Actually it is possible to use seawater to cool nuclear powerplants (and I would assume other types as well).

I've visited Seabrook before - http://www.answers.com/topic/seabrook-station-nuclear-power-plant?cat=te...

So it can be done. It's not common, but Seabrook has a safe record now of 18 years of operation...

The Millstone nuclear powerplant in Waterford, CT, USA uses sea water as coolant. It's been in operation since 1970 without incident, although it was shut down for a year for a safety evaluation in the nineties. But the safety issues raised were not related to sea water as far as I know. My roommate in college worked there in the eighties and said that safety protocols were very lax (so he quit, returned to college, and became my roommate). It's currently in operation.

Here's an article in wikipedia: http://en.wikipedia.org/wiki/Millstone_Nuclear_Power_Plant