Talk:Nuclear weapon design/Archive 2

Archive 1

Archive 2

Archive 3

Broken links

The rewrite broke links from other articles to specific sections of the old article. For example, some of the links in Reliable Replacement Warhead#Selected design. --JWB (talk) 08:52, 21 December 2007 (UTC)

Those links now fixed (I think). HowardMorland (talk) 15:34, 30 January 2008 (UTC)

There were a lot of them. I keep finding more. Unfortunately the "What links here" page does not show when a link is to a subsection.

Many of the links were for specific terms like "tamper". If the are not going to have headings in the new article, perhaps they should have their own short articles. --JWB (talk) 17:10, 12 February 2008 (UTC)

Warhead Design Safety

I don't think that discussion of the Permissive Action Link is merrited here, for two reasons.

Firstly Warhead design safety is about engineering of the actual physics package to reduce the chance of a nuclear detonation occuring from simple mechanical or electrical malfunction. This is not the purpose of a PAL, which is to prevent unauthorised use.

Secondly the speculation that PALs are not deployed on Strategic Weapons is doubtful. It was recently announced that the UK did not use PALs on it's Strategic Deterrant, attracting criticisms from both the United States and the Russian Federation. This would imply that both those powers have attached PAL's to their strategic nuclear assets.

Finally the article mixes acknowledged speculation, with implication that the hypothesysed system is in use. I have therefore removed this section. —Preceding unsigned comment added by Scruffy brit (talk • contribs) 18:11, 28 December 2007 (UTC)

Hydrogen Bomb ARE HERE

A basic Swan bomb was given that finally exemplifes true weapons. Thanks. Except.

What was critical was the level of tritium necessary! And it was of course zero. Bare naked hydrogen will fuse nicely. Even a middle core of plain lucite will fuse.

1e22 neutrons/cm^3 as a flux density will initiate fusion.

1e16 neutrons/cm^3 will initiate alpha or the super-super critical state that truely causes a massive release in natural uranium!

Alpha was discovered by the guys sticking radiation detectors against the bomb while it explodes. Alpha is the nonlinear excursion of another reaction, NOT fission. Alpha decided the design of direct alpha initiated hydrogen bombs. Discovery of the inner workings of the bomb requires access to detailed detector data and the exact reation is little known of.

Alpha is a delay time until anomalous nonlinear energy release.

There is ability to use a common deuterium_tritium accelerator target trigger for the pit to then cause hydrogen to blast. A pit amplifys the neutron flux density to the 1 e 22 level allowing a perfect triple alpha reaction.

True design data is hard to get. This is true design advice.

Alpha neutron levels for the compressed state are given.

The key to understand is that ANY EnRICHMENT can be made to blast the hydrogen layers.

All that is required was compressed uranium and a certain neutron density!

Have a nice Christmas. —Preceding unsigned comment added by 207.69.140.32 (talk) 21:50, 25 December 2007 (UTC)

Yeah, yeah, where's your cites? SBHarris 22:00, 25 December 2007 (UTC)

Dilute! Dilute! All-One-God-Faith! --JWB (talk) 22:36, 25 December 2007 (UTC)

Dr. Bronner, is that you? SBHarris 22:56, 25 December 2007 (UTC)

Explosive testing & Interstage

I have just posted my final contribution to this rewrite. It adds information about weapon design in the context of data collected from nuclear weapon tests. I believe the article is now reasonably complete, at about the same length it was before the rewrite. HowardMorland (talk) 15:08, 30 January 2008 (UTC)

On second thought, there seems to be enough information for a short new section on the interstage, which I have posted. HowardMorland (talk) 20:37, 3 February 2008 (UTC)

Well, it seems like the main purpose of the interstage is to contribute neutrons for the fissioning of the secondary. As the article explains that the main purpose of the fusion reactions in the Teller-Ulam design is essentially to create additional neutron sources for the secondary's fission, so does the interstage, although apparently through a different mechanism. In the context of maximizing the yield (and also varying the yield of a given device), most of the variability in yield seems to come from the fission efficiency of the secondary. The limiting factor in this process seems to be a time constraint: the primary brings the secondary to the correct temperature and pressure regime for truly efficient fission yields, but this state is very short lived because it destroys itself. Therefore, maximizing the fission yield from the secondary would seem to depend on maximizing the neutron flux during this time period. A certain amount of fission-inducing neutron flux is provided by the primary fission as well as by the fusion components, but adding a non-explosive interstage that enhances neutron emission would increase the fission yield without adding excess energy which would shorten the time period during which the secondary can abosrb this increased neutron flux.

Well, is that the idea? The interstage function seems to get better coverage in the article on the Teller-Ulam design itself. Argantael (talk) 20:27, 8 April 2009 (UTC)

No, you don't want neutrons inside the secondary before compression, as heating from neutron absorption will limit how much compression can be achieved. The interstage instead prevents neutrons from reaching the secondary. In the process, neutron energy will be converted to thermal energy that aids compression by reaching but not penetrating the secondary, though the neutron energy is likely not the major heat source. See NWFAQ if this is not already explained in the article here. --JWB (talk) 20:31, 8 April 2009 (UTC)

Yeah - Argantael, you misunderstand how secondaries work. Secondaries have two or three functional parts - a main fusion charge, a "sparkplug" of HEU or Pu which is also compressed to criticality, fissions, and kicks off the fusion reaction, and optionally a fissionable (DU/natural U) or fissile (HEU) tamper, where neutrons off the fusion reaction produce further energy (up to about a factor of 2 more). If there's no fissionable/fissile tamper you have an inert tamper (lead or tungsten or some such), and you always have a pusher of some sort which ablates away and pushes inwards.

Neutrons aren't what kicks off the secondary reaction. Compression of the secondary - and the sparkplug to critical mass and beyond - kicks off sparkplug fission, which then heats the fusion fuel to ignition. That ignition temperature is much lower than standard densities because of the immense compression from the primary.

Neutron pre-heating, where the secondary is warmed up directly by neutrons from the primary, can cause a failure to ignite the secondary. The dynamics of secondary compression are that you want to compress cool secondaries, THEN heat them... if you heat them first, the compression is much less efficient, so it's much harder to reach the critical combinations of density and temperature.

See the Nuclear Weapons FAQ for more details. Georgewilliamherbert (talk) 20:52, 8 April 2009 (UTC)

Now I understand my misunderstanding! According to related articles on Wikipedia and NWFAQ, the tamper-pusher ablation mechanism contributes an order of magnitude more pressure than the radiation transport mechanisms. On a first read-through, the wording (especially the subheading "radiation implosion") leads the reader to focus on that, instead of tamper-pusher ablation. I suggest that that section be re-titled and re-written to better reflect the current understanding. If, in historical development, the two stage devices were originally thought to rely on radiation transport, then that could be mentioned in the development sub-section. Argantael (talk) 15:01, 7 May 2009 (UTC)

Well, radiation is the medium for energy transfer from the primary to the surfaces of the radiation case and then the secondary, but radiation pressure is not what implodes the inside of the secondary, thermal expansion of the heated surface of the secondary is.

The best metaphor to explain the radiative energy transfer would be an oven but I've never seen this comparison used. --JWB (talk) 19:38, 7 May 2009 (UTC)

Ja, I see what you mean. The discrepancies that remain in the article are that in the intro itself, which states that two stage devices rely on the mechanism of radiation implosion by the primary's X-ray output, NOT tamper-pusher ablation. The X-ray implosion concept is also introduced and developed (perhaps correctly in the historical development context) in the sub-section on two stage devices, before mentioning tamper-pusher ablation in passing. This is where the article is confusing in describing the mechanics. The following section on the interstage is also kind of ambiguous as to the timing of the details. I gather that the time period after tamper-pusher ablation achieves criticality but before disassembly happens is the target time period for maximizing radiative energy transfer. Is that the case? —Preceding unsigned comment added by Argantael (talk • contribs) 21:09, 7 May 2009 (UTC)

too much detail?

Who monitors this page to make sure that too much detail is not given about how to make a weapon like this? Sign your username: Newtowiki2 (talk) 16:13, 12 February 2008 (UTC)

Please see The Nuclear Weapon Archive website and in particular Engineering and Design of Nuclear Weapons in the Nuclear Weapons FAQ there.

Wikipedia has next to none of the detailed physics, engineering, design equations, analysis. Other sites with that info have been reviewed by government sources and held to not be a particular proliferation risk. You have nothing to worry about here.

