Nuclear power station. Turbine (left) and steam generator (right) in a pressurized water reactor (PWR) nuclear power station. A PWR nuclear power station uses nuclear fission reactions to heat water under pressure. The water acts as both moderator (controlling the rate of the reaction) and coolant (absorbing and transferring the energy produced). The heated water itself heats water in a separate cooling loop, and this water turns into steam and drives the turbine seen here. The rotation of the turbine by the steam generates electricity. This turbine, an advanced model known as an Arabelle turbine, is part of the Chooz B1 nuclear power station in the Ardennes region of France. Brought online in May 2000, the power plant generates 1500 megawatts of power. Photographed in 2004.