Joshua PollackIran’s Neutron Initiator Test at Parchin?

Paul-Anton Krueger, who often seems intent on seizing the fallen mantle of Mark Hibbs, has advanced the story of Iran’s R&D activities at Parchin. His article in Saturday’s Sueddeutsche Zeitung — just in time for the talks in Istanbul — redeems this blogger’s foolish promise to post something about weaponization in Iran. It’s not an explosive story, but rather implosive: its subject is an alleged implosion test at Parchin in 2003, shortly before what’s believed to have been the suspension of Iran’s nuclear-weapons research. Whether and under what conditions the IAEA can visit the pertinent area at Parchin has been a subject of some dispute lately.

To make a long story short, Krueger reports that the research may have involved a neutron initiator. That’s a device that sparks a chain reaction in an implosion-type nuclear warhead. The subject isn’t completely new: the IAEA has reported on activities related to neutron initiators in Iran before. What’s new about this story is how it links three previously unconnected elements: implosion at Parchin, neutron initiation, and the assassination of nuclear scientists in the streets of Tehran.

Unfortunately for most of us, SZ appears only in German, and most of it never goes online. (You could always grab a copy during your next stopover in Munich, right?) In this case, there’s an abbreviated version of the story at the website. In German.

But guess what? You’re in luck. A translation of the complete article as it appears in the newspaper follows. Yeah. You’re welcome.

[start of translation]

Sueddeutsche Zeitung

April 14, 2012

Nuclear Grill-lighter

Iran has apparently tested a neutron initiator, an important component in a nuclear warhead

By Paul-Anton Krueger

Munich – A metal cylinder the size of a semi-trailer is expected to be the yardstick of Iran’s actual readiness to cooperate with the International Atomic Energy Agency (IAEA) in the coming weeks. During visits to Tehran, IAEA’s chief inspector Herman Nackaerts has repeatedly insisted upon being allowed to examine the chamber, which was probably built in the year 2000 at the Parchin military base, 20 km [12 mi.] southeast of Tehran. The IAEA suspects that Iran conducted research there for the development of a nuclear warhead. An inspection would show the world that Iran is cooperating with the investigation into what the IAEA delicately calls the “possible military dimensions” of its nuclear program.

Diplomats posted to Vienna where the IAEA is headquartered said that Nackaerts selected Parchin because he thought it would be relatively easy for Tehran to grant his team access there. The inspectors avoid making requests based on information from intelligence services, which Iran often dismisses as forgeries, if the IAEA cannot share the original documents. They have their own sources, having interviewed Vyacheslav Danilenko, a scientist from the former Soviet nuclear weapons laboratory Chelyabinsk-70, who is said to have helped Iran to build the cylinder, a test chamber inside which it is possible to experiment with high explosives, as well as the ignition mechanisms of nuclear weapons.

So far, the government in Tehran has resisted the request. Formally, Iran’s ambassador to the IAEA Ali Asgar Soltanieh has done so by insisting that Iran and the IAEA first establish modalities of inspection; in this connection, he has proposed a number of conditions that the inspectors find unacceptable.

However, there is apparently another explanation for Iran’s tough stance. Some diplomats, intelligence officials, and independent experts believe that Nackaerts has stirred up a hornet’s nest. They suspect that Iran used the cylinder to test a neutron initiator, a key component for a nuclear warhead. This experiment could have hardly any civil application. It would be difficult for the Islamic Republic to explain, since its Supreme Leader Ali Khamenei has rejected nuclear weapons as “un-Islamic” and maintains that they are interested only in the peaceful uses of nuclear energy.

A neutron initiator can be compared to a grill-lighter: just as it kindles the fire in a pile of charcoal, neutrons initiate fission in a nuclear warhead. The resulting chain reaction releases tremendous energy – a flash of light, deadly heat, and a tremendous blast, as well as radiation. However, for the ignition to work, several processes must occur within a split second in the proper sequence. In an implosion warhead, an arrangement of explosives and other components compresses a spherical core of highly enriched uranium so much that the metal becomes liquid. The neutron initiator, which is embedded in the center of the core, is simultaneously activated by the immense pressure.