Several of the contributors here, and there, are in contact with prominent nonproliferation experts and jounrnalists who focus on the topic area, and discuss these issues intermittently. Georgewilliamherbert (talk) 00:44, 16 February 2008 (UTC)

The real trick of making a nuclear device that would work is all concealed inside classified documents. For obvious reasons, Wikipedia cannot source from classified documents, as they are not publicly accessible sources. This is similar to the argument that I brought up on Talk:Airborne Real-time Cueing Hyperspectral Enhanced Reconnaissance. scetoaux ^{(talk) (My contributions.)} 23:19, 5 March 2008 (UTC)

Actually, we have off the record confirmation that the analysis community (NW FAQ above and associated persons) have the design information and physics right. Stating that there's something hiding in the classified document wings is silly - we know the actual detailed designs are still classified, but going from the theory and a working knowledge of the design techniques and technologies and methods used to an actual design is a relatively short step. Not everything that's known about them is in Wikipedia (or even on the FAQ, due to proliferation concerns). Georgewilliamherbert (talk) 00:27, 6 March 2008 (UTC)

I guess you're right, but there are specific details that are very important that are classified to prevent proliferation. We can't place all our money in ensuring that a country doesn't get enriched uranium or plutonium. scetoaux ^{(talk) (My contributions.)} 03:28, 6 March 2008 (UTC)

Under US Restricted Data laws, anything the DOE hasn't formally declassified on the topic is classified, to prevent proliferation. However, those laws haven't been enforced since the Progressive case (see Howard below 8-). The Nuclear Weapons FAQ, and this article here, certainly contain info which hasn't been DOE declassified. Georgewilliamherbert (talk) 04:10, 6 March 2008 (UTC)

I had considered this issue in the past, and again I've come to the same two-fold conclusion. 1) The subject is so complicated that Wikipedia is extremely unlikely to be used as a source of information by individuals or organizations seeking to build nuclear weapon(s). This isn't a topic that a non-expert could casually read about and proceed to build a bomb in his/her basement or garage. The real nuclear proliferation danger comes (mostly) from nations with the facilities necessary to do the type of work that goes into the production of these weapons. 2) Wikipedia should not censor information, even in the case of information such as this (which it might be argued should be supressed). Even though I find this technology morally objectionable, I still believe that information should only be withheld in extraordinary circumstances (which certain aspects of this topic may be). Fuzzform (talk) 20:08, 9 June 2008 (UTC)

Israel's H-bomb?

I reverted an edit by user IP 72.205.14.25, which added the statement: "(however, Israel is suspected of possessing staged nuclear weapons of the Teller-Ulam design)." It is generally accepted that two-stage Teller-Ulam devices require either a dedicated testing program or manufacturing blueprints from a nation which has conducted such a program. Israel had no announced or detected nuclear tests, and only one suspected nuclear test. In 1986, Mordechai Vanunu reported that Israel used lithium-6 and manufactured tritium in its reactor. If true, that suggests boosting. If there is a good source for more than that, it should be cited. HowardMorland (talk) 23:16, 5 March 2008 (UTC)

There seem to be a lot of reports [1] that Israel has had neutron bombs, and these would necessarily be two-stage devices. To take a specific example, "Third Temple's Holy of Holies" cites Hersh's "Samson Option", Burrows and Windrem's "Critical Mass", and Toscano's "Triple Cross" all reporting an Israeli neutron bomb. --JWB (talk) 03:37, 6 March 2008 (UTC)

I haven't read the Hersh book (I should get a library copy soon) but the 1999 "Third Temple" article from Maxwell AFB doesn't convince me that the author knows what a neutron bomb is. The neutron bomb references all seem to go back to the October 5, 1986, London Sunday Times article about Vanunu, in which the term "neutron bomb" is included in a list without explanation. At the time, the neutron bomb was incorrectly being tauted as the latest new type of nuclear weapon, and there may have been some incentive to imply that Israel had the latest thing. I have not come across any specific reference to Israel having staged, Teller-Ulam, radiation implosion devices, along with an explanation as to how the testing requirement was overcome or circumvented (i.e., clandestine, undetected testing or theft of complete designs). However, I suppose we could restore the parenthetical statement and cite the sources you mention, although I personally doubt their relevance. HowardMorland (talk) 14:55, 6 March 2008 (UTC)

The references suggest specific tests, the 1979 Vela Incident off S. Africa and two previous tests hidden by clouds, and specific application for the neutron bomb, stopping Syrian tanks. I'm not completely convinced either, but the sources are some of the most prominent secondary sources on the subject, so it would seem reasonable to mention them somewhere (in fact I think they are in other articles already) along with your reservations. As WP:V says, "The threshold for inclusion in Wikipedia is verifiability, not truth. "Verifiable" in this context means that readers should be able to check that material added to Wikipedia has already been published by a reliable source."

I haven't found any material on leakage of complete designs to Israel, although we do know that Edward Teller provided guidance to the Israeli program and that other scientists had relationships with both countries. Many of the nuclear powers are known to have received designs from other countries, including Soviet spying on the US, Soviet aid to China, US sharing with Britain, Chinese aid to Pakistan, and the alleged Chinese spying on the US, so knowledge transfer is not implausible in general. Also, there is a later report of Russian scientists coming to Israel after the end of the USSR.

The first, relatively primitive, staged thermonuclear tests by the five official powers seem to have been successful, so it is also quite possible that an untested design could be expected to have a high enough probability of working, especially as a deterrent where certainty is not essential, and would be worth producing and deploying on that basis. Computer simulation has also continued to get easier. And the Israeli deterrent against nearby countries could be delivered by aircraft, without the size/weight limitations of ICBM warheads.

Is design of an "Alarm Clock"-type device really much easier than a radiation implosion device? If anything, "Alarm Clock" seems to be marginally feasible as well as providing very limited multiplication, while the much greater power of radiation implosion seems to provide a more comfortable margin. Optimizing radiation implosion devices to produce the smallest and lightest warhead may be difficult and require testing, but simply making one that works may not be so difficult. Carey Sublette's comparison of the Ivy Mike and W-80 cases starting at NWFAQ 4.4.3.3 seems to indicate a wide variety of parameters can work.

Regarding reports of hints by insiders that some particular thing is tricky and requires testing data, what I've seen come up is boosting rather than radiation implosion. I'm not sure why this should be the case. Maybe they mean that optimizing boosting for minimum size and weight and for modulated energy release with a profile optimized to maximize radiation implosion compression of a secondary is difficult, rather than saying that D-T ignition is hard to achieve in itself. --JWB (talk) 20:23, 6 March 2008 (UTC)

There are a number of issues with hollow-core boosting (material spalling into the cavity, etc). Radiation implosion is also felt to be "hard" by some, but not all in the field. Georgewilliamherbert (talk) 01:00, 7 March 2008 (UTC)

I agree with all of the above points.

We could ask Mordechai Vanunu to weigh in on this, but if he has any hope of ever getting out of Israel, he's not supposed to talk to foreigners at all, especially not about this. Anyway, I think his Dimona work was in materials production, not component fabrication and assembly. Ted Taylor and Frank Barnaby both said his knowledge was incomplete.

I would not be terribly surprised to learn of illegal collaboration between the U.S. labs and Israel. It is even possible that some of the subsidence craters in Nevada conceal debris from Israeli nuclear tests, as long as not many people were in on the secret. The U.S. conducted way more tests than any reasonable justification demanded. That would be a great story, but it's easy to start urban myths about a secret industry, because the people who know the truth are not allowed to correct the record.

If we stick to published facts, they all seem traceable to Vanunu in London in 1986. To my knowledge, the first public mention of an Israeli neutron bomb was made on September 28, 1986, in the Sunday Mirror, a London tabloid newspaper, which stated, "An astonishing claim that Israel has built its first neutron bombs has been made to the Sunday Mirror. The bomb is the world's deadliest weapon – it can wipe out humans with a massive dose of deadly radiation, while leaving buildings intact." The Sunday Mirror then dismissed the claim, citing "grave doubts about its authenticity." That sensational article pre-empted the carefully written Sunday Times article (based on Vanunu's information) by a week. It was clearly an effort to associate Vanunu and his "agent" Oscar Guerrero (the Sunday Mirror's source) with fantastic claims and to label both of them as con men, before the Sunday Times article hit the streets. Peter Hounan, chief author of the Sunday Times article, believes the Sunday Mirror story may have been part of a Mossad plot to discredit Vanunu if the plan to kidnap him failed. The successful kidnaping, of course, nullified the con man smear (except in the case of Guerrero, who was not kidnaped, but that's another story). Meanwhile, the neutron bomb story took on a life of its own. A lot of people have cross-referenced each other on it, but without an ultimately credible original source, that I know of. It was mentioned in passing in the Sunday Times article, but not in a credible way. (These quotes are from Hounan's 1999 book, The Woman from Mossad, p. 103.)

Aside from the testing issue, my main question about Israel and two-stage weapons is what would be the motive? The original motive, at Los Alamos, was the quest for a multi-megaton bomb. Israel is more interested in keeping a low profile than in having multi-megaton bombs, or even compact, high-yield missile warheads. The neutron bomb was an obvious possibility with a two-stage device, but one that Sam Cohen, its self-proclaimed inventor, had a hard time selling in the 1950s. The Carter Administration chose it for deployment in Europe a quarter century later, because it would seem to be something new and would be perceived as an escalation. It was eventually ridiculed out of existence. A death ray bomb to kill tank crews never made any military sense. It's hard to see why Israel would want one, except for bragging rights, which is problematic with a non-acknowledged program.

