[en] This report documents the first task of a multi-task project to develop, implement, and demonstrate an on-line analysis procedure for power plant disturbances. The objective of such a procedure is to provide the operating personnel with early recognition and diagnosis of plant disturbances and recommend timely corrective action. This is expected to reduce the number of outages and therefore increase plant availability. Although the procedures to be developed will have applicability to the general process systems of a plant, the scope of the analysis and demonstration attempted in this project is limited to a representative set of disturbances in two plant subsystems. The objectives and functional requirements for an on-line disturbance analysis system (DAS), the plant subsystems selected for analysis and demonstration, and the functional requirements and preliminary outline of the DAS design are reviewed. Illustrative examples are cited and some basic criteria for evaluating the DAS are highlighted