You can see a picture showing IFI trapdoors open in the Wikipedia article: en.wikipedia.org/wiki/Mark_5_nuclear_bombThe authors apparently misunderstood what Carson Mark and others have written about potential cooling devices. They most probably would not be heat sinks stuck through the high explosive lens - as you say, that would make the hydrodynamics even more difficult than they are. And there is no real reason for that kind of difficulty, since IFI makes cooling the assembled warhead pretty much unnecessary. The high explosive lenses do not heat up too much if the pit is inserted just minutes before detonation. I actually contacted the lead author of that paper - they hadn't considered the aforesaid at all. I've been thinking about writing a rebuttal, but don't have time to do it. True, if the goal is to manufacture a military-grade nuclear explosive with its very high degree of reliability. But as I mentioned above, both Richard Garwin and Carson Mark emphasize that even a crude implosion design will reliably yield 1-5 kilotons with any RGPu, and there is always a possibility for full 20 kT yield. Even a sub-kiloton explosion would be the biggest terrorist/insurgent bomb ever, and with the attendant radiation dangers (even though the biggest danger would be imaginary), well, I'd say any Pu stocks need to be safeguarded pretty effectively. Agreed. And as you say, designing even a "crude" implosion weapon is very much non-trivial task. May I recommend Mueller's book "Atomic Obsession" for anyone interested in the particulars? But I do think the claim "RGPu cannot be used in a bomb" needs some serious qualifications, at least until some real weapons designers with expertise equaling Garwin or Carson Mark speak out and prove it's impossible. Which I doubt isn't going to happen.
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Post by anonposter on May 8, 2012 19:14:18 GMT 9.5
Until they have actually tested a bomb with reactor grade Plutonium of comparable composition to LWR spent fuel (which has never been done) they can't say that it will reliably do anything.
For all I know those people would've said bombs using Uranium Hydride would work just fine.
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Post by Janne M. Korhonen on May 8, 2012 21:41:43 GMT 9.5
Until they have actually tested a bomb with reactor grade Plutonium of comparable composition to LWR spent fuel (which has never been done) they can't say that it will reliably do anything. For all I know those people would've said bombs using Uranium Hydride would work just fine. Have you read Carson Mark's 1990 paper, "Reactor-Grade Plutonium's Explosive Properties?" www.nci.org/NEW/NT/rgpu-mark-90.pdfAs I'm no physicist, I'm not capable of independently verifying the calculations. But Carson Mark's conclusion is that "a Trinity-type device would be capable of bringing reactor-grade plutonium of any degree of burn-up to a state in which it could provide yields in the multi-ton range." He also notes that "The effect of using reactor-grade plutonium in this assembly [Trinity] instead of the high purity plutonium used in 1945 would be to increase the probability that the yield realized would fall short of the levels mentioned by Oppenheimer, but it would not greatly change the actual value of the fizzle yield - which would always be equaled, or exceeded." The fizzle yield in question is about 700 tons TNT at minimum, and can be 5000 tons. I haven't seen anyone seriously refut these claims, perhaps you have better sources? The papers Luke Weston mentioned agree that RGPu would give off an explosive yield; they only argue that building RGPu bombs is impossible because of heat generation. But the argument is seriously flawed, as they assume that the Pu pit cannot be stored separately and installed just moments before detonation - which is a perfectly feasible procedure. I tend to believe that Carson Mark and Garwin know what they are talking about. (In addition, Ted Taylor, the third weaponeer who's written about nuclear weapon design, seems to agree; if anything, he seems to think nukes are even ridiculously easy to build.) Furthermore, as far as I understand, these gentlemen haven't been anything like opponents of nuclear power, so I don't believe they have much to gain by overstating their case. In fact, I suspect the reason they've made their statements is because they very likely know something we outside the "Q" clearance do not. It could very well be that they have found that making bombs from RGPu is even easier than they let us to understand. But as they are not at liberty to discuss anything classified, they have to resort to data in public domain in order to sound a warning. Of course, they may be wrong, but I'd like to see some calculations to prove that. For the record, I don't believe RGPu is a security threat, provided that significant quantities of separated Pu are handled with proper security. But I don't think it's "unusable" either.