Finally, a neutron bomb doesn't have to be a two-stage thermonuclear bomb. Any low-yield nuclear explosion has a radius of lethality from direct fireball radiation that's greater than its radius of lethality from blast and fire. Some Hiroshima victims survived the blast and fire and died of direct radiation from the fireball. That effect would be more pronounced in a single- or sub-kiloton weapon, even without a low-yield secondary optimized for fusion and neutron escape. So, in my opinion, these dubious references to Israeli neutron bombs don't necessarily shed much light on the question of whether or not Israel has two-stage, radiation implosion weapons in its arsenal. HowardMorland (talk) 04:28, 9 March 2008 (UTC)

We do know from Vanunu that they were making ⁶LiD, and that means some kind of thermonuclear weapon. The question then is whether the thermonuclear weapons are staged or not. As you say in the article, the two-stage design is most capable and versatile, and there is little reason to not use it for almost all purposes if you have the ability. Then the question is whether staged weapons are that much more difficult than a one-stage "Alarm Clock", as well as whether the "Alarm Clock" would even be worth pursuing. The US and USSR pursued Alarm Clock/Sloika before staged weapons were known to be superior, and dropped them immediately when that became known.

Why did the US want a multi-megaton bomb? Like the US, Israel also wanted to deter opponents with the threat of mass destruction, and other things being equal, large bombs make mass destruction easier. An unused large bomb is no more high-profile than an unused small bomb. Not testing or announcing, according to "The Bomb in the Basement", is a secret formal commitment exacted by the US; beyond that constraint, Israel does not mind letting its opponents believe it has a powerful arsenal of assured destruction.

Similarly, if the US wanted to deploy neutron bombs in the 70s and 80s, why shouldn't Israel as well? Both faced the threat of massed tank attacks. In retrospect, the neutron bomb was not important, not that much better at its task than conventional small nukes, and was soon made obsolete by developments in nonnuclear antitank weapons, but there is no reason Israel would not have made a similar decision to the US at the time, especially when the US itself was already deploying.

Any low-yield weapon can be a prompt radiation weapon, but "neutron bomb" did have a specific meaning and was not applied to all US low-yield tactical weapons, most of which were deployed well before the neutron bomb was. Certainly a reporter could have gotten terms confused, and the hype about the neutron bomb does not add to credibility, but if the term "neutron bomb" actually was used within the Israeli program, it probably meant the type of design called a "neutron bomb" in the US program.

If all the Israeli neutron bomb reports do trace back to the Sunday Mirror report and that was false, that's certainly a finding worth documenting in Wikipedia, probably in Nuclear weapons and Israel or Mordechai Vanunu. (The former article now says "Vanunu revealed that between 1980-1986 Israel attained the ability to build thermonuclear weapons." and the latter now says "Vanunu gave detailed descriptions of lithium-6 separation and lithium hydride production required for the Teller-Ulam nuclear weapon design.").

Wisconsin Project does quote Taylor as saying that Israel's thermonuclears described by Vanunu appeared relatively unsophisticated, but also says that Israel was continuing research and buying supercomputers. (20 years later, the computer on your desk can probably do the same simulations.) --JWB (talk) 06:35, 9 March 2008 (UTC)

From my local public library, I got The Sampson Option, by Seymour Hersh, 1991. Good book. As I expected, the only reference to Israeli neutron bombs comes from Vanunu in London in 1986. The relevant quote is on page 200: "In 1984, [Vanunu] further reported, a new facility (Unit 93) for large-scale production of tritium was opened. . . . The opening of Unit 93 suggests that full-scale production of neutron weapons began then, for up to twenty grams of tritium are used in each neutron warhead." Not true; it suggests no such thing. Unit 93 is evidence for boosting, which Hersh explains earlier in the same paragraph. It does not imply two-stage thermonuclear weapons. The logical leap from tritium production to neutron bombs is not credible without further evidence, and the lack of an Israeli nuclear testing program argues against it. I agree with your suggestion to update the other articles on this point. I'll take a look at it. Thanks. HowardMorland (talk) 02:26, 13 March 2008 (UTC)

Thanks, I'll take a look at Samson Option too.

Depends on what "large-scale" means... If tritium production was far in excess of the several grams per primary needed for boosting, wouldn't that suggest there was some other use intended for tritium? And the number of primaries can be estimated as proportional to plutonium production, or at least that's what published estimates of the number of Israeli weapons are based on. --JWB (talk) 03:45, 13 March 2008 (UTC)

X-Ray Mirror

I believe it was in the original Progressive article, they state that the x-ray mirror in the H-Bomb is formed from layers of U-238. Multiple layers reflect x-rays by creating many boundaries, each of which reflects a small amount. I don't see any mention of this, and of course it should be checked. DonPMitchell (talk) 07:06, 20 May 2008 (UTC)

That story, as I described it in The Progressive article, is a mistake which was corrected in the Errata of the December 1979 issue of The Progressive. The proper term is radiation channeling rather than reflection. However, there may still be something to the multiple layers idea, but nothing I know of in the open literature that can be cited. HowardMorland (talk) 15:48, 22 May 2008 (UTC)

While the X-ray mirror components do have the general effect of concentrating x-ray radiation from the primary to the secondary, this re-direction is probably not a direct specular reflection from inelastic scattering,as in visible light reflecting off a mirror, or even the gradual-angle reflection in an x-ray telescope. Several references in the article mentioning the importance of relative timing in the energizing of the secondary therefore imply that the physical mechanism is more like an elastic scattering of the initial high frequency x-rays by a component into lower frequency x-rays directed at the secondary. High-frequency X-rays directly resulting from the primary are probably too penetrating to transfer energy efficiently to the secondary - having them absorbed and re-emitted at a lower energy makes the radiation implosion possible. Argantael (talk) 22:50, 7 April 2009 (UTC)

History of Lithium-6

Arthur C. Clarke stated in one of his books that the USA got the idea of using Lithium-6 Deuteride by analyzing the fallout from early Soviet tests. That's interesting, but is there some verification? DonPMitchell (talk) 07:08, 20 May 2008 (UTC)

Lithium hydride was first suggested in an unclassified book by a German, Hans Thirring, in 1946. The first Soviet test involving fusion took place in 1953; it may have used Lithium-6 Deuteride before any U.S. test did so. However, according to Herbert York in The Advisors, p 83, in the 1952 Ivy Mike test, and probably also in the 1951 Greenhouse George and Item tests, all of which ignited fusion before any Soviet test, a deliberate choice was made not to use lithium because it would add a complication to the analysis of the experiments. The fact that the first U.S. test using lithium came after the first such Soviet test does not imply that the idea came from the Soviets. HowardMorland (talk) 16:23, 22 May 2008 (UTC)

"Times less than", etc.

(Comments on an edit made a few minutes ago)

Expressions such as "[n] times less than" are popular, but logically absurd; sorry! Let's say the original dimension was 5 cm, and the new one, 0.5 cm. The dimension [0.5 cm] is surely not ten times smaller. "Times" refers to the original magnitude, and ten times 5 cm is 50 cm. 0.5 cm is plainly not 50 cm smaller!

"Times greater than", otoh, is not nearly as bad; 15 cm is two times larger than 5 cm -- it's 10 cm larger.

It's a matter of [n] vs. [n-1], and as [n] becomes larger, the "error" decreases. (A thousand times larger is roughly the same as 999 times larger, if one is not being exact.) Nikevich (talk) 06:44, 6 June 2008 (UTC)

GA Candidate

I read this article in its entirety. It's fascinating, well-written, generally devoid of errors, clear and intellectual. Needs a small amount of work but could easily become a GA. --137.186.224.147 (talk) 20:42, 16 July 2008 (UTC)

Here's my thinking on the article's B-class quality rating.

Before the re-write was posted on December 14, 2007, the article was about 9,000 words long and was organized around the principle that nuclear weapons "are divided into two classes, fission type and fusion type," with the caveat, "the distinction between these two types of weapon is blurred by the fact that fission and fusion reactions are combined in nearly all modern nuclear weapons." I thought a better organizing principle was three classes, all three of which are basically fission weapons, some of which use fusion in various ways to enhance fission.

I discussed the idea of a re-write with georgewilliamherbert and other Wikipedia contributors, as well as with other researchers and authors in the field, and posted a draft re-write on my sandbox page for comments. The re-write eventually ended up at the same length as the original, about 9,000 words.

The new information in the re-write came largely from the web-posted Nuclear Weapon Archive of Carey Sublette, from the 2,500 page CD-ROM book Swords of Armageddon by the late Chuck Hansen, and from Atom Bombs, by John Coster-Mullen. I included by own 25 years of research on the subject, based on government documents and publications. That personal research included a 7-year-long email discussion (1999-2006) I moderated with 50 experts in the field, including some experts on the inside of the security fence (who mostly observed the exercise with amusement).

A major goal of the re-write was to eliminate errors, and to reduce the technical detail and increase the descriptive detail in a way that would make the article more evenly readable for a general encyclopedia audience. I added a few line drawings for illustration and wrapped the story around a historical narrative based on the design efforts at U.S. labs. I followed the advice of Herbert York in emphasizing that nuclear weapon design is a mature technology, i.e., nothing new for a long time and nothing new likely in the future.

In the days after the rewrite, there was a lively discussion on this talk page (see above) which resulted in some content changes, but for the past nine months most of the changes have been links, footnotes, copy edits, and the like. Note: on September 16, user 216.73.251.162 made his/her only ever contribution by fixing a nine-month-old typo that nobody else had caught – thanks, whoever you are.

