Talk:Weapons-grade nuclear material

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Reactor grade test myth[edit]

Article currently reads

It is difficult to produce weapons-grade plutonium with a light water reactor because the reactor must be shut down frequently to replace the nuclear fuel rods, so weapons-grade plutonium is generally produced in small, specialized military reactors. However, a test of a nuclear weapon that used reactor-grade plutonium was successfully detonated, although the yield was relatively low.

This paragraph seems to be talking about LWRs, and so to support the widely quoted myth that LWR-produced plute has been detonated. In fact as Reactor-grade plutonium#Reactor-grade plutonium nuclear test already points out, the plute used in this particular test was from a British Magnox reactor. The Magnox was designed to be able to produce weapons-grade plute, and can produce a wide variety of grades. The actual composition used in this test has still not been made public.

Not quite sure how to restate it, and my pro-nuclear bias may be a problem if I try. But I invite someone else to! Andrewa (talk) 10:37, 20 November 2009 (UTC)

I think you mean LWR spent fuel at typical final burnups, rather than the nature of neutron irradiation itself in a LWR.
Reactor-grade plutonium has some language saying the test was with what was later redefined as "fuel-grade plutonium"; feel free to draw on this.
After reading up on fusion boosting personally I think the neutron background and heat production of even high-burnup plutonium would be little barrier to building modern nuclear weapons. Fusion boosting and external neutron initiators make neutron background irrelevant, and have been standard for 50 years now. Air-conditioning the pit during storage is not hard either. --JWB (talk) 16:20, 20 November 2009 (UTC)
Hmmmm... Yes, the problems with detonating plute from spent LWR fuel are related to burnup. Yes, the spent fuel which Carter decided not to reprocess, citing this test as a reason, was high-burnup fuel.
Yes, there have been various attempts to reclassify, clarify or whatever the composition of the plute used in the test... not including any leaks as to its actual composition in numbers AFAIK.
And yes, there's been much speculation as to whether techniques such as fusion boosting might make it practical to build a bomb from spent fuel such as is produced by the US power reactor fleet, as Carter (a nuclear engineer) apparently feared.
But the point is simply, the article currently reads as if there's been a test that demonstrated that it can be done, long ago. This is a widely believed myth, and a false one.
The speculation is encyclopedic if (and only if) notable authorities are cited. Similarly, the myth is encyclopedic if reliable secondary sources establish it to have significant following. It's not on Snopes, not yet anyway.
But there's a core of encyclopedic fact there, and while we're not Snopes, it seems to me that we're currently repeating the myth, and should do better. Andrewa (talk) 20:19, 20 November 2009 (UTC)
It's not clear from your response exactly what you are calling a myth or unfounded. The test happened and was with plutonium labeled "reactor grade", yes? That article already explains this may not be the same as "reactor grade" commercial plutonium today. I've suggested you add the same to this article if you feel clarification needed. Would this solve the problem for you or not? --JWB (talk) 22:46, 20 November 2009 (UTC)
The myth is that a test was conducted with material made in a power reactor similar to those used in the USA in July 1977 (the date that some information on the 1962 test was released) or proposed for construction currently.
This is widely believed in my experience, and justifiably so, as Carter's logic doesn't make any sense otherwise. But strange to tell (and I have to keep checking my facts because I do find it very strange indeed) it's actually false.
I have my own theories as to the details of the 1962 test, its purpose and conclusions, the plute composition and so on, gained from talking to those who did have access to such information. But these are neither encyclopedic nor even quotable, unfortunately. And my theories may even be wrong. But the myth as I have described it above is certainly false. No such test was even conducted (that's my opinion), and no evidence was ever presented that it had been (that's strange but verifiable fact, but probably not encyclopedic of itself). Most of what we do have is weasily statements using ill-defined terms such as "non weapons-grade".
It's not an easy issue for Wikipedia IMO, nor for me personally as a keen Wikipedian. It's very easy to stray into advocacy either way, and most people who do have a grasp of the issues have possible COI or even soapbox problems. I don't think the solution is to say nothing, for two reasons: Firstly, even if we delete the material completely, it will just be added again, probably by people who aren't as concerned about Wikipedian ideals; Secondly, there is some encyclopedic information available to present.
Thanks for your help in clarifying things. Andrewa (talk) 16:14, 21 November 2009 (UTC)
I have always heard that Carter's logic was to avoid legitimizing proliferation of reprocessing facilities, without reference to the suitability of plutonium at normal power reactor burnup. Once you have reprocessing faciilities it should be relatively easy to remove and reprocess fuel short of normal burnup.
Commercial reprocessing is large scale. Bombs need relatively little material, but with far more exacting requirements as to its composition. As with the reactor itself, it's far cheaper and less likely to be noticed if you build a small dedicated facility rather than disrupt the operation of a large commercial plant.
Agree. Still, if you assume anyone can build a PUREX plant, then it is any spent fuel that is the threat, regardless of whether a country has been engaging in commercial reprocessing.
Look more closely at this scenario. We hypothesise that someone has the will and resources to possibly build a bomb. We further hypothesise that they then decide to use some of these resources to build a PUREX plant to reprocess high burnup fuel. The result of this decision is that the threat of them ending up with a working nuclear explosive is reduced, and the likelihood of discovery increased.
On the other hand, the threat of such scenarios being used to cripple the nuclear industry is not only real, it's observable in recent history. Andrewa (talk) 16:56, 24 November 2009 (UTC)
