by Eric Martin
The American Foreign Policy Project has put forth a fact-based, level-headed and insightful (warning pdf) policy paper on the Iranian nuclear issue. It is both a valuable primer on the contours of the background facts and ongoing process, and a useful guide to setting achievable objectives going forward.
The report cuts through the hype to provide the facts on the current intelligence:
Although we often hear it said or implied that Iran is clearly pursuing nuclear weapons, the facts are more complex than that.
The Director of National Intelligence Dennis Blair has just re-affirmed the December 2007 finding that Iran shut downits weaponization and covert enrichment activities in Fall 2003, with no evidence of a re-start. What we know Iran to be doing is enriching uranium at Natanz, openly under IAEA safeguards, and improving its ability to enrich more efficiently, while slowly accumulating a small stockpile of low-enriched uranium. It is also building a heavy-water reactor at Arak. These projects will shorten the lead-time for developing a nuclear weapon, should Iran decide to do so in the future. That is the sense in which, as Mr. Blair puts it, we know Iran to be "developing a nuclear weapon capability" and "preserving a weapons option."
In practice, Iran's current path preserves at least three different options, the first and last of which are not mutually exclusive: (a) pursuing enrichment for nuclear energy use as a source of national pride and a symbol of Iran's refusal to be cowed, (b) using its enrichment as a bargaining chip in larger negotiations with the United States and its allies, or (c) pursuing a weapon either to deter a feared U.S. or Israeli attack, or to support aggressive goals, including expanding its influence in the region. The U.S. intelligence community believes that Iran probably has not yet made a firm decision with regard to nuclear weapons, and that decision may well depend in large part on what the United States and its allies do.
According to U.S. intelligence community estimates, Iran is not expected to accumulate enough fissile material for even a single weapon until sometime in the 2010-2015 time frame, and that would require a "break-out" that almost certainly would be detected. What this means, in Secretary of Defense Robert Gates' words, is that: "They're not close to a stockpile, they're not close to a weapon at this point, and so there is some time." The only effective way to illuminate - and, if necessary, constructively alter - Iran's intentions is to use that time for skillful and careful diplomacy.
Meanwhile, publicly assuming the worst in the absence of evidence - and issuing an immediate ultimatum based on that assumption -- is a singularly bad idea. It will provoke a needless confrontation if the assumption is wrong. It will deprive Iran of a face-saving way to shift course if the worst-case assumption is correct. And continuing to threaten to bomb Iran - as Israel is doing - is the best way imaginable to make the worst-case scenario a self-fulfilling prophecy.
To reiterate some points made in the above excerpt, Iran will not be able to create a nuclear weapon unless either: (1) it "breaks out" from the IAEA monitoring process which would set off all types of alarm bells (and would leave us a window to act military should that be the option selected - though I oppose it); or (2) Iran has secret facilities that have thus far escaped detection - in which case bombing the known facilities would serve little purpose because the secret, hidden facilities represent the real threat in terms of weaponization. In fact, attacking Iran under such a scenario would likely lead the ruling regime to redouble efforts to create a weapon via those hypothetical secret facilities, only now with an even more antagonistic and hostile posture at precisely the time that easing tensions and normalizing relations would have added urgency.
More from the report on setting realistic, attainable objectives:
In setting goals for diplomacy, U.S. policy-makers should be guided by one basic question: What observable policy changes by Iran that are realistically achievable will make us most secure, given that Iran's present intentions are unknown?
"Give up the pursuit of nuclear weapons" is not a meaningful demand since Iran denies it is pursuing weapons and the United States has no clear evidence with which to dispute that denial.
Past U.S. policy has focused to the point of obsession on forcing Iran to (a) answer all questions about alleged past weapons work, (b) suspend its open and safeguarded enrichment at Natanz, and (c) stop construction of a heavy-water reactor at Arak. Alliances have been built, UN resolutions pushed through, and sanctions imposed -- all for the purpose of pressuring Iran to submit to these three demands.
