A comprehensive program by the Duke Power Company to qualify thermal-hydraulic transient analysis methods has been completed. The cornerstone of these methods is the use of the RETRAN-02/MOD003 computer code for the prediction of reactor coolant system behavior during plant transients. A RETRAN model of the Oconee nuclear station [three 2568-MW(thermal) Babcock & Wilcox reactors] was constructed and validated by comparison with data from actual plant events. The transient data base was searched to identify those events that are challenging to the predictive ability of the code and that have sufficient information available for a meaningful comparison between the code and the data. Nine events were selected, covering the following range of transient types: loss of primary-to-secondary heat transfer, excessive primary-to-secondary heat transfer [including steam generator (SG) overfeed and SG depressurization], loss of forced primary circulation, change in core reactivity, and operational transient without reactor trip. For each benchmark, a detailed review was made of all available sources of information in order to develop a complete set of initial and boundary conditions. The plant base model was modified to match the actual initial conditions, and the event was simulated using the best representation of the key boundary conditions. Four transient benchmarks are discussed in detail. The August 14, 1984, loss of all feedwater at Unit 3 demonstrates the effect of SG dryout on the primary system. The September 10, 1982, turbine bypass valve failure involves the posttrip overcooling of the primary system due to SG depressurization. The August 8, 1982, dropped control rod group event shows the effect of a rapid change in core reactivity on the plant. The July 15, 1985, main feedwater pump trip without reactor trip is characterized by a successful runback following a large mismatch between power generation and power removal. The accurate prediction of key phenomena during these and other events provides justification for the application of RETRAN to simulate the Oconee plant response to a wide variety of non-loss-of-coolant accident transients.