Graduate Thesis Or Dissertation


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  • A literature review of current phase separation publications was conducted. Data sets were collected and compiled into a Two-Phase Flow Separation Database. Examination of this database indicating a need for further investigation into the liquid entertainment phenomena for smaller hot-leg to branch diameters and intermittent flow regimes. A detailed analysis to the prototypic phase separation process is presented and the associated phenomena are identified. Appropriate scaling criteria were employed for the design of a scaled test facility. Geometry and the flow conditions of the test facility were determined accordingly to Wu et. al (1998). A series of phase separation tests conducted at the Air-water Test Loop for Advanced Thermal-hydraulic Studies (ATLATS) and Advanced Plan Experiment (APEX) has been completed. Results show that the criteria developed by Smoglie (1984) used in RELAP5, reasonably predicts the onset of liquid entrainment. However, the steady-state entrainment correlation in RELAP5 significantly underpredicts primary coolant removal rates. This discrepancy is due to the effects of downstream boundary conditions and pool entrainment and carry-over from the reactor vessel. Due to pool entrainment, entrainment through the branch continues when the reactor vessel mixture level drops below the bottom of the hot-leg. This investigation shows that RELAP5 is non-conservative when predicting coolant removal rates due to steady state liquid entrainment in a horizontal mainline with a vertical branch for stratified, stratified-wavy, transition, and stepped hot-leg flow regimes.
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