A miner on uranium with the vanilla production chain, no kovarex, produces around 14MW worth of uranium. With kovarex enrichment, it goes up to 92MW per miner.
Producing uranium fuel assemblies, a single miner accounts for 12.5MW worth of uranium. 25MW per miner if running the enriched uranium recipe.
Mixed oxide has too many permutations for me to bother listing, since it uses byproducts as fuel, including its own byproducts, but it can be much more efficient than even vanilla kovarex.
Perhaps you forgot to account for the vanilla uranium fuel cell recipe yielding 10 per craft? This also leaves out the fact that nuclear reactors now have only a 10% neighbouring bonus, instead of the vanilla 100%. A vanilla 1440MW nuclear powerplant would be 5x2 reactors, consuming an uranium fuel cell every 20 seconds. That's 7.14 ore per second -> 28.5 miners -> 50MW per miner without kovarex, the most basic setup.
By now I've playtested this on a 1000x science requirements server with a few other people. Uranium was being mined much more heavily than in vanilla, but wasn't scarce enough to require exploring new chunks just for uranium ore patches. Balance-wise it seemed just right, but if you have a different experience in-game I'd love to hear about it.
