Yes, we can see, “enriched uranium” sounds so much more, well, more, than “uranium”. Except enriched uranium is actually less dense than natural or unenriched uranium:
[perfectpullquote align=”full” bordertop=”false” cite=”” link=”” color=”” class=”” size=””]Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 is the only naturally occurring fissile isotope, which makes it widely used in nuclear power plants and nuclear weapons. However, because of the tiny amounts found in nature, uranium needs to undergo enrichment so that enough uranium-235 is present. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. Uranium-238 has a small probability for spontaneous fission or even induced fission with fast neutrons; uranium-235 and to a lesser degree uranium-233 have a much higher fission cross-section for slow neutrons.[/perfectpullquote]U-238 – unless there’s something very weird about uranium indeed – will be denser than U-235. The process of enriching uranium is to take the U-238 away, meaning that we’re taking the denser stuff away from the less dense. And, actually, it’s this difference in mass – close to but not exactly the same as density – which we use to separate U-238 from U-235.
Ah, the joys of pendantry.
I think he thinks “enriched” means something akin to “enriched” iron ore, where you have reduced the proportion of muck compared to iron. But that’s “refined” innit?
(Digging into my memories of primary school growing up in Sheffield)
I see where you’re coming from, but that’s probably not the case, as ‘enriched uranium’ and ‘depleted uranium’ are both standard names for the results of this kind of isotope separation. Mr Worstall is quite correct to point out that an atom of U238 is going to be more massive than an atom of U235 – and hence more dense, assuming that they are the same size (though size is a bit of a hard thing to define at atomic scales). However, the density of a larger mass of the materials will depend on issues like the packing distances between… Read more »
The densest material on earth (that you could hold a lump of in your hand) is osmium – 22.65 v 19.1 for U.