No. In natural uranium, there are three isotopes. It's basically just three forms of the uranium which have different atomic masses. As I said the weight, some are less stable and some are more stable; you've got the most stable one, which is uranium-238, with a mass of 238. The next one is uranium-235, with a mass of 235, and then there's uranium-234. In normal, natural uranium, these are present in a fixed ratio.
When you use uranium to make fuel for reactors, then you sometimes want to increase the amount of uranium-235 in the fuel, which is the fuel component in the uranium. You can burn uranium-238 in fast reactors, but not in normal reactors. So they enrich the uranium by putting it through a separator, which means there's more 235 than there normally is. Instead of being about 0.07%, it goes up to 3% or 5%. At the moment, the big argument is because the Iranians are producing 20% enriched uranium, which means that 20% of the atoms would be this 235-type.
When you do that, you end up with uranium that has less uranium-235 as a by-product. We call that depleted uranium. The original thought was, well, we'll use this as breeding material in plutonium-generating fast reactors. That was the idea. Then other uses came up. It was used as a chemical because it's safer than natural uranium. Almost immediately all the fine chemicals used in chemistry labs and things like that, including uranium salts, were switched over to depleted uranium salts. Its weight was used by Boeing as counterweights in the surfaces of aircraft. It's used in a wide range of applications, including military applications for penetrators, and also armour. The United States actually uses depleted uranium as part of the armour in their Abrams tanks.
So there's a wide range, but that's the leftover product, so it's not a decay product. It's basically where you've taken the natural uranium and you processed it so that part of it is enhanced, and in the process of doing this you've created some uranium that has less radioactive material in it. You typically get about a 60% reduction in uranium-235, and 80% or 90% reduction in uranium-234.
The critical thing is that people tend to think of depleted uranium as something that is fixed, but the reality is that any uranium containing less uranium-235 than found in natural uranium is officially depleted uranium. So depleted uranium hasn't got one composition, but a variety of compositions, depending on where it came from. Most of the material that was used by the armed forces came from the Paducah plant in the United States, and there the composition always remained the same. That's the material that's used in three places. The U.K. uses it for its CHARM3 armour-piercing rounds in tanks and it's used in Phalanx guns as well. The Americans use it as well in the Warthog A-10 aircraft, which Britain doesn't operate. Those are the three uses for it.
I think in Canada, then, the only usage was in the Phalanx in the navy, and I'm not even sure if that's still ongoing. That gun has probably been taken out of service.