Jeffrey LewisCollected Thoughts On Iranian LEU

The Jedi-rejects, prancing about with lightsabers, are actually Iranian artistes holding aloft tubes of what purports to be 3.5 percent low enriched uranium (LEU), which Iranian President Ahmadinejad cites as evidence “Iran has joined the nuclear countries of the world” (full text below).

A few administrative notes. Paul and I will be blogging at TPM Cafe next week, focusing on the Iran issue. Also, We have a winner! In a split decision, Haninah Levine’s inspired submission narrowly took home the coveted “Laptop Of Death” for his powerpoint presentation, “First-Ever Review of the Glorious Nuclear Posture of the Islamic Republic.” Thanks to all who submitted.

No Impact on Iran’s Timeline

Ahmadinejad and other officials (including Rafsanjani, Saeedi, and Aghazadeh) claim Iran has successfully enriched uranium to 3.5 percent in a 164 centrifuge cascade. That fits with a January 2006 estimate by David Albright and Corey Hinderstein that Iran could “start enriching uranium in a subset of this cascade sooner, but it could take two or more months to ready the whole cascade for the use of uranium hexafluoride.” (ISIS also has new images of activity at Natanz).

Iran probably made the announcement to celebrate the very first grams of LEU. Even if the cascade has been operating for a month, assuming 2 SWU per centrifuge per year, Iran can’t have produced more than a few (say half a dozen) kilograms of uranium enriched to 3.5 percent.

Hence the dancing guys with tiny lightsabers of LEU.

If you want to do the calculation itself, the Federation of American Scientists has produced a more user friendly SWU calculator than the Urenco version I linked to a while back.


Why do I say that Iran’s centrifuges are operating closer to 2 SWU a year, instead of 3? Acting Assistant Secretary of State for International Security and Nonproliferation Steve Rademaker provided reporters in Moscow with US estimates on the time it would take Iran to produce enough highly enriched uranium for a nuclear weapon using a cascades of 164, 3,000 and 54,000 centrifuges:

We’ve done calculations of what can be done with 164-machine cascade. If [Iran] chose to use such a cascade to produce highly enriched uranium, they could produce enough highly enriched uranium for a nuclear weapon in a little over 13 years, specifically 13.6 years is our calculation. But Iran has made it clear that it does not intend to stop at 164 machine cascade. Iran has told the International Atomic Energy Agency that its intention is to construct a 3000 machine cascade beginning next fall.

We calculate that a 3000 machine cascade could produce enough highly enriched uranium to produce a nuclear weapon in 271 days. And Iran is doing this work at the Natanz facility. Natanz is an underground facility that was constructed specifically to house centrifuges. The Natanz facility is constructed to house 50,000 centrifuges. And should they choose to fully utilize the space that they have constructed in Natanz for these 50,000 centrifuges, we calculate that using these 50,000 centrifuges, they could produce enough highly enriched uranium for a nuclear weapon in 16 days.

One can reverse engineer the calculations Rademaker presented to make educated inferences about the assumptions. The way to think about this problem is how many SWU would it take to make 25 kilograms of 90 percent HEU?

Assuming natural uranium with 0.711 percent U235, I calculated—using alternate “tails assay” estimates (how much good stuff goes into the waste) of 0.3 and 0.5 percent—Iran needs between 3852-4823 SWU to produce enouch HEU for a bomb.

Time to “Bomb” (25 kg of 90 percent U235)

No. of Centrifuges 2 SWU/Centrifuge 3 SWU/Centrifuge
164 12-15 years 8-10 years
3000 234-293 days 156-196 days
54000 13-16 days 9-11 days

What should be clear is that the calculation by Rademaker implies that the United States intelligence community thinks Iran’s centrifuges are not very capable—much closer to 2 SWU a year than 3.

We couldn’t make the balls.

The really interesting claim was Saeedi announcing that “the plan for the completion of the Natanz nuclear facility, including the launch of 3000 centrifuges by the end of [the Iranian calendar] year (March 20, 2007) has been officially declared to the International Atomic Energy Agency (IAEA).”

3,000 centrifuges by March 2006?

