How can you call it clean when there is a unresolved waste problem?
With per megawatt waste for nuclear per 20 years being exponentially smaller in volume.
And where the alternative is coal /natural gas (rather than wind or solar) where these produce more volume of waste in a month/year than nuclear does in a decade. (And in the case of coal, we store worse waste in ways it often enters our fresh water supplies.
Hydro is bad for the local environment.
Nuclear has a minor waste problem which isn't really that bad.
None of these are perfect solutions. Nuclear shouldn't be ruled out of a green mix.
Storage isn't that expensive, E.g. through gas. E.g. Germany maintenances Gas storage (currently filled with non renewable gas) that can power the entire country a Quarter of a year. Without the actual need through renewables.
Nuclear with waste management would have to be cheaper than that.
(Aside from the subjective evaluation of the associated risk of nuclear energy)