The rewritten article seems to have passed muster with the regular Wikipedia editors of this topic. I think it is unique in the open literature for an encyclopedia article of this length. Until the secret world of nuclear weapon design gives up more of its secrets, there is not much more to be said on the subject. On the assumption that its quality had been improved by the re-write, I recently asked georgewilliamherbert about nominating it for featured article. He said "go for it."

My initial effort was shot down by editors who criticized it for not enough footnotes (should be one in every paragraph) and for oversized illustrations which are not in boxes. I think the article doesn't work if the illustrations are shrunk down into thumbnails, which then have to be expanded before the embedded labels can be read. The illustrations need to be on the page, in readable form, while the text is also on the page. Expanding a thumbnail (which most readers won't bother to do anyway) temporarily obliterates the text.

I withdrew the nomination, thinking that the article is less likely to be altered in unconstructive ways if it retains the obscurity of a B-class article. Others may have further thoughts on this issue. HowardMorland (talk) 13:30, 24 September 2008 (UTC)

HowardMorland's reversion

I've re-reverted HowardMorland's broad-stroke reversion of the work of several editors including myself. I feel that the article's English flow had been improved. For instance, the pit in Little Boy was supposedly "separated into two sub-critical pieces" prior to assembly which is, of course, nonsense. If that had been the case, the pit would have reached criticality before any chance of being separated in two. The improved phrase reads "was formed into two sub-critical pieces". Also, the old wording started a paragraph by saying about Little Boy that "The inefficiency was caused by" without any prior reference to inefficiency. The new wording introduces the idea that Little Boy was inefficient before describing the reason.

I've also taken out a couple of paragraphs that were unsourced, unreferenced conjecture. In the first paragraph, the sentences "Nobody has come up with a better way" and "Nobody in the public world knows this for sure" are the primary reasons the whole para was taken out as unprovable. The following paragraph uses "likely" and "probably" in guessing which nations have which bombs without citing a source. Binksternet (talk) 15:01, 28 August 2008 (UTC)

I have restored your revision. My intention was to revert only the revisions by 74.249.92.92, but I didn't know how to quickly do that, since yours was in the middle of the block. However your undoing of my reversion has restored the inaccuracies that 74.249.92.92 introduced. There is really nothing of the 74.249.92.92 contributions worth saving. Regarding the "The inefficiency was caused by" issue, that confusion was caused on Aug 6, when John took out a sentence for which a footnote had been requested. I have restored that sentence and added the requested footnote. HowardMorland (talk) 15:32, 28 August 2008 (UTC)

The first paragraph of conjecture ("better way") that you removed was published by me in the Cardozo Law Review (I have added a footnote) after manuscript review by Herbert York. It has also been discussed at length on this talk page. The other paragraph was added by 74.249.92.92, and I agree with taking it out.HowardMorland (talk) 15:55, 28 August 2008 (UTC)

I'd like to say that I approve of what HowardMorland was trying to do, as 74.249.92.92's "contributions" amounted to no more than blatent speculation, which wouldn't even qualify as "original research". "Likely" and "probable" tend to reflect the opinions of individual editors rather than documented expert discussion, and so belong in the Talk section, not the article. There is actually a resource somewhere that states that the Indian and Pakistani Nuclear weapons are "boosted" rather than thermonuclear. —Preceding unsigned comment added by Scruffy brit (talk • contribs) 12:21, 29 August 2008 (UTC)

Another minor correction

Both reactions generate roughly a million times more energy than comparable chemical reactions, making nuclear bombs a million times more powerful than non-nuclear bombs, which a French patent[3] revendicated in May 1939.

AIUI, "revendication" is a French legal term relating to the enforcement of (or perhaps "reclaiming of") a French patent. It probably is not the correct word to use in the above sentence.

Although I have not read French Patent No. 971,324 (which is the linked reference), I assume that the author of the article meant that the patent "describes" or "asserts" or "explains" the statement that nuclear fission and fusion reactions are about a million times more powerful than comparable chemical reactions. Someone who is fluent in both French and English could probably come up with a better word. Also, although the patent was filed in May 1939, it was not actually published until January 1951. Perhaps a better way to get the idea across would be:

Both reactions generate roughly a million times more energy than comparable chemical reactions, making nuclear bombs a million times more powerful than non-nuclear bombs. This relationship was known at least as early as May 1939[3].

64.105.72.6 (talk) 00:20, 23 December 2008 (UTC)

I prefer your version, but I'm curious what the editor meant by "revendication." I believe Leo Szilard tried to patent the fission chain reaction to prevent its misuse, and perhaps the editor is suggesting something like that. NPguy (talk) 04:03, 24 December 2008 (UTC)

I'm fluent in French and English. For the phrase in question, an idiomatic English translation just yields "which a French patent claimed in May 1939", which makes more sense. It says that this datum was claimed as patentable. Argantael (talk) 21:31, 6 May 2009 (UTC)

labs

it seems a little odd to me to have a section on design labs that includes only Berkeley (which only was active in this from 1940-1945 or so), Los Alamos (US only), and Livermore (US only from the 1950s onward). obviously such a list would be much longer if it was even reasonably complete.... thinking here of Sandia, of Arzamas-whatever, of the UK labs, Dimona, etc. etc.

I am not sure what purpose this section serves for such an article? ought not the specifics of various country's nuclear complexes be discussed in country-only articles, like nuclear weapons and the United States? --98.217.8.46 (talk) 21:55, 4 January 2009 (UTC)

Good point! I don't see how a quick summary of these three labs needs to be in this article. Rather than trying to globalize the section, I think it can be deleted. Binksternet (talk) 01:02, 5 January 2009 (UTC)

I'd agree that the section as it stands is inappropriate (gives too much weight to just the three labs). It would be nice though to have a brief overview of design labs worldwide, especially if it could include the computing facilities and physics knowledge which are needed to establish a design facility (not to mention the security). Franamax (talk) 01:31, 5 January 2009 (UTC)

All of the innovations in nuclear weapon design which are discussed in this article originated from these three labs in the manner described. Other nuclear weapon design labs in other countries duplicated those design innovations independently, reverse-engineered them from fallout analysis, acquired them by espionage, or whatever. In the article, there was no effort to make a complete list of design labs around the world, only to mention briefly when and where the first ideas originated.

In particular, I think it is important to know how much of the conceptual work was done at Berkeley before Los Alamos was created. There has also been much incorrect information about the division of labor between Los Alamos and Livermore.

The Sandia labs operate as extensions of the main two labs and thus are not mentioned, nor is the Metallurgical lab in Chicago (which evolved into Argonne), because it designed material production processes, not bombs.

There seems to be no Wikipedia article on nuclear weapon design labs in general, and there may not be enough information available to write one. (For example, hardly anything is known about designs produced at Dimona, although there is much speculation -- see above Israel's H-bomb?.)

I think the information given here about these three labs is relevant to the topic of nuclear weapon design. HowardMorland (talk) 03:32, 5 January 2009 (UTC)

All innovations in nuclear weapon design originated in the United States

Im pretty sure this is false. Im going to go through my sources and correct it ( I know for a fact the USA had to be prompted by the British to take nuclear weapon design seriously, and that the Germans where investigating it ). While its certainly true to say the USA built the first atom bomb, this statement as it stands is false. —Preceding unsigned comment added by 86.129.219.241 (talk) 09:59, 5 February 2009 (UTC)

The US developed the concepts of gun-type bombs, lensed implosion, levitated pits, hollow pits, linear implosion, polymer-bonded explosives, alarm-clock/layer cake type fission-fusion, staged secondary implosion fission-fusion (Teller-Ulam configuration), two-point indirect implosion lensing, two-point direct implosion lensing. Someone else may have independently re-invented some of those (Sakharov et al probably independently reinvented alarm clock / layer cake, at least, and the historical origins and design choices of the French and Chinese and Israeli and Indian and Pakistani and North Korean designs are unclear in a properly documented sense). But they all seem to have been done first in the US. That's what the statement means. Georgewilliamherbert (talk) 18:34, 5 February 2009 (UTC)

You may wish to read http://en.wikipedia.org/wiki/Tube_Alloys. It provides considerable information on the input of the French, German, Canadian and British input into the concept and construction of the atomic bomb. —Preceding unsigned comment added by 213.106.93.67 (talk) 22:50, 16 July 2009 (UTC)

Fourth generation weapon information - hypothetical vs real

User:Uruk2008 has repeatedly inserted the following paragraph into the Nuclear weapon design article here and the Nuclear weapon main article as well:

The most advanced fourth generation thermonuclear weapons use no fission primary,utilizing extreme heat and pressure conditions generated by conventional shaped charge compression techniques.A device used to obtain these conditions with conventional high explosive material is known as a Voitenko compressor,where a plane diaphragm or shaped charge is driven by an implosion wave into a secondary small spherical cavity that contains pure deuterium or hydrogen gas at one atmosphere.

There are a number of inaccuracies in this.

First of all, the four Greenpeace weapons illustrations are of hypothetical second generation (normal boosted fission and Teller-Ulam Fission-Fusion multistaged) weapons - the casing is based on the W80 and some similar Russian weapons shapes, but the internals are thought to be at least partly wrong by experts (we have some of the actual B61/W80 components in photographs, and they don't look quite like that). None of those images are related to fourth generation weapons.

