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April 09, 2009

Comments

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?

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.

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.

[...] Kazakhstan's President Nursultan Nazarbayev said Monday that his Central Asian country would be an appropriate place for such a depository, as it was giving up its own Soviet-era nuclear arsenal.

If created, the global fuel bank would undermine claims by Iran and other states that they need to develop their own fuel enrichment programs.

Nevertheless, Iran's leader Mahmoud Ahmadinejad said during a two-day visit to Kazakhstan that he supported the project.

"We believe Nazarbayev's proposal to create a nuclear fuel bank in Kazakhstan is a very good proposal," Ahmadinejad was quoted by Russian agency RIA-Novosti as saying at a news conference Monday in the Kazakh capital of Astana. "Nuclear powers should be disarmed in such a way as they can dispel their anxiety and the anxiety of all mankind."

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.
[...] Each of the Parties to the Treaty undertakes to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete 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.

"Were these remarks intended exclusively for domestic public consumption?"

You didn't ask me, but fwiw, I think pretty much so.

Thanks Mssr. Farber.

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?

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?

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?

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?


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.


"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.

"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.

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.

"...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.

:-)

But I'll stress again that miniaturizing your weapon to fit on a missile still remains tricky.

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.

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.

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.

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.

Thanks again, y'all. I leave this thread much more informed than I began.

"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!

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.

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.

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.

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.

Weird. I have no idea why it posted without the blockquotes, and then with them, etc.

There are definitely Typepad gremlins today.

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.

"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.

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.

The U.S. is joining the five-party nuclear talks with Iran that the Bush administration largely disdained.

WASHINGTON — The Obama administration said Wednesday that the United States would start participating regularly with other major powers in negotiations with Iran over its nuclear program.

The decision was a further step toward the direct engagement with Iran that President Obama has promised. It followed an invitation to Iran to join in a new round of talks, which would include Britain, France, Germany, Russia and China. And it coincided with an unusual expression of conciliation toward the United States by President Mahmoud Ahmadinejad of Iran.

Mr. Ahmadinejad said Wednesday in a speech that his government would welcome talks with the Obama administration, provided that the shift in American policy was “honest.”

The Bush administration largely shunned these European-led negotiations with Tehran; last July, it reluctantly sent a senior diplomat to a single round of talks that ended in stalemate.

More there.

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