The third objective responds to a longer-term concern and can be readily incorporated into the diplomatic strategy that we propose. However, in our judgment the first two of these objectives are simply the wrong priorities. Iran has shown no indication that it is willing to take such actions, even under international pressure, and focusing on these demands comes at the expense of other achievable steps that would provide greater benefit to our security. Rather than simply take up where the Bush Administration left off, the Obama Administration needs to re-think its objectives with three key points in mind:
(a) Open, declared, safeguarded enrichment is not the greatest threat. Let us suppose for the sake of contingency planning that Iran were to decide to pursue a nuclear weapon. How would it do so? U.S. officials are not unjustified in worrying that Iran might close off access to the Natanz facility, evict inspectors, and start transforming its low-enriched uranium into high-enriched weapons material. North Korea did something analogous with spent reactor fuel and plutonium a few years ago. It's a most unlikely scenario, however, in the case of Iran. Any such maneuver would be immediately known, confronting Iran with a high risk of a forceful response, from Israel if not others. This being so, any Iranian decision to pursue a weapon would much more likely follow a clandestine path.
(b) Focus on transparency. Past U.S. policy has so fixated on stopping all open, safeguarded enrichment in Iran that it has left itself half-blind to the more consequential risk of a clandestine program, should Iran decide to pursue a weapon.
Guarding against the clandestine risk requires, first and foremost, getting Iran to resume implementing the co-called "Additional Protocol" to each country's Safeguards Agreement with the IAEA. The Additional Protocol is not a panacea. One still needs intelligence to tell the IAEA where to look. But with the Additional Protocol one has a way of confirming or denying suspicions of clandestine nuclear work furnished by intelligence. Without it, there is none.
Adherence to the Protocol is voluntary, however. Brazil is pursuing enrichment, but hasn't signed the Protocol. Iran signed the Protocol and had been voluntarily implementing it, but stopped doing so in response to UN sanctions aimed at stopping Iran's safeguarded enrichment.
Iran has offered to resume applying the Additional Protocol and possibly accept other safeguards in the context of an overall settlement. There is only one way to find out whether this offer is serious or not, and what its contours are: start talking to Iran.
(c) The West probably can't have it all. Ideally, of course, one would get it all. Iran would simply capitulate: stop enriching, come clean about its past and resume implementation of the Additional Protocol. In the real world, this is unlikely to happen, and it is vitally important that the best not become the enemy of the good.
While the Additional Protocol probably should be required of all nations who engage in nuclear activities, it is currently a voluntaryarrangement that has to be bargained for. Moreover, as the relevant UN Security Council resolutions acknowledge, Iran is entitled under the Nuclear Non-proliferation Treaty (NPT) to use nuclear energy for peaceful purposes, and that right has long been understood to encompass enrichment under safeguards. Nothing in the NPT or Iran's Safeguards Agreement supports the notion that a country is barred from enriching uranium if it has ever pursued a weapons program, even one halted years ago.
What this means is that the dispute that has put Iran at loggerheads with the West is not over whether Iran may enrich uranium. It is over whether Iran must first suspend enrichment for a period and answer all questions about allegations of past weapons work to regain the "confidence" of the international community - before resuming enrichment.
In our judgment, this difference is not so fundamental as to be worth the conflict it has evoked. Achieving a temporary suspension of open and safeguarded enrichment at the cost of the Additional Protocol would be a pyrrhic victory - and might well just drive enrichment underground. And forcing Iran to answer potentially embarrassing questions about the past is far less important than safeguarding the future.
The statement "The West probably can't have it all" is one of the strongest critiques of the brash, petulant, bellicose foreign policy that has come to dominate the Republican Party in recent decades. It is a foreign policy posture that is born out of maximalist fantasy of the United States' position in the world, fed by delusions of unipolarity on steroids. In this cartoonish view, the United States is so omnipotent that it can traipse across the globe, disregarding the interests of other states (which, when counter to our own in any way, are de facto illegitimate), making demands that must be met en toto...or else! No compromise. No give and take.
In fact, according to those that subscribe to these theories, the United States is so all-powerful that it should seek to marginalize groups like the United Nations and NATO because such alliances demand compromises (tying us down like the Lilliputians did Gulliver), while the benefits offered are superfluous given our unipolar might. In truth, those alliances have long served to promote US interests, even if in a roundabout way at times, with a more collaborative approach. Recent events have revealed just how vital they are, with chastened US leaders left to try to make amends in the hope of receiving greater assistance in Iraq, Afghanistan and elsewhere.
In shooting down proposals to attempt to reach a negotiated settlement with respect to North Korea's nuclear program, Dick Cheney famously quipped, "We don't negotiate with evil, we defeat it." But we didn't defeat it. Instead, North Korea developed nuclear weapons while we made unrealistic, maximalist demands.
