Coal is cheaper, and also plentiful in the US.
It's also very dirty, both to mine and to burn. It even releases more radioactive waste than nuclear does, and unlike in nuclear plants this stuff is not concentrated and collected - it just wafts away into the air, into your lungs.
Coal plants are cheaper to build but power from nuclear plants is produced at far lower costs than coal. Look at the run up in coal prices and you'll see that it isn't as cheap as it used to be.
http://www.eia.doe.gov/cneaf/coal/page/coalnews/coalmar.html
No free lunch on these, either:
Only Two Things Wrong With Coal, You Can’t Mine It, And You Can’t Burn It
So say the wackos, anyway. Time to go back to the caves and bearskins.