Emergency measures are planned to counteract unexpected, major events in nuclear power plants in order to prevent damage to the reactor core or, at least, limit the radiological impact on the plant of such events. In such events, an emergency organization is convened whose members know the margins remaining in the plant under extreme conditions, which it will then have to exploit. In the interest of observing higher-level goals of protection it may even be necessary, in extreme cases, to take decisions which take precedence over competing actions resulting from interlocks and reactor protection steps. Drills of the emergency staff are to take this aspect into account. The drills thus serve to improve the training of, and cooperation among, the persons delegated into this emergency organization in an effort to test existing technical and organizational means under the most realistic conditions. Employing the nuclear power plant simulator in such emergency drills offers the advantage of allowing the sequences of events and technical developments to be shown impressively, as the measures taken by the plant personnel cause clear and irreversible feedback by the simulator. The drills performed at the Biblis nuclear power station with the inclusion of so-called on-line drills using the simulator have proved their effectiveness and will be continued. If an on-line drill were impossible for specific reasons, at least the desired scenario of the drill will be prepared in the simulator. The drills will later be integrated as modules into the simulator retraining courses, thus allowing roughly the same sequence of steps, and the same level of knowledge, to be shared with the entire plant crew.