The Bush administration's approach to Iran has been no different: demanding everything, offering almost nothing, while doing little to actually alter the course of events in terms of uranium enrichment. The supposed supreme military dominance that girded PNAC ambitions of remaking the globe through American hegemony (and preventive war in many instances) has been revealed as an oversold bill of goods, and foreign government's aren't buying.
Yet the GOP continues to act as if war with Iran AND North Korea are feasible policies despite the strains of two wars still left unfinished (with both heading toward conclusions that fall far short of the grandiose expectations that preceded them). Theirs is the refuge of the preener and poser that gets to talk tough, demand it all and then carp from the sidelines about all the "appeasement" and "giveaways" to groups and governments that they would have refused to offer a thing. Instead, opting to simply "defeating" them. Or not.
The rest of the American Foreign Policy Project report sets forth, in greater detail, the parameters of a possible deal and the right way to go about pursuing it. In acknowledging that the US and the West won't be able to "have it all," it has the admirable quality of operating from within the context of the real world. Which means GOP leadership (outside of the Lugar wing) will find it an unacceptable appeasement of the next Hitler/Stalin/Fascism.
For the rest of us, it's well worth the read.
Eric, given that there is so little question as to Iran's progress towards weaponization and given the problems you highlight regarding strong-arming Iran and denying them a face-saving out, why do you think both Obama and Clinton have recently made public statements suggesting that Iran is actively pursuing a nuclear weapon? They know that this is not true and presumably are savvy enough to see how it makes future negotiations harder, so what benefit is there in doing this? Were these remarks intended exclusively for domestic public consumption?
Posted by: Turbulence | April 09, 2009 at 01:04 PM
That's a great question turbo.
I think the domestic audience aspect is something to consider. A sharp departure from the party line at this point will raise a lot of fury with little gain on the home front.
By taking the "tough" pose, maybe he can move more silently toward the reasonable position.
One hopes.
Posted by: Eric Martin | April 09, 2009 at 01:11 PM
Eric, if I might suggest, your link goes to the front page of the AMFP's site; the paper will disappear from there in the future, replaced by next major issue they address. It might be better, for the long term, to switch your link to here, despite its being a .pdf, because it's going to suffer link rot a lot less quickly.
On substance, I'd also emphasize the point in the paper that Iran is perfectly within its rights to engage in low-enriched uranium (LEU), as guaranteed by the Non-Proliferation Treaty (NPT), which the U.S. is a signatory to and creator of. All the huffing and puffing about Iran's enrichment tends to obscure this point which is the most important point so far as the Iranians are concerned, and legitimately so. It's a point of their sovereignty, and given the U.S. history of trampling all over Iran sovereignty, and manipulating their government and events in Iran, it's a point even the most moderate and reasonable of Iranian government is going to cling to at least the face of.
However, it needs to be pointed out that Ahmadinejad has spoken favorably of taking up the idea of Kazakhstan's proposed nuclear fuel bank, i.e., Kazakhstan, which has major nuclear facilities left over from Soviet days, serving as a source and storage place of low enriched uranium for many countries.
This is a promising idea, and should be followed up upon as part of a negotiating package. As well, the U.S. needs to set its own example, as it, too, is bound by its commitment in the NPT to ultimately engage in complete nuclear disarmament. The Obama administration's moves to negotiate a major cutback in nuclear weapons stocks with Russia is an important step in the right direction.Posted by: Gary Farber | April 09, 2009 at 01:42 PM
"Were these remarks intended exclusively for domestic public consumption?"
You didn't ask me, but fwiw, I think pretty much so.
Posted by: Gary Farber | April 09, 2009 at 01:44 PM
Thanks Mssr. Farber.
Posted by: Eric Martin | April 09, 2009 at 01:51 PM
What we know Iran to be doing is enriching uranium at Natanz, openly under IAEA safeguards, and improving its ability to enrich more efficiently, while slowly accumulating a small stockpile of low-enriched uranium. It is also building a heavy-water reactor at Arak. These projects will shorten the lead-time for developing a nuclear weapon, should Iran decide to do so in the future.
How will a stockpile of low-enriched uranium and a heavy-water reactor shorten the lead time for developing a nuclear weapon?
