A nuclear accident could easily release a lot more radiation than a coal plant. You are confused by the often-quoted fact that when operating normally, a coal plant can release more radiation. An accident though means the plant is not operating normally.
This may mean that the risk from the radiation from either type of plant when operating normally is pretty low. It's fun to point out that more radiation comes from a coal plant, but I'm pretty certain the danger from breathing the other crap that comes out of the coal plant way outweighs the radiation danger.