Under 1.8.0 (the current build), Uranium Combs are making IC2's "Crushed Uranium Ore" (NEI reckons they have a 50% chance, though I'm thinking I'm getting a bit more then that). I haven't actually tried processing the ore yet, but NEI also tells me that a Thermal Centrifuge would turn it into one "Tiny Pile of Uranium 235" and four "Uranium 238"s (assuming I didn't purify it with an Ore Washing Plant first, in which case it'd give two such tiny piles and five full ones).