Jeffrey LewisUranium Deuteride Initiators

You have no doubt seen the Times of London story, in which Catherine Philp claims to have obtained a 2007 “technical document” from from Iran that “describes the use of a neutron source, uranium deuteride, which independent experts confirm has no possible civilian or military use other than in a nuclear weapon.” (The Times published a more detailed discussion of UD3 in a separate article).

I have no idea whether the document is authentic, but I do want to confirm that Pakistan appears to have used uranium deuteride (UD3) as a neutron initiator.

The Times story doesn’t adequately convey that this is a relatively novel source of neutrons for a bomb design. Technically inclined readers may recall that earlier accusations against Iran focused on more traditional route of polonium-beryllium (Po-Be). Several colleagues have emailed me, expressing surprise that Pakistan is alleged to have used UD3 instead of the Po-Be.

But yes, it appears that both China and Pakistan explored the use of UD3 as a neutron source. There are two data points of which I am aware.

The first, and most colorful, is a well-known picture (above) of AQ Khan from the cover of his book, modestly titled Dr. A. Q. Khan on Science and Education.

AQ Khan graces the cover, holding a soccer ball (which is basically the size and configuration of the shell of high explosives in a nuclear weapon), standing in front of a blackboard showing a nuclear weapon diagram. The most shocking detail is the notation “Uran Deuteride Initiator.”

(A funny side note, the book Deception (2007) by Adrian Levy and Cathy Scott-Clark reproduces the image, with a portion of the blackboard redacted. Unfortunately, they redacted the wrong portion!)

Now, you may be thinking “How does that work?”

Four scientists from the Southwest Institute of Fluid Mechanics in Sichuan (which is the part of China’s nuclear weapons complex responsible for hydrodynamic research) published a detailed explanation in a 1989 paper entitled “Fusion Produced by Implosion of Spherical Explosive.” The paper is included in the proceedings of an American Physical Society meeting published as Shock Compression of Condensed Matter, (S. C. Schmidt, James N. Johnson, Lee W. Davison, editors, North-Holland, 1990.)

I had previously sort of steered clear of mentioning this on the blog, but between AQ Khan’s entrepreneurial activities and the Times of London, there’s not much point in denying it.

I won’t put the paper on line, but you can readily purchase your own copy.

Update | 3:09 pm ISIS has placed Farsi and English versions of the document online, along with a short analysis that basically describes the process outlined in the Dong et al paper.

Late Update | 6:12 pm Danny Stillman and Tom Reed mentioned the picture and the Dong et al paper in Nuclear Express on pp 250-251:

In 1997, a publishing house in Lahore, Pakistan, relaesed a collection of mid-1980s to mid-1990s lectures by A. Q. Khan entitled Dr. A.Q. Khan on Science and Eduction. This book discloses some of Dr. Khan’s early knowledge about nuclear weapons, including a sophisticated neutron initiation scheme. Initiators are the devices needed to assure an adequate supply of neutrons to the weapon core at the moment of maximum supercriticality. During World War II, the United States achieved this result by mixing beryllium and polonium at the center of an implosion. In later years the United States and most other nuclear weapons states turned to pulsed neutron tubes, essentially mini-accelerators, to produce a surge of neutrons when needed. But in 1989, at an American Physical Society conference in Albuquerque, the Chinese explained their very different approach to neutron generators. That Chinese initiation scheme appears with Dr. Khan’s book, and thus the origins of Pakistan’s A-bomb are unambiguously confirmed.

I should say that the first place I heard about all this was a talk we organized at Harvard for Danny. I didn’t link it to Danny since the talk was under the Chatham House-rule, but since he was able to put it in a book …


  1. John Field (History)

    What’s the big deal?

    Any alpha with enough energy and any neutron rich low Z will pretty much do it, right? Deuterium is a large and weakly bound nucleus. And uranium is a lot cheaper than polonium, even if it doesn’t decay so fast.

  2. bts

    Every few years secret evidence shows up which proves Iran is building this and that

    Iran is building neutron initiator
    February 3, 2005

  3. ignoramus (History)

    Fusion? Does that makes this a fusion-boosted fission device?

  4. Hairs (History)

    Jeffrey, a little needless hair-splitting:

    The newspaper is “The Times” not the “Times of London”. I know that readers in the USA often assume that “The Times” automatically refers to “The New York Times” but I’m afraid we Brits bagged the short form of the title about 60 years before the NYT was founded.

    Sorry to be so pedantic, but if one is to be correct about the spelling of “The Grauniad” then one must also be correct about the use of “The Times”! :-)

  5. Bill Robinson

    If that’s a “smiling” AQ Khan, I’d hate to see him with a bland expression on his face.

  6. M Ahmed (History)


    How are you so sure that Pakistan used UD3 neutron initiators in its nuclear weapons and not Po-Be? Are your conclusions in this respect based on the above photograph or on what A Q Khan told the Iranians about bomb designs, if any? Some published sources on Pakistani nuclear weapons have stated the source to be Po-Be. Secondly were these initiators built by KRL or PAEC?


  7. Allen Thomson (History)

    Could someone savvy in such things comment on what’s supposed to be going on with the UD3 initiator? Do the neutrons come from (α,n), in why case why not use a traditional polonium (or, I guess, americium-241)/beryllium device? Or is, as the title of the Chinese paper suggests, deuterium fusion happening (which would considerably surprise me)?

    Or what?

  8. Alex W. (History)

    While we’re looking closely at the diagrams—what’s with the “steel rod”? That is not something that is usually in such diagrams (says someone who has spent quite some time looking at “public” representations of bomb designs). It seems comparatively innocuous (at least compared to the initiator), but it does stand out as the only other unusual thing.

  9. Carey Sublette

    There are several different ways that UD3 might be used in a neutron initiation scheme:
    1. As a deuterium bearing target for an pulse neutron tube;
    2. As a deuterium storage medium that releases it upon heating as a gas for hollow core shock-induced neutron generation and/or boosting;
    3. As the actual target material for shock-induced neutron generation.