That accomplishment (presumably the first of 18 modules, up to a planned 54,000 centrifuges) would acelerate Iran’s time to a bomb.

There are at least three reasons to be skeptical of this claim:

First, I am not sure Iran can assemble that many centrifuges that quickly. The IAEA reported that Iran assembled 70 centrifuges during a one month resumption of production in June-August 2004. Assuming Iran has been assembling 100 centrifuges a month since the beginning of January (and had 700 on hand) and continues to do so, Iran won’t have 3,000 centrifuges until November 2007.

Second, Iran probably doesn’t have enough components or the ability to manufacture them. Albright and Hinderstein cite “senior diplomats in Vienna” as claiming that Iran has “components for up to 5,000 centrifuges” and “other senior diplomats” suggesting that some components are of poor quality and that Iran has components for an additional 1,000 to 2,000 centrifuges.

Hard to know which components are scarce, although Mark Hibbs has been all over this story about the export of ball bearing preforms to Pakistan and the question of whether Iran can indigenously manufacture it’s P-1 centrifuge.

It isn’t at all clear, Hibbs writes, that Iran’s tiny balls are good enough to get the job done:

The bottom bearing is one of the most critical components of a gas centrifuge. For both the original Urenco centrifuge models and the knock-off designs in Pakistan and Iran, it consists of a steel ball slightly larger than the head of a pin affixed to a stem which is then attached to the bottom end cap of the rotor assembly. The rotor assembly is then mounted onto a cup filled with lubricant, which is attached to the base plate. A spiral groove pattern is etched onto the bottom half of the ball. For models which serve as the design basis for P-1 and P-2, the dimensions of the bearing parts and their manufacturing tolerances are specified in single microns (one micron is 0.001 millimeter). Unless the bearing is precisely manufactured and assembled to these specifications, the centrifuges may not balance properly, their lifetimes will be substantially reduced, and they may crash soon after operation begins.


On Feb. 24 the IAEA Department of Safeguards refused to comment on whether Iran can make the ball bearings for its centrifuges.


Western officials investigating Iran’s centrifuge program said that Iran has experienced difficulties in getting its P-1 centrifuges to operate as predicted and that, during interaction with the IAEA, certain questions asked by Iranian experts suggested there were gaps in Iran’s expertise in development, production, and quality control. According to one official close to the IAEA investigation, the IAEA’s technical assessment suggested that, were Iran to resume centrifuge production now and quickly connect and begin operation of about 1,300 centrifuges it has set up at Natanz, “a large number of the machines might fail.”

Iran pleads incompetence with respect to with ball bearings to explain the cessation of work on the P-2 design. “We couldn’t make the balls” one offical told Hibbs—although some Western officials doubt that Iran could make one without eventually being able to make the other. Neither, of course, is a distinct possibility—at least in the near-term.

Finally, as the long blockquote suggests, quick installation and operation of large cascades might result in quality control problems. Some of you may be familiar with the “rush to failure” concept from selected major defense acquisition programs.

So, overall, I am treating this “3,000 centrifuges by March 2007” claim with some skepticism.

Full Text of Ahmadinejad’s Remarks

AHMADINEJAD (THROUGH TRANSLATOR): The reason behind holding this glorious ceremony was the news related to the offering of a report on major progress made in the field of nuclear energy. Ambassador Aghazadeh presented that technical report.

Gaining access to the nuclear fuel cycle is a demand by the Iranian nation. Our people in different parts of the country and different parts of the world, wherever they are, they have emphasized the necessity to gain access to this technology.

The best manifestation of such a national resolve was the massive presence of the people on the 22nd of Bahman, which marks the victory anniversary of the Islamic revolution.

And by taking part in massive rallies, the people voiced their firm

And later on, on every occasion, the Iranian nation has stressed the importance of this demand, voiced by the people.

On the threshold of the birth anniversary of Prophet Mohammed and in the vicinity of the holy shrine of Imam (inaudible), peace be upon him, at this historical moment, I announce that, with the blessings of God Almighty and with the efforts made by our young scientists and the prayers made by the vigilant Iranian nation, the nuclear fuel cycle at the laboratory level has been completed and uranium with the desired enrichment for nuclear power plants was achieved on 20th of Farvardin, 1385, Iranian calendar year.