The IAEA stated in its report of November 2011 that it has received information indicating that Iran has worked on such a neutron initiator, and may have tested it – but without establishing a direct connection to Parchin or the metal cylinder. However, a person associated with a Western intelligence agency told Sueddeutsche Zeitung that the IAEA has been presented with “solid evidence” that Iran had conducted this type of secret experiment there. Another source from a different Western country stated, “That’s just what Nackaerts suspects.” The IAEA declined to comment and merely referred to their reports.

The experiment – or experiments – would have taken place in the year 2003 under the direction of two Iranian scientists who were the targets of simultaneous bomb attacks in Tehran on November 29, 2010. An assassin on a motorcycle fastened a bomb to the car of physics professor Majid Shahriari during the morning rush hour, killing him. His colleague Fereydun Abbasi-Davani narrowly escaped an assassination attempt perpetrated in the same way, escaping from his car with his wife; both sustained injuries in the explosion. Iran accused Israel and the United States of being behind the attacks. President Mahmoud Ahmadinejad appointed Abbasi-Davani as the head of the Atomic Energy Organization of Iran and as one of his own deputies in February 2011.

According to intelligence-service information, the two scientists were at Parchin as project managers partly responsible for developing a special array of neutron detectors and installing it outside of the test chamber. It was used during an experiment to see whether the neutron initiator worked, releasing sufficient particles. In addition, a flash x-ray camera was installed that would capture the implosion of the test system in the metal cylinder at very high resolution. The data from both sources combined allow an assessment of whether the ignition mechanism for a nuclear warhead would work.

According to intelligence sources, two other scientists whose identities are known to the IAEA assisted Shahriari and Abbassi-Davani. Mohammed Reza Sedighi Saber, allegedly an expert from the Ministry of Defense, was entrusted with the simulation and computer-assisted analysis of the experiment. According to this information, Ali-Reza Mola Heidar, an expert on instrumentation, contributed to the development of the flash x-ray system and the positioning of the neutron detectors.

Since the experiment took place about ten years ago, it is unclear whether IAEA inspectors would find anything at Parchin. The neutron initiator itself consists of a few grams of nuclear materials. Traces of it would still be detectable, provided that the cylinder is still inside the building and has not been thoroughly cleaned. Although IAEA Director-General Yukia Amano did not confirm reports about cleanup work at the military base, he spoke in this context about “information about activity that has taken place there.”

Diplomats consider the clarification of the incident at Parchin to be very important, because the development of the neutron initiator is one of three areas in which Iran is said to have continued research and development activities after 2003. At that time, according to the estimate of the U.S. intelligence community, the country suspended its program for the actual creation of nuclear weapons. An inspection at Parchin “would be a very nice confidence-building step,” one European diplomat said, referring to the nuclear talks this Saturday in Istanbul.

[end of translation]

For further reading: The IAEA’s November 2011 report, GOV/2011/65, which contains a lengthy annex on “possible military dimensions,” is here. ISIS has published repeatedly about the events at Parchin (see here, here, here, and here). According to Michael Adler at AOL, ISIS has a report in draft on the same subject as the article above. Jeffrey previously blogged about suspected neutron initiation experiments in Iran. Mark Fitzpatrick wrote about the diplomacy of Parchin at I translated one of Paul’s previous stories about Iran.


  1. Johnboy (History)

    Just one quick question to start the ball rolling.

    Q: If this relates to test conducted in 2003 then why didn’t the IAEA look at that chamber in 2005?

    After all, they asked to vist Parchin twice in 2005, and both times the Iranians allowed them to have a poke around.

    • joshua (History)

      Because they didn’t know about it at the time. My understanding is, they haven’t visited this particular building at Parchin.

    • Johnboy (History)

      But didn’t that information come from the Laptop of Death, the contents of which were referred to the IAEA in… 2005?

      Are you saying that the IAEA asked to visit Parchin in 2005, the Iranians said “sure, pick any five buildings you want, and we’ll let you poke around” (which they did) and the IAEA simply picked the wrong five buildings?

      Bit of a gamble from the Iranians, wasn’t it?

      After all, a bus-sized detonation chamber isn’t something you can play pea-and-thimble with.

    • joshua (History)

      I don’t believe the IAEA was allowed the run of the place.

