Uranium Fuel rod from FBR

Allow production of Uranium fuel rods for use in nuclear locomotives from FBR enrichment, which would remove the depleted uranium byproduct.
I would like the option to either produce 4% enriched uranium from enriched blanket fuel, or preferably the ability to produce 3-4 fuel rods from 1 20% enriched uranium (this would allow 20% uranium enrichment to do double duty fuelling nuclear trains and asteroid