Posted by: Nell | April 09, 2009 at 02:01 PM
In case it's not obvious, my question above is just the question it seems to be. I don't claim to have a firm grasp on the steps to nuclear weapon production. All I know is that a weapon requires highly enriched uranium.
What role does a heavy-water reactor play in converting a stockpile of low-enriched uranium into highly enriched uranium, or in some other way shortening the time required to produce a nuclear weapon?
Posted by: Nell | April 09, 2009 at 02:06 PM
Don't sanctions that prevent implementation of the NPT violate the NPT? Aren't we obliged to provide Iran with full cycle nuclear power capability under the treaty?
Posted by: jrudkis | April 09, 2009 at 02:11 PM
How will a stockpile of low-enriched uranium and a heavy-water reactor shorten the lead time for developing a nuclear weapon?
Funny Nell, I've read this a few times and just sort of accepted it as sciency type stuff that I don't grasp. And, there it is: I don't know exactly.
The only thing I could add is that the heavy reactor somehow played into North Korea's approach.
Where's Cheryl Rofer when you need her?
Posted by: Eric Martin | April 09, 2009 at 02:12 PM
I think the reactor provides plutonium as part of its waste. The waste can then be reprocessed as weapons grade plutonium.
A close examination by the IAEA of the radioactive isotope content in the nuclear waste revealed that North Korea had extracted about 24 kilograms of Plutonium. North Korea was supposed to have produced 0.9 gram of Plutonium per megawatt every day over a 4-year period from 1987 to 1991. The 0.9 gram per day multiplied by 365 days by 4 years and by 30 megawatts equals to 39 kilograms. When the yearly operation ratio is presumed to be 60 percent, the actual amount was estimated at 60% of 39 kilograms, or some 23.4 kilograms. Since 20-kiloton standard nuclear warhead has 8 kilograms of critical mass, this amounts to mass of material of nuclear fission out of which about 3 nuclear warheads could be extracted.
Estimates vary of both the amount of plutonium in North Korea's possession and number of nuclear weapons that could be manufactured from the material. South Korean, Japanese, and Russian intelligence estimates of the amount of plutonium separated, for example, are reported to be higher -- 7 to 22 kilograms, 16 to 24 kilograms, and 20 kilograms, respectively -- than the reported US estimate of about 12 kilograms. At least two of the estimates are said to be based on the assumption that North Korea removed fuel rods from the 5-MW(e) reactor and subsequently reprocessed the fuel during slowdowns in the reactor's operations in 1990 and 1991. The variations in the estimates about the number of weapons that could be produced from the material depend on a variety of factors, including assumptions about North Korea's reprocessing capabilities -- advanced technology yields more material -- and the amount of plutonium it takes to make a nuclear weapon. Until January 1994, the Department of Energy (DOE) estimated that 8 kilograms would be needed to make a small nuclear weapon. Thus, the United States' estimate of 12 kilograms could result in one to two bombs. In January 1994, however, DOE reduced the estimate of the amount of plutonium needed to 4 kilograms--enough to make up to three bombs if the US estimate is used and up to six bombs if the other estimates are used.
On 22 April 1997, U.S. Defense Department spokesman Kenneth Bacon officially stated, "When the U.S.-North Korea nuclear agreement was signed in Geneva in 1994, the U.S. intelligence authorities already believed North Korea had produced plutonium enough for at least one nuclear weapon." This was the first time the United States confirmed North Korea's possession of plutonium.
Posted by: jrudkis | April 09, 2009 at 02:29 PM
"How will a stockpile of low-enriched uranium and a heavy-water reactor shorten the lead time for developing a nuclear weapon?"
Having low-enriched uranium means that it can more quickly be enriched to high-enriched condition than starting with plain old U235.
A heavy water reactor, as opposed to a light water reactor, or other kinds of reactors, can create plutonium out of uranium.
Plutonium would be used for making a more powerful implosion type bomb (or Nagasaki type weapon), rather than a gun-type Hiroshima-type weapon. The Hiroshima gun-type is much easier to make -- a few good engineers can make one in their backyard, as indeed John Coster-Mullen has -- and an implosion weapon requires far more sophisticated effort, but a heavy water reactor producing plutonium will allow you to bypass any need to enrich uranium at all, in favor of deuterium ("heavy water") enrichment. Also, it will allow you to produce tritium, and increase your weapon's yield.