    • Strangelove (History)

      Creating a neutron initiator should at first hand be no problem for iranian scientists. They could use either polonium or americium (as India did). Polonium can be extracted from so called polonium-combs which are used in highspeed printing machines all over the world. Americium is used in the oil industry as a neutron source to search for oil fields. They have also Beryllium and voilà they have a neutron initiator. But the problem is the timing and the correct construction. Remember, you need 60 shakes for a viable chain reaction and the last five shakes decide if you get 300 tons or 20 kilotons. Using polonium/beryllium or americium/beryllium initiatiors is also only viable in a so called crude device. If you want to have a real design you would need an accelerator which produces in the exact moment the exactly needed quantity of neutrons.

    • anon (History)

      Evidently in 2005 the IAEA lacked information about the location of the test. It was allowed to pick a few locations to visit. Parchin is a large site, so this would have been a needle in a haystack exercise.

    • Johnboy (History)

      “Parchin is a large site, so this would have been a needle in a haystack exercise.”

      But a remarkably reckless offer by the Iranians, no?

      After all, while they may have known the gist of the allegations, the IAEA had *not* (and still haven’t) shown the Iranians the original documents.

      So offering to let the IAEA visit any five buildings of their choosing meant that they had to take it on trust that
      (a) while the IAEA did know what they were looking for
      (b) they would be a bunch of Keystone Cops when it came time to go looking.

      Isn’t the more likely explanation that the Iranians had no idea what the IAEA was prattling on about and, therefore, didn’t much care which five buildings the IAEA poked a stick at?

  2. Cheryl Rofef (History)


    Those anonymous western diplomats in Vienna. When are the reporters going to tell us who they are?

    A historical note. They should be able to find beryllium, if an initiator was tested, although not likely the polonium. Maybe some lead.

    • joshua (History)

      It may have been a uranium-deuteride initiator, not a Po-Be. See:

    • joshua (History)

      By the way, those are some great posts. Nuclear archaeology in the most literal sense!

    • Cheryl Rofer (History)

      Thanks, Josh! It was great fun to be able to read the old memos and try to figure out who did what where. And we did turn one trash heap over to the Bradbury Museum for a real archaeological dig. There was a photo of it there the last time I visited.

      I’ve read Jeffrey’s stuff on the uranium deuteride possibility, and, if I were going for a nuclear weapon, I’d take the easy way – Po-Be. OTOH, might be worth trying out some new stuff. I’m not sure what the products of uranium deuteride would be, and uranium residue could indicate a number of things. The deuterium would probably be gone.

    • Strangelove (History)

      Uranium deuteride didn’t work satisfactorily when used in Operation Upshot-Knothole. They never got it to work. Also Germany made tests with uranium deuteride targets when Franz-Josef Strauß was Secretary of Defence and planning t build the bomb. It didn’t work either – I spoke to the man who delivered these Targets. So there’s no reason why a few iranian scientists would succede where the american nuclear community failed.

  3. Rob Goldston (History)

    Is this consistent with the nightmare that Iran largely stopped weaponization because they had largely completed the job? And that the upcoming test in North Korea could be of an Iranian uranium warhead, ready to fly on an Iranian missile? I would very much prefer this to be untrue, so request counter-arguments.

    • joshua (History)

      Excellent questions. No idea about weaponization. As for the upcoming test, Iran is not known to have made any HEU, but HEU traces have been found in North Korea twice.

    • rwendland (History)

      … though worth noting Josh that the IRT-2000 pool-type research reactor at Yongbyon is fueled with IRT-2M type assemblies of 36% and 80% HEU. A plausible explanation for HEU traces on the Yongbyon paper records.

      Do we know for sure that these HEU traces were not from this HEU fuel?

    • joshua (History)

      All over imported aluminum tubes and copies of the operating records for the GCR and reprocessing plant? Seems unlikely.

    • Rob Goldston (History)

      How confident are we that Iran hasn’t had a few thousand SWU/year of centrifuges hidden away someplace working on a few tens of tonnes of yellowcake?

    • joshua (History)

      A complicated question and unfortunately one that could be asked of more than one country.

    • rwendland (History)

      As far as the paper operating records go, it seems perfectly plausible that Yongbyon would analyse and store records for both its operating reactors in the same office and/or store room. So it seems plausible that traces on the HEU fuelled IRT-2000 paper records could transfer to the GCR paper records – they both might have been analysed on the same desk.

