From memory, suggest fact check, the French nuclear subs use less enriched uranium so require more frequent refueling. If the French agreed to give us access we would basically be acquiring nuclear technology to be able to maintain them ourselves. I think the US/UK lawyered their way around things. They provide more highly enriched fuel which is closer to weapons grade, and so more of a proliferation risk. However it goes back to the US for servicing very infrequently (10 yrs or something) and we claim we just operate the reactors and there is no technical proliferation? Or something like that. Like everything from the US I would guess the reactor tech is more like a rental with extensive T&C.

Converting the French subs to diesel seems to have been a source of problems. If we had been up front with France about the US/UK promising nuclear subs they might have been open to negotiation. We took the first offer like suckers.