Thermal and hydraulic response of the Semiscale Mod-1 core during forced feed reflood tests

Selected experimental data and results calculated from experimental data obtained from the constant reflood rate tests of the Semiscale Mod-1 reflood heat transfer test series are analyzed. These tests were designed to provide information on the core thermal and hydraulic response during the reflood portion of the loss-of-coolant accident (LOCA). The data are analyzed to determine the effects of initial system conditions on the rod cladding temperature response and the core hydraulics during the reflood process. The heat transfer coefficients calculated from experimental data are compared with those calculated using heat transfer correlations selected from the literature to evaluate the capability of the correlations to describe observed heat transfer regimes. The test data and the core thermal response calculated with the REFLUX, SUPERH, and FLOOD HT/2 computer codes are compared and the capabilities of these codes to predict the thermal-hydraulic behavior occurring in the core region are evaluated. The analyses presented in this report are valuable for improving the analytical models used to predict the core response of a pressurized water reactor (PWR) during the reflood portion of the LOCA