I was discussing the significance or lack of it of Carter's order, and not arguing that reprocessing LWR SNF is a likely proliferation avenue - this has been underlined by the last several nations that have pursued other methods. The halt to reprocessing was just the last event before stagnation of the nuclear effort in general set in and the fact that antinuclear groups continue to oppose reprocessing along with everything else nuclear is of little significance. There is little reason to reprocess LWR fuel at all since single thermal MOX recycling extracts only 12% more energy; the only reason that makes any sense at all would be to burn plutonium and MA in fast reactors, and in that case it reprocessing can be deferred until fast reactors need it, as reprocessing methods can only improve and fission product radioactivity continues to decline. --JWB (talk) 18:39, 24 November 2009 (UTC)
Agree with much of this, but with some important qualifications.
Carter's order is significant mainly in that it gave ammunition to the antis everywhere. Its practical effect was mainly felt in the USA, who had enormous resources to develop reprocessing technology, but who had already lost much of their wartime lead in this field to other countries, notably France, India, the UK, the USSR and Japan. The stagnation of the nuclear effort in general wasn't worldwide, it included only one of these countries, the UK; Outside of the Western block nuclear power has always been doing well overall, the biggest setback has been Bataan Nuclear Power Plant in the Philippines, and of course even within the Western block France has gone ahead undaunted. Reprocessing has certainly stagnated worldwide, owing to cheap uranium which has been partly due to the stagnation of the US nuclear industry, of which Carter's overall energy policy was an important part. The failure to commercialise first generation FBR technology was both a driver and a result of the lack of widespread reprocessing, and also driven by cheap uranium. Both FBRs and reprocessing lack purpose in this environment. On the other hand, driven by the neccessity of upgrading existing units while no more could be built, the US leads the way in increasing the burnup possible with the once-through LWR fuel cycle, which has further decreased the worldwide need for both FBRs and reprocessing and put still more downwards pressure on uranium prices.
In my view PUREX is good at separating pure plutonium for bombs and bad on volume of waste generated, and pyroprocessing makes much more sense for simply recycling reactor fuel, which merely needs reduction of levels of neutron poison fission products. Building more PUREX plants would not have been progress by any measure. What we should be doing is cheap research and development of diverse pyro methods so that they will be available if and when reprocessing is needed.
In my opinion, there is no call for commercial reprocessing at present, either environmentally or economically, nor can we predict at what stage there will be. Hard-nosed economics favour once-through LWR fuel cycles with long-term burial of the intact fuel elements. The idealist in me would prefer that some thought was given to their eventual recovery. I don't think we can predict what the reprocessing technology of the future would or should be. Andrewa (talk) 17:16, 27 November 2009 (UTC)
We don't know what the future holds, but it's possible to give it some thought. Geological repository disposal has been delayed enough that the de facto plan at least in the U.S. is pool and cask storage of SNF for decades. With potential repository sites all saying NIMBY, storage at each reactor site may go on longer than anyone imagines now, until a time when medium-lived fission product radioactivity is significantly reduced. When most radioactivity is from actinides, reprocessing for actinide recovery and burning may make sense. We don't know what methods will be used, but it is safe to say that not creating voluminous reprocessing wastes is desirable. --JWB (talk) 21:31, 28 November 2009 (UTC)
This is still IMO both speculative and US-centric. IMO the operators of any plant (nuclear or otherwise) should be required to plan for the disposal of the wastes before the plant is allowed to operate. In the case of nuclear power plants Sweden has done exactly this; The US unfortunately has not. If technology arrives that means it makes good sense to change these plans before they are completed, change them by all means. But a realistic plan should be in place before the waste is generated, and this same principle should be applied to reprocessing plants if (and I expect when) it is proposed to reprocess existing spent fuel at some time in the future. Andrewa (talk) 12:30, 30 November 2009 (UTC)
Yes, I was discussing the US in that paragraph. Is it simply that Sweden has a repository while the US has canceled its repository? If you mean generation of SNF, obviously the time to plan in advance was decades ago. If you mean wastes from new reprocessing, it seems unlikely that will happen without more thorough consideration of disposal including long-term. --JWB (talk) 17:31, 30 November 2009 (UTC)
Sweden made it a condition of the operation of nuclear power plants that plans for disposing of the waste were in place first. That's why, despite an active and reasonably successful anti-nuclear movement, their repository hasn't been such an easy target. But politics aside, I think their model is the correct one for any industrial activity, including nuclear power generation, nuclear fuel fabrication and reprocessing, manufacture of Barbie dolls, and many others.
I don't want to be too hard on the US, the waste disposal practices of the Manhattan Project were reasonable given the circumstances, but it got them off to a rather bad start. Andrewa (talk) 10:21, 1 December 2009 (UTC)
Ths US federal system certainly makes it harder. I wouldn't say the US disarray over Yucca Mountain is good, but on the other hand I don't think SNF disposal anywhere is likely to be permanent. Despite the concern over communicating about the repository to people tens of thousands of years in the future, it is likely that over a scale of hundreds of years someone will choose to recover and reprocess at some point. At the other end, early repository placement is limited by heat generation. --JWB (talk) 16:49, 1 December 2009 (UTC)
(Hope you don't mind me adjusting your indenting)
Agree whole-rod SNF disposal is unlikely to be permanent. That's not the point. It can and should be planned to be indefinite. That's this generations's responsibility, and it's achievable. Whether recovery is in hundreds or thousands of years (or even never) is not a problem we can or need to solve.
Agree that early repository placement is a very bad idea. I hope nobody is proposing that! The planning needs to be early; The indefinite burial, as late as possible. Again, this is exactly the Swedish model.Andrewa (talk) 15:48, 2 December 2009 (UTC)
Not sure what you mean by "outside the Western block". Reactor orders worldwide as well as fast reactor development fell off after Chernobyl. The EU, CIS, and Japan+Korea+Taiwan each get around 30% of electricity from nuclear, only slightly higher than US 20%, and the world as a whole is at 12%. Rising powers like China and India have ambitious plans but currently use 2-3% nuclear. --JWB (talk) 17:05, 26 November 2009 (UTC)
