PIV measurements of the flow patterns in a CANDU-6 model

•The flow patterns in a 1/4 scaled model of CANDU-6 reactor were explored using PIV.•The jet impingement positions for different inlet and heating conditions were measured.•Momentum-dominated and mixed flow patterns depending on Ar were examined.

Particle image velocimetry (PIV) measurements of the flow patterns in a pressurized heavy water reactor (PHWR) were made in a 1/4 scaled-down model of the Canadian deuterium uranium (CANDU) reactor. Archimedes’ number (Ar) was introduced to evaluate the dynamic similarities between the isothermal (Ar = 0) and heating conditions. Small and large PIV fields of view were used to measure the overall flow field. Flow patterns were analyzed by measuring the spatial velocity distributions and the impingement positions of the inlet jet. The momentum-dominated flow patterns were measured under isothermal conditions (Ar = 0). The impingement position bias increased as Ar increased due to buoyancy effects. The overall moderator circulation characteristics were explored for various Ar values up to 0.157.