Nuclear plants generate pollution; how much depends largely upon how quickly those responsible for storing high-level waste get fed up with storing it. Even if the high-level waste is safely contained indefinitely, low-level waste causes some degree of pollution, as does mining uranium ore.
Solar, wind, wave, tidal, hydro and geothermal power all have much lower levels of pollution than fossil fuels. Most of the pollution arises from the construction and eventual disposal of the plant.