Posted by: Gary Farber | April 09, 2009 at 02:29 PM
"Having low-enriched uranium means that it can more quickly be enriched to high-enriched condition than starting with plain old U235.'
To elaborate, LEU is produced out of U238 by, put simply, spinning it through centrifuges at high speed, over and over and over and over. The longer you keep recycling the uranium through the centrifuges, and purifying it, the greater the enrichment you'll achieve.
So to get to HEU, you have to go through LEU. If you start from LEU, you're already part way to your goal.
The Iranians currently have, reportedly, a bunch of 3% enriched uranium. Getting it up to 80% is where they'd want to be for bomb-grade. So it's not very far along. But it's a step.
And, of course, the more centrifuges you have going, the more enrichment you can engage in. The idea is to have thousands and thousands and thousands.
These require very fine tolerances of machine work; it's easy to make a flawed centrifuge that will spin apart. This is the part of generating your own bomb-grade fuel that is so time-consuming, and requires so much industrial infrastructure. Putting together a gun-type bomb itself is relatively very simple, and there are no secrets about it, save when you want to start miniaturizing, and even there, plenty of knowledge is in the public domain, or obtainable, or deducible.
But I'll stress again that miniaturizing your weapon to fit on a missile still remains tricky; the North Koreans are immensely unlikely to have accomplished it. Iran is more sophisticated, so I'd rely on reports from experts to judge such a thing, but it's the sort of thing no one outside any Iranian program is apt to know.
Posted by: Gary Farber | April 09, 2009 at 02:43 PM
There is one more security concern for which Iran may feel the possession of a Nuclear capability would help. Their neighbor Pakistan is an unstable Nuclear power. And Pakistan is primarily Sunni. It is not inconceivable that a failed Pakistan would be run by Sunni extremist groups, and that such groups might consider Shia Iran (as well as non-Muslim Israel and America) to be their mortal enemy. So the temptation to get one or two steps closer to weapons capability is not nonexistent, and can't be wholly assuaged by anything the US could do.
Posted by: Omega Centauri | April 09, 2009 at 03:14 PM
"...and can't be wholly assuaged by anything the US could do."
We could promise to put Iran under our nuclear umbrella and retaliate against Pakistan if Pakistan nukes Iran.
:-)
Posted by: Gary Farber | April 09, 2009 at 03:21 PM
Absolutely. Fat Man and Little Boy weighed approximately 5 tons each. Estimated payload capacity of a Taepodong is about one metric ton, max, and that max figure probably has some detrimental effect on max range.
Sure, we build them much smaller nowadays, but we've had many decades of testing to refine warhead design.
Posted by: Slartibartfast | April 09, 2009 at 03:36 PM
Thanks Slarti, Gary, and jrudkis. That helps a lot.
All those carefully-machined centrifuges sound like a pain in the ass, though I gather the Iranians have been doing the best they can with what they have in the way of centrifuges. The excerpts jrudkis provided give a pretty good idea of the quantities and time involved to get plutonium from heavy-water reactor electricity production.
So what kind(s) of bombs does Pakistan have -- Hiroshima-highly-enriched-uranium-gun or Nagasaki-plutonium-implosion? My understanding is that A.Q. Khan's know-how passed to the North Koreans, so I'm expecting to hear the latter.
What kinds of bombs does Israel have? It's hard to imagine how we could embark on any serious arms-reduction initiatives without ending the pretense that if we don't talk about Israeli nukes, they aren't there.
Posted by: Nell | April 09, 2009 at 04:00 PM
This is probably the best information that you can get on Pakistan's nuclear program that won't get you killed. Likely it's replicated over at Wikipedia and fas.org.
Here's a similar treatment of Israel's weapons.
Posted by: Slartibartfast | April 09, 2009 at 04:26 PM
What kinds of bombs does Israel have? It's hard to imagine how we could embark on any serious arms-reduction initiatives without ending the pretense that if we don't talk about Israeli nukes, they aren't there.
Nell, this report suggests that the Israelis definitely have plutonium based weapons and probably also have Hiroshima style bombs as well.
It is indeed difficult to imagine how we can continue pressing Iran on nuclear weapons while adamantly pretending that Israel has none, all while keeping a straight face. Nevertheless, despite the difficulty, I'm sure our government is up to the task.
