Power control of nuclear power plant units

The power of up-to-date pressurized water reactors can be controlled in the range of 15-100% of the optimum output. In WWER type reactors the average temperature of the primary coolant or the pressure of the secondary coolant circuit can be regarded as major control parameter. According to these aspects, different kinds of power control philosophies can be distinguished. Reactor power is affected by reactor-related activities, i.e. the movement of control rods or changes in boric acid concentration. The power control system of the Paks-1 reactor including the control and safety system as well as the manual and automatic power control of the unit are discussed. Possibilities of operation at different power, thus the role of nuclear power plant in the Hungarian electricity system are mentioned. (V.N.)