Jeffrey LewisIran Produces HEU

Iranian President Mohamed Ahmadinjed, aka A-Bomb, has announced that Iran has produced the first “consignment” of 20 percent highly enriched uranium (HEU). I don’t know what a consignment is, but I would think in this case, it is less than a kilogram.

Arms Control has obtained GOV/INF/2010/2 — the 10 February IAEA document on Iran’s preparations to create highly enriched uranium.

Amano notes that IAEA inspectors were informed on 10 February (talk about quick turnaround!) that Iran was feeding UF6 into one cascade for passivation purposes. For those of you who don’t remember, reader Russel provided a fine description of passivation:

One of the preparatory processes that is required before using a centrifuge component for the first time is “passivation” – which basically involves bathing any UF6 exposed bits in UF6 so that anything with a remaining potential to react will react in a controllable environment rather than in the vacuum system.

The Iranians told the IAEA the would be begin to produce HEU “within a few days.” Hence A-Bomb’s announcement.

For more, David Albright and Jacqueline Shire have published an analysis of Iran’s potential HEU production and its implications.

Update | 12:38 pm George Jahn has a story on the document. Of course, we have the full text!


  1. MWG

    According to the IAEA document, Iran plans to produce “up to 20% enriched UF6,” i.e. still (barely) LEU. I expect that Iran will aim to avoid crossing the line to HEU production.

  2. Jeffrey Lewis (History)


    I disagee. If you look at the IAEA Safeguards glossary, it is “equal or greater than” 20 percent.

    More importantly — since manipulation and measurement are not so easy; you can’t just set the dial to 19, 20 or 21 percent — the conceptual difference is captured by the fact that this is a “second pass” through the cascade for the material, which as I noted in the post, accomplishes a significant amount of the work toward producing bomb grade material.

    So, I think of 20 percent as one more red line that Iran is crossing to establish a precedent, rather than one it is avoiding crossing.

  3. Andrew

    The IAEA document and an IAEA press release both describe it as less than 20% and Jeffrey’s ISIS link describes it as 19.75%, but the difference wouldn’t seem to mean much of anything at all.

  4. Carey Sublette

    We will have to see how Iran plays this.

    They could either produce 19.75% enriched uranium (the standard LEU used in converted research reactors) and stay within the redline, or produce 20.001% and deliberately exceed it.

    While it may not be possible to to “dial-in” a precise 19.75% enrichment from the cascade, they can certainly adjust it with unenriched UF6 when extracting it to bring the product into conformance with IAEA standards if they so desire.

  5. Jeffrey Lewis (History)

    I think they are just going to run it through a second time and call it “twenty percent” — which they don’t really know anyway, see the earlier differences between the daily logs and the PIV.

    I continue to think the whole purpose was to cross a Western redline and establish more “facts” about Iran’s program. That certainly would have been my goal, were I the Iranians.

    This actually reminds me of something I meant to ask readers. I seem to recall learning that the methods used to measure enrichment levels are not uniform, so that Russian measurements are slightly different than American ones. Anybody want to remind me, and other readers, about that?

  6. scud

    The IAEA document says very precisely “up to 20%”. You can interpret this in different ways. A good legal document would say “up to and including” 20% if it was meant to say including 20% per se. But I guess that a lot of people have an interest in leaving some degree of (theoritical) fuzziness here.

  7. Arnold Evans (History)

    Otherwise known as A-bomb?

  8. Jeffrey Lewis (History)

    Yes, but then there is the mathematical notation, which is: “HEU (235U ≥ 20%)”

    See page: 23.

    You people are wonderful readers, and scary smart, but did I mention you were tough to blog for?

    By the way, even if the Iranian’s don’t cross 20 percent — say then get, like 19 and change — I suspect they will round up just to make the point.

    That will be a good test of my hypothesis about their motives, whether they round up or down.

  9. MWG

    Iran claims it is enriching uranium to fuel the Tehran Research Reactor. TRR was converted to use LEU fuel. Iran lacks the technical know-how to make TRR fuel, but I think it will at least try to keep up the pretense. Crossing the symbolic threshold to HEU would further undercut Iran’s credibility in those limited circles (mostly the Non-Aligned Movement) where it still has any. That’s why I think Iran will try to keep the enrichment level below 20%.

  10. Bahram Chubin (History)

    Can an expert here explain what the technical hurdles are in creating the fuel needed for generating the medical isotopes? And what is the likelihood that Iran will overcome them? I would appreciate your educating me about this.

    As for calling Mr. Ahmadinjead “A-Bomb,” the label seems too tendentious. He has said Iran will not attack any country, not even Israel (yes, he has said this specifically about Israel). I’ve also lost count of the number of times he has said Iran does not want atomic weapons. At the same time, Israel does have atomic weapons, and not a month goes by without Israeli officials & press discussing the need to bomb Iran.