      What I cannot understand is why this possibility was not flagged at the time, or that we were told it had been disproved by analysis showing it could not be from Soviet 36% and 80% HEU fuel (or did I miss such a statement?).

      The aluminium tube traces are quite another matter.

      It would be interesting to know if it is common for traces to get into the environment from elderly fuel elements in pool type reactors – I don’t know.

    • Rob Goldston (History)

      But not many countries have a military R&D relationship with North Korea (I hope), that would lead North Korea to perform nuclear testing for them.

      I found this interesting in the Annex to the November 2011 IAEA Report:

      22. According to the Agency’s assessment of the information contained in that documentation, the green salt project (identified as Project 5.13) was part of a larger project (identified as Project 5) to provide a source of uranium suitable for use in an undisclosed enrichment programme. The product of this programme would be converted into metal for use in the new warhead which was the subject of the missile re-entry vehicle studies (identified as Project 111).

      Do we have reason to believe that this was for Natanz, Fordow, or something else?

  4. b (History)

    Apparently my earlier comment did not go through.

    What about the thinking that, as Danilenko is an expert for creating nanodiamonds in blast chambers, the mysterious bus sized chamber in Parchim is exactly for that?
    IAEA’s “Soviet Nuclear Scientist” Never Worked on Weapons
    By Gareth Porter*

    Technical question: Why would one test a neutron initiator in a chamber at all? Does that really make sense? Would it not be better to set up an implosion sphere and test the initiator by igniting that sphere? How would a chamber help with that?

    • joshua (History)

      If I understand the story correctly, it’s described as both an implosion test and a test of a neutron initiator. Unless I’m mistaken, the former would be needed for the latter.

      Mark Gorwitz has covered the Danilenko story at the ISIS website, so I’ll refer you there. Bottom line, I don’t think it’s very likely that there would be an experimental nanodiamond procedure, especially one with such elaborate instrumentation, at the Parchin military base. Nor, if the suspicions described in Krueger’s story are accurate, would it make intuitive sense that nuclear scientists would be involved with nanodiamonds. One might add that nanodiamond production is unlikely to be surrounded by such secrecy and sensitivity. One expects they’d just let the IAEA have a look and that would be that. Dr. Danilenko himself would probably have no reason to be so squirrelly about it, either. So there are a number of reasons to suspect that’s not what was going on.

      On the other hand, if there was a weaponization R&D effort through late 2003, the reports of implosion testing at Parchin would be consistent with that.

      Regardless, this is one of those things that probably can’t be resolved definitively without further Iran-IAEA interactions.

    • Anon2 (History)

      Q. “What about the thinking that, as Danilenko is an expert for creating nanodiamonds in blast chambers, the mysterious bus sized chamber in Parchim is exactly for that?”

      Possible Answer: It makes no sense to conduct civilian nana-diamond research at a secret military installation like Parchin. Whatever was being done at Parchin is being done in secret because it has military dimensions. Nano-diamonds do not have military dimensions.

    • hass (History)

      Parchin is not a “secret” militay installation. It is a military installation, and about as “secret” as any other. And in fact it makes perfect sense to investigate a process that involves explosions, at a site that is dedicated to testing explosives. Again, all this amounts to little more than innuendo.

  5. hass (History)

    You statement that “further IAEA interactions” can resolve this overlooks the current politicization of IAEA reports under AMANO (as noted by the Non-Aligned Nations objections to his last report on Iran) as well as the previous statements of the IAEA itself with regard to its inspections at Parchin:

    GOV/2005/67, dated 2 September 2005, paragraph 41, “As described by the DDG-SG in his 1 March 2005 statement to the Board, in January 2005, Iran agreed, as a transparency measure, to permit the Agency to visit a site located at Parchin in order to provide assurance regarding the absence of undeclared nuclear material and activities at that site. Out of the four areas identified by the Agency to be of potential interest, the Agency was permitted to select any one area. The Agency was requested to minimize the number of buildings to be visited in that area, and selected five buildings. The Agency was given free access to those buildings and their surroundings and was allowed to take environmental samples, the results of which did not indicate the presence of nuclear material, nor did the Agency see any relevant dual use equipment or materials in the locations visited.”

