Investigation of two-phase flow characteristics in the BWR steam separator -- Air-water experiment and 3D two-fluid model analysis

Two-phase flow with swirl motion in the BWR steam separators was examined both experimentally and analytically. Experimentally, one third (1/3) scale model of the current ABWR steam separator was tested din the atmospheric air-water test loop. Using the test section made of transparent plastic to facilitate understanding of flow patterns, the complex two-phase flow behaviors at various locations of the current BWR steam separator were visualized. Qualitatively, using the air-water test loop, geometrical effects of the current BWR steam separator on carryover rate were examined. In parallel, a computer code based on two-fluid model formulation in axially symmetrical 3-D space was developed. After comparisons of the code predictions with both the air-water and the steam-water carryover test results, it is found that both air-water system and steam-water system can be analyzed successfully by the single two-fluid model and that the two-fluid analysis can be used in both design work and performance analysis of steam separators