AHMADINEJAD (THROUGH TRANSLATOR): At this holy place, in the vicinity of the holy shrine (inaudible) peace be upon him, I wish to seek this opportunity, I wish to offer my congratulations to the martyrs, the Imam of the martyrs, the supreme leader, and all the young scientists, and Iran has joined the nuclear countries of the world, and this is the outcome of the efforts made by the Iranian nation and the resistance.

And this is a starting point for more major points of success for the Iranian nation. Our nation, particularly the youths, on the basis of divine blessings and their self-reliance, have managed to gain access to this very important technology.

At this historical moment, I commemorate the late founder of the Islamic revolution and the martyrs which, the 20th of Farvardin, 1385, Iranian calendar year, a very important day in the history of the Iranian nation—this would be considered a historical date and would remain a significant and important date in the Iranian history.

I wish to mention some points regarding this major development. Knowledge and science can serve humanity. On the basis of religious beliefs, science, along with religious beliefs and faith, can lead to progress.

We have announced on various occasions that we seek peace and calmness on the basis of justice. We have on various occasions announced and we do announce that our nuclear technology serves peaceful purposes.

We do announce that those who have (inaudible) 50 years ago are in need of nuclear weapons.

Those who believe that political and cultural equations can be changed to one’s benefit by using nuclear weapons, those who are the ones who (inaudible) nuclear weapons.

Our nation is a civilized nation that relies divine beliefs and the will of its young people.

Our nation, in order to fulfill its objective causes, relies on the sublime beliefs that lie within the Iranian and Islamic culture.

Our nation does not get its strength from nuclear arsenals. The source of our strength comes from our profound faith and our profound beliefs.

We have announced that our nuclear activities have been under complete and an unprecedented supervision by the IAEA, and today we are interested to operate under IAEA supervision.

What has been achieved and what is going to be achieved in the future is within the framework of the rights of the Iranian nation and on the basis of regulations, including our nation’s rights within the IAEA and the Nuclear Non-Proliferation Treaty.

On the basis of international regulations and our inalienable rights to (inaudible) our path for the protection of industrial fuel for our power plants.

Unfortunately, in this path, our nation has faced acts of obstructionism and bullying stances and ill-tempered stances by certain powers.

They do have an historical record of this. In the course of the
nationalization of oil that was an inalienable right of our nation, some of these powers conducted acts of obstructionism and they resisted the legitimate rights of the Iranian nation. And its outcome was nothing but a permanent hatred toward them by the Iranian nation.

The same powers are making use of a similar literature and argumentation, making use of psychological warfare, and in this they hamper the Iranian nation from making use of its legitimate rights.

I do recommend them not to repeat the bitter experiences of the past. I do recommend them not to create an everlasting hatred in defiance of the Iranian nation and the freedom-seeking nations of the world.

We have announced on various occasions and I do announce to you that Islamic Iran’s progress and the strength has always served peace and security of the neighboring states and the world community.

The government, on behalf of the nation, and all the efforts made by the elite (inaudible) and the innovative youths and the talented young people pay homage to the national progress and we do support their efforts.

I, as the servant of the Iranian nation, wish to express my appreciation to all those who were involved in making this progress and this great victory.

The distinguished scientists, researchers, managers and the atomic energy organization and the (inaudible) I appreciate them all and I call on them to make use of all (inaudible) and take steps toward the production of the nuclear fuel for all power plants.

The government of the Islamic Republic thanks God Almighty for achieving this objective. And I call upon the Iranian nation inside and outside the country to thank God for achieving this progress.

I do, accordingly, thank you all for attending this historical meeting and this historical ceremony.

I wish to thank all the (inaudible) and military commanders. I wish to thank the military commanders(inaudible) the researchers, the students and the distinguished participants coming from different sectors (inaudible) the distinguished families of martyrs and the disabled of war and, in particular, the representative of the Supreme Leader (inaudible).

I wish to thank you all. And I wish health, success and dignity for you and the Iranian nation.


