How nuclear power can be styled as 'clean energy' is beyond me. Suppose it is if you totally ignore the thousand years or so half life of of the waste.
Two reasons it is ultimately clean:
Carbon is the main problem causing global warming and nuclear power isn't a CO
2 generator.
Most of the nuclear waste from ALL stages (mining to consuming in conventional reactors) is depleted uranium which is also a fuel if used in fast breeder reactors. We already have good working fast breeders** but don't do that at present since it is more expensive, but we will when uranium runs out and if we haven't succeeded with fusion. So then almost all of that waste will become a very precious fuel.
** French Phoenix and Superphoenix, Russian BN300 and BN 800. The USA had already nominated the BN800 as their chosen fast breeder design if that day arrives, though they have produced their own design since, the travelling wave reactor (TWR).
We also produced two, at Winfrith Heath and Dounreay, but made a terrible mess of it with the Dounreay pollution and resulting clean up still present. So hopefully we'll buy French again as we do at present if that day arrives
.