The thing with nuclear reactors is that they don't go off that easily or that often, but when they go off, the impact is both very large (Chernobyl spread to Bavaria!) and very long-lasting in its impact (Chernobyl is still a no-go zone, and to this day you have to inspect and throw away game and shrooms collected in Bavaria if it is impacted by radiation).
Coal power plants have a much larger impact, new ones have been cleaned up, but in the 1960s they were putting lots of radioactive waste into the air which rained down around the world and is still there.
