The article discusses an approach that combines expert systems and dynamic models in an intellectualized operator information support system (IOISS) for nuclear power plant units. The main goal of this approach is to provide operators with the most complete and accurate information for the efficient management of power units (PU). The main functions of the IOISS of NPP PUs are highlighted, and a path is proposed for their full-scale implementation based on the use of predictive dynamic modeling of PU parameters and expert systems (ES). The use of predictive dynamic modeling makes it possible to predict the behavior of a power unit based on available data and calculate optimal control parameters. ES, in turn, provides expert knowledge and specialist experience, allowing operators to make informed decisions and respond to possible emergencies. The structure of the ES, which is part of the IOISS and includes modules for data analysis, decision-making, and information visualization, is considered. All these components work together to ensure the efficient and reliable operation of NPPs. This approach to IOISS is the basis for developing upper-level systems for instrumentation and control systems of NPPs. It can significantly improve the safety and efficiency of power units and simplify operators' decision-making process.