Feedwater control over full power range for pressurized water reactor

Abstract

A feedwater control system and method for a pressurized water reactor steam generating system having first and second output signals. The first output signal is determined by first and second input signals, and, when combined with a third input signal automatically controls at least one feedwater pump and first designated valves which regulate water flow from the one or more feedwater pumps to a steam generator when a steam generator steam load and reactor are operating at a first predetermined power level. The first input signal is determined by a downcomer feedwater flow differential pressure. The second input signal is determined by a reactor power level. The third input signal is determined by a steam generator level. The second output signal, determined by a steam generator water level, automatically controls at least one startup feedwater control valve when the steam generator steam load and the reactor are operating at a second predetermined power level. In a preferred embodiment, the first designated valves include at least one economizer feedwater control valve and at least one downcomer feedwater control valve. Also, in a preferred embodiment, the first predetermined power level is between about 5 and about 20 percent, and the second predetermined power level is between zero and about 5 percent.