Another interesting thing (and sorry the threads and indenting are getting a little confused)... The stagnation in the US industry wasn't actually a consequence of Chernobyl, or even of TMI. I remember in the mid '70s (so before TMI) hearing a senior executive from a US utility that operated several nukes address about 200 interested employees of the AAEC (including myself). He said in part When you order a nuke in the US at present, you play a game called "You bet your company". I don't know anyone wanting to play that game right now. As I said, that's long before Chernobyl, and even before TMI. That these accidents were the reason for opposition to nuclear power is another myth. The opposition was well organised and getting results before them, and in the case of Chernobyl, long before. Andrewa (talk) 19:48, 2 December 2009 (UTC)
My point was the low level of orders after all of those events had happened. I was not trying to neglect economic and regulatory factors. --JWB (talk) 21:36, 2 December 2009 (UTC)
I respect your opinion that the whole of the world's nuclear industry experienced stagnation but I think it's overstatement. Chernobyl was certainly, and rightly, a setback, and raised many issues, as did TMI. It wasn't business as usual, but unlike the US and most of Western Europe, it wasn't closed UFN either. Andrewa (talk) 20:34, 27 November 2009 (UTC)
How many reactors were ordered during the 90s? I don't have a figure but looking at List of nuclear reactors etc. and dates for starting operation, it looks small worldwide. --JWB (talk) 21:31, 28 November 2009 (UTC)
Don't know offhand exactly how many. China, India, Japan and South Korea all ordered new nuclear power station units during the 90s which have subsequently come online. Such major investments even if few in number don't speak of stagnation IMO. Andrewa (talk) 12:30, 30 November 2009 (UTC)
Also, higher burnup does not necessarily increase efficiency in terms of original U-235 and original natural uranium before enrichment. AFAIK the breeding ratio is the same with about 1/3 of lifetime energy production from bred Pu. --JWB (talk) 17:31, 26 November 2009 (UTC)
Interesting. If that's correct then this may not be a downwards driver of uranium prices after all, as I believed. It's still interesting to me as, despite the stagnation of the US nuclear industry, LWR fuel technology is an area in which the US industry has continued to produce internationally respected progress. Andrewa (talk) 17:16, 27 November 2009 (UTC)
It's easy to overstate the bad news, and the antinuclear lobby have been very good at it. But there are limits.
My agenda here is simply to keep Wikipedia as accurate, complete and NPOV as possible. I still feel we are propagating a myth by the wording of this particular article. It's not the only problem; We once had an article on nuclear power phase-out, created largely by those who wished to trumpet the initial successes of the movement. Now that this effort is seen to have failed at significant cost to those countries that adopted it, the article has been redirected. Of course, like the fossil fuel bridge, it's still an important historical part of the development of energy policy and politics worldwide, and while the article on nuclear energy policy covers the topic you need to search or scroll down to find it. I expect it will be some time before Wikipedia has articles on either the phase-out movement of the fossil fuel bridge concept, which I think is unfortunate. Andrewa (talk) 16:17, 26 November 2009 (UTC)
I encourage you for the third time to fix the language you see as inaccurate, which would only take a few words. The table in Nuclear power by country links the German and possibly Swedish phase-outs. All of these are in good shape compared to the silliness in Peak uranium. --JWB (talk) 17:26, 26 November 2009 (UTC)
When I feel strong I will. Thank you! Andrewa (talk) 17:16, 27 November 2009 (UTC)
And I now have, see below. Andrewa (talk) 17:53, 9 December 2009 (UTC)
Plus, I think the demise of commercial reprocessing is blamed too much on Carter's order when it was mostly due to availability of cheap uranium and failure to commercialize breeder reactors.
I have not encountered the myth that the 1962 test was with high-burnup plutonium comparable to today's power reactor discharge. I've only read the Wikipedia articles and NWFAQ saying it was Magnox plutonium of some intermediate burnup. Where have you run into this?
Glad to hear it. Knownukes Yahoo group is one place I've found the rumour, it's been quickly answered there but has turned up a couple of times. And many other discussions, some may even have been on Wikipedia.
I would be interested in hearing your speculations about the 1962 test, even if they are not suitable for article text.
Knownukes would be one suitable forum for this, but I'm currently inactive on it, don't even lurk, and it can be quite a high throughput group. Hmmmm... not sure where else would be suitable.
There are also personal blogs.
In my opinion the case for usability of high-burnup plutonium in modern nuclear weapons is not in any weapons tests that have been conducted, but just in the facts we know about nuclear weapon design. The principles behind fusion boosting are independent of plutonium composition; only a yield of 300 tons is required to reach the necessary temperature, and according to analyses like the ones at NWFAQ this yield should be easily achievable with even the worst plutonium. --JWB (talk) 17:08, 21 November 2009 (UTC)
IMO that's a dangerous exaggeration. With pure Pu-238, for example, even this yield won't be easily achievable, will it?
I could argue this is within the range of cooling systems, but pure Pu-238 is not a possible reactor discharge. High-burnup plutonium is still only a couple of percent Pu-238.
That's my point exactly... you could argue this, and it would be pure speculation. Just as there is now a published theoretical "critical mass" for Pu-238, but nobody has ever assembled a critical mass of it or ever expects to.
Agree that high-burnup fuel has only a little Pu-238. That wasn't the point.
The question is still, has there been a test of any of this speculation, and particularly of the possibility of using spent PWR fuel to build a nuclear explosive? Andrewa (talk) 09:27, 24 November 2009 (UTC)
The case for usability of high-burnup plutonium in modern nuclear weapons is one of the "big three" of bombs, wastes and accidents. Like the other two, it quotes some accurate and scary facts, but doesn't hold together under careful scrutiny. If a bomb had been built from spent PWR fuel in 1962, that would be a different story, and many seem to believe it was (but that's my unsourced opinion). But it wasn't, and that's a verifiable fact. Andrewa (talk) 13:38, 23 November 2009 (UTC)