  1. Max Postman (History)

    I was a little confused at first by Ahmadinejad’s endless references to “the young people.” If I had to speculate, I’d say that he’s trying to forestall the ideological movement of Iranian youth West-ward, something that has been predicted based on the younger generation’s mass exposure to American culture. It seems similar to the situation in North Korea: While KJI uses the nuclear issue to retain the support of the military, on whom his immediate retention of power depends, Ahmadinejad uses the nuclear conflict to mobilize younger Iranains, whose political and global orientation will dictate the long-term survival of Iranian theocracy.

  2. Yale Simkin (History)

    Dr. Jeff…

    Why did you assume 25kg HEU as required for a bomb? Even if you are assuming a 20% loss in the processing that still is WAY higher than required in even crude designs.

    BTW – for fun, use the handy-dandy FAS swu calculator to re-do the figures using LEU at VVER-1000 enrichment of 4.4% with tails at 3.4%.

    Considering that to fuel its new reactor, Iran will need onsite ~100 tons of LEU (as contracted from Russia). And inasmuch as Iran has told IAEA in 2003, 2005, and 2006 to go screw themselves and removed its seals, it appears that fun times are ahead.


  3. Hass (History)

    Of course “time to a bomb” calculation assumes that Iran in fact wants a bomb. That has not been established, and is mere speculation.

    What is your view of Javad Zarif’s piece in the New York Times and International Herald Tribune

    Incidentally Max, what makes you think that the young people of Iran don’t support Iran’s nuclear program?

  4. Jeffrey Lewis

    25 kg is the “official” number derived from the IAEA definition of a “significant quanty.” It is also the number that US officials use in public presentations.

    As such, 25 kg is almost certainly the assumption in the calculations presented by Rademaker.

    Whether that assumption is reasonable or not is an interesting debate — see Cochrane and Paine, The Amount of Plutonium and Highly-Enriched Uranium Needed for Pure Fission Nuclear Weapons — but totally irrelevant for the task of recreating Rademaker’s estimate.

  5. pete

    Intrigueing stuff.

    Can anyone explain me how a 164 centrifuge cascade produces 3.5% LEU? I imagine that one would have to run a quantity of UF6 through the cascade, which I assume does not come out of the cascade 3.5 % enriched, but much lower. The enriched LEU would have to go through the casacade again (several times I presume). I assume, the cascade would have to be empty before the enriched product can be entered again. Taking into account the tails this means that the final quantity of LEU cannot be very much. And the production of it cannot have much to do with proper R&D aimed at building a reliable cascade. Or?

    Anyone has some intelligent technical remarks to help me understand it all?

  6. John Field (History)

    Hey, what is the pressure that the centrifuges like to run at? Are you caught in a bind between the solidification points of UF6 and the mean free path size of the rotor diameter?

    It seems there is a problem with mean free path in the countercurrent centrifuges if you drop the pressure too low – as you drop into a Boltzmann equation regime.

    If not, why can’t the Iranians drop the pressure and jack up the enrichment per stage(like in the later sections of the rectifier) so they can go all the way to HEU in their 164 unit cascade(albeit at a slow production rate)? Did I miss something here?

  7. Dave Schuler (History)

    In reference to Hass’s comment above, doesn’t Occam’s Razor lead one to the conclusion that Iran does, indeed, seek nuclear weapons? The electricity generation explanation sounds farfetched: Iran vents enough natural gas from its wellheads to generate more power than their nuclear power plant would over its lifetime. Additionally, does Iran have enough uranium to power the plant for its lifetime? If not, doesn’t importing uranium work at cross-purposes to their stated goals?

    In other word, if you assume that the Iranians are neither insane nor ridiculous, doesn’t that lead you to conclude that their power generation explanation is unlikely?

  8. John (History)

    I listened to this speech on CSPAN, and I find some text missing from your “Full Text” as printed in your post. The President of Iran also said “Death to England, Death to America, Death to Israel”.

    Why did you leave this out of your post and describe his comments as “in full”?

  9. Jeffrey Lewis

    It is a commercial transcription.

    If I find out you are lying about the omission, I am banning you from the comments.

  10. Gregory (History)


    If people were chanting in the audience it most likely wasn’t in Arabic, but Persian/Farsi – the national language of Iran.

