Abstract: A method is provided for recovering operating margin in a nuclear reactor. The reactor includes a steam generator, a Reactor Coolant System (RCS) having a hot leg with a temperature, Thot, and a cold leg with a temperature, Tcold, a Reactor Trip System (RTS) having an Over Temperature Delta Temperature (OTDT) trip function and an Over Power Delta Temperature (OPDT) trip function, and a control system. The method improves the RTS by filtering only the hot leg temperature signal of the RCS. Thus, the needs for separate Tavg and Delta-T filters, and for filtering of temperature signals in both the hot leg and cold leg are eliminated. A reactor system is also disclosed.

Abstract: A method is provided for determining and controlling feed water level in a steam generator of a nuclear power plant, whereby the water level sensor is calibrated in terms of the pressure drop across structural components in the feed water path. The water level differential pressure sensor is calibrated so that maximum water level is indicated as the level corresponding to the upper tap level plus the pressure drop across the foregoing structural components at maximum power plant power.

Abstract: A method of controlling the feedwater flow to the secondary side of a steam generator in a pressurized water nuclear reactor monitors various process variables such as the feedwater and the steam flows and pressures around the secondary side of the steam generator and then generates process signals based upon the process variables. An error signal based upon selected process signals is generated. The error signal is filtered by a deadband filter network for generating a control signal with a deadband. The control signal with a deadband is sent to a proportional-integral controller for generating a demand signal. The demand signal is then sent to an operator such as feedwater valve positioner or a feedwater pump speed controller for controlling the feedwater flow into the steam generator.