Posted by: Turbulence | April 09, 2009 at 04:27 PM
Thanks again, y'all. I leave this thread much more informed than I began.
Posted by: Nell | April 09, 2009 at 06:56 PM
"Having low-enriched uranium means that it can more quickly be enriched to high-enriched condition than starting with plain old U235."
Oopsie! I meant "plain old U238," of course!
Posted by: Gary Farber | April 09, 2009 at 08:06 PM
FWIW, Nell, a year ago Ahmadinejad claimed they were installing 6,000 centrifugues. Iran has begun installing 6,000 new centrifuges at its main nuclear plant in Natanz, President Mahmoud Ahmadinejad has said.
[...]
Later, Mr Ahmadinejad claimed Iran had tested on Tuesday advanced new equipment - thought to be a reference to a possible new generation of centrifuges.
'Five times greater'
"The capacity of these new machines... is five times greater than the current machines," he told a televised event in Tehran. Some details about Natanz from 2003.
Theoretically it could hold 50,000 centrifugues, although Iran claims nowhere near that number for now.
Their current claim is 7000. Iranian President Mahmoud Ahmadinejad has officially inaugurated a new plant to produce uranium fuel for a heavy-water nuclear reactor, in a step likely to further exacerbate tensions over Iran's nuclear program. Iran's president also used his appearance to say Iran is ready to hold talks on its nuclear program.
It was a day of jubilation for many Iranians who turned out to celebrate their country's nuclear program on the day their government had officially designated as national nuclear day.
President Mahmoud Ahmadinejad inaugurated a new plant to produce fuel for a heavy-water nuclear reactor in the city of Isfahan, in a move likely to increase fears in the West about Tehran's nuclear ambitions.
Until now, Iran has only taken the step of enriching uranium at its facility in Natanz to produce fuel for a light-water reactor. Producing fuel for the heavy water reactor could lead Iran to the capability to make plutonium, which can be used in a nuclear warhead.
[...]
Iran's nuclear chief Gholamreza Aghazadeh said Iran has now installed about 7,000 centrifuges at its Natanz uranium enrichment complex, 1,000 more than previously revealed. Iranian officials also say they have tested a new more efficient type of centerfuge.
During his comments to mark the opening of the new nuclear facility, President Ahmadinejad said his country would be willing to hold talks with the United States and other western nations about its nuclear program, but only if the talks were based on what he called "respect and justice." Uranium centrifugues: [...] The creation of the centrifuges is a huge technological challenge. The centrifuges must spin very quickly -- in the range of 100,000 rpm. To spin this fast, the centrifuges must have:
* very light, yet strong, rotors
* well-balanced rotors
* high-speed bearings, usually magnetic to reduce friction
Meeting all three of these requirements has been out of reach for most countries. The recent development of inexpensive, high-precision computer-controlled machining equipment has made things somewhat easier. This is why more countries are learning to enrich uranium in recent years.
Now you need to turn the uranium hexafluoride gas back into uranium metal. You do this by adding calcium. The calcium reacts with the fluoride to create a salt, and the pure uranium metal is left behind. I have another link, which I'll save for another comment, so as not to go over the four links limit.
Posted by: Gary Farber | April 09, 2009 at 08:25 PM
FWIW, Nell, a year ago Ahmadinejad claimed they were installing 6,000 centrifugues.
Some details about Natanz from 2003.Theoretically it could hold 50,000 centrifugues, although Iran claims nowhere near that number for now.
Their current claim is 7000.
Uranium centrifugues:Posted by: Gary Farber | April 09, 2009 at 08:26 PM
More details on how centrifuge enrichment works. [...] A single centrifuge might produce about 30 grams of HEU per year, about the equivalent of five Separative Work Unit (SWU). As as a general rule of thumb, a cascade of 850 to 1,000 centrifuges, each 1.5 meters long, operating continuously at 400 m/sec, would be able to produce about 20-25 kilograms of HEU in a year, enough for one weapon. One such bomb would require about 6,000 SWU.
A typical centrifuge facility appears to have a capacity of 10-20 SWU/meter square, and to consume in the range of 40-50 kWh per SWU. A facility capable of producing one bomb per year would thus require about 600 square meters of floor space, and consume in the range of about 100 kWe.
