In a nuclear station electricity is generated through heat which turns water to steam in steam generators. The steam is then used to drive turbine generators. This is similar to the process of generating electricity in a coal-fired steam station. The main difference is the source of heat. In nuclear power stations uranium atoms undergo fissioning or splitting. The chain reaction produces heat which is transferred to water. In coal-fired steam stations burning of coal is the source of heat.
There are two types of nuclear reactor in common usage today—the boiling-water reactor (BWR) and the pressurized water reactor (PWR). In BWRs, such as the ones at Fukushima Daiichi, the heated water is allowed to boil and turn into steam to turn the generator. In PWRs, which constitute many of the western nuclear power plants, the heated water is kept under pressure so that it heats but does not boil (see picture below). Water from the reactor and the water that is turned into steam are in separate pipes and never mix.
In both types electrical pumps keep the water running and an additional water system (connected to a cooling tower or e.g. a lake) cools the steam.
For more information see:
- US Nuclear Regulatory Commission
- BBC News, Uncertainty surrounds Japan’s nuclear picture
- Generating Electricity with Nuclear Power (Duke Energy)
- How Nuclear Power Stations Work (PDF, Department of Atomic Energy, India)
- US Department of Energy (Resources for students)
- US Department of Energy (Resources for teachers)
Also of interest
- Nuclear Meltdown
General facts on a nuclear meltdown
- General Facts on Radioactivity
General facts on radiation, inhalation and radioactive isotopes