Streamline rotodynamic pump model for two-phase flow simulation

Abstract This study is concerned with the simulation of water-vapor two-phase flows in pressurized water reactors (PWR) primary pumps. The correct modeling of such flows is essential to predict the consequences of a Loss Of Coolant Accident (LOCA), an accident scenario involving a rupture in the reactor primary circuit. During such accidents, pressure loss leads to important coolant vaporization in the circuits, pumps and other system components. A review of turbomachinery streamline models, used to represent pumps in system codes, is presented. Particular attention is paid to the model used in the CATHARE-3 system code, as its development is the motivation for the present work. Numerical simulations were then performed using CATHARE-3 streamline pump model, currently validated for single-phase liquid flows. These simulations included test cases for pure liquid and vapor conditions, as well as one two-phase flow case, with inlet void fraction of approximately 10 %. For pure liquid water, the agreement is good for discharge between 75% and 150% of nominal discharge. Results are satisfying up to 300% of nominal discharge for the single-phase vapor case. The two-phase results are close to experimental values around 75 and 130 % of nominal discharge. Further work is required in order to consolidate the physical analysis and to improve and validate CATHARE-3 streamline pump model for two-phase flow conditions.