A steady-state simulation of a 19-tube model once-through steam generator (OTSG) was performed with the TRAC-PF1 thermal-hydraulic computer code. The predicted steady-state results were not in good agreement with the experimental data. Underprediction of the observed superheat temperature was obtained. The current safety analysis computer programs use the Chen correlation. A modification in the Chen boiling correlation produced satisfactory results for use in OTSG analysis.