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PostPosted: Sat Sep 02, 2006 10:40 am 
The recent UN tussle with Iran is based on the assertion that Iran's new uranium plant is intended to produce enriched uranium; Iran claims that uranium is meant for nuclear power plants, but the Western powers (mostly the US) claim that it is a precursor to weapons development.

On the one hand, it is true that they would not need enriched uranium for a power plant; indeed, natural uranium (that is, uranium wherein the ratio of U235 to U238 hasn't been modified) is much easier to produce and handle, and from the very first, several power plant designs (especially the proposed sub-critical-reactor and CAESAR designs, as well as some pebble-bed-reactor designs) use it specifically to avoid the problems with enriched uranium. Indeed, historically there were 'reactors' which formed in nature from uranium deposits (though at the time the naturally occuring percentage of U235 was much higher than today, since U238 has a longer half-life). Any country which was looking to develop peaceful nuclear power would find it much cheaper and easier to use natural uranium fuel rather than enriched fuel.

On the other hand, enrichment need not be for weapons use; many power plants use a limited enrichment of about 3% (the same as in the naturally occuring 'reactor') to make it easier to sustain and moderate the reaction. A plant capable of enriching uranium to 3% does not necessarily have the capacity to enrich to the 70% required for weapons development; it becomes progressively more difficult to separate the isotopes as the percentage increases. Again, I have heard conflicting claims about this regarding the Iranian plant.

On the gripping hand, I've recently heard at least two people claim that the Iranian factory isn't designed to enrich uranium, but merely refine it (purify it and form it into fuel pellets). Supposedly, the Bush administration and other Western governments involved are mistranslating the Iranian announcements (either intentionally or due to projection of expectations onto the text), creating an appearance of a threat that isn't really there. True, the people who made such claims were, to say the least, not the most reliable sources of information, but when I heard the same thing from two unconnected people, I had to wonder if this was at least a rumor going around. Certainly it goes against everything I'd heard about it up until now, and it goes against the known facts (e.g., the plan to purchase a number of industrial centrifuges, which would be one of the means to enrich uranium but wouldn't be necessary for refining) as well. Has anyone else heard anything about this, and can anyone confirm or (as I suspect is more likely) refute the assertion?

(BTW, I recently heard that the reason that Iran changed it's name in the 1930s was as a show of support for fascism - according to Wikipedia, which claims that there is a standing controversy over the name, 'Iran' is the Farsi word meaning of 'Land of the Aryans', a term which before the Nazis grabbed it referred to the inhabitants of Persia (Iran), Afghanistan, Pakistan and northern India. The connection to Germany, as I understand it, came from popular articles garbling some of the theories about the Indo-European migrations, and especially Schliemann's work regarding 'Troy'. I'm not sure that this was really the reason that Reza Shah Pahlavi changed the country's name or not but it would make a certain amount of sense given the friction at the time between Persia and the British Empire over Mesopotamia (Iraq). The Wikipedia article on the country doesn't mention this, but the article on Reza Shah supports the claim. Again, confirmation or refutation would be appreciated.)

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PostPosted: Sun Sep 17, 2006 11:27 am 
Actually, another point has occurred to me: if they were primarily bent on building bombs, they wouldn't be enriching uranium at all, they would be building a breeder reactor to produce Pu-239. Uranium enrichment is a lot of work for a relatively inefficient result, really, and while the 'Little Boy' design is often presented in popular works as 'the' atomic bomb, the truth is that the gun assembly is pretty much useless for a practical weapon compared to the implosion type - it is easier to build and in the early days probably more mechanically reliable, but it doesn't scale well and the enrichment process is far more difficult and expensive than producing a suitable amount of plutonium. No one - at all - uses the gun-type design today, and IIRC only two such devices were ever actually detonated (Little Boy, and the 'Grable' nuclear artillery test shot). The only country other than the US known to have ever built a gun-type bomb is South Africa - everyone else went straight to the implosion design.

The main reason that uranium bombs are a concern with regards to terrorists is because, once they have a critical mass of U-235 available, the gun-type bomb would be fairly easy to build at the target, or at least close enough to simply moved into position by a flatbed truck. For a nation building a full bomb production facility, though, plutonium would be the way to go - if you have the money and technical talent to build an enrichment facility, you would also have the ability to build a breeder reactor and the shaped charges which are the critical factor in a 'Fat Man' type bomb. Not only that, but you can make those far smaller than you can make the gun type bombs, and they can be used (eventually) in fusion-boosted bombs or even true fission-fusion-fission bombs, the latter of which realistically cannot be ignited with a gun-type bomb as far as I am aware.

All told, while it is certainly possible that Iran is building their enrichment facility for weapons-development purposes, if that is the case it is a foolish move on their part, when they could have built a 'civilian' breeder reactor using natural uranium feedstock and then quietly used the resultant plutonium for weapons development instead.

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