  11. Jeffrey Lewis

    A good point, unless maybe it is something from the Koran. Need to check with the service again.

  12. Jeffrey Lewis

    Here is the FBIS translation.

    It is plausible that at least one of the chants (“God is great”) was in Arabic, while others weren’t (“Khamene’i is our leader”, “Down with those who oppose the rule of the supreme jurisconsult”, “Down with America”, “with Britain”, “Down with Israel”).

    This may explain why the above commenter heard “Death to America” etc.

    Iran: Ahmadinezhad Announces Completion of Nuclear Fuel Cycle, Uranium Enrichment
    Speech by Iranian President Mahmud Ahmadinezhad at a ceremony attended by senior military officers, “foreign guests,” and government officials at Imam Reza Auditorium in Mashhad—live
    Vision of the Islamic Republic of Iran Network 1
    Wednesday, April 12, 2006 T07:54:35Z
    Journal Code: 8230 Language: ENGLISH Record Type: FULLTEXT
    Document Type: OSC Translated Text
    Word Count: 1,497

    In the name of God, the Merciful, the Compassionate. O God, please hasten the advent of the Lord of the Era and grant us the honour of becoming his pious companions. Peace be upon Imam Reza, the son of Ali.

    O noble and honourable nation of Iran: May God’s peace and salutations be upon you. Blessed be the souls of your martyrs. And may God honour the devotion of your war-disabled and war veterans. God’s greetings upon our noble youths, who are crossing the frontiers of science, through their own endeavour. These young people have taken our nation to the rooftop of knowledge, science and global technology. And they will continue to make progress in this sphere.

    Yesterday, it was thanks to the devotion of your courageous youths (on the battlefields of the Iran-Iraq war) that our dear Iran managed to climb onto the rooftop of independence and honour. And today, the beloved young people of our Islamic homeland are going ahead to conquer the summits of science and technology.

    The noble Iranian people deserve to study science, to conduct research and to undertake selfless scientific endeavour. And this is a justified demand of our dear nation.

    The beloved Prophet Muhammad of Islam called on all human beings to learn knowledge and acquire technology. In accordance with the same instructions (of Prophet Muhammad), our creative scholars and youths began extensive efforts to acquire various modern technologies. And praise be to God, they have managed to make considerable progress in medical science, engineering, aerospace and nuclear technology.

    The reason for holding this glorious ceremony is the news concerning our major progress in the field of nuclear energy. The technical report on this progress was presented to you by (the head of Iran’s Atomic Energy Organization) Mr Gholamreza Aqazadeh.

    Access to nuclear fuel cycle is a national demand of the entire Iranian people. At their gatherings in cities, villages and in all parts of the world, our people, wherever they may be, have, time and again, stressed that point.

    The most important manifestation of that national demand was on previous year’s 22 Bahman (11 February; the anniversary of the Islamic Revolution) when the people, with their participation in tens of millions, in all cities of Iran, districts and many villages as well as various parts of the world, responded to a call by their servant. I had asked them to express their views. They expressed their decisive support and cried out their unanimous demand.

    Since then and without exception, during any event or gathering, they have also stressed this rightful demand of theirs.

    On the threshold of the birth anniversary of the honourable prophet of Islam and beside (the shrine of) Imam Reza, peace be upon him, and at this historic juncture, I would like to announce that, thanks to the blessing of His Holiness Lord of the Age (the 12th imam), may God hasten his noble advent, and thanks to the efforts of Iranian scientists, committed and creative young people and prayers of the brave, intelligent and ever-on-the-scene people of Iran, we have completed the nuclear fuel cycle at the laboratory level and our young people enriched uranium to the enrichment level required by nuclear power plants on 20 Farvardin (9 April) of the current year, 1385.

    (Chants of: “God is great”, “Khamene’i is our leader”, “Down with those who oppose the rule of the supreme jurisconsult”, “Down with America”, “Down with Britain”, “Down with Israel” and other indistinct slogans)

    I would like to cordially congratulate all the martyrs and the Imam of the martyrs, the supreme leader and the great nation of Iran, and the dear youth of this country wherever they are inside or outside the country, at this holy place next to the shrine of the eighth Imam, on this great success; and officially declare that our beloved Iran has joined the nuclear countries of the world. This great historic achievement is the outcome of the endeavours and resistance of the great nation of Iran. And this is the beginning of greater and greater successes. Our nation, particularly our youths, managed to find access to this very important and valuable technology relying on God and on their power of will and innovation. I wish to pay tribute to the Imam (Khomeyni) and the martyrs at this historic moment.