    The possibility that it is being used to produce neutrons through alpha->n reactions seems slight, since a non-modulated neutron generator seems of little value in a weapon, and other systems are much more effective in this role than UD3.

    The production of neutrons through shock compression of deuterium has been established in the open literature at least since 1982 by the work of Sagie and Glass, and Derentowicz et al., and the possibity of using shock compression of deuterium or D-T to create bomb initiators has been discussed publicly at least as long.

  10. Sean (History)

    So what do you suppose has been erased in the photo just above the “1 Kg U_235”?

  11. Fred Reinheimer (History)

    I feel like a dum-dum here. Are we talking about a URCHIN-style, center-o’-the-pit dealie or (as I blithely assumed) an external D-T tube arrangement?

  12. Carey Sublette

    Correction of my earlier post: the publicly published work of Derentowicz et al in convergent shock neutron generation via fusion goes back to 1977.

    My website discusses this method of initiation briefly as well, and has since 1996.

  13. Carey Sublette

    From the Dong article it is clear that the degree of effective shock convergence required (i.e. before symmetry is disrupted) for sufficient neutron generation using this method is very high, on the order of 80-to-1 (8 cm radius down to 0.1 cm).

    This is very hard to do, and a much stiffer requirement than needed just for fissile material compression (since most of the material is in the outer layers, a low degree of convergence achieves most of the compression).

    The Chinese used a 252 point implosion system, though a good 2-point system should do as well or better.

  14. George William Herbert (History)

    $64,000 question:

    Why would Iran (or anyone else) chose this method of neutron generation / initiation in the modern era?

    It’s not like external pulse tubes are particularly difficult or expensive…

  15. Yale Simkin (History)

    Here is another paper on the subject: Explosive-Driven Hemispherical Implosions for Generating Fusion Plasmas

    aZr@el wrote:
    …(Khan) was an arms smuggler whose specialty was enrichment of uranium, not a weapon designer by any stretch of the imagination.

    Yes, but he had Chinese blueprints directly in hand, which he gave to his clients. He would KNOW what was in the design.

    azr@el wrote:
    In what universe will that poor rendering of fat boy convert 1 kg of U235 into 20kt?

    I think he was saying not that the bomb contained only 1kg of U235, but that 1 kg yields (somewhat less than) 20kt when fissioned (out of a core totaling 15-20kgs, whatever).

    azr@el wrote:
    Uranium deuteride has a serious drawback as a neutron source… and yet d-t boosted gas designs still require a separate neutron pulse to get the fission reaction going first. Why? Because significant D-T fusion does not happen without the onset of precisely timed fission to warm things up, chemical explosive compression will not be sufficient.

    The point you are missing is seen in your use of the word significant. Boosting requires mega-gazilions of neutrons to flood the fissiles, and much heat and much compression is needed. If you’re requirements are more modest – just a butt-load of neutrons to spark maybe a single fission chain, then the quantity of fusion generated with a spherical shock implosion from an HE shell can produce enough fusion. This has been demonstrated.

    azr@el wrote:
    Recall we’ve actually tested uranium hydride devices in the hipster 50’s and the difference between using hydrogen or deuterium is nil. Both devices fizzled, both devices massed about 3.5 tons, both devices required a betaron for neutron initiation and the deuteride device failed to reach a high enough temperature to fuse any significant quantity of deuterium

    The uranium hydride tests in the ’50s were not fusion tests. The purpose of the 2h was as a MODERATOR for the neutrons, which was supposed to allow a much smaller quantity of fissile for a critical mass. Unfortunately, moderating implies slowing, just what you don’t want. THATS why they fizzled.

    Fred asked:
    Are we talking about a URCHIN-style, center-o’-the-pit?


    Alex asked:
    what’s with the “steel rod”?

    Looks like the supports for the more central components in the implosion assembly

  16. George William Herbert (History)

    Azr@el –

    Two points.

    1. The sketch on the board behind Khan does not suggest a 1 kg HEU core. The component weights/dimensions aren’t listed. 1 kg HEU (fully fissioned) is about 20 Kt energy released – more precisely, 17.6 Kt. How much fissions, and how much is there, are unclear from that sketch (if it’s an accurate device model at all, though the general levitated pit it shows is not obviously flawed as a design concept).

    2. The Uranium Deuteride designs being discussed here are for neutron generators/initiators, a la the Urchin and later models in US weapons, which used Polonium. They’re not a whole hydride type device, which relies on moderated fission (UH3 or UD3) rather than fast fission. The Hydride designs work – both Upshot Knothole Ruth and Ray generated several hundred tons TNT yield – but they’re huge devices (tons of HE), and their extremely slow fission process due to the use of moderated fission reactions is extremely limiting to their yield.

    They’re not what we’re talking about here.

  17. Yale Simkin (History)

    One of the reasons designers might avoid polonium-beryllium initiators is that they are extremely short-lived. As much hassle as tritium decay creates, its half-life is more than a decade. Polonium210 has a half-life less than 200 days. Routinely swapping out the hardware at the center of an A-bomb is a major pain, particularly in a missile warhead.

  18. Robert Cross (History)

    I find it very difficult to understand why this document, even if authentic, is being promoted as the “smoking gun” regarding Iranian intent. There’s practically nothing here that unequivocally indicates a connection to weapons design. Why anyone would even think about using UD3 to initiate an implosion-assembled weapon is beyond me, because the presence of high atomic number elements such as uranium will quench a fusion reaction by bremsstrahlung emission. I find the so-called analysis by Mr. Albright quite unsatisfying, like much of his other material. The lack of physics-based argument speaks for itself. The provenance of the document is also questionable, reminding me of nothing so much as the “proof” offered by Rumsfeld, Powell and Rice in the run-up to Iraq. It seems like thinly-disguised cover for a certain hot-tempered nuclear-armed nation in the Middle East to launch an attack in “self-defense”.