    GOV/2005/67, dated 2 September 2005, paragraph 49, “Iran has permitted the Agency, as a measure of transparency, to visit defence related sites at Kolahdouz, Lavisan and Parchin. the Agency found no nuclear related activities at Kolahdouz.”

    GOV/2005/87, dated 18 November 2005, paragraph 16, “On 1 November 2005, following a meeting held on 30 October 2005 between Mr. Larijani, the Secretary of the Supreme National Security Council of Iran, and the Deputy Director General for Safeguards (DDG-SG), the Agency was given access to the buildings requested within the area of interest at Parchin (see para. 41 of GOV/2005/67), in the course of which environmental samples were taken. The Agency did not observe any unusual activities in the buildings visited. Its final assessment is pending the results of the environmental sample analysis.”

    GOV/2005/87, dated 18 November 2005, paragraph 21, “The Agency welcomes the access provided to the Parchin site.”

    GOV/2006/15 dated 27 February 2006 paragraph 32, “On 1 November 2005, the Agency was given access to a military site at Parchin where several environmental samples were taken. The Agency did not observe any unusual activities in the buildings visited, and the results of the analysis of environmental samples did not indicate the presence of nuclear material at those locations.”

    GOV/2006/15 dated 27 February 2006 paragraph 52. In this regard, Iran has permitted the Agency to visit defense related sites at Kolahdouz, Lavisan and Parchin. The Agency did not observe any unusual activities in the buildings visited at Kolahdouz and Parchin, and the results of environmental sampling did not indicate the presence of nuclear material at those locations.

    • joshua (History)

      Well, without the consent of Iran to investigate the building in question, I suppose the IAEA could simply assume the worst and report accordingly. But that doesn’t seem to be their way.

      As I’m sure you realize, there is a massive stack of evidence about Iranian weaponization R&D in the IAEA reports, especially the Nov. 2011 reports, that remains to be explained in any other terms. Sooner or later, there will have to be a credible accounting, not just more hand-waving. I think that can be done as part of a settlement of the remaining issues. But I’m glad that I don’t personally have to be the one to try to negotiate it.

  6. hass (History)

    The job of the IAEA is not to “assume the worst”. The job of the IAEA is legally spelled out in Iran’s safeguards agreement, which explicitly states — twice– the the “exclusive” function is to measure Iran’s declared nuclear material to ensure non-diversion. And every single IAEA report has verified this.

    And no, there is no “massive stack of evidence” — there’s the Laptop of Death, and documents such as that which the Israelis provided to ElBaradei, who laughed out loud at it and returned it to the Isaelis (as detailed in his book.)

    Furthermore, prior to the previous IAEA “inspections” of Parchin, the IAEA and Iran agreed to a modalities note for the visit — this was sent out by the Agency on 25 October 2004 which outlining modalities under which
    the visit could take place. Iran has not refused yet another visit to Parchin but has simply requested a simliar arrangment. After all, Parchin falls OUTSIDE of the IAEA’s legal authority and Iran isn’t legally obliged to provide any access at all.

    • joshua (History)

      Your account bears very little resemblance to the description of the evidence and its sources given in the Annex of the Nov. 2011 IAEA report. You may wish to refer to Section B to refresh your memory.

      As you will see, it is not so lightly dismissed.

      As for DG ElBaradei, he did not have the privilege of rendering definitive personal judgments upon documents in the hands of the Safeguards Division. It’s not in the job description. If anything like that had actually happened, it would be an institutional failure — even if the safeguards reports are styled as the reports of the DG.

      There is room for different interpretations of the facts, but I don’t have time to police wholesale misinformation. So: enough.

  7. bob (History)

    My concern re Uranyl Deuteride (and also Uranyl Hydride) is not its use in a neutron initiator, but rather its potential use as the major fissile component of a bomb.

    Think relevant Upshot Knothole tests.

    Were they really the total failures that they were portrayed as? Would the US have tried to pursue this avenue further if the shortage of fissile material had not abated?

    Could current level technology mitigate the shortcomings?

    • George William Herbert (History)

      They were not utter failures, no. But they both yielded about 300 tons TNT equivalent yield, which by nuclear terms is a “pop”.