  11. Azr@el (History)


    The TRR was modified to run on ~20% HEU down from weapons grade HEU. As far as the technical hurdles of fabricating fuel rods, this is significantly exaggerated. If a nation can handle the metallurgy to produce space rocket engine components that operate at relatively high temps and pressures then they can handle the task of fabricating uranium zirconium alloys into fuel rods.

  12. Ataune (History)


    Iran’s motive is simpler than you think. US thought that it was rusing Iran to give-up a big bargaining chip in the negotiation, but now Iran is showing that it can make an even bigger bargaining chip. The 20% threshhold is not important at all politically, now the ball is in the Administration camp: If the next step is a resolution (probably with China’s abstention) other surprises are waiting in the corner.

    On this issue the US strategy has failed and cannot have a wining outcome (Guess why): Today even a war is in the loss column for US.

  13. bts (History)

    Is it even possible to make 1 kg 20% LEU in 1 day using only one cascade? or is this more like 10 mg?

  14. George William Herbert (History)

    Bts asks:
    Is it even possible to make 1 kg 20% LEU in 1 day using only one cascade? or is this more like 10 mg?

    Less than that, even. Calutrons have a very high separative ratio per pass, and get you small quantities of pure material immediately. Centrifuge cascades (and gaseous diffusion cascades, etc) have to establish the enrichment gradient across the cascade before any useful output happens. That’s part of the system start up period. Before the gradient is established nothing is coming out at the eventual target enrichment, though you may be taking a dump quantity off the top to establish the flow volume which the gradient will eventually support. You can re-feed that dump back into the input, as the enrichment slowly ramps up off the top end…

  15. Yale Simkin (History)

    Jeff, I suspect that the Iranians will produce an end product that is almost, but not quite 20% and not round it up. This will allow them to claim that they are absolutely kosher in only producing (in what they claim is their right) legal LEU, yet at the same time they will demonstrate that they are competently capable of producing HEU, which magically comes into existence by going from 19.999999999% to 20.0%.

    This way they get the best of all worlds.

    Although the may produce >20% hex due to imprecision in enrichment they will downblend as Carey pointed out and the IAEA will eagerly give them a pass on the overlimit trace samples.

    I personally don’t get freaked by Iran enriching to almost 20% – except for their desire to be provocative.

    I already passed freaked when they produced 3.5% LEU.

    Seventy percent of the heavy lifting in enriching nat-U to LEU is already in the can. It is only a bit longer going from 3.5 to 90% rather than from 20% to 90%. The difference is in weeks not years.

  16. wise

    I saw in the Farsi article that the level was 19.75%. The orginal reactor was delivered with Weopens grade but was modified to work with 19.75% a few years back.

  17. John Schilling (History)

    A cascade, in this case, probably means 164 P-1 centrifuges, previously estimated here at 0.87 kg-SWU/yr capacity. Assuming the Iranians use existing 3.5% LEU as feedstock, and are willing to lose 50% of the U-235 to the tails (which can be fed right back into one of the many other cascades, of course), it would take them just about two weeks to produce 1 kg of 20% LEU.

    Assuming 24/7 operation and not counting setup time. I suspect that once the Iranians get a cascade set up properly, they probably can run it close to 24/7 for at least a few weeks straight.

  18. Hairs (History)

    At the risk of stating the obvious, maybe the announcement is just a large smokescreen.

    Up to a few days ago if the inspectors had found any uranium enriched to around 20% then suspicions would have been raised that secret, “bomb related” work was going on. Now if anything is found, the Iranians just say, “Yeah, well we told you – so what’s the secret?” After all, lab tests are exquisitely sensitive at telling us about what the level of enrichment is, but not half so good as saying when it was enriched, or where.

    It seems very suspicious to me that the first batch of ca. 20% enrichment was produced so quickly – almost as if the Iranians were concerned that a 20% enriched particle would be found somewhere in the near future, and they wouldn’t be able to explain it. Now, though, it’s perfectly explicable.

    Of course, political shenanigans may be the primary driver of what’s happening, but the time between announcing the 20% enrichment target and (seemingly) achieving it does seem mighty short.

  19. Hairs (History)

    “This will allow them to claim that they are absolutely kosher…”

    I’m not sure if your joke was intended or not Yale, but thanks anyway – claiming that their production is halal just wouldn’t have the same ring to it! 🙂

  20. anon


    I’m not sure about the difference between Russian and US measurements, but it could be as simple as atom % vs weight %. The two are slightly different.

  21. Yale Simkin (History)

    Hairs, yes I was being ironic, altho I disingenously claimed otherwise here

  22. hass (History)

    Iran has been blocked from purchasing the required fuel for the reactor interntionally. So, why should it not try to make its own fuel?