Second, no references currently extant here or elsewhere assert direct fusion merely by high explosive compresion - Gsponer isn't suggesting it, see his comments at the bottom of pp 15 and Table 2 on pp 16 of the reference of his cited above. He also has never suggested it in real-life conversations.

Uruk2008 has been sticking the Voitenko compressor all over a number of explosives related Wikipedia pages, some of which it belongs on, but this one it does not. It's not a technology used in nuclear weapons, unless there's something inside Russian weapons that the US has never heard of, which is unlikely at best and at least unreferenced and original research.

Gsponer's work on fourth-generation weapons (the advanced and microignition concepts) is real and valid, as is the third-generation directed energy stuff. Both of those could use some inclusion as hypotheticals. But nobody working in the field believes that fourth generation weapons are on the shelf or have ever been tested anywhere. The ICF assemblies are multi-thousand-ton buildings full of high power lasers, and the antimatter concepts require more antimatter than has ever been stored in cool form in one place at one time on earth, that we know of. We cannot put hypotheticals into Wikipedia articles as established fact. Gsponer's research is that - not tested proven fact, not deployed weapons... Georgewilliamherbert (talk) 10:12, 11 February 2009 (UTC)

Agreed. The 4th-gen stuff is only hypothetical. Binksternet (talk) 11:16, 11 February 2009 (UTC)

This diff shows Uruk2008 reverting back to his challenged version without engaging in discussion here. One more such reversion and I will head over to WP:AN3 to report edit warring. Binksternet (talk) 17:09, 11 February 2009 (UTC)

Inelastic collisions of fission products?

The introduction to fission under Nuclear Reactions states that "[the fragments'] high electric charge causes many inelastic collisions with nearby nuclei." The context would suggest that the chief effect of the collisions is the redistribution of kinetic energy among nuclei, but the use of the word "inelastic" in nuclear reactions seems to suggest the further breakup of these fragments, as stated mentioned in the Inelastic collision article. My understanding of the process tends toward the former: the fragments slow down by electrically bumping into other nuclei, but the nuclear "inelastic" processes aren't significant. It may not be the most appropriate word choice. Or if it's right, some further explanation may be worthwhile. Experts? —Preceding unsigned comment added by Tstroman (talk • contribs) 21:53, 14 June 2009 (UTC)

I see what you're concerned about, but the subatomic inelastic collision and atom-level are different things... Atomic level collisions rarely lead to any nuclear fragmentation events. Georgewilliamherbert (talk) 23:54, 15 June 2009 (UTC)

Collisions that only exchange momentum and kinetic energy are by definition elastic, whether they refer to atoms, quarks, nuclei, or billiard balls. The term "inelastic" seems incorrect. NPguy (talk) 22:02, 16 June 2009 (UTC)

My understanding of this is limited, but I think the point here is that they do not only exchange momentum and kinetic energy, they also slow down and release electromagnetic (heat) energy, like the basketball illustrating the Inelastic collision article.HowardMorland (talk) 18:47, 21 July 2009 (UTC)

Elastic collision = total system kinetic energy conserved. Inelastic = some or all system kinetic energy converted to some other kind of energy. Since you'd get complete conversion of fission fragment kinetic energy to heat, even if all the inital fragment collisions WERE completely elastic, it not a terribly important distinction to make. But in a real solid material, at reasonably high temperatures (room temp and above), heat will be stored about 50% in the potential part of atomic vibration (the other 50% in the kinetic part of these vibrations), so somewhere along the line, inelastic collisions have to put kinetic energy into the potential energy part of vibrational bond excitation where the heat capacity of solids mostly resides (remember Dulong-Petit Cv = 3R/mole; half of this is kinetic and half potential for 3 degrees of freedom).

Remember also, there's a difference between elastic and inelastic collisions at the multi-atom system, vs. atomic or subatomic level, as regards whether heat is created. Heat NEEDS lots of atoms, because it needs a system with a lot of possible quantum states where entropy can be measured. You can't heat a single atom-- all you can do with the kinetic energy missing from an inelastic collision is "hide" it in some kind of excitation of a potential energy sink (electronic potential or nuclear potential energy or some such) or else in the creation of one or more new particles (including photons). For compound objects where entropy can be defined and heat is possible (heat is a statistical thing) inelastic collisions can create heat directly as the missing kinetic energy is distributed into many possible microstates of the system where it can be held in various forms of potential and kinetic energy (not the same kinetic energies of the same particles as you started with). SBHarris 19:31, 21 July 2009 (UTC)

Request energy distribution, atmospheric vs vacuum detonation

The table titled "Energy distribution of weapon" gives energy distribution of standard vs enhanced devices. However this assumes atmospheric detonation.

A common misconception about nuclear devices is they produce large blast and fireball effects even in space. To give readers a more complete picture, can anyone add info about how energy distribution and weapon effects vary between vacuum and atmospheric detonation? This isn't hypothetical, as many nuclear devices have already been detonated in space, and are discussed as a last-ditch asteroid mitigation strategy. Joema (talk) 13:57, 6 November 2009 (UTC)

The neutron bomb was designed for atmospheric radiation. There would be little point in detonating it underground.

The proportion of energy released as thermal radiation should not be that different in space. It may not make sense to speak of blast when there is not a medium dense enough to carry shock waves and sound. --JWB (talk) 17:07, 6 November 2009 (UTC)

There are various types of enhanced radiation warheads, not all designed for atmospheric use. E.g, the W71 ER warhead used on the Spartan ABM was intended for use outside the atmosphere. The W71 energy distribution was shaped to emphasize X-rays, since blast effects are minimal in space.

The misconception is widespread that nuclear warheads make a big blast and fireballs when detonated in space. The same warhead detonated in space will have very different proportions of energy distribution than if detonated atmospherically. However I can't find any authoritative information on the difference. Since this article is so high quality, I thought maybe one of the experts might have this info and add it. Joema (talk) 19:24, 6 November 2009 (UTC)

Actually, the proportion released as X-rays vs thermally does change significantly. It doesn't require a whole lot of tailoring of the weapon...

The initial fireball in atmospheric detonations is x-ray heated air, not bomb debris expanding. The air provides several levels of energy downshift from the original bomb debris. A cube of sea level air 10 meters on a side has a mass of about a ton.

For detonations outside the atmosphere, there's no air. The fission x-rays heat the bomb components, and some escape the bomb directly into space. The bomb components are heated enough to emit X-rays themselves (cf the process inside a thermonuclear bomb, with the radiation case and the x-ray photon gas). There's no secondary downshifting by the atmosphere - only the primary, by whatever energy fraction of fission gammas/xrays is absorbed by the bomb components initially.

There are several good books on this, but "The Effects of Nuclear Weapons" is a good start. Georgewilliamherbert (talk) 22:03, 6 November 2009 (UTC)

Actually by "thermal" I meant photons of any wavelength as opposed to kinetic energy of bomb debris. --JWB (talk) 00:15, 7 November 2009 (UTC)

Missing stuff

Another wiki article mentioned neutron generators being part of early bombs. Granted that a critical mass can go critical, and there is a miniscule amount of U235 undergoing spontaneous fission all the time, however doing the math of half-life times fraction fissioning spontaneously times statistical curve times loss quotient doesn't seem to guarantee that chain reaction will occur in the microseconds that the explosives have optimally configured the bomb. Need on the order of 10e5 neutrons per second? Neutron source "1×10e6 to 1×10e8 neutrons per second".

All nuclear weapons, fission or fusion are thermonuclear. The term thermonuclear was coined before hydrogen bombs. Their energy is created by nuclear reaction and their energy of destruction is thermal.

Gamma rays, X-rays, and "heat" (infrared and visible light) is made of photons.

The energy reactions neglect the energy loss to the neutrino generated in fusion reactions. There should be a note about short lived isotope contribution to energy release of fission reactions.

See topic Uranium. Technically U235 'FUSES' with a neutron to create a high energy version of U236* (or U236m) whose nuclear configuration allows it to rapidly decay by spontaneous fission. U235 itself has a low probability of decomposing by spontaneous fission. U236, from decay of higher nuclides or from bombardment of U235 with Tritium (deuterons taking away energy of reaction of U235 fusing with neutron), has a half life of 2.342×107 years.

Another reasom for mentioning above is Neutron source generation from "usual combinations of materials are plutonium-beryllium (PuBe), americium-beryllium (AmBe), or americium-lithium (AmLi)". "Radioisotopes which decay with high energy photons co-located with beryllium or deuterium: Gamma radiation with an energy exceeding the neutron binding energy of a nucleus can eject a neutron. Two examples and their decay products: ⁹Be + >1.7 Mev photon → 1 neutron + 2 ⁴He and also ²H (deuterium) + >2.26 MeV photon → 1 neutron + ¹H." "photons above the nuclear binding energy of a substance are incident on that substance, causing it to undergo giant dipole resonance after which it either emits a neutron or undergoes fission. The number of neutrons released by each fission event is dependent on the substance. Typically photons begin to produce neutrons on interaction with normal matter at energies of about 7 to 40 MeV"

The "Beryllium Shell" will interact with (24000 yr half life) Plutonium before explosion to create neutrons and after the explosion create neutrons from particles/gammas greater than 1.7 MeV (Be metastable energy state is about .6 MeV above ground state). Lithium itself fuses under Solar conditions. In addition to high energy neutrons, high energy photons (Gamma Rays) will be responsible for some of the U238 fission.

