Why are you comparing fossil fuels and nuclear “per tonne” that makes no sense. You replace tens of tones of nuclear fuel per year any you burn millions of tones in a comparable fosil fuel plant.
And regarding the carbon emissions from enrichment… Just use nuclear to power your enrichment plants. This way your emissions are extremely low because you don’t need much fuel and you use nuclear energy to produce nuclear fuel. French example: …m.wikipedia.org/…/Tricastin_Nuclear_Power_Plant