Abstract: In a nuclear reactor the feedwater control system receives steam generator water level signals, including information to determine signal quality. The signal quality and additional signal validation determine how the water level signals are to be used by the feed-water control system. In the preferred embodiment, each water level signal is compared with a possible range and the difference or differential between all possible pairs of the signals is calculated and compared with an acceptable differential range. While alarms are sounded if any of these checks on the water level signals indicate an invalid signal, the water level signals are used to calculate a median level signal until there is less than two water level signals with good quality within the possible range or all differentials are outside the acceptable differential range.

Abstract: A system for improving the performance of nuclear power plant feedwater control systems and simplifying steam generator low water level reactor protection logic includes a plurality of water level channels for measuring steam generator water level and generating a plurality of signals representative thereof. The median steam generator water level signal is selected from among the plurality of steam generator water level signals. The median steam generator water level signal is then communicated to the feedwater control system through an output interface.