Take a coal-fired plant generating electricity and a nuclear fission electricty plant. If both are running properly (within regulations), which one releases more radioactivity into the environment?
The coal plant does. Here are some links to studies on the topic:
- A U.S. Geological Service (USGS) report from 1997
- A Oak Ridge National Laboratories (ORNL) report from 2001
Of course, worst-case disaster scenarios for nuclear plants release large amounts of radiation.
And the end-of-life for nuclear power results in concentrated radiation. Of course, end-of-life coal-fired plants also leave behind their own environemental toxins, but those tend to break down more quickly.