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Post by grlcowan on May 9, 2012 2:00:50 GMT 9.5
And so we're going on and on about an unprovable negative.
How is this any more sensible than going on and on about the gun proliferation potential, or absolute and mathematically demonstrable lack thereof, of car engines?
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Post by grlcowan on May 9, 2012 2:03:27 GMT 9.5
... and thanks to the moderator for cleaning up my earlier comment.
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Post by davidm on May 9, 2012 4:41:59 GMT 9.5
Are there experts around writing papers on the potential for car engines being a source of gun proliferation?
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Post by grlcowan on May 9, 2012 5:19:40 GMT 9.5
Are there experts around writing papers on the potential for car engines being a source of gun proliferation? Not that I know of, although I've devised a title they could use: Transport/Crime: Breaking the Thermodynamic Link. As said at the top, there is no market for such stuff. If horses and horse-drawn carriages were heavily enough taxed, and for some reason cars could not be, governments might see car proliferation as a reducer of their incomes, and then the above title might appear.
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Post by jagdish on May 10, 2012 17:29:33 GMT 9.5
All forms of energy can be used as weapons. Moving vehicles kill a large number of people by their kinetic energy. The last major attack on the US was made by flying aircraft. Yet I will not forego fire from my kitchen. I also drive a car in spite of the fact that my mother was killed by a moving car. First two uses of nuclear energy were as weapons. Still, nuclear energy is required for meeting increasing energy demand. By all means concentrate on safety from fire, moving vehicles or nuclear reactors. Yet you cannot ban them.
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Post by Anders on May 10, 2012 19:06:10 GMT 9.5
On this subject, Frank von Hippel has a letter in Nature which mostly talks down MOX (with good reason) but also dismisses fast reactors for UK Plutonium disposal: www.nature.com/nature/journal/v485/n7397/full/485167a.htmlMaybe Barry or others with academic credentials could try to get a response published?
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Post by davidm on May 10, 2012 21:07:37 GMT 9.5
We keep going back and forth on this question of whether or not plutonium is a proliferation concern. Here Frank von Hippel offers a free article expressing those concerns. Both proliferation and economics and feasibility are used as arguments against breeders.
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Post by anonposter on May 10, 2012 21:20:04 GMT 9.5
Yet India produced the Plutonium themselves, they did not buy it from anyone.
As for breeder reactors, with higher Uranium prices (quite a lot higher I should add) they'd become economically viable (and it should be noted that the BN-600 has a pretty good operational record). The choice to develop fast breeders though was probably a mistake (the money should have instead gone to molten salt thorium breeders which probably would have ended up cost competitive with LWRs, but also useless to anyone wanting the bomb).
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Post by Janne M. Korhonen on May 10, 2012 23:49:24 GMT 9.5
What Frank von Hippel utterly fails to mention are advances in centrifuge enrichment of uranium that have happened since India's 1974 nuclear test. These have made enriched uranium the material of choice for would-be proliferators.
It makes absolutely no sense whatsoever to fret over more difficult technology as long as an easier alternative exists. And thanks to A. Q. Khan's network and the fact that it is pretty much impossible to undiscover something, centrifuge enrichment is here to stay - for good and ill.
The only reason why plutonium was ever used was because it was cheaper to produce than highly enriched uranium. Now, the trend is clear: with centrifuges being 10x more efficient in separating U235 than old diffusion process, and with laser enrichment promising to be 10x more efficient than centrifuges, future nuclear weapons will be build either from a) existing WGPu stocks (that is, from recycled warheads) or b) weapons-grade uranium.