  19. Allen Thomson (History)

    I’m humbly grateful to the up-thread posters for the pointers to explosively-produced D-D fusion demonstrations. I’d had no clue about it before now.

    But I’m still unclear as to why it’s desirable in a UD3 manifestation as a bomb initiator, given the other ways to achieve the same end. Longevity, as implied by Yale?

  20. Carey Sublette

    After reading the translated paper on the ISIS website it is pretty clear what is being discussed.

    They are talking about using a metal hydride gas generator to supply deuterium gas to a plasma focus neutron generator – which is a perfectly reasonable modern neutron generator for a variety of purposes, such as producing laboratory quantities of radioisotopes (possibly the samples they are referring to to be marketed to other research centers).

    The UD3 is the hydride currently in use, but they want to replace it with TiD2 – a perfectly reasonable substitution to avoid “U pollution” (Ti hydride gas generators are an old established technology).

    There a several known uses of UD3, of which hydrogen storage is the most prominent (either for release as a gas or as an accelerator target).

    The AQ Khan blackboard diagram is, I think, a red herring. The significance with regard to Khan is that it was probably in an old Chinese design. But this has nothing to do with Iran.

    So nothing ulterior here?

    Possibly – this is a dual use technology though. A plasma focus tube can be used as a weapon initiator quite nicely.

    The use of a metal hydride gas generator to provide deuterium gas for this application is maybe a little unusual. Deuterium is commonly available as a pure gas in a bottle, and a hydride generator typically has a less pure product.

    The hydride generator perhaps makes more sense if they are thinking about using it with tritium later on.

  21. anon

    “The Chinese used a 252 point implosion system, though a good 2-point system should do as well or better.”

    Round bombs generally require less SNM.

  22. Yale Simkin (History)

    Another reason a proliferator would avoid Po-Be initiators is concealment.

    Po210 is created in a reactor and would be tough to hide from prying eyes. Beryllium is also tough to hide.

    Iran was grilled by the IAEA because there was evidence of Po210 production in the ’80s and ’90s.

    Uranium and deuterium Iran has by the hottub-full. And since they apparently are working on testing the initiator with a titanium-deuterium proxy, they don’t have to immediately be concerned with detection of the weird UD3 compound – at least until they got exposed by the memo.

  23. Carey Sublette

    <i>Round bombs generally require less SNM.</i>

    Two point intiation is in no way tied to a non-spherical implosion system. Air lenses (and similar techniques) can initiate a highly regular spherical implosion.

  24. John Field (History)

    OK, I now believe you guys that it is fusion happening at the pressure spike. It’s got to be.

    This thing seems like it would be very much pre-initiated. Not surprising. But now for the $64 question: Why is it that the boost gas doesn’t pre-start the neutrons in the modern weapons?

    You can’t have it both ways; you either are very preinitiated or you must not get the nice uniform pressure spike – not once, not ever. The buildup time is too fast for the return shock to transit back to the outer edge of the pit, and all the mass is out there by the periphery.

    Well, bloggers, which one is it?

  25. Fred2 (History)

    Is this news seen as politically important?

    That would imply there are dolts who are still denying that Iran is working on a nuclear weapon. Is this news to them? And are there any such people in important positions?

  26. FSB

    Research into the physics of nuclear explosions (ie. obtaining the know-how to achieve a nuclear weapons capability) is different from pursuing an active weapons program. (ie. diversion of material, of which there is no evidence).

  27. Robert Cross (History)

    For those interested in prior experimental work on producing neutrons by implosion of deuterium with conventional high explosives, this link might be of interest.

  28. John Schilling (History)

    Boost-gas preignition could only occur in a very small volume at dead center of a hollow core; if you don’t want preignition, you could put something else there instead – a small levitated core, a hollow capsule of inert gas, or some other “spoiler”. Alternately, controlled irregularities on the inner surface of a hollow core possibly prevent the formation of a single, strong converging shock. Though that might also adversely effect the implosion itself.

    Also, if there is preignition of the boost gas, that might not matter much. Even with initiation at the moment of criticality, a lightweight weapon can probably generate a good fraction of a kiloton, which may be enough to fully ignite the boost gas. And strong boosting will give respectable efficiency with even a barely-critical core.

    That people with boosted-fission weapons are still using pulsed neutron sources argues against the latter option, so I suspect some sort of spoiler at the center of any boosted hollow-core weapon. Plenty of ways to do that, and we don’t need to speculate as to the exact details here.

  29. Carey Sublette

    Why is it that the boost gas doesn’t pre-start the neutrons in the modern weapons?

    This will take a little bit of explanation to make clear. Bear with me.

    Pre-initiation is only a problem in devices with a high pure fission yield because it is only in these bombs that you have an intrinsic disassembly-limited yield, and thus the requirement that a very high “alpha” (neutron multiplication rate) exist at disassembly time.

    Alpha ramps up as implosion proceeds, and if you integrate the neutron multiplication rate over the implosion time you find that in a high yield pure fission device the total number of doubling intervals that occur between criticality and full assembly is a large number – like 100 or so, while the number required to generate enough energy to disassemble the bomb at full yield is only 80. This is why disassembly is a problem – any neutrons introduced in the first 20 doubling intervals will cause disassembly before maximum supercriticality.

    In a boosted weapon the pure fission yield is only about 300 tons (boosting kicks in around 200 tons), and the number of integrated doubling intervals between criticality and full supercriticality are LESS than the number of intervals required to take one neutron up to the population required to produce a full (that is to say, a 200 ton boost threshold) yield. This means that not only is pre-detonation not a problem, you can design the bomb so that you actually have to inject a large pulse of neutrons into it to get it to explode at full yield.

    The fact that boosted weapons can be designed to be immune to pre-initiation had major implications to the arms race. Targeting strategies where large numbers of MIRV’d warheads explode over a single target require the warheads be essentially immune to the neutron bursts from the other warheads. By the same token, ABM systems cannot use pre-intiation to defeat the incoming warheads, they must physically destroy them.