Some possible sources[edit]

Interesting this does not mention predetonation as a reason but only ease of handling. --JWB (talk) 18:47, 3 December 2009 (UTC)
...the point being...? Andrewa (talk) 10:08, 4 December 2009 (UTC)
That maybe they do not view predetonation as a credible reason any more? --JWB (talk) 18:10, 4 December 2009 (UTC)
In other words, more speculation. Andrewa (talk) 19:08, 4 December 2009 (UTC)

More to follow as I find them. Andrewa (talk) 19:39, 2 December 2009 (UTC)

This cites personal communication from Marvin Miller. You could contact him to verify. --JWB (talk) 18:47, 3 December 2009 (UTC)
It's at least evidence that some do appear to believe the myth cited above. Of course this is risking being WP:OR, but the first step towards being encyclopedic is to be accurate. Andrewa (talk) 10:08, 4 December 2009 (UTC)
Aren't you curious whether this person listed as being at MIT is a real expert, or mistaken, or just misquoted? For that matter, if he is being misquoted, he might want to know about it. --JWB (talk) 18:10, 4 December 2009 (UTC)
Not very. I'm curious about everything, but this isn't much of a priority. The point is simply that someone believed the myth, once upon a time. I was a little taken aback that anyone doubted this, having heard it repeated so confidently and often over the years, but hey, we're all learners, myself especially. Maybe this particular myth is in its death throes. I'm equally astounded that the fossil fuel bridge has been so quickly forgotten, it was such a popular cause in the 1970s, but there you go. Nor have I any wish to rubbish anyone for believing either of these, or to try to track down and harass those who may have spread them. History may judge them, or forgive them, or forget them. Not my problem. The agenda here is just to make Wikipedia the best resource of accurate, verifiable, NOR etc information possible. Of course, this information may be unwelcome for some. Again, not my problem. I'm wrong sometimes, and try to see it as a good thing when I have the opportunity to find out exactly how I'm wrong, but this attitude isn't always easy to adopt, and never possible to enforce on others. Andrewa (talk) 19:08, 4 December 2009 (UTC)
If he is a reliable technical source, he may have information we haven't heard yet on the actual technical question, which would be relevant and likely suitable for the article. If he was misquoted, he should be allowed to put it straight, which does not need to be rubbishing or harassing whoever misquoted him. If it is a myth that grew through misunderstanding, maybe he can shed light on the misunderstanding. If you don't have sources documenting how it is a myth, then that assertion is just your speculation. If you simply believe some statements about reactor-grade plutonium are incorrect, then for the fourth time, by all means please insert the sourced information you believe is correct into the article. BTW I have never heard the phrase "fossil fuel bridge" before. --JWB (talk) 20:06, 4 December 2009 (UTC)
The fossil fuel bridge was a concept promoted by some anti-nuclear activists in the 1970s. The idea was that as there is enough fossil fuel to last at least 200 years, nuclear power would not be needed in that time. It sounded as stupid then as it does now.
I intend to update the page, as I said before, unless someone else does in the meantime. This section was created as preparation for that.
Speculation? I think not. I have stated what I believe the myth to be, and why I believe this. I'm still investigating how and even whether I can sustantiate this to Wkipedia's standards. That's what this section was intended to be. It's a tricky question, as I said before, but I think I'm making progress.
The exact wording of the rewrite depends of course on what citations I come up with.
Approaching Marvin Miller for an explanation of the web page in question is certainly a possible line of further enquiry. I have several others already underway. But it may not happen overnight. Andrewa (talk) 06:05, 5 December 2009 (UTC)
It sounds strange with the recent popularity of peak oil theory, but fossil fuel and other resource continue to expand with exploration and technology. Just in the last couple of years, shale gas has caused huge upward revision of US gas reserves. Coal reserves are also large. Today we have some people arguing that fossil fuels are about to run out, and other people making no claims about exhaustion but arguing that carbon emissions should be curtailed for climate change.
To say something is a myth rather than simply saying it is wrong, is to say that a falsehood has been persistently propagated, and although you say you aren't rubbishing anyone, the word questions their intelligence and/or honesty. In this case the actual evidence about the test is scanty and there is plenty of room for confusion. --JWB (talk) 11:25, 5 December 2009 (UTC)
Agree. But I think the word myth is the accurate one here, and belongs here on the talk page. IMO it doesn't belong in the article unless it turns out to have been used by someone who is a citeable source themselves, and even then I'd be cautious.
And that's the whole point. If the charge is true, it's an issue that calls for some caution on the part of Wikipedia, just as we should be very careful about peak oil, middle east politics, and many other politically charged issues. It's good to include these issues, and policy to assume good faith, but not too naively.
I still maintain I don't wish to rubbish anyone. On the other hand, if people are held up to ridicule because of things they have said for whatever reason, I'm not going to let that worry me either. This includes the links I have given here, and others I hope to find, and of course you and I. Sauce for the goose.
It gets even trickier when others are named on sites we cite of which they may have no control or even knowledge, and this Marvin Miller is of course a case in point. IMO the Nuclear Control Institute is notable enough to be a suitable citation, but obviously they have a particular agenda, as do the Friends of the Earth and World Information Service on Energy organisations whose pages I also listed.
If they've misquoted Marvin Miller in any way, I'm afraid that's his problem. He might appreciate an email, or might not. Not convinced it's the best way to go. Feel free to send him one if you are. Andrewa (talk) 14:11, 5 December 2009 (UTC)

