Check this out. On the left, the cooling tower for a nuclear power plant near Oswego, NY. Contrary to popular belief, that tower is not the reactor smoking. All it is is a big radiator (like in your car), where they pump hot water into to be cooled by the water from Lake Ontario. Ever wonder what it looks like inside the control room of a nuclear power plant? Look at the picture on the right. Each of those little squares represents a fuel rod and it's position inside the reactor.
Want to build your own? Click here.
But, before you try to build one yourself, you should read about this guy in Michigan, David Hahn, who did. Try.