The key components common to most types of nuclear power plants are:
- Neutron moderator
- Coolant
- Control rods
- Pressure vessel
- Emergency Core Cooling Systems (ECCS)
- Reactor Protective System (RPS)
- Steam generators (not in BWRs)
- Containment building
- Boiler feedwater pump
- Steam turbine
- Electrical generator
- Condenser
Conventional electrical power plants all have a fuel source to provide heat. Examples are natural gas, coal, and fuel oil. For a nuclear power plant, this heat is provided by nuclear fission inside the nuclear reactor. When a relatively large fissile atomic nucleus (usually uranium-235 or plutonium-239) is struck by a neutron it forms two or more smaller nuclei as fission products, releasing energy and neutrons in a process called nuclear fission. The neutrons then trigger further fission. When this nuclear chain reaction is controlled, the energy released can be used to heat water, produce steam and drive a turbine that generates electricity. It should be noted that a nuclear explosion involves an uncontrolled chain reaction, and the rate of fission in a reactor is not capable of reaching sufficient levels to trigger a nuclear explosion (even if the fission reactions increased to a point of being out of control, it would melt the reactor assembly rather than form a nuclear explosion). Enriched uranium is uranium in which the percent composition of uranium-235 has been increased from that of uranium found in nature. Natural uranium is only 0.72% uranium-235; the rest is mostly uranium-238 (99.2745%) and a tiny fraction is uranium-234 (0.0055%).
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