Still looking, Andrewa (talk) 11:38, 3 December 2009 (UTC)

If you want the official DOE press release a cite for it is in 1958 US–UK Mutual Defence Agreement : "Additional Information Concerning Underground Nuclear Weapon Test of Reactor-Grade Plutonium". US Department of Energy. 1994. Retrieved 2007-03-15. Unknown parameter |month= ignored (help) Rwendland (talk) 19:15, 9 December 2009 (UTC)
Thank you! I'll have a look at it. Andrewa (talk) 20:26, 9 December 2009 (UTC)

Rewrite commenced[edit]

I've done a first cut. Obviously there are some references needed, but these tags would have been equally appropriate on the section before the rewrite. And there's at least one redlink.

I hope it's accurate and even-handed, and an improvement, but it's not finished by any means. Andrewa (talk) 17:53, 9 December 2009 (UTC)

It makes it sound like the question of usability of lower-grade plutonium for explosives is about having a full-scale explosive test, which it is not. It can be extrapolated from the known properties of the isotopes.
Agree that the 1964 test is of marginal significance in deciding this.
On the other hand, the websites (given above) of three important antinuclear organisations (and probably others) all make it sound as if this particular test is extremely significant to this issue. That's what has created a connection. It's a tricky one to report objectively and without straying into WP:OR or WP:ADVOCACY, but important.
It could be that they report everything in this tone. Also this is looking at their pages on this test in isolation from their other pages.
Agree. It doesn't alter the point being made.
Disagree that the performance of a bomb can be extrapolated from the known properties of the isotopes. This sometimes works, but sometimes it doesn't. The gadget and Little Boy both worked first try, but some subsequent tests have fizzled unexpectedly, and at least one has delivered a far greater yield than predicted. Better models for predicting bomb behaviour have been developed based on information gathered from many such tests, but much of this information remains secret. It would be very interesting, for example, to know the yield predicted for the 1964 test, against actual.
Some tests produced unexpected results because nuclear properties of isotopes were not completely known at the time, for example Castle Bravo. Others used less certain experimental designs. All the plutonium isotopes are fast fissionable and their critical masses have been estimated.
Agree. The point is, the warheads we are discussing here would be every bit as experimental as Castle Bravo.
Disagree completely. A basic reaction of lithium-7 was not known. By now we have over 60 years of observations of plutonium in thermal and fast reactors and many different experiments, with Pu-240 as the second most common isotope. The only properties that are relevant are reaction cross-sections and spontaneous fission neutron background, both very well known.
I think we might just need to agree to disagree on this point. Andrewa (talk) 02:11, 12 December 2009 (UTC)
But the cause of the underestimation of the Castle Bravo yield is an interesting example of the use, and limitiations, of NWFAQ. NWFAQ does explicitly say that the cause was the failure to account for a particular Lithium-7 reaction, as you say. Over the years I've heard a number of other theories, and what they are is not terribly relevant, just that other causes have been proposed, either as alternative or as partial answers to this same question.
If I had to guess I'd guess that NWFAQ has it right, it does make sense. But let's look carefully at the claim and the evidence. The claim is that this is the nature of the error in some top-secret calculations. The calculated and actual yields have been published, but that's not what we're talking about here. We're interested in why the calculations and the results differ. These calculations have not been officially published, and are unlikely to be any time soon, as they contain some still very secret data.
So, what sources does the NWFAQ cite? None. The bibliography of the current version is not yet available. There's no footnote. There is however a general claim that everything in NWFAQ is from published sources. At this point I'm going to speculate that there are two possible types of published source for factoids such as this, and these are personal accounts by people who were there at the time, and lobby groups (including but not only antinuclear ones).
We can eliminate the lobby groups as good sources, as they all in turn quote NWFAQ as their source, so that would be a circular argument. As we've both said, NWFAQ has a deservedly good reputation.
So that leaves personal accounts, memoirs and the like. The problem is, while these people were there, they may not have seen the calculations either. Following the very public problems with this particular test, everyone had a theory as to what went wrong. The vast majority of these theories were speculation, in fact probably all of them were. Those in the know were not saying.
