Sunday, November 21, 2004

Iran is asking for it

President Bush is expressing concern over Iran's nuke intentions.

SANTIAGO, Chile (Reuters) - President Bush (news - web sites) on Saturday warned Iran of growing international concern over reports that Tehran is preparing large amounts of uranium for an enrichment process that can be used to make nuclear weapons.

"This is a very serious matter. The world knows it's a serious matter and we're working together to solve this matter," Bush told reporters during a meeting with Japanese Prime Minister Junichiro Koizumi in Santiago.

The two leaders were in Chile for a summit hosted by the Asia Pacific Economic Cooperation (news - web sites) forum.
A serious matter. The last time Bush got serious Saddam had to go job hunting. I think he got a job as a sewer cleaner. I guess when times are rough you have to take what you can get.
Bush was referring to reports from diplomats that Iran was aggressively producing uranium hexafluoride, or UF6, days before a Nov. 22 deadline by which Tehran promised the European Union (news - web sites) that it would freeze enrichment and all related activities.

UF6 is the form of uranium that is fed into gas centrifuges, which purify uranium for use as fuel in nuclear power plants or weapons.

Iran had promised France, Britain and Germany to freeze its enrichment program in a bid to ease concerns that its nuclear plans are aimed at producing atomic weapons and to escape a referral to the U.N. Security Council when the International Atomic Energy Agency, or IAEA, meets on Nov. 25.
Do you suppose the Iranians are spinning the Euros? I wonder if that is such a good idea.

The AP looks into the diplomatic reports:
While Iran says it is only interested in enrichment to generate power, the United States and its allies accuse Teheran of pursuing nuclear technology to manufacture weapons-grade uranium.

In the latest accusation, US Secretary of State Colin Powell on Wednesday said he had seen intelligence to confirm claims by an Iranian dissident group that Teheran was secretly running a program intended to produce nuclear weapons by next year.

Iranian Foreign Minister spokesman Hamid Reza Asefi dismissed that allegation Thursday. "There is no place for weapons of mass destruction in Iran's defense doctrine," Asefi said, according to the official Islamic Republic News Agency.
Asefi suggested that US officials "reconsider their intelligence sources."
Colin Powell is concerned. Colin Powell!

I think this means Bush has no intention of letting Iran get nukes.
A senior EU diplomat said its decision to carry out uranium processing right up to the freeze deadline disappointed the Europeans and cast doubt on Tehran's goodwill - even if it did not violate the letter of the agreement.

It also appeared to bolster the United States' push to have the UN Security Council examine Teheran's nuclear activities. When the deal was announced last week, it looked set to weaken the US drive, even though the agreement commits Iran to suspension only while a comprehensive aid agreement with the EU is finalized.

Asked about quantities being processed at Isfahan, one of the diplomats said "it's not little" but declined to elaborate.

But another diplomat familiar with the International Atomic Energy Agency - the UN nuclear watchdog - said the Iranians apparently were in the process of converting 22 tons of uranium into gas, either as a precursor to uranium hexafluoride or all the way to the end product, racing to finish before the Monday deadline.
So let us see if we can get a rough idea of what is involved.

22 tons assuming they mean American tons - is 20 metric tons. 10,000 kg of Uranium Hexaflouride.

I know the atomic weight of Uranium is 238. What is Flourine? 19.

That would be (238/(238 + 6(19)))(.0035) to get aproxmately the amount of U235 they will get assuming they can get 50% processing efficiency. That would yield about 24 kg of bomb grade material, about 50 lbs American. Probably enough for one bomb.

My guess is that they chose this amount for the express purpose of indicating that they know what they are doing.

Now what do we know about
Uranium hexafluoride
Uranium hexafluoride or UF6, is a compound used in the uranium enrichment process that produces fuel for nuclear reactors and bombs. It forms solid grey crystals at STP (0°C and atmospheric pressure.)

It is highly toxic, reacts violently with water and is corrosive to most metals. It reacts mildly with aluminum, forming a thin surface layer of Al2 F3 that resists further reaction. It has only a single stable naturally occurring isotope. By subjecting UF6 to repeated boiling and condensing, separation of U-235 from U-238 occurs by statistical enrichment. This process is very energy intensive.
Now the Iranians are not using the gaseous diffusuuion method. They are using centrifuges because it makes the whole process easier to design and build.

It is still very energy intensive.

The DOE has a nice bit on UF6.
Uranium hexafluoride (UF6) at ambient conditions is a volatile, white, crystalline solid. Solid UF6 is readily transformed into the gaseous or liquid states by the application of heat. All three phases — solid, liquid, and gas — coexist at 147°F (64°C) (the triple point). Only the gaseous phase exists above 446°F (230°C), the critical temperature, at which the critical pressure is 45.5 atm (4.61 mPa). The vapor pressure above the solid reaches 1 atm (0.1 mPa) at 133°F (56°C), the sublimation temperature.
Now here is the bit I have been looking for:
Density of solid UF6 at 68°F (20°C) is 317.8 lb/ft3 (5.1 g/cm3). A large decrease in UF6 density occurs when UF6 changes from the solid to the liquid state, which results in a large increase in volume. The thermal expansion of the liquid with increasing temperature is also high. Therefore, it is important to maintain control of the total mass and physical state of UF6 throughout an operational cycle. To avoid hydraulic rupture, when items with restricted volumes, such as traps and containers, are filled with UF6, full allowance must be made for the volume changes that will arise over the working temperature range to which the vessels will be subjected.
So what I want to find out is how much space (aproximately) 22 tons of UF6 will take up. (22tons * 2000lbs/ton)/(317.8lbs/cu ft) = 138.5 cu ft. A cube about 5 1/4 feet (1.6 m) on a side. It would easily fit in your living room.

