Experimental study of the hydrodynamic characteristics of the coolant flow at the outlet of the fuel assembly for the RITM nuclear icebreaker reactor

The paper presents experimentally determined hydrodynamic characteristics of the coolant flow at the outlet of the RITM nuclear icebreaker reactor fuel assembly. The studies were carried out according to Pitot tube measurements based on the theory of hydrodynamic similarity using a model of the fuel assembly outlet with an air working medium. Friction factors were determined for several sections located at the outlet of the fuel assembly. The distribution of the hydrodynamic characteristics of the coolant flow is visualized by cartograms of the axial velocity at the outlet of the fuel rod bundle, in the wide and narrow parts of the nozzle, as well as in the fragments of drain windows in the upper base plate. The flow of the coolant through the central displacer and pipe for conducting the coolant to the resistance thermometer is determined. According to the performed studies, the asymmetric nozzle, coolant sampling pipe of the resistance thermometer, and upper base plate are the essential parameters affecting the formation of the field structure for the axial flow velocity.