Integrated alarm annunciation system with dual communication capability and operator assisted messaging for nuclear power plant applications

Integrated Alarm Annunciation System (AAS) in a Nuclear Power Plant (NPP) is an electronic unit which receives alarm signals from various plant control systems, receives operator inputs and controls the windows as per a standard alarm sequence. The AAS is located in the control room. In Fast Breeder Reactor (FBR), AAS receives alarm signals from plant control systems in the form of potential free digital input contacts. Important safety systems directly issue potential free contact signals to the AAS. However, less significant systems raise alarms in the form of Ethernet packets and are converted into digital signals using a separate Alarm Generation System (AGS). This segregation is used, to maintain high reliability of important systems as well as to reduce cabling in the case of less significant systems. The important aspect in the design is that any failure in the module receiving Ethernet packets has no affect on the module which receives the potential free contacts. The AAS is CPLD based. The system also has additional features like driving text to LCD/LED screens for operator information along with the Alarm log window. The AGS also have a built in self testing (BIST) feature to periodically test the healthiness of the system and indications for failures. The significance of this system focuses entirely on FBR control rooms. This paper discusses the real time implementation of the above mentioned AAS for the NPP using CPLD.