RELAP5-3D modeling of PWR steam generator condensation experiments at the Oregon State University APEX facility

This report describes modeling using RELAP5-3D of a series of six steam generator U-tube steam condensation (without non-condensable gas) tests conducted at the Oregon State University Advanced Plant Experiment Test Facility from 2005 through 2007. These tests were designed to evaluate steam condensation rates in a scaled pressurized water reactor steam generator at various primary and secondary side pressures and inlet steam mass flow rates. Comparisons between the experimental data and the RELAP5-3D model results are made to quantify the effectiveness of RELAP5-3D in handling steam condensation in U-tube steam generators. RELAP5-3D tends to over predict the condensation rate and heat transfer coefficient when compared against the experimental data when the code uses the laminar Nusselt correlation to determine the heat transfer coefficient. When RELAP5-3D results are used with the Shah correlation the comparison between the heat transfer coefficients is much improved.