Excerpts from netnews.sci.electronics: 16-Apr-93 Re: What do Nuclear
Site's .. by R_Tim_Coslet@cup.portal. 

Great Explaination, however you left off one detail, why do you always
see them at nuclear plants, but not always at fossil fuel plants.  At
nuclear plants it is prefered to run the water closed cycle, whereas
fossil fuel plants can in some cases get away with dumping the hot
water.  As I recall the water isn't as hot (thermodynamically) in many
fossil fuel plants, and of course there is less danger of radioactive
contamination.