Nuclear create no polution (emission gases), altough it does create radioactive waste, but the waste itself can be isolated by burying the waste underground (at depth about 500 m) so that it will not contaminate the environment. Or, the waste can be isolated somewhere safe, and thus, there is a way to decrease the radioactivity by decreasing the neutrons activity, so the waste will degrade sooner than just leaving it to degrade naturally. All of that is the way to just throw the "trash" away, you can also recycle some of the waste for power plant usage or medical usage.....
(PS: This answer is based on my theory mixed with some internet sources, for more accurate theory, browse online)
(PS: This answer is based on my theory mixed with some internet sources, for more accurate theory, browse online)