Wikipedia should report this theory as to what went wrong. But we should say it's what NWFAQ says, not making any claim either way as to whether ot not it's true. That's unless we can find the source(s) NWFAQ is relying on, in which case we cite them as well or perhaps even instead. It may even turn out that one of these sources is someone who was in the know at the time (and now long retired etc) and has subsequently let the cat out of the bag. But it's not safe to assume this. Andrewa (talk) 00:38, 14 December 2009 (UTC)
I believe the claim primarily because it logically makes sense. Lithium was the new component. Other components had been used before and were better understood. Lithium-7 fission requires neutron energies beyond even most fission fast neutrons, and it makes sense that it would not be observed until D-T fusion neutron sources were available for experiment. AFAIK nobody has later questioned that lithium-7 is in fact split by energetic neutrons. Fission in the secondary was proportional to fusion neutrons since U-238 does not sustain a chain reaction. It is hard for me to think of any other possible cause than misestimation of tritium and neutron production from lithium-7. The only others that come to mind are misestimation of how completely lithium-6 and deuterium were burned, but most likely Li-6 was burned to completion and there was already information about the D-D reaction. NWFAQ's claims almost always make logical sense to me, which reinforces the overall credibility of the source. --JWB (talk) 06:54, 14 December 2009 (UTC)
In other words, it's one layman (yourself) assessing and extending the work of another layman (Carey Sublette) on a highly technical subject.
There's a place for this. IMO it's even appropriate from time to time on Wikipedia talk pages. But we should also bear in mind that it's a long way short of Wikipedia's standards of verifiability, and be very wary of the danger that such conclusions might leak into articles. Andrewa (talk) 19:51, 16 December 2009 (UTC)
Quadrupling the proportion of Pu-240 would only move up predetonation by two doubling times - and predetonation is not even an issue with fusion boosting. Achieving yield in a primary is about the implosion system and boosting much more than about the plutonium quality. In a secondary, it is even less of an issue.
I'd be very interested in knowing your sources for these ideas.
Corey Sublette's Nuclear Weapons FAQ is the most comprehensive source for nuclear weapon design. I've cited him before whenever this has come up and the Wikipedia articles cite him extensively. He discusses the specific issues mentioned here. Of course 4x the quantity of Pu-240 producing 4x the neutron background is also simple logic. --JWB (talk) 20:19, 11 December 2009 (UTC)
Certainly a very useful site, but risky to use it as the only basis for claims such as you are making IMO. And I don't think even he suggests that a yield of 300 tons would be easily achievable using pure Pu-238 by using modern cooling systems, or does he?
Pure Pu-238 is a case only you have brought up, which has absolutely no relevance to plutonium produced by reactors.
Agree. Any nuclear engineer will instantly say "OK, that stuff isn't bomb material at all", but many who have just read antinuclear sites will give the opposite answer, equally confidently. IAEA safeguards don't cover pure Pu-238 at all, while they do of course and for example cover natural uranium, which (fortunately) won't go bang either, but is still a significant proliferation risk. But Pu-238 ain't. Andrewa (talk) 02:09, 12 December 2009 (UTC)
IAEA safeguards may be written to not interfere with spacecraft RTGs, but that doesn't mean the US or Russian governments are handing out Pu-238 to anyone else. It also doesn't mean it wouldn't be easy to make a few kg of Pu-238 explode with at least enough energy to vaporize it and spread a potent alpha emitter around the area. IAEA safeguards may date from before the era of concern about dirty bombs. So some less technical or poorly informed people might confuse one dangerous radioactive plutonium isotope with another. This is news?
Hmmm, are you really suggesting that the IAEA would compromise safeguards so as to not interfere with spacecraft RTGs? A bit of a stretch IMO. See below re dirty bombs.
I am suggesting the Pu-238 provision of the safeguards was written with spacecrafts RTGs in mind, since that is pretty much the only application of Pu-238 and reason why anybody thinks of the isotope at all. --JWB (talk) 04:57, 12 December 2009 (UTC)
Agree with this, but so what? The IAEA has consistently said that Pu-238 is not under safeguards simply because it's not a proliferation risk.
Pu-238 also once made an excellent pacemaker power source. Andrewa (talk) 09:29, 12 December 2009 (UTC)
You've brought Pu-238 up twice so far.
Yes. And explained its relevance. Andrewa (talk) 00:38, 14 December 2009 (UTC)
I didn't look at dirty bomb before posting, but it actually has a sourced statement that "Only nine reactor produced isotopes stand out as being suitable for radiological terror: americium-241, californium-252, caesium-137, cobalt-60, iridium-192, plutonium-238, polonium-210, radium-226 and strontium-90,[8] and even from these it is possible that radium-226 and polonium-210 do not pose a significant threat."
