there's a longer supply of fissiles than of fossils
and crucially, we're fairly well aware of the finite availability; at the *beginning* of the useage curve. If the public knew how scarce oil really was back when oil first kicked off; would it have been so misused? (Oil- and gas- fired power stations FFS!*) We have now a fairly good idea how much accessible nuclear fuel** there is; which is the cornerstone of budgeting it's use.

* I know, useful for short lead-time temporary capacity; but it shouldn't be used for regular generation just because gas is cheap at that moment.

** According to wikipedia, A 1,000 MW coal-burning power plant could release as much as 5.2 tons/year of uranium (containing 74 pounds (34 kg) of uranium-235) and 12.8 tons/year of thorium. So could we run nuclear-stations off coal-station waste?
(The Incredible Sulk Finally remembered his password on, Fri 20 Feb 2009, 5:49, Reply)