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Post by BNC Moderator on May 16, 2012 16:06:39 GMT 9.5
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Post by Janne M. Korhonen on May 16, 2012 22:53:29 GMT 9.5
No, it does not. There is another discussion here: bravenewclimate.proboards.com/index.cgi?board=gendis4&action=display&thread=77&page=1which might be transferred to this section. The Depleted Cranium article claims that it is completely impossible to build an atomic explosive device from plutonium in spent fuel from power reactors. There is very high likelihood, in my opinion, that such a sweeping claim is false. One probably would not choose to build a bomb from RGPu, but a device with a yield of about 1+ kilotons might be possible. There is public research dating to 1970 (if I recall correctly) that discusses the possibility. Perhaps the most damning evidence is given by J. Carson Mark (former director of Theoretical Division, Los Alamos National Laboratory) in his 1990 paper, where he shows that a Nagasaki-class device loaded with any RGPu would reliably yield about a kiloton at least, with a distinct possibility of achieving even the full yield of 20 kt. Depleted Cranium claims that such a "fizzle bomb" "wouldn't be much more powerful than its own weight in dynamite." It should be obvious that even a very bad fizzle - perhaps 600 tons - would be bad news in any city center, being equivalent to 600 very large truck bombs going off at once. I'm aware that there are people who disagree and claim that RGPu is completely unusable. They may be right, but there are also credible arguments that it is usable, and the only ones who really know are not talking. And some of the arguments against RGPu are just plain wrong - the heat generation problem, for example, completely ignores the fact that nuclear weapons can be and often were fully assembled just minutes or seconds before detonation. ("Sealed pit" weapons were actually a relative sophisticated and late development.) In my opinion, it does no credit to the pro-nuclear movement to try to argue that it is impossible to build a bomb from RGPu. In addition, it doesn't advance our cause at all. What should be argued is that it is not a very good bomb material, and that easier routes to the bomb are available to would-be proliferators. Whether or not RGPu is usable for bombs is even irrelevant. What is more relevant are questions like 1) Does the spread of nuclear power necessarily mean the spread of nuclear weapons, and 2) Would nuclear weapons be eliminated if the world turned its back to nuclear power? The answers are, obviously, no and no.
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Post by anonposter on May 16, 2012 23:09:51 GMT 9.5
If it could reliably yield one kilotonne then it would be militarily useful (and until it has actually been tested the idea that you can use reactor grade plutonium in a bomb is unproven and should not be given any credence, if the anti-nukes want to claim you can use it the burden of proof is on them).
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Post by grlcowan on May 16, 2012 23:50:02 GMT 9.5
"Why You Can’t Build a Bomb From Spent Fuel" -- because, no matter how bad you are, you don't want to, just as you don't want to make an old V8 into an eight-barrel cannon (with which, perhaps, to rob eight banks at once. Or two, anyway, one on each side of the street).
Packard attempts to prove a negative that can't be proved, and which is irrelevant, as Korhonen suggests.
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Post by Janne M. Korhonen on May 17, 2012 19:35:07 GMT 9.5
If it could reliably yield one kilotonne then it would be militarily useful I don't buy this argument, at least completely. Nuclear weapon establishments around the world have spent a great deal of time and trouble trying to ensure the reliability of their stockpiled nuclear weapons. Among other things, reliability means making sure that when the bomb is scheduled to go "bang," it does so exactly as planned, with a reliable yield. RGPu would make for an unreliable weapon, perhaps not in a sense that it wouldn't go bang, but that it would do so with an unpredictable yield. (Carson Mark's calculations suggest that the yield might vary from 1 to 20 kt for a relatively primitive weapon.) Too big a yield is almost as big a problem as too low a yield. For example, nuclear targeting and delivery tactics may require a pretty reliable yield. Personally, I believe this is the biggest reason why we don't see RGPu bombs in any arsenals. Producing weapons-grade Pu is easy enough and avoids this and other complications that make RGPu a poor choice for stockpiled, standardized nuclear arsenals. But "emergency capability" weapons might be a different matter. I can imagine, for example, certain (unlikely) scenarios where small countries might be tempted to construct a few crude fission devices, perhaps from RGPu extracted from spent fuel. Nevertheless, I find it difficult to construct scenarios where the bomb builder could have all the other infrastructure and know-how required for a bomb, but simultaneously be unable to build the relatively simple atomic pile for producing WGPu.
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