The operators of nuclear power plants are generally trained to handle a standardized set of typical accidents. This set is designed to define a package containing the event combinations that might be hypothesized. Because of the large number of hypothetical events, diagnostic ability requires continuous training. The development of, and experience with, a flexible training device is described that basically presents realtime scenarios. It could be shown that even complex events can be displayed successfully. Real plant transients as well as those calculated with sophisticated computer codes can be displayed. Test sessions with responsible technical personnel at reactor plants in the Federal Republic of Germany demonstrated the capabilities of the system.