Side note that fusion of ⁷Lithium and Hydrogen or ⁶Lithium and Deuterium yields ⁸Be which instantly fissions to 2 Alpha. —Preceding unsigned comment added by Shjacks45 (talk • contribs) 02:05, 29 January 2010 (UTC)

Note from "Nuclear Weapon"

shows use of UD₃ as a neutron amplifier requiring smaller percentage of Uranium enrichment. (The Uranium deuteride is in a sphere surrounding the small ²³⁵U core). In the documentary "Mission for Mussolini" the authors show evidence for a nuclear weapons test by Nazi Germany refering to low enrichment Uranium alloyed with light metals. Addition of Lithium, Berylium, Deuterium, even Boron not only increases the number of effective neutrons per fission but also generate fast neutrons that can fission ²³⁸U. Shjacks45 (talk) 20:41, 8 February 2010 (UTC)

Some tweaks

Article now says[2]

The fission of one plutonium atom releases ten times more total energy than the fusion of one tritium atom, and it generates fifty times^{[citation needed]} more blast and fire. For this reason, tritium is included in nuclear weapon components only when it causes more fission than its production sacrifices, namely in the case of fusion-boosted fission.

But this article on arXive has some things to say about this. The first being that the extra neutrons from tritium fusion are always useful in any bomb. They probably boost fission fraction by more than one extra fission per tritium, since there is a neutron multiplier effect in any fission process, so it's better to use your reactor neutrons to make tritium since you get back 2.5 neutrons from any extra fission inside a bomb. Even if tritium didn't boost fission fraction in the primary, it would be worth including it there if it underwent fusion, since fusion neutrons can be used to fission non-fissile stuff like DU, natural uranium and (a clever idea) even Pu from old used-up fuel rods which is contaminated with too much Pu-240 to make a good primary. It's still perfectly useful for a secondary jacket, and this article even claims that India does this with its own thermonukes. This explains some of the "nuclear proliferation" concerns that go with even completely used fuel reprocessing, and also the scattering of DU in Iraq. Enough DU and some very ordinary LiD can make a fission bomb a hundred times more energetic and 20 times more deadly without adding very much weight, and with engineering no more difficult than making the first bomb, if enough fissile material has been collected already. A terrorist bomb of 10 kt is one thing (you lose some of Manhattan), but a 1000 kt bomb in the same place would take out all 5 boroughs.

The "citation needed" for the above statement in the article (which somebody else wrote) is only barely needed, as the energetics are easy to look up, and the factor of 5 comes from the fact that 4/5ths of the energy of the secondary is "wasted" against non-tank targets if the neutrons are not captured for fission: neutron energy is deposited in air too thinly to make a good blast or shock, and anybody not in a tank killed by neutron radiation would already be dead from blast if the neutrons had been used. For this reason, modern strategic bombs (even those carried on cruise missiles) pay no attention to the gross yield/weight of the fusion secondary, but use the fusion stage entirely for a neutron factory, minimizing total fusion yield, and maximizing fission yield. The figure-of-merit for a thermonuke is thus not raw energy yield/weight (a point not made in Nuclear weapon yield) but blast energy yield/weight-- not quite the same-- and a figure toward which any neutrons escaping the bomb hardly count. That's why thermonukes like W88 carried on cruise missiles don't simply have big lightweight fusion secondaries, to save weight. It doesn't save on blast/weight. The authors of the paper above suggest that the better blast effect from fission and the lost blast energy from fusion is the reason that modern weapons are probably far dirtier than the original thermonukes: instead of 50:50 fission/fusion yield, they are more like 80:20. Of course, much of that 20% does not escape the bomb but is absorbed in the secondary, and thus is converted to blast. SBHarris 19:22, 5 May 2010 (UTC)

Photofission/photodisintegration?

Is it possible for a nuclear bomb to use primarily photofission or photodisintegration? Could a bomb entirely avoid the use of radioactive materials? Might such a bomb even avoid producing any radioactive fallout? Wnt (talk) 17:33, 27 July 2010 (UTC)

Do we know how difficult this is?

Is there any public knowledge on how difficult it would be for e.g. a terrorist organization, taking it as a given that they somehow acquire a suitcase full of plutonium, to produce a working bomb? Please add such info if you have it (and are allowed to do so, lol) -- 92.229.151.102 (talk) 13:06, 12 April 2010 (UTC)

My understanding is that it is a simple industrial task. But it cannot be done without an adequate industrial infrastructure. Most of the Manhattan Project effort and expense went into producing the fissile material. The devices were assembled at Los Alamos in small wooden buildings. A few competent machinists, chemists, and physicists did the job in a few months, using 1940s technology. Terrorists have never had even those modest resources, and more importantly they have never acquired the necessary fissile material. HowardMorland (talk) 19:19, 1 June 2010 (UTC)

Making a Hiroshima-type fission bomb out of enriched uranium is relatively simple, which is why global authorities are so attentive to uranium-enrichment capabilities. However, the maximum power of such a bomb, while much larger than anything conventional explosives could do, is also orders of magnitudes smaller than any of the thermonuclear weapons in the arsenals of the USA and Russia. Making bombs of the sort in these two arsenals is still well beyond the capacity of any small- or even medium-sized nation-state. I suspect that non-state organizations would find it extremely difficult to successfully build and explode a plutonium bomb of any kind. The engineering details behind even the first plutonium bomb ever exploded, the one that destroyed Nagasaki, are much more complex (and were successfully kept secret for much longer) than the details of the enriched-uranium bomb. --arkuat (talk) 00:21, 27 August 2010 (UTC)

   If all the terrorist organization wanted to do was to cause a mass-casualty event, and were not overly concerned with wasting fissile material with a sub-optimal yield, all they would have to do would be to form the plutonium into a sphere, enclose the sphere in a beryllium shell, pack some high explosives around it (with some some of ignition mechanism), and then cast the whole thing in concrete. By the way, the diameter of the plutonium sphere could vary anywhere between 95mm and 210mm, depending on the type of plutonium in question (which the OP did not specify). Of course, the whole bomb would ultimately weigh a few hundred kilograms, and would not be deliverable by any conventional weapons delivery system, and would have to be transported to the target by a small truck. It would also be impractical to unload the device from the truck, and a using a time-delay fuse or remote detonation to detonate the bomb is also be impractical, due to the risk of the nuclear truck-bomb being discovered and defused.

   The only reliable method of delivery and detonation would be for a terrorist to drive the nuclear truck-bomb to the target, then manually detonate the bomb - so it would have to be a suicide terrorist. Of course, in all likelihood the device, would only produce a very sub-optimal yield in which most of the fissile material would be wasted, but even such a fizzle could destroy several city-blocks. In addition, the wasted fissile material would likely be spread over a wide area, causing long-term radiation ailments to the target population. So most of the damage done by such a bomb would be in the long-term health effects to those exposed (which would be a much larger number, probably by an order of magnitude) than the number of people killed/injured in the immediate explosion. Rocketshiporion (talk) 04:52, 27 August 2010 (UTC)

Redirecting Thermonuclear weapons?

Years ago, my English teacher – who had in the US experienced the Cold War excitement of the nuclear arms race – told me, that she did not remember which was more powerful, the Atom bomb or the Hydrogen bomb. (I could not help her, I did not even know a "hydrogen bomb" was a nuclear weapon.) Looking at this article, I cannot gasp how anyone with this level of understanding about nuclear physics could extract the relevant information from this article – or, for that matter, from the related article Teller–Ulam design.

This is a list of the related redirect I would like to move someplace sensible. The information I would like to pop up first is that while an conventional "atom bomb" can kill tens of thousands of people a "hydrogen bomb" can kill millions of people, i.e. it can be a thousand times more powerful.

• Thermonuclear weapon now redirects to Nuclear weapon design
• Thermonuclear weapons now redirects to Thermonuclear_weapons#Fusion_weapons
• Fission weapon now redirects to Nuclear weapon design
• Hydrogen bomb is indefinitely locked to Teller–Ulam design
• H bomb now redirects to Teller–Ulam design

There used to be something at Hydrogen bomb, but it was deleted as a copyvio. -- Petri Krohn (talk) 00:29, 9 August 2010 (UTC)

The problem is that "atom bomb" and later "atomic bomb" wasn't a very good term, as all bombs involve atoms. Nuclear bomb is a little better but people really didn't foresee the quick invention of more than one type of nuclear weapon, at first. The "H bomb" is a thermonuclear weapon, and probably should redirect there. These things are USUALLY more powerful than simple fission devices, but there's a big overlap. The most powerful pure "A-bomb" Ivy King ever fired was 500 kt, whereas the least powerful "H-bomb" W80 (nuclear warhead) has a dial-a-yield amount of tritium that can be bled off the secondary to give 150 kt (full H-bomb) all the way down to 5 kt (assumed then with no working fusion component at all, but nobody is saying). So you cannot say for sure which type is always more powerful. SBHarris 00:51, 9 August 2010 (UTC)

But I do agree with the general sentiment that the "basic" version should be spelled out: fission bombs are powerful, hydrogen bombs, generally speaking, are more powerful. That's not even terribly clear from Nuclear weapon unless you read through all of the "types" section and do a lot of thinking about what it says there. Obviously to those who are "in the know" the taxonomy is more complicated. But even we could state it in historical terms: the first fission bomb was in the range of 20 kt, the first hydrogen bomb was in the range of 10 Mt. That's probably all most people are expecting at a first glance. --Mr.98 (talk) 13:12, 26 August 2010 (UTC)

I've tentatively added the following to the beginning of the Nuclear weapon article:

The first fission ("atomic") bomb test released the same amount of energy as approximately 20,000 tons of TNT. The first thermonuclear ("hydrogen") bomb test released the same amount of energy as approximately 10,000,000 tons of TNT.

