Abstract: Provided is an apparatus for controlling a gain according to a water level change rate of a steam generator in nuclear power plants.

Abstract: An apparatus for controlling an output of a pressure setting signal to automatically control a steam bypass control system includes a pressure setting signal output unit for outputting a pressure setting signal according to a cold leg temperature of a reactor coolant; a first logic value output unit for outputting a first logic value that is changed according to reactor power; a second logic value output unit for outputting a second logic value that is changed according to a temperature difference between an average temperature of the reactor coolant and a reference temperature; a NAND gate circuit unit for outputting an inverse logic value according to the first and second logic values; and a first output control unit for controlling whether to output the pressure setting signal according to the inverse logic value of the NAND gate circuit unit.