      Some years ago I did a bunch of modeling of hydride (D or H) devices and (assuming I didn’t screw the physics up) came to the conclusion that because of the time scale differences (moderated vs fast fission) these devices are essentially all about imploding a big enough tamper around the fissile material. You can’t make them light; they optimize wierdly, but roughly the yield scales with the tamper mass. I don’t know that militarily useful weapons can be produced in that manner, though I can’t rule it out. Certainly not city-busters one can actually transport to a target.

    • Ano N. Ymous (History)

      Has anyone done any (public) analysis of uranium hydride gun designs? Could the slower reaction make the design easier to get right? Or help reduce the assembly time requirements? Might a plutonium hydride gun bomb be feasible?

      Lots of questions, but that’s what you get when you manage to get someone who knows nothing about the subject matter interested. 😉 I’ll presume the answers are ‘no’ all around unless someone tells me differently.

    • George William Herbert (History)

      Anon writes:

      Has anyone done any (public) analysis of uranium hydride gun designs?

      No published analysis, not that I have seen.

    • bob (History)

      In reply to George William Herbert:-

      Not ICBM delivered city-busters no, but regime savers, yes. Weight is not a consideration for an underground test to signal capability to the world via seismic monitoring.

      Though I generally agree with your analysis, increasing tamper mass may not be the only way to extend confinement time.

      Let’s not forget the reason the US tried this out.

      Also, at the risk of digression, there are other delivery system options that are not mass sensitive. Churchill fretted about ship delivery, of all things, and the UK did in fact test this off the coast of Australia.

  8. Ara Barsamian (History)


    Please…..A 1944-vintage Po-Be initiator, or UD3 initiator in year 2000? While supposedly testing a super-sophisticated R-265 (UK Super-octopus” like knock-off) implosion system?

    Community, Wake-up! A vacuum tube D+D neutron generator would do the trick without Tritium, using a couple of “drops” of heavy water they already have to get the D! Plus cannibalizing a capacitive discharge ignition system from any modern (1990 and later) car…To boot, use the spark-gap from a Xerox machine or any laser printer (take your choice of brands).

    Who’s feeding the community all this nonsense?!

    Somebody needs to give a Nuclear Weapons Intro 101 to the community…and maybe the news media…the info exists in unclassified form….with color pictures…

    • Cheryl Rofer (History)

      The question is what the Iranians tested. There are many reasons that they might choose something old-fashioned. And, if the information provided is accurate, they tested something explosively. That points to Po-Be or uranium hydride, not a vacuum tube neutron generator.

      In 1990, the comment might have been “Electromagnetic separation? Get real! Today’s technology is centrifuges/laser isotope separation.”

      But electromagnetic separation was what Saddam Hussein chose.

    • George William Herbert (History)

      EMIS is what Saddam chose in the 1980s; it was discovered in the 90s.

      While it is possible that one would still use an alpha to neutron reaction neutron generator today (who would have thought we’d be talking about someone weaponizing a folded path two-initiation-point system?…), I personally find it unlikely. They require regular pit access, the alpha emitters which are intense enough to be useful have short halflives. The relevant neutron generators that are used in one-shot pulsed mode for weapons are very close to those used in industry and oil exploration, which are not significantly regulated nor particularly difficult or secret. My understanding is that one could apply more voltage (bigger capacitor) to commercial down-hole neutron generators used for oilfield work worldwide and get nuclear weapon useful neutron counts out. Once, but then that’s all that matters.

      The current (public as of this weekend, at least….) allegations include both neutron generators and a flash-xray setup on the implosion test. One could see a scenario where that was used with a natural U core, and n-U238 reactions were measured externally as another timing confirmation that the neutron pulse and implosion density time profile were properly matched for weapon purposes. The one serious trick with pulse neutron stuff is timing.

      That’s an engineering analysis and hypothesis, perhaps an educated guess, not evidence. The evidence in the public eye at the moment is inadequate for specifics.

    • John Schilling (History)

      If it is important that your nuclear program lead to a useful weapon design in a limited time (before the Nazis get the bomb, before El-Baradi finds Parchim, whatever), it is not unreasonable to pursue multiple paths in parallel. Pulsed D-D or D-T tubes would obviously be preferable on technical grounds, but a team of first-generation weaponeers might miss something subtle but important. Having the B-team work on Po-Be or UH3 is cheap insurance, and you test their work by tossing it in with an ordinary implosion cold test.

