Solar, wind and batteries have no fuel concerns, and they are inherently decentralized.
With some work and investment European nuclear fuel supply could be 100% free from Russia, which anyway is peanuts compared to billions spent on Russian LNG. Uranium ore can come from Canada, Kazakhstan and Australia, not only African countries.
They will keep working for years as you find new suppliers for spare parts. When the reach EOL you need to find a new supplier.
In the meantime the already existing required firming capacity might be run a bit harder to manage any shortfall.
But in the nuclear cult that is equivalent to still not being able to decouple Europe from the Russian nuclear industry 3 years into the war.
It's not taboo, the answer is just extremely simple: mining needs people willing to work in a dangerous and exhausting field, so when practical, rich countries tend to prefer outsourcing this (capitalism does not tend to reward ethics). It's very practical for uranium because nuclear reactors need a tiny volume which is trivial to ship and to store. Most countries with a nuclear program keep a stockpile of multiple years.
Mining uranium in other places is very feasible, as are other more expensive options like extracting it out of the ocean. After all, with nuclear the cost of the fuel is a tiny amount of the actual cost of power generation. This is not happening because there's really no need to. In the past, there have been uranium mines in pretty much every european country, see https://en.wikipedia.org/wiki/Uranium_mining_by_country#Euro...
(Refining/processing is a different story. But that's more obviously a "money/care" problem - there's no possible physical constraint for refining/processing as there could be for mining.)
Australia, Kazakhstan and Canada are main suppliers.
I know the soviets dug up half the Czech Republic for uranium deposits though. There's still some left there, not sure how much though. I have a feeling that the reliance on Africa and Russia is more price and environmental regulation driven.
Denmark also have 3700 tons of uranium ore just laying around, not sure how much actual uranium you can extract from that, very little I suspect.