Good? Bad? It seems to me that it would probably be useful for the casual reader, who just knows them as "atomic" and "hydrogen bombs" and wants to know their general order of magnitude. I've qualified it ("first", "approximately") so that there is nothing inaccurate about it. Please feel free to refine. Goal is simplicity and clarity. We might consider variations for the intros of this article and for Teller-Ulam. --Mr.98 (talk) 13:21, 26 August 2010 (UTC)

I might suggest taking out the parentheticals and adding a line explaining that in popular culture, the term "atom bomb" was popularly used in the English language to denote a fission weapon and that "hydrogen bomb" was likewise the popular term for a weapon incorporating fusion. I've no reference for the above but it should be easy to find one. Comet Tuttle (talk) 16:57, 26 August 2010 (UTC)

Role of EPFCGs in Nuclear Weapons Design

Nuclear weapons create extraordinarily high EMP fields and contain the components of a very effective explosively pumped flux compression generator (EPFCG). Properly arranged, EPFCGs can confine and initiate fusion reactions. Should this article have a section discussing the role of EPFCG in the design of nuclear weapons? sn‾uǝɹɹɐʍɯ (talk) 21:54, 3 October 2010 (UTC)

The EMP is produced by late stage fireball physics, not the immediate detonation. Georgewilliamherbert (talk) 22:52, 3 October 2010 (UTC)

OK; mentioning standard EMP wasn't correct. But, if a magnetic field existed within a conductive layer of the tamper just before implosion (e.g. a Be layer), then the implosion would compress the B field and act as an EPFCG generating enormous currents. The current can then be arranged to confine the plasma and improve its fusion yield and/or to create an electromagnetic field in a subsequent stage in preparation for the compression and ignition of that later stage. Magnetized target fusion employs the same plasma confinement principle without using fission power. The public drawings of Teller-Ulam designs, such as the W80, show a secondary arranged in a cylindrical manner similar to EPFCG designs. sn‾uǝɹɹɐʍɯ (talk) 22:34, 5 October 2010 (UTC)

I don't know that that's useful or necessary; the fusion burn runs to completion just fine contained by the inertial mass of the remaining tamper/pusher. Thermonuclear weapons are pretty darn efficient already - the compression factors involved are enough to produce 10-50% burns in the fusion stage, to the point that fusion byproducts start to interfere with the ongoing fusion process.

There's no need to add another system; if inertial confinement and compression works, why get electrical/magnetic confinement involved?

Have you worked out numbers for the confinement energy of such an imploded field compared to the inertial confinement?

Are you familiar with the Nuclear Weapons FAQ section on Radiation Implosion, http://www.nuclearweaponarchive.org/Nwfaq/Nfaq4-4.html#Nfaq4.4.3?

Georgewilliamherbert (talk) 22:59, 5 October 2010 (UTC)

pusher

the article says it's supposed to reflect some of the wave backwards. i believe this to be misunderstanding of the physics, use of a lower density material like alumin would reduce wave impedance, therefore reducing the impedance mismatch between wave and material leading to less of the wave being reflected away into the other direction. —Preceding unsigned comment added by 87.162.47.244 (talk) 23:17, 13 April 2011 (UTC)

Length of the lead section

Currently, the beginning lead section goes on for paragraphs and paragraphs before we get to the index. I'm not intimately familiar with Wikipedia styling, but this seems excessively long, and like most information should be moved down below the index Raptortech97 (talk) 13:55, 2 May 2011 (UTC)

Wikipedia:Manual of Style (lead section) --80.217.2.28 (talk) 08:47, 9 May 2011 (UTC)

Diagram inconsistency

Disclaimer: I am *so* not a nuclear physicist...

The diagram given in the section "Oralloy thermonuclear warheads" claims to be a cross-section of the W88. It shows a spherical primary. The section on the W88, however, shows a more complex egg shape, and also provides some references to support that diagram. Can someone who knows The Real Deal please clarify one or the other? — Preceding unsigned comment added by Riventree (talk • contribs) 21:43, 13 December 2011 (UTC)

Look again: the W88 diagram in this article shows a spherical secondary (below the prolate primary). Compare W87 with W88. This stuff is all from newspapers and a popular book written by somebody who is obviously not a nuke engineer, or else they'd be in jail. I have the feeling that the people who know the "real deal" about the innards of W88, have probably signed security/secrecy contacts which prevent them from contributing directly to Wikipedia about that subject, on pain of imprisonment. So don't get your hopes up. SBHarris 22:22, 13 December 2011 (UTC)

Question about back pack nuclear bomb

The South Korean media is describing a North korean back pack bomb (which oddly seems to be deployed near the China border) along with a picture of the design. See:

NK Running 'Backpack Bomb' Unit – Daily NK

Question: There are four bottle-like structures located in the upper left of the image. Two are red, outside the barrel. The other two are light orange, inside the barrel. What are they? 172.162.40.132 (talk) 03:57, 27 November 2011 (UTC)

And how can this information be used to improve this article? --80.217.2.199 (talk) 16:57, 29 November 2011 (UTC)

Its a question about nuclear weapon design.172.162.39.45 (talk) 22:32, 5 December 2011 (UTC)BG

That diagram appears to be a non-technical experts' "how a small gun type bomb might look", not derived from an actual design.

I would not assume it has any basis in an actual design.

If someone who can read Korean can translate the illustration captions it would help see what the shapes are supposed to represent.

I don't think it's relevant or appropriate to include in the article. It's almost certainly an artists' conception not the real thing. Georgewilliamherbert (talk) 01:05, 6 December 2011 (UTC)

Good article. I (fortunately) don't have to read -neese to determine what that graphic is about. It is a drawing and photograph from the legendary Kurt Weldon incident. You know, where the staffer built a mockup with a lantern battery, household light switch, wood, water pipe and aluminum foil, and now everybody thinks its' a credible design?

Happy to help,

Shawn Hughes 98.70.111.10 (talk) 01:47, 10 January 2012 (UTC)

Single-stage weapons of India, NK, etc - not in source

About "The other nuclear-armed nations, Israel, India, Pakistan, and North Korea, probably have single-stage weapons, possibly boosted" - there is no information about such nations in the [21] "Howard Morland, "Born Secret," Cardozo Law Review, March 2005, pp. 1401–1408.". Please, recheck. `a5b (talk) 00:06, 15 May 2012 (UTC)

Post war german nuclear weapons program?

Below the drawing of the swedish artillery shell design, there is a line about a "post-war german nuclear weapons program" witout a citation. Where does that come from? I am german, and there almost certainly couldn´t have been such a thing in post war german history - simply, because germany was under Allies control until reunification in 1990 - and i doubt if the Allies had allowed germany to continue the development of nuclear weapons right after... ...uhm... ...say, big efforts had been necessary to keep the world from beeing swallowed by the nazis. Even if there had been a top-secret program, it would either be still top secret and therefore there wouldn´t be any open sources to cite from, or i should have noticed "Dresden ´45 reloaded" happening in some nearby cities around here in germany... 109.193.29.218 (talk) 00:07, 14 June 2012 (UTC)

I think that you are right. The Kriegswaffenkontrollgesetz expressly prohibits this, and there is no evidence that DE carried out research in the post-war years. I will delete.Theeurocrat (talk) 18:37, 4 January 2013 (UTC)

Linear Implosion

Can someone show me where in the literature, not theoretical, but in a SAND-type publication where the rationale for a cylinder-type implosion device was ever used? And, please don't point out the W48.

Others have speculated the W48 is a gun weapon, again with no relevant reference.

In the November - December 1993 edition of the Energy and Technology Review, published by LLNL (doi:10.2172/10127762, 4.5 MB), there is an article on an incident involving dismantlement of one of these devices. They state on page 10 (13 in the PDF) a heavy spring is used to hold the pit in place. There are no pits in a gun system.

Then, on that page, they describe a cracking of the outer shell of the pit. This means the pit isn't solid, and further reading suggests that the pit is in fact layered. Finally, on page 13 (16 in the PDF), they further describe the pit as a hemishell. Failure of the pit was attributed to a failed waist welding procedure.

Looking at the Brookings institution photo of the guy with the grin on his face, and a finger inside the artillery round, and referencing it against the most interesting line drawing on the Greenpeace site, I am saying it's spherical implosion. Of course, assuming the entire article wasn't disinformation, and the display round was complete in its innards.