    If it were not for boosting, the arms race would have taken a dramatically different course. For example a small unshielded pulsed nuclear reactor sitting on top of a missile silo would have made counter-force targeting impossible.

  30. George William Herbert (History)

    John –

    It’s not entirely clear what you are asking.

    Do you mean, why doesn’t the shockwave from initial implosion system detonation cause a spike of fusion in the boost gas?

    The system is significantly subcritical at the moment that shockwave traverses the system. The implosion is much slower than that, and takes time to bring the system into criticality and supercriticality.

    Initial density of boost gas is also very low, which will reduce fusion rate. If we take a mole of boost gas as a rough number, we’re talking about roughly a liter of volume or more; that’s only about 23 atm basic pressure. UD3 density is about 0.27 g/cc Deuterium, about 1000x higher than STP and 40x greater than uncompressed boost gas.

  31. Alex W. (History)

    I’m still struck at how generic everything else on the blackboard is, even including the bomb itself, yet it has all sorts of tiny specific details (the initiator, the fact that it is levitated), which are not really necessary to get across the general concept. It’s also hard for me to fathom why it was worth reproducing, in really quite wonderful detail, figure 2.07a from Glasstone and Doran. In three different colors of chalk, at that!

  32. Mark Gubrud

    The document does not appear to report ongoing work, but to propose and outline the requirements for a program of work, which may or may not be underway at this time.

    The program of work described in the document is hardly a complete nuclear weapons program, but does appear to comprise the groundwork for developing what could be a neutron source for initiating a nuclear weapon. It appears to propose that this work be kept hidden behind a more public program using the same of the same labs and equipment to produce sample materials for nonweapons purposes.

    The proposed activities include measurements of neutron pulses from “NG” and “PF” sources (presumably spallation neutron generators and plasma focus devices per Carey Sublette). These appear to be preliminary to conducting tests with “hot sources” which could be the bomb initiators. Calculations related to design of the “hot sources” and preparations for testing them are proposed in the document.

    The document suggests the continued existence of a covert network of researchers committed to development of a nuclear weapons option for Iran, which must have government support, but may not be very active due to the “political situation” it refers to. The document could be a forgery. However, the possibility that work at this level continues in Iran, intended to ensure that they will have the option to quickly weaponize, should they decide to do so in the future, does not seem terribly unlikely. It is not inconsistent with Iran having suspended the bulk of its nuclear weapons development effort, does not prove that Iran intends to weaponize, and is certainly not a casus belli, nor is it proof that efforts to engage Iran positively, and to stabilize the situation short of Iran actually producing nuclear weapons, are necessarily doomed.

  33. Robert Cross (History)

    John Field asked “Why is it that the boost gas doesn’t pre-start the neutrons in the modern weapons?” Very good question! The answer is that the boost gas is a gas and as the converging shock heats it to a few hundred eV it radiates bremsstrahlung, to which the gas is transparent, and thus doesn’t reach the several keV required for fusion prior to fission in the surrounding pit. UD3, on the other hand, is dense and high atomic number. For these reasons, UD3 is opaque to its own bremsstrahlung radiation and will heat to several keV, fuse and release initiating neutrons.

  34. VS (History)

    I just want to send my sympathies and admiration to the poor graduate student that was probably assigned by “Professor” Khan to draw the exquisitely neat drawings on the board (hats off to the detail on the “matallic-shine” drawn at the sides of the “bombtail” and to the depiction of the mushroom and the chain reaction) and then also for the meticulous cleaning of the lower wooden part of the board where you place the chalk.

    Such detail and neatness cannot be obtained on the spot by the teacher while he teaches. It has to be done before class, by a poor student.

    I bet that student is now working in some enrichment facility keeping it as clean n’ tidy as the board in the pic. Such an artistic talent wasted…

  35. Robert Cross (History)

    Carey, you said “This means that not only is pre-detonation not a problem, you can design the bomb so that you actually have to inject a large pulse of neutrons into it to get it to explode at full yield.” This is certainly true for weapons with a low intrinsic neutron background and a low maximum alpha. But how does it explain why the required neutron injection is not provided from compression and heating of the boost gas by the pressure spike, and that an external initiator is still required? A supercritical pit cannot distinguish between a neutron from the boost gas or an external initiator, can it? The fact that an external initiator is required seems to imply that compression and heating of boost gas does not produce sufficient neutrons to initiate a persistent chain. It seems far less than certain that UD3 located at the center of the pit could do so either. I am troubled that the hypothesis that UD3 is a workable initiator seems to be accepted as fact in some quarters.

  36. John Field (History)

    To Robert Cross:
    I like your point; it stopped me in my tracks for a while, but I suspect it is not true.

    If only for a few neutrons, the fusion seems to start by only several hundred ev – if only in the tails of the thermal distribution. Not clear if there might not be some fraction very hot ions around too.

    The average gas density must be close to 5e23/cm^3 at the time of pressure spike. Density at the spike will be like 10^25/cm^3 maybe more. Now, the spike is tiny, but even that small radius is not going to be optically thin to radiation of 300 eV or so given the density. Check out the numbers yourself.

    See my point? Maybe you disagree?

  37. Robert Cross (History)

    To John Field:
    I would agree with you if the boost gas compression was as high as you suggest. I think your density would correspond to a compression of 2e5. But I’m fairly certain that it isn’t nearly that high in an explosive driven system.

    By the way, the link I posted above doesn’t seem to work today. This link is a direct link that should work.

  38. Carey Sublette

    Whew, this getting to be pretty lengthy digression from the original Iran-specific post!

    But how does it explain why the required neutron injection is not provided from compression and heating of the boost gas by the pressure spike, and that an external initiator is still required? … It seems far less than certain that UD3 located at the center of the pit could do so either. I am troubled that the hypothesis that UD3 is a workable initiator seems to be accepted as fact in some quarters.

    I’m not saying boost gas compression doesn’t produce some neutrons (I’d have to run some numerical experiments to evaluate the likelihood), just that its not a germane issue in a modern style primary. It is neither a problem, nor a necessity when they have initiators that make billion neutron pulses (thus shaving off 30 doubling times required to get a full yield population).

