What is a nuclear reactor?

A nuclear reactor is a system that contains and controls sustained nuclear chain reactions. Reactors are used for generating electricity, producing radionuclides (for industry and medicine), conducting research, and military purposes. A nuclear reactor produces and controls the release of energy from splitting the atoms of certain elements. In a nuclear power reactor, the energy released is used as heat to make steam to generate electricity. (In a research reactor the main purpose is to utilise the actual neutrons produced in the core. In most naval reactors, steam drives a turbine directly for propulsion.)

The principles for using nuclear power to produce electricity are the same for most types of reactor. The energy released from continuous fission of the atoms of the fuel is harnessed as heat in either a gas or water, and is used to produce steam. The steam is used to drive the turbines which produce electricity (as in most fossil fuel plants).

Courtesy of NRC USA and Mr.Shamsul Amri, TNB Nuclear Division