    The 20 Farvardin of 1385 is a great day. It will be chronicled in the history of Iran. It will continue to inspire this nation and will encourage this country’s youth in all their endeavours.

    I find it necessary at this point to highlight a few aspects of this epic event. Science and technology should serve humanity. Science must be accompanied with faith in order to serve peace, tranquillity and progress. We have repeatedly stated that we pursue only peace and stability based on faith and justice for all people. As we have always maintained and continue to do so, our nuclear technology is only used for peaceful purposes. We maintain that the only people who need weapons of mass destruction are those who are stuck in a frame of mind dating back to 50 years ago. These are the same people who still believe that by amassing weapons of mass destruction they can exploit political, economic and cultural interactions to their own advantage.

    This is a civilized and cultured nation. It relies on the will of its faithful youth. In order to realize its aspirations, our nation depends solely on its noble ideas and values which are deeply rooted in the Islamic and Iranian culture. The source of our nations’ strength is not nuclear arsenal. The strength of our nation stems from its deep religious faith. We have always maintained and continue to state that all our nuclear activities, in all its facets, have been within the IAEA guidelines. The agency has closely monitored all our activities. We would like to continue our activities while being monitored by the agency. What we have achieved and continue to achieve has been and will be within our nation’s irrefutable rights. Our achievements are in line with the recognized rules and regulations including our rights as stipulated by the IAEA and the Non-Proliferation Treaty (NPT). We will continue on this path while adhering to international laws and pursuing our undeniable rights until we have produced industrial-level fuel which we will use in our power plants.

    Unfortunately, in its path towards progress and development, our nation has been faced with some powers’ anger, wrongdoings and bullying. Of course, our history is filled with such approaches. During the movement for the nationalization of oil, which was our nation’s inalienable right, some of these powers demonstrated their opposition and impudently stood against the Iranian nation’s undeniable right. Of course, I stress this point one hundred times, that this approach bore no results but the everlasting hatred of the Iranian nation towards them. Today, the very same people are using the same justification, language and psychological warfare and want to stop the Iranian nation from using its undeniable and unalienable right. I advise them not to repeat their bitter experience of the past and respect the Iranian nation’s right. I advise them not to create everlasting hatred towards them in the minds and history of the Iranian and other freedom-seeking nations.

    We have always maintained that the development and strength of the Islamic Iran aimed to serve peace, tranquillity and stability for all our neighbours and the world. The country will continue on the same path. As the representative of the people, the government fully supports the country’s ulema, researchers, scientists and our talented youth who work towards advancing the country in various fields. The government fully supports their efforts. As a public servant I thank all those who have played a role in achieving this victory especially our scientists, researchers, mangers and employees of the Atomic Energy Organization and of course Mr Aqazadeh. I ask them to use all their abilities, speed up efforts and move at a greater pace towards fully realizing our goal of producing nuclear fuel for use in the power plants.

    The Islamic Republic government would like to bow down before God and thank him for this great achievement and divine blessing and I would like to ask all Iranians outside and inside the country to thank God for this great blessing. I would like to sincerely thank the academics, intellectuals, foreign and domestic guests, honourable Majlis deputies and military commanders, students and the dear young people, artists, released POWs, the honourable martyrs’ families, war-disabled, people from various walks of life from various parts of our Islamic homeland, and especially the leader’s special representative, for taking part in this magnificent and historic meeting. I wish all the best and ever-increasing success and dignity for you and the dear Iranian nation.

    (Description of Source: Tehran Vision of the Islamic Republic of Iran Network 1 in Persian—state-run television)

    Compiled and distributed by NTIS, US Dept. of Commerce. All rights reserved.

  13. John (History)

    I think they are sanitizing the transcription. When CSPAN aired the comments, even the translator hesitated in repeating what he said. It was not “down”, it was “death”.