    And I support your questioning of the D-T kinetic heating initiator model as a practical design. It seems possible, but the convergence requirement is really pretty severe to get this to work (252 detonation points!). I haven’t tried to work out what a minimum convergence might have to be.

    In the Sagie and Glass experiment they had a really nifty system to do this: a hemispherical metal cavity filled with a D2-O2 gas mixture. They initiated it with a spark at the exact center, the expanding detonation wave reflected off the wall to make a very, very good implosion wave. Real bombs aren’t such an elegant physical system.

  39. Mark Gubrud

    There is something fishy about a brief document that discusses the technical and programmatic needs of a fairly small project requiring only two PhDs working part-time plus several Masters Degree personnel working full-time, and in the same document makes so many references to political and security issues: the personnel must “trustworthy,” the work is divided into “ordinary” and “special” categories, the “special” work is to be hidden behind some more visible “ordinary” work, “mobile laboratories” are to be prepared, “decisions must be taken regarding the locations where such experiments used to be conducted,” and references are made to a mysterious “Centre”, “organisation” and “Committee” one infers to be responsible for clandestine bomb work. Is this a well-constructed forgery, in which the plausible technical work program proposal is being used as a vehicle for the suggestion of a continuing, possibly larger, covert Iranian nuclear weapons program?

    Then again, if the document is authentic, then taking it at face value, it could be nothing more than a proposal that was made by someone hoping to revive such work within possibly vague guidelines that might have been given to his “neutron group” assuming the work had been stopped but the group not completely disbanded at the management level. Or, perhaps he was asked to outline a proposal for continuing his group’s work, as a hedge, without attracting too much attention. There is, again, no indication either of a date or whether the work was actually undertaken.

    So, I think it’s pretty outrageous to call this document, by itself, a “smoking gun,” let alone a “casus belli.”

  40. Mark Gubrud

    Carey, on a face-value reading of the document, I find your interpretation in terms of “using a metal hydride gas generator to supply deuterium gas to a plasma focus neutron generator” completely implausible; the document refers directly in point 2-1 to “Setting up the reactor again to produce D gas to meet the requirements of PF systems and the impossibility of supplying such gas.” As you point out, if they have D, they can bottle it, and for a plasma device there is no need for high density, as there might be for the initiator. I don’t know if Yale is correct about D being plentiful in Iran – I don’t know if the Arak plant is up and running yet, or if it was when this document was written, and they might have (or been having) trouble importing D, which might be the “impossibility of supplying such gas.” The intent seems to be to ensure that the gas is available for the PF machines so that the latter will be available as n sources to test the measurement systems. The document also refers (1-4-1) to “detection experiments using NGs and PFs” and (1-4-2) “detection experiments using a hot source” so clearly the “hot source” is something other than a PF; what is your sense of what it could be, if not the implosion-driven UD3 or TiD2 source? This is presumably the experiment which “cannot in practice be conducted within the Institute” and for which “decisions must be taken regarding the locations where such experiments used to be conducted.”

    The latter point is to me very suspicious, since it points to another publicly-known factoid, pre-2003 Iranian implosion experiments. As Mr. Barlow, the “former CIA analyst” said, this is a very good forgery, if it is one. I am tending to think that it is.

  41. Robert Cross (History)

    I have to agree with Mark Gubrud that the document in question is far short of a smoking gun. As an example of a true smoking gun report, look at page 10 of this IAEA report I hate to post another link, because the links I posted above work when posted, but later do not. But I think the contrast between these documents is quite interesting.

  42. Yale Simkin (History)

    mark wrote:
    I don’t know if Yale is correct about D being plentiful in Iran

    From the latest IAEA report GOV/2009/74 16-Nov-2009

    On 25 October 2009, during the DIV at the Uranium Conversion Facility (UCF) at Esfahan, the Agency observed 600 50-litre drums said by Iran to contain heavy water. In a letter dated 10 November 2009, the Agency asked Iran to confirm the number of drums and their contents, and to provide information on the origin of the heavy water.

    This would fill 15 to 20 hot tubs.

    This D2O stockpile is rather disturbing in that it fits the pattern of an undeclared supply of bomb-related material.

    This is not from the Arak Heavy water Plant, which has been operational intermittantly.

  43. FSB

    It is disturbing that Robert Cross’s links are being taken down.

    Who is doing that? (Rhetorical question — I think we know)

    Robert I suggest, if you have copies of these, to send them to Jeffrey who can put them on ACW.

    I don’t know if the document is a forgery, but you most certainly do not need this device to make a nuclear bomb. If not a forgery, then it appears to be a low level classified research project.

  44. Robert Cross (History)

    Yale Simpkin said: “This D2O stockpile is rather disturbing in that it fits the pattern of an undeclared supply of bomb-related material.” There is certainly precedent for a proliferator obtaining undeclared stocks of D2O by shady means.

  45. Mark Gubrud


    Very good, but that is Oct. 2009, and we don’t have a date for the neutron memo. The real question is whether D2 gas was available when this memo was supposedly written. If you think so, how would you interpret “Setting up the reactor again to produce D gas to meet the requirements of PF systems and the impossibility of supplying such gas.” -? Is that the smoking gun that proves the memo is a not-so-great fake? Or does it tend to confirm Carey’s hypothesis about UD3 gas generators (“the reactor”?) for the PF machines? Which also would make sense only if D2 gas were not available in a bottle.

  46. Robert Cross (History)

    FSB wrote: “I don’t know if the document is a forgery, but you most certainly do not need this device to make a nuclear bomb.” There is more than a little truth in this statement. Initiators triggered by the shock arriving at the center of the sphere are apparently known for activating at times different from the optimum. High voltage initiators are said to be triggered more accurately in terms of the timing of the peak metal compression. I wonder if a more plausible explantation might be as a substitute for DT gas in a boosted pit?

