Intelligent decision aids for abnormal events in nuclear power plants

German nuclear power plants are characterized by a high degree of automation, not only for normal operation but also for abnormal events. Therefore the role of the operating personnel is mainly a supervisory function. Nevertheless, for a spectrum of unexpected events the operating personnel have to react with manual recovery actions. In order to minimize human error in such recovery actions, different kinds of intelligent decision aid support the operators today. In this paper such aids are discussed and one of them integrated disturbance analysis, IDA, is described in more detail. It is applied in Biblis B reactor to the whole secondary circuit with special account of the condensate from the hotwell to the steam generator including all the support systems. (author)