PROBLEM TO BE SOLVED: To provide an equipment diagnostic method and a diagnostic system capable of presenting the diagnostic result at an appropriate time for users by appropriately setting a threshold value which determines a time to present a diagnostic result, in equipment diagnostic of a nuclear power plant. SOLUTION: The equipment diagnostic method and the equipment diagnostic system for diagnosing the status of the equipment under operation in the nuclear power plant includes the following processing; measurement for measurement data indicating status quantity of the equipment, calculation of an abnormality level of the equipment based on the measurement data, acquisition of maintenance history information on the equipment, calculation of failure possibility of the equipment from the maintenance history information, setting of a threshold value for abnormality level based on the equipment failure possibility, and presentation of a diagnostic result when the equipment abnormality level is over the threshold value. COPYRIGHT: (C)2012,JPO&INPIT
