In a nuclear-fueled power plant – much like a fossil-fueled power plant – water is turned into steam, which in turn drives turbine generators to produce electricity. The difference is the source of heat. At nuclear power plants, the heat to make the steam is created when uranium atoms split – called fission. There is no combustion in a nuclear reactor. Here’s how the process works.

There are two types of nuclear reactors in the United States:

Pressurized Water Reactor

Pressurized Water Reactors (also known as PWRs) keep water under pressure so that it heats, but does not boil. This heated water is circulated through tubes in steam generators, allowing the water in the steam generators to turn to steam, which then turns the turbine generator. Water from the reactor and the water that is turned into steam are in separate systems and do not mix.

View animated image of a Pressurized Water Reactor

Source: Nuclear Regulatory Commission

Boiling Water Reactor

In Boiling Water Reactors (also known as BWRs), the water heated by fission actually boils and turns into steam to turn the turbine generator. In both PWRs and BWRs, the steam is turned back into water and can be used again in the process.

View animated image of a Boiling Water Reactor

Source: Nuclear Regulatory Commission

Power plants are one of our current substantial power energy resources that we rely on. However they have their very controversial bad points. They are highly linked to global warming and some may say one of its biggest contributors.  

http://www.duke-energy.com/about-energy/generating-electricity/nuclear-how.asp (Accessed: 27/02/2013)