Did Aum Shinrikyo set off a nuclear bomb in Western Australia in 1993?

Factgirl's official verdict: No. After reviewing the movement and assets of the cult (the most interesting being Patrick Bellamy's False Prophet: The Aum Cult of Terror at http://crimelibrary.com/terrorists/aum/main.htm) and doing a little research into Nuclear Science and Geology:

1. There are no former uranium mines in Western Australia.

2. Uranium is hard to mine but harder to concentrate. For every 25,000 tons of Uranium ore that is mined from the earth, only 50 tons of Uranium metal can be refined from that, and 99.3% of that metal is U-238 which is too stable to be used as an active agent in an atomic detonation. To make matters even more complicated, no ordinary chemical extraction can separate the two isotopes since both U-235 (the bomb kind) and U-238 possess precisely identical chemical characteristics. The only two concentrators in the entire nation are both owned by Anaconda Uranium Corporation a Company with home offices in Canada.

3. At the time of 1992-1993 the cult was still doing its big membership drive and concentrating on its efforts to sell electrical helmets (to stimulate your spiritual thoughts, $70,000 a piece or rent for $7,000 a month) to work up to its big doomsday event. They hadn't the resources or the personnel to build an atomic bomb. The plans for the bomb are available on this here internet, but as the site's disclaimer wisely indicates: (and I paraphrase) if you don't blow yourself up along with your neighborhood, you will die of radiation poisoning.

Later that day...

I am not a chemist or physicist and I promise you if I ever accidently become one I will eat my kids - much respect to Rook for the true facts regarding separation of U235 from U238! My info was as much research as my teeny wrinkly brain could comprehend and node within a reasonable time frame (in this case about 18.2 minutes).The site I quoted, http://serendipity.magnet.ch/more/atomic.html stated: The only methods that can effectively separate U-235 from U-238 are mechanical methods. I don't know how to separate Uranium using any method.

It is possible to extract u235 from u238 ore by using a complex gaseous-diffusion process involving a compound of uranium and fluorine. I don't know if this is what factgirl meant when she said no "ordinary" process. The two isotopes are chemically identical, but their different masses allow separation to take place. u238 is fissile, but you need some really excited neutrons to keep a chain reaction going, so it's just not practical.

The minimum size a u235 chunk must be in order to support a chain reaction is a sphere of 18 cm weighing 53 kg (or about 117 pounds). That's a lot. (You can get smaller devices from plutonium, which does not occur naturally.) You'd need to refine more than 16,600 pounds of ore in order to hope to get enough u235 for one bomb. And even then, unless you're pretty smart and can successfully nest shells of u235 and u238, you'll get a fission bomb, which will be nowhere near as powerful as a thermonuclear fusion bomb--something on the order of one-thousandth the potential power of a fusion bomb.

My conclusions: If the cult did go down this path, they weren't very smart. Any device they could have potentially made would have likely been big and bulky, and Western Australia is probably about the only place they'd be able to detonate it with any secrecy. But I think it's extremely unlikely that they built a device on-site, as the industrial requirements are pretty major. Plus, I gotta believe it's easier to buy a bomb from the former Soviet Union than to build one. I read a report in 1991 that suggested that a radical mafia faction known as The Star bought one, though I don't know why.

And that's conclusion #2--I think that any organization that 1) had the wherewithal to buy a bomb and 2) the desire to use it, would have already done so. Consider Hamas, which basically has the full financial support of the entire Syrian government. If it was easy to buy and move a bomb, wouldn't they have done it already, at a time when the Soviet Union's borders were falling apart and no one was looking? If I was out to buy a bomb, that sure as hell is when I would have done it.

Rook is entirely correct, except for substituting pounds for tons when discussing how much uranium ore is necessary. He failed to mention two things. First, uranium hexaflouride, the uranium gas used in the gaseous diffusion process, is highly caustic. This requires both special process piping and special diffusion filters. During the Manhattan Project, these caused no end of trouble. They would cause just as much trouble today as they are not exactly off the shelf items and attempting to purchase them directly would have raised all kinds of red flags.

Second, there are other ways to seperate uranium. The most common is to use a magnetic field to seperate the isotopes by weight. This is pretty low yield and requires ungodly amounts of electricity.

I concur with Rook's assesment that it's easier to a) steal weapons grade fissionables, b) buy them from Russia or China, or c) buy a whole bomb from a source like that. Making it from scratch is a huge industrial endeavour.