In passing heat from a "hot source" to a "heat sink", all thermal electric power plants produce mechanical energy, that they then transform into electricity. Conventional plants use the heat given off by the combustion of fossil fuels (fuel oil, coal, gas) and nuclear plants that resulting from the fission of uranium or plutonium atoms. The heat produces steam. This latter is then expanded in a turbine which drives a generator producing 3-phase electric current with a voltage of 400,000 V. After pressure reduction, the steam then flows into a condenser where it cools in contact with tubes containing circulating cold water from the sea, a river or a cooling tower.

Each reactor comprises a nuclear island, a conventional island, water intake and discharge infrastructures and possibly a cooling tower.

The nuclear island mainly consists of the nuclear steam supply system comprising the primary system and the systems designed for reactor operation and safety: the chemical and volume control, residual heat removal, safety injection, containment sprinkling, steam generators feedwater, electrical, I&C and reactor protection systems Various "support" function systems are also associated with the nuclear steam supply system: primary waste treatment, boron recovery, feedwater, ventilation and air-conditioning, backup electrical power (diesel generating sets). The nuclear island also comprises the systems removing steam to the conventional island as well as the building housing the spent fuel interim storage pit.