I use to be a Rad worker and have even cleaned up a few "spills". Nuclear accident fears are based on accidents that occurred in plants that were designed with primitive nuclear technology by people who were just starting to understand the technology. Innovations like pebble bed reactors make release of fission particles highly unlikely. Just like rocket technology though nuclear technology has advanced leaps and bounds. It's also the only power source that could get us to Mars.
Accidents occur but this needs to be compared with alternative sources of energy. Even dams cause much more environmental issues and casualties than nuclear [1]. And let's not even talk about coal.