With current technology, a single gas centrifuge is capable of about 4 separative work unit [SWU] annually, while advanced gas centrifuge machines can operate at a level of up to perhaps 40 SWUs annually. Separative Work Unit (SWU) is a complex unit which is a function of the amount of uranium processed and the degree to which it is enriched, ie the extent of increase in the concentration of the U-235 isotope relative to the remainder. The unit is strictly: Kilogram Separative Work Unit, and it measures the quantity of separative work (indicative of energy used in enrichment) when feed and product quantities are expressed in kilograms.
[...]
A kilogram of LEU requires roughly 11 kilograms U as feedstock for the enrichment process and about 7 separative work units (SWUs) of enrichment services. To produce one kilogram of uranium enriched to 3.5% U-235 requires 4.3 SWU if the plant is operated at a tails assay 0.30%, or 4.8 SWU if the tails assay is 0.25% (thereby requiring only 7.0 kg instead of 7.8 kg of natural U feed).
An implosion weapon using U235 would require about 20 kg of 90% U235. Roughly 176 kg of natural uranium would be required per kg of HEU product, and about 230 SWU per kg of HEU, thus requiring a total of about 4,600 SWU per weapon. To enrich natural uranium for one gun-type uranium bomb would requires roughly 14,000 SWUs. Thus, producing one HEU weapon in a year would require between 1,100 to perhaps 3,500 centrifuges.
About 100-120,000 SWU is required to enrich the annual fuel loading for a typical 1000 MWe light water reactor. A 20,000 kg-SWU per year centrifuge plant would fit within a typical factory building and would consume only 600 kW electrical power. More detail at the links if you're interested.
Posted by: Gary Farber | April 09, 2009 at 08:26 PM
More details on how centrifuge enrichment works.
More detail at the links if you're interested.Posted by: Gary Farber | April 09, 2009 at 08:27 PM
Weird. I have no idea why it posted without the blockquotes, and then with them, etc.
Posted by: Gary Farber | April 09, 2009 at 08:28 PM
There are definitely Typepad gremlins today.
Posted by: Nell | April 09, 2009 at 08:39 PM
Instead of hiding a nuclear weapons program, I wonder what would happen if Iran simply put it right in the middle of its oil production or exporting facilities?
Can you imagine that any country would risk the destruction of any sizable exporting capacity, particularly if it would contaminate the area, and prevent rebuilding?
Iran could hold its own oil hostage, and therefore the world (by taking 10 percent of reserves off the table for a long period of time). I doubt China would want to put up with that.
Posted by: jrudkis | April 09, 2009 at 08:58 PM
"Can you imagine that any country would risk the destruction of any sizable exporting capacity, particularly if it would contaminate the area, and prevent rebuilding?"
Blowing up a centrifuge plant, such as the one at Natanz, that hasn't gotten to an extremely high level of HEU wouldn't contaminate anything to any point where anyone would be significantly bothered, so far as I know.
The uranium hexafluoride wouldn't be something you'd want to roll around in, or spend a ton of time breathing in -- but it's not my underderstanding that there'd be a significant "contamination" problem, certainly not in any radiological sense, if the HEU is even close to bomb-grade.
I know this accord with everyone's idea of how scary things nuclear are, but it's plutonium that's deadly. You could carry a fifty pounds of 80% enriched, bomb-grade, uranium, in a leather pack over your shoulder for a week, and you'd be in more danger from getting a bad suntan.
And a centrifuge plant, as I quoted above, takes up a huge huge huge amount of space. So I'm afraid your plan just wouldn't work; it would be bombable, and the bombing wouldn't endanger surrounding oil fields at all.
Seems to me, anyway. I am no kind of expert, of course.
Posted by: Gary Farber | April 09, 2009 at 09:33 PM
Have I linked William Langewiesche's How To Get A Nuclear Bomb? If not, I highly recommend it to everyone.
On making your own bomb, I also repeat my recommendation above, where it may have gotten lost in the sea of links, of this New Yorker piece on John Coster-Mullen's reconstruction of the Hiroshima bomb.
He's a truck driver. Check it out.
Posted by: Gary Farber | April 09, 2009 at 09:38 PM
The U.S. is joining the five-party nuclear talks with Iran that the Bush administration largely disdained.
More there.Posted by: Gary Farber | April 10, 2009 at 02:57 PM