There's "uranium in the planet" - lots! - and "uranium accessible to humans" - not so much.

The other fuel used would be plutonium and thorium, I believe. My understanding (not a nuclear scientist) is that there's a cycle of enrichment and decay that produces more fissile materials than it consumes.

Interestingly, from my perusal of wikipedia, it seems like you effectively can recycle the uranium isotopes indefinitely in such a reactor, as well as generating fissile plutonium and thorium.

Again, the problem is that generating fissile plutonium is how you make a bomb