  9. JohnLopresti (History)

    How abous space platform based observation of energetic small particles generated as by-products of the neutron wource experiments?

    • Allen Thomson (History)

      What energetic small particles do you have in mind? A space platform would have more than 100 km of distance and a mass of atmosphere equivalent to at least 10 meters of water between it and the source. Not too promising for an experiment contained in a steel container that would block photons. Other than photons, what are the candidates?

  10. Davey (History)

    Regarding Strangelove’s comment about oilfield neutron generators…

    Yes, geophysical companies use Am-Be neutron sources to measure the porosity and liquid content of subsurface geologic formations. They also have sealed tube neutron generators for other similar measurements.

    However, they aren’t suitable for weapon use. See Jeffrey Lewis’ comment in

    • George William Herbert (History)

      Davey wrote:

      Regarding Strangelove’s comment about oilfield neutron generators…
      Yes, geophysical companies use Am-Be neutron sources to measure the porosity and liquid content of subsurface geologic formations. They also have sealed tube neutron generators for other similar measurements.
      However, they aren’t suitable for weapon use. See Jeffrey Lewis’ comment in

      Without speaking to Am-Be devices, sealed tube neutron generators are basically functionally identical to weapon PNGs the US and others use. The oilfield ones are tuned down to energy levels that allow them to be “fired” either continuously or for many many many pulses, whereas weapons ones are “single use” (or, very few use, with a couple of calibration and performance tests, and then sitting on the shelf for a 12.3 year T halflife or two). Weapons ones often use higher voltages and triggering mechanisms like EBW or EFI detonators use, or so say the sources (and, the unclassified US weapons labs writeups of ENG maintenance and refresh…).

      It’s not entirely clear whether a large capacitor plus an oilfield sealed neutron tube equals a weapons usable one, but when I asked someone at a company that made them about that I got a nasty glare and no further information. Particularly since I had an idea of how many neutrons were in the resultant pulse already and was just asking to confirm, and since he knew that I study nuclear devices.

      I could buy one and test, but I have better things to do. Put it down in the “highly likely” category…

  11. Ara Barsamian (History)

    If Iran can put together a R265 setup with fiber optics probes, streak camera, etc, they certainly can put together a D-D neutron generator, or just salvage/refurbish one from existing oil prospecting neutron activation equipment.

    You can see the “wonderful Radio Shack” catalog of neutron generators at
    VNIAA is the same outfit that supplied the USSR/Russia neutron generators for their warheads.

    As far as performance, most of them put out 10E8 to 10E10 neutrons in a pulse widths of 100ns to 6us in adjustable steps of about 20ns to account for the “transit time”, again no great technical feat.

    Please remember we are in 2012, not 1944…and the Iranians have published research in inertial confinement fusion, and they are not a bunch of retards…

    As far as Hydrides for a realistic weapon, George is absolutely right, just wishful thinking..

    • bob (History)

      Well, with all due respect (which is considerable), George is generally right, not absolutely right.

      In my view, hydrides could be a viable path for a strategically useful design.

      Available technology has improved since the Upshot Knothole test shots.

    • George William Herbert (History)

      Technology has improved a lot, yes, but I’m not sure the physics involved has changed any with the newer technologies.

      Upshot-Knothole were the standard 54″ implosion assemblies around a tamper and pit I won’t further describe in public. I believe one could shrink the explosives a lot with more modern engineering, but the pit characteristics and physics seem pretty fixed (or did, when I looked at it).

      The reaction speeds were more like chemical explosives, and the energy transfer and disassembly mechanisms unlike any other nuclear weapon. Density tricks and the like didn’t do much good; the timing of the mechanical / solid state rebound was as fast as yield was building up.

      I haven’t focused super hard on trying new tricks with it, though I did explore a bunch of variations at the time. If you have an idea you want to bounce off me in private my email is pretty well known. I won’t start posting equations in public at this time.

  12. Mark Lincoln (History)

    Why develop an inefficient and limiting urchin when compact neutron generators are commonly used in oil well logging and other industrial processes?

    Iranians are not idiots.

    • Ano N. Ymous (History)

      Why only try to adapt a design with completely different requirements regarding neutron yield and durability when there exists a simple, well known and proven design that can be engineered in a parallel program?

      Iranians are not idiots.

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