Nuclear waste is still an unsolved problem that absolutely no one wants to touch with a ten foot pole. Also nuclear power is a pretty expensive method of power generation and can't be insured, leaving all risk of disaster on the shoulders of society. To be clear: society will be pretty fucked when a nuclear disaster happens anyway.

It's a lot better than coal, though.

It's unsafe, not renewable, not independent from natural resources (which might not be present in your country, so you need to buy from dictators) and last but not least crazy expensive.