France, a rich, functional, liberal, western democracy, is more or less uncontroversially nuclear powered to a very high degree. There are no more practical difficulties than any other large, important project. The only problem is politics.
Personally, I think it would be an enormous mistake not to invest enough to at least assess the feasibility/practicality of cleaner nuclear sources. I really hope France keeps on investing in nuclear energy & research.
Especially compared to the fate of nuclear in most other countries around Europe.
It turns out that nuclear physics is really quite hard. That is not a reason to not do something. But we shouldn't take these issues so lightly.
Or, put in another way: the hardness isn't why we're not doing it.