Velocity measurements in convective boiling flow using radioactive particle tracking technique

The design, performance, and safety analysis of nuclear reactors, in particular boiling water reactors, requires information about the vapor–liquid flow dynamics. Such data are necessary for stand-alone analysis of the thermal hydraulics, as well as to serve as a database for validation of computational fluid dynamics models. Challenges in collecting such data are magnified in the context of flow boiling, which is known to be a complex, multi-scale problem. The present work focuses on investigating the two-phase flow dynamics of convective boiling flows on a test section equipped with different heater rods arrangements. Noninvasive radioactive particle tracking (RPT) has been used for measuring liquid velocity field, mean flow patterns, and turbulent kinetic energy of the liquid phase. A novel tracer particle reconstruction algorithm based on support vector regression has been applied in this study. This is the first application of RPT for measuring liquid velocity fields in convective boiling flows.