Why Pressurized Water?


Why do we use HIGH-PRESURE WATER as coolant to carry away energy from the fuel rods? Won't the pressurization of water make it process lots of energy already? How come it can stilll be used to carry away other energy from the fuel rods?


In the pressurized water reactor we do not want the coolant to boil so we must raise its pressure above the saturation pressure for the operating temperature of the reactor coolant. Due to the relative incompressibility of the water the energy requirements to raise its pressure is a tiny fraction of the thermal energy transferred from the fuel rods. Also there is a partition of energy so that the elevated pressure does not reduce the heat capacity of the coolant.