  47. kme

    Robert: That article certiainly makes interesting reading 20 years on. This paragraph in particular seems to have relevance today (with the obvious change of a few Qs to Ns):

    Israel’s official nuclear defense policy is one of “ambiguity“—making or being able to make nu-clear weapons, but stopping short of open deployment or testing. This is really a policy of regional dominance. Whatever benefit ambiguity has disappears once a rival becomes ambiguous too. Nuclear rivals must each react to what the others do, or appear to do. Freedom of action is inevitably lost, and the rivals slide from a covert to an overt nuclear arms race. Preserving ambiguity may have been the real reason for Israel’s attack on Iraq’s reactor. Iraq was not threatening Israel’s military position nearly as much as it was Israel’s ability to remain “ambiguous.” Ambiguity in Iraq would require Israel to test and deploy in order to maintain Israel’s advantage. To retain its current policy, Israel must remain the only nuclear power in the Middle East.

  48. Yale Simkin (History)

    Here is the doc that Robert Cross wants: Kaliski’s explosive driven fusion experiments

    …and I’m doing this in spite of his embedding a gratuitous “p” in the middle of my name! ;-p

  49. Yale Simkin (History)

    Mark G.,
    Being unencumbered by the facts, I have the luxury to speculate wildly.

    As to the time of the documents (assuming they’re real), the Times story claims Foreign intelligence agencies date them to early 2007…

    The doc may date to the time before the Arak facility came on-line and before they obtained blackmarket D2O.

    Now the IAEA, in 2003 pointed out “In a 19 August 2003 letter to the Agency, Iran … stated further that laboratory scale experiments to produce heavy water had been conducted in Esfahan in the 1980s using electrolysis techniques.”

    So, the memo may be from a time period that Iran was not producing deuterium.

  50. Allen Thomson (History)
  51. Robert Cross (History)

    Mark, D2 gas is readily available to anyone who has D2O, as it is easily manufactured by electrolysis of D2O. The quantities of D2 gas used for research on a plasma focus would not be enormous, and could be made from a few liters of D2O which is available almost anywhere in the world, export controls notwithstanding. Sometimes hydrogen isotopes, especially T, are stored as U hydrides simply because it is so convenient. Heat the hydride and the T gas enters the experimental apparatus; cool the hydride down and the T goes back into the hydride bed. In grad school we used this routinely for T targets used for neutron production. Another use for TiD and perhaps UD3 is as a source of D in an ion source used to produce a beam of D ions for acceleration. TiD makes a nice self-contained ion source without a lot of plumbing to admit D gas. All of these uses are nuclear related, but not necessarily weapon related.
    I think that the “Iranian” document is too cryptic to attempt to decipher; that’s why I posted the link to the Iraqi document, which leaves no doubt about their intentions.

  52. Yossi

    I think the Chinese 1989 paper can be posted on ACW without a real proliferation risk and would be an interesting reading.

  53. Stephen E Hughes (History)

    Does anyone remember the Tinner Files ? Most of which was not released to the public, this may have some key information related to this subject matter as (UD3) as a neutron initiator. Since this was part of the Nuclear Black Market Network(s) . It bears scrutiny for this issue

  54. Mark Gubrud

    Yale and Allen,

    Even if deuterium has always been available one way or another to Iran, I think the point is that at one time it may have been hard for Iran to openly import bottled D2 gas and to openly supply it to unsecured university labs as suggested in the memo.


    I didn’t realize I needed to make clear that I do know D2 gas is easily produced from D2O.

    Anyway, I take it that you think Carey may be correct in thinking UD3 or TiD2 might be used as a source of D for the PF machines, with TiD2 preferred so that traces of U are not found in them, causing more trouble with the IAEA, etc.

    This theory still leaves a lot unexplained in regards to the “Iranian” memo:

    * What is meant by 2-1 “Setting up the reactor again to produce D gas to meet the requirements of PF systems and the impossibility of supplying such gas”? Could the “reactor” in this case be a hydride gas generator? Or, would a nuclear reactor ever be used to make deuterium?

    * Why does the memo so clearly (1-4-1, 1-4-2) indicate a progression from “experiments using NGs and PFs” to “experiments using a hot source”?

    * What is the “hot source” if not the hypothesized UD3 or TiD2, implosion-driven fusion neutron generator?

    * How could “source materials” be produced in the “mobile laboratories” (2-4), particularly if this requires a “reactor” (2-3)?

    * Is it possible the “hot source” is actually a Po/Be or some other radioactive (“hot”) combination, rather than the UD3 device?

    I see you have already written that the memo is “too cryptic to attempt to decipher” but my point is just that I don’t think you can put it to rest with the theory that it is all about innocent deuterium generators for harmless experiments with PF machines. Actually, I think the document points pretty clearly to clandestine nuclear weapons work.

    That doesn’t mean I believe it is authentic; and I gather the USIC isn’t convinced by it, either.

  55. Yale Simkin (History)

    I think the electrolysis referred to in the document is not for the end production of D2 gas from heavy water, but instead for the initial separation of heavy, semi-heavy, and light water.

  56. Murray Anderson (History)

    Could this memo be a piece of Iranian disinformation to discourage an attack by suggesting Iran is closer than it really is to a bomb?
    Assume it is directed at the political leadership of Israel, attempting to deter a nuclear attack. Then technical implausibilities would not be important, sowing uncertainty and doubt in the minds of other politicians would be the main thing.

    Two objections:
    a) this kind of thing turned out badly for Saddam Hussein;
    b) Israel isn’t very likely to use nuclear weapons.

    To that I would counter:
    a) Circumstances are very different now than in 2001-2003, and anyway people aren’t always wise;
    b) I don’t think Israel will attack at all, with or without nuclear weapons, but I’m not an Iranian politician.

    Murray Anderson

  57. Robert Cross (History)

    I second Yossi’s request to post the Chinese paper. It probably wouldn’t have been published in the open literature if it posed a proliferation risk.

