Jeffrey Lewis100 Kilos of LEU?

The Iranian Students News Agency (via AFP and Reuters) reported that Iranian Interior Minister Mostafa Pour-Mohammadi said Iran “currently [has] 3,000 operational centrifuges and [has] delivered more than 100 kilogrammes of enriched uranium to warehouses.”

Then the Interior Ministry denied the statement:

Public relations of Iran’s Interior Ministry in a fax Friday denied some quotations attributed to Interior Minister Mostafa Pour-Mohammadi on extent of enriched uranium and number of country’s centrifuges.

The tele fax received at IRNA Head Office reads, “The Interior Minister took part at a commemoration service on the 26th martyrdom anniversary of Dr. Mostafa Chamran, in Dehlaviye, Khuzestan Province, where he also focused latest status on country’s nuclear program.” It added, “Pour-Mohammadi in a part of his address referred to Iran’s nuclear progress in production of the UF6 gas, but he said nothing regarding the extent of enriched uranium, or the number of installed centrifuges in Natanz.

“Thus, the information published quoting him in those respects are quite falsified,” adds the Interior Ministry Public Relations’ fax.

The Interior Ministry Public Relations has meanwhile advised the media, particularly the foreign media working in Iran, to refrain from quoting the Iranian officials through unofficial sites and news agencies.

Well, so, did he say it or didn’t he? Or, more to the point, do they have 100 kilos of LEU? (And, yes, I love calling them “kilos”—very Miami Vice.)

David Albright estimated that Iran’s eight cascades did not produce more than 26 kilograms of LEU between April 15-May 13. Prior to that, between June 2006-February 2007, Iran may have produced about 10 kilograms of LEU at the Pilot Fuel Enrichment Plant.

So, could Iran produce another 64 kilograms in 41 days?

A 164-machine Iranian cascade produces about 7 grams of 4.5 percent enriched uranium an hour.

Iran would require approximately 9 fully functioning cascades to operate continuously over the 41 day period to produce an additional 64 kilograms of LEU. If Iran’s centrifuges were operating at David Albright’s estimate of 65 percent of capacity, then more than 14 cascades would be necessary.

That’s a very quick calculation—and probably has at least one error or unexamined assumption. But I would judge the claim that Iran has stockpiled 100 kilograms of LEU to be plausible, though not likely.

Of course, Iran will eventually have a stockpile of 100 kilograms of LEU, certainly within another month or so.

The real magic number is, or should be, about 550 kilograms of UF6, which the ol’ URENCO SWU calculator reminds me would from the basis of a so-called breakout capability to produce 25 kilograms of HEU from 16 cascades in about two months.

When they ship that amount to a warehouse, you might want to think about programming the coordinates into a JDAM.


  1. hass (History)

    Are you suggesting that missiles should be launched even if the LEU is not converted to HEU?

  2. yale (History)

    Just for a (painful) giggle, let’s look back to the oft-referenced at ACW Dafna Linzer’s WaPo article from 2005

    The new estimate extends the timeline, judging that Iran will be unlikely to produce a sufficient quantity of highly enriched uranium, the key ingredient for an atomic weapon, before “early to mid-next decade,” according to four sources familiar with that finding. The sources said the shift, based on a better understanding of Iran’s technical limitations, puts the timeline closer to 2015 and in line with recently revised British and Israeli figures.The estimate is for acquisition of fissile material…

    Using the figures in Dr J’s post (which I believe is way too conservative)..

    The Iranians are producing 1.6 kg/day of LEU. To accumulate the further 450 kg would take until Feb-March of 2008. To run that to HEU brings us to May of next year.

    Being even more conservative, here is an estimate that I had previously made at TotalWonkerr..

    The Iranium FEP would (using my parameters) produce a bombs worth by December of 2008. Compare that to the ‘official” estimates of 2012-2015.

    You can see what a nonsensical pile of crap that “official” estimated timeline was, is, and shall be.

    How can policy be made, if the facts one works with is BS?

    BTW Part 1, it’s too late to call in the (ineffective) JDAM if they have the LEU. It is indestructible.

    The centrifuges must stop enriching NOW.

    BTW Part II, people who have pointed out the urgency of the threat are not the demented Chicken Littles that are implied here

    I think a “Cassandra” would be far more appropriate.

  3. Sparks (History)

    Suppose the scattered reports that there is a second underground site are correct. Could we be looking at 100kg of HEU?

  4. hass (History)

    Like I said, it seems to me that the Chicken Littles want to have it both way – that Iran’s nuclear program is advanced enough that it should be bombed NOW, and yet is not so advanced that bombing it would be ineffectual. But whatever you do, don’t enter into any sort of negotiations with them! No, a peaceful resolution would be bad thing and would deprive us of justification for a war.

  5. jay denari

    How much HEU, and of what percentage, is needed for a Hiroshima-size bomb? I know I’ve seen various figures, but right now I’m drawing a blank…

  6. yale (History)

    Hass – bombing is not the only tool available to stop the enriching. However, if these other steps are not taken (and soon), then I fear violence will be used.

    Sparks wrote:

    (Possible) second underground site … Could we be looking at 100kg of HEU?

    Unlikely. Assume a possible, but very extreme number of clandestine centrifuges, say 1000, running for the last six months.

    These would have produced only 2 kilograms of HEU. Altho this quantity (if you’re really good) can produce a sub-kiloton weapon (with a lethal zone a kilometer across), Iran would likely be shooting for about 15 kilograms plus of metal.

    Jay wrote:

    How much HEU, and of what percentage, is needed for a Hiroshima-size bomb?

    With a first generation implosion device (with excellent reflector), very roughly15 kg of 90% U23520 kg of 80% U23525 kg of 70% U23533 kg of 60% U23550 kg of 50% U235

  7. hass (History)

    The “violence” used would be a breach of international law and even planning it is itself a war crime, Yale.

  8. Ak Malten (History)


    These comments are scary! – especially the calculationof how much time there is before bombing is no longereffective as a prevention measure !

    Besides that it is Illegal – it equals calculating the time when mass murder should take place !!

    Ak Malten,Global Anti-Nuclear Alliance

  9. yale (History)

    Looking back at a previous post of mine, I’ve been re-running the numbers.I think 2 kg of HEU may be a bit low for a weapon under reasonable designs.

    Somewhere between 2.5 and 3 kg should be the right number to get some yield with a very high quality design.