We have passed the peak of oil production. Nuclear is the only solution to mitigate the crisis we are going to face. I think we will need to get rid of nuclear at long term (like 50 years). But for the next 20 years (probably 40), we need nuclear.
https://www.bbc.co.uk/news/uk-wales-53595839 "Trawsfynydd was shut down in 1991 after operating for a quarter of a century. Magnox said it still expected the site to be completely cleared by the 2083 target."
I don't really know if any other country with nuclear power plants have any sort of a plan for what to do with it.