An intelligent alarm-processing system for boiling water reactor (BWR) power plants is developed, to mitigate information overload for operators. To optimize the amount of information for disturbance detection, efforts are focused on alarm handling. The functions of the system are (a) to extract relevant alarms from the large number of alarms in the control room and (b) to provide the operators with a clear overview of the process status. The constituent methodologies for alarm handlings are realized by using logical expression and are implemented with a process computer. The test results of the system using a full-scope BWR plant simulator are quite satisfactory.