Again I preach caution. Another favourite antinuclear line of argument is to confuse the issue of nuclear explosives with dirty bombs. Weapons grade of course refers to nuclear explosives, nuclear proliferation etc.. Anything will explode if you stuff it full of gelignite. As you say This is news? Andrewa (talk) 04:17, 12 December 2009 (UTC)
As far as I know he has always had a policy of keeping his personal details, includng his technical background, off the web, as is his right and we should respect it. He may be a nuclear engineer for all I know, but we can't assume either way. Many of the nuclear engineers I speak to are even more reluctant to be quoted, unfortunately, but again I respect their rights in the matter. Andrewa (talk) 23:02, 11 December 2009 (UTC)
Not sure of your point here. I haven't tried to research any of his background and hadn't even thought to. I've read his site, it makes sense to me, and it is rated by others as the best reference. --JWB (talk) 00:41, 12 December 2009 (UTC)
What I've read of the site has been excellent, agree. My main reservation about it would be that some of it seems to be easily misquoted. That's no reflection on the site, more on the complexity of the issues and the politics. And Wikipedia is in the same tricky position, maybe even more so.
But most important, it's not intended to be cited as an expert source on technical matters, or even on Federation of American Scientists opinions, as the two disclaimers (one by the author and the other by the FAS who host the site) point out. Andrewa (talk) 02:09, 12 December 2009 (UTC)
In law and medicine, this kind of disclaimer means "I'm not a licensed official practitioner in this field, don't sue me." I don't take it as any comment on the quality of the source. NWFAQ is higher quality than most sources cited on Wikipedia. --JWB (talk) 03:06, 12 December 2009 (UTC)
Agree mostly. The problem is, for several reasons, many who are a licensed official practitioner in this field can't be quoted, eiher for reasons of official secrecy (some and not all of it justified) or simply because they've had enough abuse over the years. So there's a bit of a vacuum, and the NWFAQ fills it well. Unsure whether it's better or worse than the median Wikipedia source, and not particularly interested, not a useful statistic IMO. We should just do the best we can, case by case. Andrewa (talk) 04:17, 12 December 2009 (UTC)
I see now he says The US actually tested a nuclear device made from plutonium with a Pu-240 content of >19% in 1962. The yield was less than 20 kt. Although this was first made public in 1977, the exact amount of Pu-240, yield, and the date of the test are still classified. I hadn't remembered that statement. --JWB (talk) 12:20, 12 December 2009 (UTC)
Interesting. also gives the date as 1962, and in view of that and assuming that this information has only been released about one such test) I've corrected it in the article. Can't even remember where the 1964 date came from, it may have been in the article already. I wonder where the information as to the composition came from, and why this source whatever it was didn't give a better estimate of the yield, in particular what it was greater than, rather than just what it was less than. As it is, we have little idea what successful means. Andrewa (talk) 13:24, 12 December 2009 (UTC)
Perhaps the article should be merged with Reactor-grade which already discusses the issue. --JWB (talk) 05:49, 10 December 2009 (UTC)
That could work. I'd hope that some and perhaps all of the recently refactored material would be included in the merged article. It's a lot clearer than the text at reactor-grade plutonium in some important aspects.
What would the merged article be called? Andrewa (talk) 15:27, 11 December 2009 (UTC)
Could be called Weapons grade and Reactor grade, or vs.. Could also be called Plutonium grades. --JWB (talk) 20:19, 11 December 2009 (UTC)
Plutonium grades seems encyclopedic and a good topic, but doesn't cover the whole scope of weapons-grade, so the redir is a bit problematical. What about fissile material grades? This could cover both IAEA and DOE grading, both current and historical, for both uranium and plute. When this high-level article takes shape, it will be easier to see what lower level articles are needed. Andrewa (talk) 02:09, 12 December 2009 (UTC)
I haven't looked at fissile material lately either. Many articles might fit in. At the least, though, reactor-grade and weapons-grade plutonium are defined in opposition to each other and it would make sense to discuss them together. --JWB (talk) 03:06, 12 December 2009 (UTC)
Agree. It also gives redirect targets for fuel grade and non-weapons-grade which wouldn't qualify for articles IMO. Andrewa (talk) 04:17, 12 December 2009 (UTC)
By the way, in which ways do you think reactor-grade plutonium is unclear? --JWB (talk) 12:20, 12 December 2009 (UTC)
I'll have another look. Watch this space! Andrewa (talk) 00:38, 14 December 2009 (UTC)

