Yes, building reactors is too expensive. However, that's mostly because the people building them in the US are utterly incompetent (source: I'm a Georgia Power ratepayer on the hook for Plant Vogtle 3 and 4) and also because every project has to fend off an army of unfounded lawsuits from misguided environmentalists.
The waste issue is mostly just fake: not only do we have a perfectly good place to put it that we refuse to use for stupid reasons, even that was unnecessary to begin with because we should be reprocessing it instead.
Insurance, sustainability, waste, catastrophic risks, centralisation are all factors against nuclear energy and everything considered, I wouldn't call it clean.