[chris (OP)]

When we hear on the news that Iran is building centrifuges to prepare uranium for nuclear weapons or reactors, what does this mean in practical terms?

Chris

[DoctorBeaver]

A jet of gas is pumped into 1 end of the rotor, and 2 jets are taken from the opposite end. Condensation containing the heavy isotope forms in the rotor cap which is drawn off.

I think

[Soul Surfer]

The important fact is that different isotopes of an element have different atomic weights and so if you spin therm in a centrifuge the heavier ones tend to sink to the bottom and the lighter ones stay on top.  However this difference in weight is very small and you need extremely powerful centrifuges running at incredible speeds to have any effect at all in the concentration of the isotopes and even then one pass through a centrifuge will only concentrate the lighter isotopes (these are the ones that are required for fission devices) very slightly.  so you need lots of centrifuges (or a lot of passes through one centrifuge) to get any significant isotope separation.

[DoctorBeaver]

Well, yeah - there's that too  []

[chris (OP)]

So how do they actually do it - how is the uranium processed? Isn't it dissolved in hydrofluoric acid or something?

[paul.fr]

a very basic picture diagram

[syhprum]

I am curious to know what actual 'G' force is generated in the centrifuge, is the figure published or classified?

[Bored chemist]

They spin fast, you could get some idae of the G forces involved from here.
http://en.wikipedia.org/wiki/Zippe-type_centrifuge