    Iran would have had no problem importing deuterium from China or Russia. D2 gas is really quite available on the open market, as Allen pointed out. It is not controlled to the extent that tritium is controlled. I don’t think that the date when Iran might have obtained D2 or D2O really tells us anything at all about what they are talking about in this document.

    Mark, nuclear reactors are not really useful for making deuterium, although small amounts are formed by neutron capture in light water coolant.

    I don’t really subscribe to Carey’s hyporthesis about using UD3 or TiD2 for gas storage, but it is plausible and is often done in physics labs. However, the mention of “source hydrodynamics” certainly sounds like a reference to compression as in an initiator (or boost cavity).

    The references to “hot source” and “mobile laboratories” don’t necessarily imply weapon connections, although mobile lab may imply something that can be taken to a high explosives testing site, which would be suggestive.

    Do I think whatever is being described here is innocent? I don’t know, but words like “reactor” do not point directly to a weaponization program. The context of “reactor” is not consistent with a nuclear reactor. More likely it’s a bed of hot reducing metal to generate D2 from D2O vapor.

    Yale, electrolytic separation of hydrogen isotopes is really obsolete compared to chemical exchange, but I suppose it could be. As I noted above though, I think they probably didn’t need to separate D2O to obtain the small quantities probably needed for these experiments. (sorry about the p).

    All of this is extremely interesting, however we still do not know the origin of the document. I also wonder why Iran would have felt the need to use so many cryptic references (that we cannot interpret). They wouldn’t have expected anyone outside their program to read it. That’s the reason I posted the link to the Al Atheer progress report; it uses the word “initiator” explicitly with no attempt at concealment and I don’t see why Iran would not have done the same.

  58. Yale Simkin (History)

    Mark wrote:
    Yale and Allen, Even if deuterium has always been available one way or another to Iran, I think the point is that at one time it may have been hard for Iran to openly import bottled D2 gas and to openly supply it to unsecured university labs as suggested in the memo.”

    I have not been clear in my postings.
    We are totally on the same page on this. As I pointed out: So, the memo may be from a time period that Iran was not producing deuterium.

    It would not be easy for a country on the “A-List”: Cuba. NK, Iran, etc. to get even a few kgs of D2O without unwanted risk.

    The memo (if authentic) is bemoaning the difficulty in conducting the R & D on initiators.

    They would assume that adequate quantities of D2 would be available from Arak (or as it turned out – black market) output when production time came – the “hot-tubs-full” I referred to.

  59. Yale Simkin (History)

    Robert –
    Yes elecrolytic is old, but it was in fact what Iran said was the process they used. It does lend itself to small production. I read the memo as pondering the liklihood of re-ramping up a small D2O-extraction line – but thats just one possible reading.

    Also recall that Iraq was attempting to use calutrons to produce HEU, and NK uses 1950’s gas-graphite reactors. Agencies must be on guard for any possible pathway to a weapon, not just to what is efficient, advanced, cost-effective, whatever.

    With my standard Chicken Little mindset, I have been concerned for years that proliferators could enrich HEU with 10’s of thousands of low-cost, low-tech crude centrifuges – each capable of <<0.1 swu/yr, but not requiring fancy materials, advanced machining, etc.
    These don’t even need to be co-located.
    These could fly totally under the radar.

  60. George William Herbert (History)

    Robert Cross wrote:
    It probably wouldn’t have been published in the open literature if it posed a proliferation risk.

    Alas. The open literature is littered with proliferation risk information…

  61. Mark Gubrud

    I agree with Robert that the use of “so many cryptic references” is strange, since the document also makes enough references to security and political issues as well as providing enough clues to the nature of the work proposed that it ends up being not only incriminating but very effectively so. That’s what I find so fishy about the document. Murdoch couldn’t have asked for anything more suggestive and intriguing to publish in The Times. Yet, if we are to believe it, this was circulated to a fairly long list of recipients.

  62. Robert Cross (History)

    George wrote “The open literature is littered with proliferation risk information…”

    Do you mean the vast universe of information derivable by competent physicists? The equations of state and radiative opacities used by astrophysicists? The neutron transport codes used by nuclear engineers? Robert Serber’s Los Alamos Primer? The radiation hydrodynamics codes freely available for download on the internet? There is no “Secret of the Atom Bomb”, at least not since Eisenhower’s Atoms for Peace in the 1950’s. Many have said the only secret was that nuclear explosions are possible and I tend to agree. These horses are long out of the barn. You can stamp basic physics “Secret RD” until the cows come home, but some physicist somewhere will eventually have the same bright idea. I think any nation with the wherewithal to operate centrifuge cascades can probably afford to hire a good physicist or 50.

    I also agree with a well-known nuclear weapons expert who said:

    “The difficulty in making nuclear weapons is not in not understanding the physics of their operation in a reasonably sophisticated level, it is the cost and difficulty in acquiring fissile material, and the difficulty in engineering an actual working weapon.

    The type of information that is damaging to proliferation efforts are detailed designs of actual nuclear weapons and key fissile material production technologies, and detailed weapon test data. Another useful way to think about it is anything about nuclear weapon design that requires a nuclear weapons test to know should be kept secret.”

  63. FSB

    Does anyone know if the (flawed) design leaked by CIA to Iran had such a neutron initiator?

    I am talking, of course, of the CIA Operation Merlin.

    If so, we might have a small scale research project to correct the flaws of the CIA design “leaked” to the Iranians via a Russian double agent. Geopolitics is so much fun, especially when it comes to bite you in the ass.

    Hypothetically speaking, of course.

  64. b (History)

    Haven’t seen that here so I’ll put it in just for the record

    NYT: Nuclear Memo in Persian Puzzles Spy Agencies

    “This information’s been sloshing around for well over a year,” said one American official, who insisted on anonymity because he was discussing sensitive intelligence information. “It’s not new to the intelligence people. They’ve taken account of it. If, in fact, the document’s on the level, it shows the Iranians at some point were interested in testing an initiator. That’s not a warhead or the core of a bomb. It’s another reminder — as if one were needed — that the Iranians have a lot of explaining to do when it comes to things nuclear.”

