Control rods - Control rods are movable roads that readily absorb neutrons in a thermal fission reactor.

Degraded Energy - Energy transferred to the surroundings that is no longer able to perform useful work.

Energy density - The amount of energy released per unit mass of fuel consumed. It is measured in J kg-1

Enrichment - Enrichment is the process by which this percentage composition of a fuel is increased to make nuclear fission more likely

Generator - a coil of wire rotated in a magnetic field to produce electrical energy from mechanical energy.

Heat exchanger - The heat exchanger allows the nuclear reactions to occur in a place that is sealed off from the rest of the environment in a thermal fission reactor.

Moderator - Collisions between the neutrons and the nuclei of the moderator slow them down and allow further reactions to take place in a thermal fission reactor.

Sankey Diagram - Energy flow diagrams that identify where the energy is transferred.