Nuclear Weapons FAQ[edit]

As JWB correctly states above, there are a number of citations of NWFAQ in Wikipedia, Google gave me 49 ghits (note your results may vary depending on your location and perhaps other factors) many of which are cited references in English Wikipedia articles. A local Wikipedia search gave me 292 hits in the article namespace.

But we don't appear to have an article on the Nuclear Weapons FAQ. Perhaps we should have? Andrewa (talk) 20:10, 16 December 2009 (UTC)

It's notable, but you were just saying the author's privacy should be respected, which would limit the material to be covered. --JWB (talk) 20:17, 16 December 2009 (UTC)
Agree. And of course material on the author must be assumed to be covered by WP:BLP.
There's some information about the author in the FAQ itself, some of it encyclopedic IMO. But probably not enough for a separate article on the author. Andrewa (talk) 23:23, 16 December 2009 (UTC)


The part on U-233 needs some cleanup / corrections. The claimed limits of 50 ppm and 1 ppm of U-232 are not supported by the given Ref..

Good catch on the 1PPM mention in ref, but RE 50PPM, am I misreading? "weapons-grade U-233 can be produced with U-232 levels of around 5 parts per million (0.0005%). Above 50 ppm (0.005%) of U-232 is considered low grade." -- Limulus (talk) 08:53, 3 July 2012 (UTC)

The 1 ppm limit applies to other impurities if certain (not given) U-232 concentration is present. Some more information could be found here: [1]. So at least up to 1998 there was not official IAEA definition. The comparison with the Pu-240 levels is a little misleading: Pu240 can reach levels way above 10% in normal reactors, while U-232 levels hardly reach 0,5% when breeding from thorium. So it is naturally that U-232 levels are much lower (e.g. a factor of 100) than PU-240 levels.--Ulrich67 (talk) 20:14, 2 July 2012 (UTC)

Countries producing weapons grade nuclear material[edit]

Shouldn't the list of countries include USSR instead of, or possibly as well as , Russia? I think that most of the production of this material was done at the time of the USSR, and I think that it was done in other republics than Russia so having "Russia" is misleading. But I'm not sure so I hope that someebody can change this if necessary. Boleslaw (talk) 13:37, 24 August 2012 (UTC)DB

Article Error: Pu-239 decays to Pu-239![edit]

Weapons-grade plutonium[edit] Pu-239 is produced artificially in nuclear reactors when a neutron is absorbed by U-238, forming U-239, which then decays in a rapid two-step process into Pu-239. It can then be separated from the uranium in a nuclear reprocessing plant. — Preceding unsigned comment added by (talk) 12:17, 5 June 2013 (UTC)

This is not an error. It does not say Pu-239 decays into Pu-239. It says U-239 decays to Pu-239. NPguy (talk) 01:52, 6 June 2013 (UTC)

Unclear writing[edit]

I find this paragraph really hard to digest:

Plutonium recovered from LWR spent fuel, while not weapons grade, can be used to produce nuclear weapons at all levels of sophistication,[10] though in simple designs it may produce only a fizzle yield.[11] Weapons made with reactor-grade plutonium would require special cooling to keep them in storage and ready for use.[12] A 1962 test at the U.S. Nevada National Security Site (then known as the Nevada Proving Grounds) using non-weapons-grade plutonium produced in a Magnox reactor in the United Kingdom. The plutonium used was provided to the United States under the 1958 US-UK Mutual Defence Agreement. Its isotopic composition has not been disclosed, other than the description reactor grade and it has not been disclosed which definition was used in describing the material this way.[13] The plutonium was apparently sourced from the military Magnox reactors at Calder Hall or Chapelcross. The content of plutonium-239 in material used for the 1962 test was not disclosed, but has been inferred to have been at least 85%, much higher than typical spent fuel from currently operating reactors.[14]

For instance, just the 'sentence' "A 1962 test at the U.S. Nevada National Security Site (then known as the Nevada Proving Grounds) using non-weapons-grade plutonium produced in a Magnox reactor in the United Kingdom."

A 1962 test what? This is a sentence fragment, and the remainder of the paragraph does nothing to even describe which test it was, let alone part of which series. A quick google suggests that it was not part of any series and was kept secret for 15 years, but much of this detail is left out. It may not be necessary, but this entire piece is vague at best. Furthermore, it repeats itself in several locations, and just generally could use some streamlining. AnyyVen (talk) 03:41, 23 February 2015 (UTC)

Requested move 17 May 2017[edit]

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: moved per general consensus and WP:NOUN policy. (non-admin closure) --QEDK () 18:14, 3 June 2017 (UTC)

Weapons-gradeWeapons-grade nuclear material – or perhaps Weapons-grade fissile material, per WP:NOUN and clarity. For example, as the article already says, "Substances for chemical and biological warfare may also be described as weapons-grade", but this article is only about substances for nuclear warfare. —BarrelProof (talk) 19:51, 17 May 2017 (UTC)--Relisting. TonyBallioni (talk) 00:37, 27 May 2017 (UTC)

  • Support this move (talk) 16:04, 22 May 2017 (UTC)
  • Oppose. The unsourced claim that non-nuclear materials are or should be included in the scope of this article should instead be removed from the lead, or sourced. If it can be sourced, then that's a new ball game, but there's currently no evidence of non-nuclear usage. Andrewa (talk) 01:28, 26 May 2017 (UTC)
    @Andrewa: here are some examples of non-nuclear usage: [2][3]. Since the scope of the article doesn't currently include these, I'd be inclined to support the request, for clarity. I guess we don't currently have any article on those other things, though, so perhaps it's borderline. THanks  — Amakuru (talk) 08:49, 26 May 2017 (UTC)
    Interesting... still not convinced that those constitute common usage, and as we have no article on such materials there is no need to disambiguate, so I'm still opposed... but the proposed move would do no great damage in view of your sources. Thank you. Andrewa (talk) 13:13, 26 May 2017 (UTC)
    Please note that 1) The first mentioned motivation in the proposal was WP:NOUN, which hasn't been commented on. 2) I haven't noticed anyone in this discussion claiming that "non-nuclear materials are or should be included in the scope of this article", and I don't think that would be desirable if someone did suggest it. 3) The second mentioned motivation was clarity, not disambiguation – I just think the title should be phrased in a way that effectively communicates to the reader what the article is about, and I don't think the current title does that. —BarrelProof (talk) 16:18, 26 May 2017 (UTC)
  • Support current title is missing a noun. Weapons-grade...WHAT? Plantdrew (talk) 00:59, 28 May 2017 (UTC)
  • Support for reasons cited above. Weapons grade can refer to things other than nuclear material. The article title should be a noun. NPguy (talk) 17:22, 29 May 2017 (UTC)
  • Support moving, but no opinion on what to move it to. The current title clearly fails WP:NOUN (note that even though it contains the noun "weapons" the title is an adjective phrase), but it may be that something along the lines of Weapons-grade material or Weapons-grade substance may be more appropriate if, as others say, the nuclear sense of the term is the clear primary topic. (talk) 17:55, 1 June 2017 (UTC)

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.