    Maybe a review of the audio from CSPAN is in order.


  14. John (History)

    Since I dont speak Arabic, maybe the translator was repeating what the crowd was chanting and not what the president was saying. I assumed that the translator would only be repeating what Ahmadinejad had said.


  15. John (History)

    I found the “death to America quote”.

    If you go to CSPAN and download the speech (search for “iran by date and see the 4/11/2006 item titled “Iranian President Mahmoud Ahmadinejad Speech on Nuclear Enrichment Program”), at 6 minutes and 20 seconds, he says “Death to England”, Death to America”, “Death to the infidels”, Death to Israel”.

    The camera is panning over the audience at the time of these comments, and I do not see the crowd chanting these words, so one would have to assume, it is coming directly from the President himself.


  16. Hass (History)

    Dave—the myth that the natural gas that Iran flares can be a substitute for nuclear energy was investigated and dismissed by the Foreign Affairs Select Committee of England’s Parliament in March 2004:

    ‘It is clear … that the arguments as to whether Iran has a genuine requirement for domestically produced nuclear electricity are not all, or even predominantly, on one side’…Some US arguments against Iran ‘were not supported by an analysis of the facts’, the committee added, noting that much of the natural gas flared off by Iran – which US officials say could be harnessed instead of nuclear power – was not recoverable for energy use.

    (For more, see

  17. John (History)

    After further analysis of the video and speech, it does seem that the death chant was coming from the audience, but I can not be 100% sure. It is difficult to determine with the translators voice and Ahmadinejad speaking at the same time, but it does sound like there is a pause from Ahmadinejad with the translator continuing to speak.

    However, there have been numerous occasions in the recent past (even the same day: where Ahmadinejad himself has said these particular phrases.

    Sorry about my “Arabic” comment earlier, as I meant “Farsi”.

  18. Ali

    I can now confirm that, as reported earlier in FT and in this blog, not only was Larijani¹s deputy – Nahavandian – in DC a few days ago to catalyze talks, but also another key official. Both were blown off by the White House, specifically VP Cheney who said that “talking to the Iranians will make us look weak.”

    Looks more and more that the US prefers threats, to diplomacy.

  19. Hass (History)

    So what? Are we supposed to get our underwear in a bunch because he said a chant? We have threatened to NUKE them. I think its kinda a wash…

  20. Yale Simkin (History)

    Dr. Jeff..

    The Significant Quantity (SQ) for 90% HEU is 27.8 kg, not 25 kg.
    Rademaker was probably using the actual SQ of 27.8 kg and a tails of .5% (.5% is the tails that someone building a bomb in a hurry would use.)

    With those numbers, his time-2-bomb is right on the money for a SWU/yr of 2, just as you most excellently reversed out.

    BTW – a superb set of online uranium calculators are here:

    The unit SQ is pretty bogus. IAEA defines it as “the approximate quantity of nuclear material in respect of
    which, taking into account any conversion process involved, the possibility of manufacturing a nuclear explosive device
    cannot be excluded.”

    This actually says nothing about what the actual minimum amount a first-time builder could or would use.
    You wrote:

    “Whether that assumption is reasonable or not is an interesting debate”

    It may be debatable on political or detection grounds, but there is no debate on the physics or engineering.

    The critical mass of 90% HEU is 20.8kg with a 4” NatU tamper and only 15.5 kg with a 4” beryllium tamper.

    The design that Iraq was working on pre- 1st gulf war had a core of 15 kg.

    In any event, since these are implosion systems, MUCH less than 15 kg HEU is needed. The critical mass falls inversely to the square of the compression. The old trinity bomb compressed the core to twice the density and created four critical masses. Also, by playing with implosion speed, compression, manipulating shock waves to minimize rarefaction, etc, extremely small amounts of HEU can be used.

    Rademaker’s use of SQ tends to give a false sense of available time.


  21. John (History)


    Please point me to an American President ever saying in public, “we will nuke you” as you claim should be a “wash”.

    There is a significant difference between a head of state, who when they speak, articulates official state policy, and a congressman saying silly things after having one too many beers. If you are referring to Congressman Tancredo, he said this in the context of retaliation “if” we were first attacked by Iran with nukes. There is a big difference between having an official state policy that spans many years of destroying a country (Israel and the U.S.) vs. speaking in terms of retaliation. Your “wash” comparison has no merit.

