A very important aspect of nuclear steam supply system (NSSS) model development is the process of comparing the computer model results against actual plant responses. Good comparisons will qualify the computer model for specific engineering analyses. Flow rates and decay heat power levels were obtained from planned and unplanned natural circulation events that occurred at Arkansas Nuclear One, Crystal River, Davis-Besse, and Oconee nuclear power plants. A one-loop RETRAN model of the Oconee NSSS is used to attain a spectrum of steady-state equilibrium conditions at different power levels of 25, 50, 75, and 100 MW. The benchmark comparisons are respectable. The comparisons also illustrate the ability of the Babcock & Wilcox raised-loop plant to induce a greater natural circulation flow rate.