Technical Note

USS Clueless has a good primer on the Iraqi reactor at Osirak that was destroyed in 1981 by Israel.

There is a little tiny technical blip worth noting (and no, it doesn't detract in any meaningful sense from the overarching article) and I wanted to touch on it simply because a lot of people are unwaware of it.

While most folks know that a big step in producing weapons grade Uranium is seperation of isotopes to get large amount of U-235, while the Plutonium deal is getting Pu from irradiated U-238.

However, beyond that, the Plutonium isotopes themselves need to be further separated.

Pu 239 is the isotope preferred in weapons systems, while Pu 240 is preferred for power generation. The difference is that Pu 239 is relatively more difficult to make react than Pu 240. So starting a chain reaction is a bit easier with Pu 240, making it easier to use in reactors. Conversely, the problem with Pu 240 in weapons is that it can (if the concentrations are high enough) cause the device to start reacting too early. By starting off too early, the device would "fizzle" and while still producing a large weapon, would not create nearly as large an explosion as the weapons was intended to produce.

More reading on fissile materials can be found here.