The World Nuclear association and nuclear related (no skeptics) talk about 80-100 years for sure with present reactors and present technology and present price.

They claim 3 million tones of Uranium of known reserves in well-developed and audited countries. Check any web site

http://www.world-nuclear.org/education/mining.htm

http://www.world-nuclear.org/education/mining.htm

The same mining companies claim that an increase in the uranium price  (doubling it) would put the useful reserves at 10 million tones.. with a limit of 300 years

Skeptics would probably say that  it is very optimistic..and that you could recover much more less. Being very (VERY VERY) pessimistic I would say that you have 60-80 years at present rate.

To cover gas you need to mutiply by three , which would put you at 20-30 years. Considering the huge quantities of Uranium which can be used from the weapon race.. even an skeptic would accept 10-20 more years of the diposits of weapons materials.

And then you have to recall that oil is twice coal.. so you would need anther factor three. This puts you in the 10-20 limits

An increase of 5% energy use will bring it to the 5-10 years (a standard, present 1-2% growth will put you back at 10-20 years.. but again you could be VERY VERY pessimistic about weaponry and Russia and the US not demossioning all the arsenal they claim to dismantle).

As you may know I am quite sure there are around 200 years reserves (with high degree of reliance) at present consumption all things nuclear considered (uranium,  recovery, reprocess 150+30+20 years)... so I would put the reserves in a full transition (coal and oil) at around
40 years minimum. BUt more important, since I defend only the substitution of coal, the reserves would be rouhgly 70 years.

A pleasure

I therefore claim to show, not how men think in myths, but how myths operate in men's minds without their being aware of the fact. Levi-Strauss, Claude