ABSTRACT
The most common reactor coolant is ordinary water which is sometimes called light water. Fast reactors use metallic coolants such as sodium, potassium, and mercury instead. These coolants are excellent conductors of heat, and they also have very high boiling points. Liquid sodium also has a very high boiling point, and so reactor coolant loops can be operated at very high temperatures and very low pressures. This means that large, heavy, and expensive pressure vessels are not required to hold the coolant. The amount of energy required to set the coolant in motion can be expressed in terms of a parameter called the pump work. The work done by a coolant pump on a reactor coolant is an example of flow work. In pressurized water reactors, the coolant pumps are typically vertical, single-stage centrifugal pumps that can move large amounts of coolant through the core.