  65. FSB

    So it seems Project Merlin did not use UD3 initiators.

    But it is also evident that there are many forgeries out there re. such things.

  66. Alex W. (History)

    Mark: I have nothing to add about this particular document, but your reasoning reminds me a bit of what Goudsmit had to say about the German program during Alsos: “The lack of secrecy in Germany with regard to nuclear physics matters is striking. Letterheads and envelopes bear the title of the Reichmarshall’s Deputy for Nuclear Physics and stationary for the KWI for physics at Hechingen carries the complete address. According to the OSS in Switzerland, an envelope of the KWI Physics of Berlin was mailed into Switzerland bearing a Hechingen post mark.” That is, the fact of things being discussed so relatively openly (in comparison with the Manhattan Project) was seen as an indication that the German program was not actually sufficiently developed. I recognize of course that you are implying something quite different (that the document is potentially a fake), but it came to mind as an analogy.

  67. George William Herbert (History)

    Robert –

    Beyond the physics, there are numerous engineering and sample component design examples out in the open literature as well. Plenty of stuff with the abstract starting something like “This has nothing to do with nuclear weapons, …” which is ultimately some form of a baldfaced lie to get it into an unclassified journal or conference.

    And some, as that expert pointed out, of the things that it takes a nuclear test to know have leaked as well.

    We are fortunate that detailed plans seem to have stayed in the black (or at least deep in the darker grey as far as public distribution) so far, excepting the literally first generation weapons.

  68. Bahram Chubin (History)

    The following article argues that the document is not authentic. I myself am in no position to evaluate the document:

  69. Yossi

    Bahram Chubin above provided a link to a very interesting article written by Gareth Porter. CommonDreams quote their source as IPS/Inter Press Service – North America

    Porter says that Philip Giraldi told IPS that the USIC thinks the document was forged by Israel, maybe UK. If true there is not much point trying to technologically assess the doc. However let me raise a theory which explains many of the USIC objections mentioned by Giraldi:

    Maybe the doc was written by an Iranian physicist who stumbled upon the 1989 Chinese paper and saw an opportunity to get a grant. Having no real ties with the Iranian nuclear weapons program (if it exists…) he didn’t know to whom he should address his proposal and of course there is no security classification or official logo in it. The authorities who got his letter probably rejected the proposal, the Kaminai anti-nuclear fatwa should be viewed as an analog of a US presidential executive order in such a case.

    What do you think, do the doc looks like a research proposal by a young scientist trying to impress his elders, maybe to drag them into forbidden waters?

    By the way, maybe the poor physicist who disappeared in Saudi Arabia was the source of this doc? The USIC may have known that he didn’t do any secret work and thus had one more reason to reject the doc. Hopefully he wasn’t murdered to get this silly letter…

    PS in view of the stupidity of ME secret services maybe Jeffrey is being wise not to post the Chinese paper?

  70. Robert Cross (History)

    “PS in view of the stupidity of ME secret services maybe Jeffrey is being wise not to post the Chinese paper?”

    As if the ME security services don’t have a credit card with which they can order the document over the web? It’s not classified, it’s in the open literature.

  71. Yossi

    As if the ME security services don’t have a credit card with which they can order the document over the web? It’s not classified, it’s in the open literature.

    I agree. Probably every serious proliferator already have the doc in his library. No third world country is going to develop fusion boosted fission bombs because of Jeffrey posting the paper. There is no real proliferation risk.

    The fuzzy risk I saw was some ME secret service foolishly thinking Jeffrey is aiding its adversaries. On a second thought a much more probable danger is a certain lobby which is used to blindly attack its imaginary opponents. Unfortunately this lobby carries a lot of political weight and can do (and did) much harm.

  72. Bahram Chubin (History)

    In a press conference the transcript of which was published in Etemad-e Melli newspaper, Iran’s Salehi said that the physicist who disappeared in Saudi Arabia had no involvement with Iran’s nuclear program. (I’m not in a position to evaluate this statement, though I see no reason to doubt it.)

  73. Yossi

    Just another too imaginative comment…

    Why the Chinese researchers, who work at a weapon lab, published this paper? Maybe they thought it provided a method to help ignite a fusion reactor?

    The Iranians are seriously working on fusion, e.g. this, and this . You may laugh at them but maybe the cryptic document we are studying is connected to their fusion research?

    And of course Robert Cross is right that every potential proliferator could buy and probably already bought the Chinese paper. My hint was nasty political and better ignored.

  74. Bahram Chubin (History)

    Yossi: You’re right. Salehi has stated that because in 40 to 50 years fusion will be the standard way to generate nuclear energy, Iran intends to conduct fusion research at least on a small scale. Whether this fact relates to the discussion on the authenticity of the document is not something I’m qualified to comment on.

  75. Norman (History)

    For the use of UD3 to store deuterium gas and regenerate it when heated to 450 C see
    G. G. Strathdee and M. J. Quinn, Can. J. Chem. 50, 3144 (1972)

  76. Arby (History)

    Thanks for the education on UD3. I was unaware of this as a neutron activation source. My background is deuterium production, being the technical superintendent of a plant that produced several tonnes a day of heavy water, D2O using the same H2S dual temperature process as at Arak. Analysis of the pictures of their plant shows it is quite limited, perhaps 8 tonnes/year per train. Based on the sulfur precipitation in their lagoon, they had one unit in operation and a poor effluent stripper when the Google Earth pictures were taken. This plant is to produce the D2O moderator for the adjacent heavy water reactor, an efficient producer of Plutonium. The reactor will also yield Tritium, useful in fusion reactions producing neutrons. The amount of deuterium required for a neutron activator is trivial. It does not justify the Arak plant. Small amounts can be produced through electrolysis and even distillation. OK the energy requirement are large as you have to process 7000 times the amount of your product at 100% efficiency. But small amounts like the 50 ml in my basement could be easily produced in developing countries like Iran.

  77. Beta

    Apparently the Times published more info on the Iranian document.

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