I think we are probably at cross purposes. I was simple...

I think we are probably at cross purposes. I was simple referring to UF6 being the same for all isotopes of uranium (i.e U238, U236, U235, U234, U233 & U232 - all others have half lives of fractions of secs & minutes or a few days/weeks and unlikely to be present in RepU held in a pond for 10 years). Agree that fuel bundles need to converted to UF6 - I think Moosey answered your question about this being practical (Tenex and Areva have done it) but due to the presence of U232 needs special handling (U232 daughter products are high energy gamma emitters). I Can't see any way around this for turning RepU into UF6. Once as UF6 it would seem possible using silex to:

1. Enrich the U235 isotope in RepU without concentrating the U236, U234 & U232 which with centrifuge enrichment becomes more radio active due to centrifuge being even more efficient at enriching isotopes of uranium lighter than U235 than the U235 itself (i.e the RepU after enrichment has proportionally more U232 than the raw product). Thus enriched RepU is even more difficult to handle thus making the recovered fuel bundle and loading processes more complex.
2. It would seem possible that once the RepU was in UF6 form the U232 could be removed (or at least diluted) by the Silex process to make the resulting enriched UF6 compatible with current downstream process handling for natural uranium products. In addition by removing U234 and U236 (nuclear poisons) the fuel product would not need as much compensating enrichment of U235 were these poison present.

When the BWR is licensed to a maximum of 5% U235reduced concentration of poisons important and if these poisons can also be removed the product will be of higher quality, easier to handle and can be reused more time. Another option for REMIX is to blend the product with natural enriched uranium and possibly Pu to make the fuel more attractive.

The USA has to find a home for it's surplus 35T of weapons grade Pu to meet its obligations to the Russians, you can be sure that Putin would ask an arm and a leg for the Russians to take the US surplus Pu to generate "free" electricity in their VVER - 1000 reactors.