My idea is to make a new form of enriched uranium fuel (or more accurately, a substitute for enriched uranium) that's made by mixing uranium-233 (transmuted from thorium in a breeder reactor) with a larger quantity of natural uranium. The uranium-233 is a substitute for the additional uranium-235 in traditional enriched uranium. This would most likely be done by countries that operate both thorium-cycle reactors and uranium-cycle reactors.
As far as I see, this would be advantageous over light-enriched uranium. This might be cheaper than uranium enrichment in the long-term. But the advantage I see in Uranium-233 is that it has a higher fission cross-section & fission/capture ratio than Uranium-235, especially at intermediate neutron energies. This may give better neutron economy for the Reduced-Moderation Water Reactor (in development), which is likely to have a broad range of neutron energies including intermediate spectrum. It also might allow reduced moderation for other reactor types, such as gas-cooled reactors. Fast reactors utilizing U-233 may require less fissile material, due to the higher fission cross-section of U-233 compared to U-235.
Surprisingly, I can't find any research papers on this idea. Would this nuclear fuel I'm proposing have any problems operating in a reactor designed for light-enriched uranium? Would it work for a reactor designed specifically for it? How would it behave differently? Would this fuel be more difficult to reprocess once spent than traditional uranium fuel?