Abstract
Under postulated accident conditions in a pressurized water reactor (PWR), steam and condensate water form countercurrent gas-liquid flows in a hot leg and a pressurizer surge line, so that countercurrent flow limitation (CCFL) may occur. There are many studies for CCFL in hot leg models, but there are only a few studies for CCFL in a pressurizer surge line (consisting of a vertical pipe, a vertical elbow, and a slightly inclined pipe with elbows). In our previous studies, we measured CCFL characteristics in a 1/10-scale model of a pressurizer surge line using air and water, developed a one-dimensional (1D) computation model, and also did three-dimensional (3D) simulations for the inclination angle of 0.6 deg (slope of 1/100) to validate simulation capability. 1D computations and 3D simulations gave good agreement with the 1/10-scale air-water data for the inclination angle of 0.6 deg. In the present study, we did 1D computations and 3D simulations for air-water countercurrent flows in the 1/10-scale model of the pressurizer surge line to validate them for effects of inclination angles on CCFL. Although 1D computations and 3D simulations gave good agreement with measured data for the inclination angle of 0.6 deg, they slightly underestimated effects of inclination angles on CCFL for the inclination angles of 0 deg and 1.0 deg.
