One thing that needs to be stressed is that realistically there is a rather limited amount of Uranium than can be extracted from the earth for nuclear power. That if we could magically convert to 100% nuclear power - it wouldn't last that long.
from wikipedia
"Still, the world's present measured resources of uranium, economically recoverable at the arbitrary price ceiling of 130 USD/kg, are enough to last for between 70 and 100 years"
https://en.wikipedia.org/wiki/Nuclear_power#Conventional_fue...
reactors have a life of around 60 years I think. So maybe you could double the amount of nuclear power? But it's not like the world can magically go to 100% nuclear indefinitely.