    When a head of state says something, we have to assume they mean what they say, especially since recent past behavior of blowing up buildings, funding terrorists and taking hostages seems to match thier rhetoric.


  22. John (History)


    What, if any changes would you make to your calculations if Iran obtained HEU from another source?

    If Iran did so, what level of enrichment would be expected in a) the HEU received and b) the time needed to enrich it further (if necessary)?

    If Iran was able to obtain, or attempt to obtain HEU, from a physical dimension perspective, how large is it? For example, how many cannisters/containers and truck or shiploads would be required for something useful to them?


  23. Ali

    The head of state did not say “death to America” – listen and you will see it is the audience. It’s so clear!

  24. Yale Simkin (History)

    interesting banner on the side of a Shihab 3:


  25. mehdi

    I wish people stop giving Ahmadinejad all this publicity and coverage—after all the office of presidency in Iran and his role as the president is not like say what we have in US. Just look at Articles 113, 125 and 126 of Iranian constitution and you’ll see his limited role. The real decision makers in Iran are the likes of Khamanei, Rafsanjani, Larijani etc … so basically he doesn’t have access to the supposed red button that everyone is worried about. Having said that I do understand thought that his off the cuff comments (like some other leaders we know) are entertaining and ideal for getting the attention of those with short attention span and no time for an indepth analysis (like the one made by Jeff here).

  26. Hass (History)

    When asked whether he intends to nuke Iran, Bush said “all options are on the table”—Conclusion: he threatend to nuke Iran.

    And before you deny it, just assume the tables had been turned, and Ahmadinejad had said the same thing in response to the same question—wouldn’t we be flipping out? Why assume the Iranians are supposed to react any differently? Who is really more threatening to whom?

  27. John (History)

    Hi Ali,

    This will be my last post on this subject since it is somewhat off topic.

    Yes, Ahmadinejad may have not directly said those words on that day in that speech. However, I can point you to many quotes by Ahmadinejad and Ayatolla Khamenei that are not that proper for heads of state:

    10/26/2005 – Ahmadinejad – “God willing, the force of God behind it, we shall soon experience a world without the United States and Zionism”

    6/24/2004 – Ayatolla Khamenei – “The world of Islam has been mobilized against America for the past 25 years. The peoples call, death to America…Who, besides the Islamic Republic and the Iranian people, used to say this? Today, everyone says this”

    10/26.2005 Ahmadinejad – “Anybody who recognizes Israel will burn in the fire of the Islamic nation’s fury..”

    I was merely pointing out that Ahmadinejad and previous Iranian Presidents have openly called for the destruction of another country, whereas we do not.


  28. tpajax (History)

    The head of state in the US has said that he considers nuking Iran to be an option—so Iran would be right in concluding that Bush has threatened to nuke Iran. Who is a threat to the world now?

  29. Ali

    The US does not openly call for destruction of another country – they are smarter; they JUST DO IT. Case in point: Iraq. Or they threaten to do it. Case in point: Nuking Iran.

  30. geoff (History)

    Just to clarify the discussion here of Assistant Secretary Rademaker’s centrifuge production estimates as he described them in Moscow: These are generic calculations, that assume a P1 performance of 2 SWU, a tails assay of 0.4%, and assume production of 25 kg of 93% HEU. One should not draw conclusions about USG assessments of Iran’s centrifige production capability at Natanz based on A/S Rademaker’s remarks. They were illustrative, based on standard assumptions as noted above.

  31. Yale Simkin (History)

    Rademaker’s generic assumptions are dangerous.

    1) They assume HEU enriched all the way to US Oralloy equivalent, which is much higher than needed,

    2)a lower tails assay than a crash program would use,

    3) assumed quantities almost twice the amount that a first-time bomber could reasonably design with,

    4) used the lowest estimate on centrifuge performance.

    This adds up to a doubling of the time Iran could potentially take in stockpiling a bomb core.

    What would be Rademaker’s rationale for minimizing the urgency of the potential threat?


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