UF6 is some very nasty stuff to work with chemically.
For UF6 to be handled as a liquid, the pressure must be in excess of 0.15 mPa (1.5 atm) and the temperature above 147°F (64°C) because the sublimation temperature lies below the triple point. Thus, any process using liquid UF6 is above atmospheric pressure and is subject to a potential leakage of UF6 to the environment, with vapor loss and cooling occurring simultaneously. Solidification occurs exothermically when the pressure falls below 1.5 atm (0.15 mPa). Thus, if a cylinder heated above the triple point is breached, a rapid outflow of the UF6 occurs until the pressure drops sufficiently to start the solidification process. The rate of outflow then decreases but continues until the contents cool to about 133°F (56°C), which is the atmospheric sublimation temperature. Some release of material may continue, depending on the type and location of the breach.

UF6 is hygroscopic (i.e., moisture-retaining) and, in contact with water (H2O), will decompose immediately to uranyl fluoride (UO2F2). When heated to decomposition, UF6 emits toxic fluoride fumes.
So whatever process is used has to be completely seal from the atmosphere. This cannot be done in open vats. Both for moisture and pressure reasons. In addition because of its corrosive nature it cannot be processed in metal containers. My guess is that everything this stuff comes in contact with must be teflon lined. Why do I think that? Because teflon was used in the Manhattan project.
Scientists working on the Manhattan Project faced the difficult problem of separating the isotope U-235 (which makes up about 0.7 percent of the element uranium in its natural state) from the far more plentiful but inert U-238. The method they settled on was gaseous diffusion, in which a gas is forced through a porous material. Since heavy molecules diffuse more slowly than light ones, multiple repetitions of the diffusion process will yield a gas enriched in the lighter isotopes. Gen. Leslie Groves, director of the Manhattan Project, chose Du Pont to design the separation plant. To make it work, the designers needed equipment that would stand up to the highly corrosive starting material, uranium hexafluoride gas, which destroyed conventional gaskets and seals. PTFE was just what they needed, and Du Pont agreed to reserve its entire output for government use.

For security reasons PTFE was referred to by a code name, K 416, and the small production unit at Arlington, New Jersey, was heavily guarded. Despite the tight security and Du Pont’s efforts to control the polymerization process, the Arlington production unit was wrecked by an explosion one night in 1944. The next morning construction workers stood by while Army and FBI investigators looked for evidence of sabotage. Working with Du Pont chemists, they found that the explosion had been caused by uncontrolled, spontaneous polymerization that was detonated by the exothermic, or heat-releasing, decomposition of TFE to carbon and tetrafluoromethane. When the investigators left, the construction crews took over, working two 12-hour shifts a day. Within two months the unit had been rebuilt with heavy barricades surrounding it.
This is some very serious stuff to fool with. The article goes into more of the history and other uses of teflon. Neat stuff. The military uses a lot of it as wire coating. It is an excellent insulator too. Expensive though.


Update 02:59z 21 Nov 2004

It turns out some of my premises were wrong.
But another diplomat familiar with the International Atomic Energy Agency - the UN nuclear watchdog - said the Iranians apparently were in the process of converting 22 tons of uranium into gas, either as a precursor to uranium hexafluoride or all the way to the end product, racing to finish before the Monday deadline.

Iran has huge reserves of raw uranium and has announced plans to extract more than 40 tons a year.

Converted to uranium hexafluoride and repeatedly spun in centrifuges, that amount could theoretically yield about 100 kilograms (220 pounds) of weapons-grade highly enriched uranium, enough for about five crude nuclear weapons.

Iranian officials say the Isfahan plant can convert more than 300 tons of uranium ore a year.
So 22 tons of uranium? Do they mean Uranium oxide or pure uranium? Let us try pure uranium this time and assume 100% U235 extraction.

So 22 tons of uranium would make ((238+114)/238)) * 22 * 2000 lbs of UF6 about. About 65,000 lbs. A cube about 5.9 ft (1.8 m) on a side. It would yield at 100% extraction 22 * 2,000 * .007 lbs of U235. About 310 lbs. Probably two or three bombs worth. Maybe more.


Update: 04:08z 21 Nov 2004

Here is a political update from Arieh (don't ya just love the name) O'Sullivan of the Jerusalem Post.
The IDF believes that Iran is running a secret nuclear weapons program in parallel to the one it had agreed this week to temporarily suspend.

Senior military sources told The Jerusalem Post that in the worst-case scenario Iran could produce a nuclear bomb within two years.

"Without a more determined stance by the West against Iran, they will reach a point of no return within six months," said a senior officer. From then it would take another 18 to 24 months to produce a nuclear bomb, they added.
The train is leaving the station. Next stop Iran.The Post goes on to say:
"The Iranians have a 'declared' secret program which they have agreed to temporarily suspend," said one senior Israeli officer. "But they also have a 'secret' secret program. The agreement with the Europeans is not touching this program. Furthermore, it is our understanding that the suspension is only temporary and partial."

The military source said the negotiations Iran conducted with Britain, France, and Germany over the pace of its uranium enrichment program amounted to a "Persian bazaar."

The military sources declined to give details about their knowledge of Iran's parallel program.

The assessment in the IDF is that once Iran has converted several dozen tons of uranium tetrafluoride (yellow cake) into UF6 (uranium hexafluoride), it would be able to make a few bombs.
You know this is starting to look like the run up to the Iraqi battle of the war.

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