There is my reference. Cite yours in your response, and don't bother with third hand tales.

What say ye now??? —207.65.105.202 (talk) 04:02, 19 May 2011 (UTC)

(Just to get this on the record)

I look at these things a lot, and the state of the public information on what the W48 really is, is extremely poor. There are written descriptions as a linear implosion weapon, but the data out there sucks. Some of the published photos have at times made me think that they were intentional disinformation.

I think it's healthy to step back from the W48 and assume there's something seriously wrong with our understanding of what it was. Georgewilliamherbert (talk) 02:54, 5 January 2013 (UTC)

Fission-fusion-fission

As it stands, this is confusing. There is a section "Fission-fusion-fission bombs" that explains how this terminology is confusing, yet that very same terminology is used in the preceding section. Theeurocrat (talk) 19:21, 10 November 2012 (UTC)

I think the section is not needed, as it duplicates other sections. The term should be used somewhere in the article to express the fact that there's a lot of fission going on in the secondary. A recent edit to this section adds the term "jacket," which is not explained or used elsewhere but appears to correspond to the "tamper" or "pusher" of the secondary. I thought about trying to fix it, but the simpler course would be to delete it. Other views? NPguy (talk) 02:27, 9 January 2013 (UTC)

They're talking about the tamper/pusher. Frankly, the article has evolved into a major mess, of which this is a minor part, but I have not the time at the moment to fix it.

It is covered elsewhere, but is not inaccurate where it is now in that section.

Georgewilliamherbert (talk) 02:56, 9 January 2013 (UTC)

W80 diagram leaked by Greenpeace

How come the leaked diagram that according to Greenpeace actually came from a military nuclear weapons manual isn't here? It's the only weapons diagram that came from an official government source.

http://fas.org/sgp/eprint/cardozo.html (down the bottom of the page)

There is some dispute over what type of weapon it is. It looks like a W80, but it claims to be British. To my knowledge the British never used the W80 design. 124.169.53.245 (talk) 06:42, 2 March 2015 (UTC)

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Fission

The last sentence in the sixth paragraph of this section, "In practice, bombs do not contain such amounts of uranium or plutonium, and typically (in a modern weapon) about 2 to 2.5 kilograms of plutonium, representing 40 to 50 kilotons of energy, undergoes fission before the core blows itself apart," makes very little sense grammatically. I'd like to edit it, but I really have no idea what the original intent was. — Preceding unsigned comment added by 72.238.148.8 (talk) 01:00, 23 September 2014 (UTC)

See what you think now. SBHarris 01:34, 23 September 2014 (UTC)

A certain amount, critical mass, is needed to start the reaction, but most of it doesn't have a chance to fission before it is blown apart. The actual energy yield is very sensitive to that fraction. Does that help at all? Gah4 (talk) 21:42, 3 December 2015 (UTC)

Energy loss

There is the statement The charged fragments' high electric charge causes many inelastic collisions with nearby nuclei. Seems to me that the energy loss is more from interacting with electrons than inelastic nuclei, but I could be wrong. Anyone know about this? Gah4 (talk) 21:45, 3 December 2015 (UTC)

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Sorry bot, but the datasheets for the public version of the MCTL are not available online. I've substituted the 1998 one from fas.org. OK? Debouch (talk) 01:53, 28 February 2016 (UTC)

Explosive Testing

The citation to the effect that computing power is not great enough to simulate the detonation sequence of nuclear bombs is from 2000. The computational power that exists now, especially that which the national labs can make use of, is so much greater than it once was that the Monte Carlo approach has become the most widely-accepted method for criticality tests. And, compared to full-size power reactors, bombs are relatively simple to model in computers. Unfortunately, I don't have citations to back this up beyond personal experience, but it may be worthwhile to find more recent information to this effect. IRSpeshul (talk) 16:33, 22 September 2012 (UTC)

I suppose it depends on how close you want to simulate. Turbulence in 3D is very difficult, even for the biggest compute farms now. (It is used to simulate a core-collapse super-nova, for example.) The 1D (spherical symmetry) calculation is much simpler, but also misses much physics. Gah4 (talk) 23:39, 17 May 2016 (UTC)

Stage counting

The neutrons released by fusion will fission U-238. This U-238 fission reaction produces most of the energy in a typical two-stage thermonuclear weapon. Not sure how they count the stages, but wouldn't a fission-fusion-fission bomb be three stages? Gah4 (talk) 23:43, 17 May 2016 (UTC)

Cobalt bomb section confusing

The section Cobalt bomb is a little confusing. The section starts out describing the device as "A fictional doomsday bomb" which would lead casual readers to regard it as fictional, yet the article says they were seriously investigated and possibly built and tested. The comparison of radiation produced by fission products to cobalt-60 after a nuclear explosion is inadequately described - is this from a putative cobalt bomb? Thanks. --Chetvorno^TALK 20:12, 7 October 2014 (UTC)

In the case of fission products many decay, and their daughter nuclides decay, in seconds, minutes, or hours. Sr-90 and Cs-137 have half lives in tens of years, and so are the dominant radioactivity after a few years. The cobalt bomb intentionally creates a large amount of Co-60 with about a five year half life. That makes it the dominant radioactive nuclide for some years, and much more radioactive than the Sr-90 and Cs-137 for many years. As far as is known, none have been built. Gah4 (talk) 03:11, 16 October 2016 (UTC)

Units?

The Fat Man device specifically used 13.6 lb (6.2 kg), about 12 US fl oz or 350 ml in volume) It seems wrong to use a liquid volume unit for Pu. Gah4 (talk) 02:17, 16 October 2016 (UTC)

Both mL and (counterintuitively) fl oz are measurements of volume in general, not just fluids. I think it is helpful to the reader for them to be able to picture the volume taken by the 6.2 kg of Pu. VQuakr (talk) 00:30, 17 October 2016 (UTC)

I suppose so. As far as I know, it should be mL for liquids, and $cm^{3}$ for solids, but then everyone knows that they are the same. And $in^{3}$ for solids, and fluid ounces for liquids, but it could be that U.S. people can imagine the volume easier in fluid ounces than in $in^{3}$. In recipes, butter and sifted flour are more like liquids than solids. I wasn't actually suggesting changing it, but just wondering. Thanks. Gah4 (talk) 04:11, 17 October 2016 (UTC)

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Intro needs a severe prune

A good start would be to trim back each of the bulleted types to a sentence or two. - Snori (talk) 08:42, 3 October 2018 (UTC)

gun design and assembly velocity

There is no discussion of assembly velocity and gun design. As well as I remember, when I first learned about the gun design, I though that you just put the two parts together. It turns out that they need to be assembled at very high speed, as you get from a bullet in a gun. As well as I know, you need 1000ft/s for uranium and 3000ft/s for reactor bred plutonium. Should these be in the article? Gah4 (talk) 22:09, 13 June 2019 (UTC)

I looked up this one again. (In the Los Alamos Primer.) It is that 3000ft/s is supposed to work for pure Pu239. That was the original plan. Reactor bred Pu won't work at 3000ft/s, and guns can't go much faster. Gah4 (talk) 22:17, 29 September 2019 (UTC)

U238 fission

There are recent edits related to U238 fission and bomb yield. From Nuclear_weapon_design#Implosion-type_weapon, about 20% of fat-man energy comes from fission of the U238 tamper, from fast neutrons leaving the reaction. But U238 fission in fusion bombs also adds to their yield. It seems, then, to apply to both. Gah4 (talk) 19:19, 28 September 2019 (UTC)

Read it again. It doesn't say that. It ways U-238 helps reflect neutrons and that 20% of the Pu fissioned. NPguy (talk) 21:19, 29 September 2019 (UTC)

It says: (The natural uranium tamper did not undergo fission from thermal neutrons, but did contribute perhaps 20% of the total yield from fission by fast neutrons). It is hard to read that as anything other than U238 fission. Later, it mentions increased yield. As usual, the exact number is pretty sensitive to design details, so likely isn't so well known. Gah4 (talk) 22:15, 29 September 2019 (UTC)

It is estimated that about 30% of the total yield of the Trinity test came from fissioning of the uranium tamper, which translates to about 6 kilotons of energy. [3] Hawkeye7 (discuss) 22:44, 29 September 2019 (UTC)

Thanks for the correction and fascinating citation. I hadn't realized that there was enough overlap between the fission neutron energy spectrum and the U-238 fission cross-section to produce an appreciable fission yield in a tamper. I still think the text as I reverted it makes most sense in context. In a thermonuclear weapon, the sources seem to say (and it is logical) that most of the U-238 fission will come from the highest-energy neutrons, i.e. those released from D-T fusion. NPguy (talk) 02:19, 1 October 2019 (UTC)

Warhead design safety section is trash

I was trying to clean it up a bit, but it's a big task. The section is mostly uncited, contains lots of loaded language and quite often defies the sources given in the full articles of the topics it discusses.

I will try to rewrite this section in the next week or so. I'd like to consolidate the various methods that insert neutron poisons into the core as they all operate the same way. I also think the sections on weak links/strong links and PALs needs to be expanded and properly cited. If you want to get a head start go right ahead. Kylesenior (talk) 08:11, 14 April 2020 (UTC)