Very Bad Things

Update 9/29, 8am: It looks like the story below is now proving to be inaccurate: Ha’aretz is reporting that the amount seized was in the hundreds-of-grams range, not 15 kilograms. See their story here.
Glenn is first off the mark this morning with some breaking news: Turkish authorities are claiming to have arrested men carrying more than 33 pounds of weapons-grade uranium.
Although there is no official indication (yet) as to what the smugglers’ final destination was, we can all take a pretty good guess, I think.
More as it develops…
Update: In Glenn’s original post, he commented on the amount of uranium seized: “That’s critical mass folks — enough for a bomb all by itself”
But then I noticed this UPI story on the matter, which says: “While substantial, 15 kilograms alone of enriched uranium is not quite enough to make a “proper” nuclear bomb, according to U.S. government information. Twenty-five kilograms is considered the standard threshold to ignite such a device’s searing force. Nuclear bombs also require at least least 8 kilograms of plutonium.”
So who’s right? Well, I did some research and dug up some information. Please note up front, however, that this is the product of a bit of net surfing, and nothing more: I’m learning this as I go, so read the primary sources yourself and make your own judgments.
Here are the sources:
This paper from the Center for Contemporary Conflict (CCC), associated with the U.S. Naval Postgraduate School, says “Approximately 25 Kg of highly enriched uranium (HEU) is needed to build a gun-assembly device” (A gun-assembly is the same kind of weapon as ‘Little Boy’, the bomb which the U.S. dropped on Hiroshima).
This page on the history of the Manhattan project states that the total quantity of uranium used in the ‘Little Boy’ weapon was about 140 lbs (64 kg), considerably more than was seized. One would assume, however, that Little Boy was an inefficient design and a modern one would require significantly less uranium.
This page by the Federation of American Scientists has a number of relevant statements embedded within it, including the following:
– A uranium bomb could be constructed using an implosion-sphere design with anywhere from 15 – 56 kg of weapons-grade uranium. (‘Fat Man’, the weapon used on Nagasaki, was an implosion-sphere design, except it used plutonium rather than uranium. Note that my understanding is that an implosion-sphere design is significantly trickier than a gun-type design, and would not be a good choice for a terrorist or government without the means to perform testing. It is possible, however).
– The nuclear weapons developed by South Africa were gun-type designs, and each used 50kg of uranium.
This PDF file, a 1993 report entitled “Technologies Underlying Weapons of Mass Destruction: Technical Aspects of Nuclear Proliferation” from the U.S. Congress Office of Technology Assessment, has a great deal of information on weapons development and various designs, and also states the following: “Significant quantities of nuclear materials have been defined by the International Atomic Energy Agency (IAEA), which is charged with ensuring that these materials not be diverted from peaceful uses into weapons… [t]hese thresholds, which the IAEA considers sufficient for processing into a weapon, are 8 kg of plutonium (total element) or 25 kg of the isotope uranium-235 in highly enriched form…”
This citation appears on page 55 of the document. (Note that I attempted to find a direct citation from IAEA, but their website is a nightmare and I was unable to find a relevant document. ) This document also repeats the same information as above — that an implosion sphere design would require 15-56kg of uranium — but appears to me to be quoting from the same root source as the FAS document.
So what’s the bottom line? Well, you can decide for yourself, read the sources. But my conclusion is that the 15kg seized in Turkey is not enough for the sure-fire gun design which you could be pretty sure would work the first time. But it is apparently just barely enough for a weapon using the tricky implosion-sphere design that isn’t sure to work without prior testing. So Glenn squeaks by!
UPI, on the other hand, isn’t so lucky. Leaving aside their estimate of uranium required, note that none of the sources above suggest that plutonium would be required in addition to uranium to devleop a nuclear bomb. So I would conclude that the UPI story was incorrect in its statement that “Nuclear bombs also require at least least 8 kilograms of plutonium.”. (That sounds suspiciously like the amount of plutonium required for a plutonium-only bomb, actually: so perhaps UPI confused an “OR” with an “AND” in this case).
As usual: Advantage, Instapundit!
As I said in my preface, I just learned all of this with a bit of web surfing, so please review the primary sources yourself and make your own judgements. And by all means, if anyone has any additional information or feedback, send it my way and I’ll share with the class.
Another Update: Another relevant question, given that we presume (or fear) that Iraq was the intended destination for the uranium, would be, “What types of weapon designs do we know Iraq has worked on?”
Handily, the British government helps us out here. The recently released Iraq’s Weapons of Mass Destruction: The Assessment of the British Government (PDF) states that, pre-Gulf War, “Iraq