Safety aspects of the modernization of I and C and process information in nuclear power plants with special regard to alarm annunciation

In particular for older German nuclear power plants there are projects to modernize I and C and process information systems. This modernization mainly aims at improvements in plant operation. For instance, using modern computing technology, the plant operation can be optimized, according to further details. Furthermore, the problem of spare-part keeping for out-dated components can be solved. For modernizing the I and C or the process computer system, safety-relevant aspects have to be taken into account. For instance, the compatibility of the system modification with the existing alarm annunciation concept shall be considered, and for each modernization step, the interfaces between the equipment of different safety significance shall be assessed and observed. The functions and the associated equipment have to be qualified in accordance to their safety significance. At present, the regulatory framework for computer-based instrumentation and control as well as for information systems is being elaborated in Germany and worldwide. Recently, the guidelines of the German Reactor Safety Commission have been extended with regard to the introduction and safety application of modern computer-based I and C in nuclear power plants. Furthermore, some of the essential requirements for design and qualification of modern I and C can be derived from the existing rules and standards. Particularly, concerning the alarm annunciation system, this report summarizes safety-relevant aspects of the modernization of the instrumentation and control system as well as the process information system in nuclear power plants. (author). 4 refs