Experimental study of coolant flow mixing processes in a pressure chamber model of nuclear reactor

Abstract

The paper presents results of experimental research, the purpose of which was to simulate the phenomenon of mixing of loop coolant flows inside the model of the pressure chamber of the water-cooled reactor. The study was conducted at the high-pressure aerodynamic test bench of NNSTU n.a. R.E. Alekseev. The scale model consisted of elements characteristic of water-cooled nuclear reactors (lowering annular channel, lower pressure chamber). Experimental studies were carried out in the range of Reynolds numbers from 20,000 to 50,000. The axial velocity field was studied at the entrance to the reactor core simulator, using a pneumometric research probe. The temperature field was simulated using the impurity diffusion method by introducing a contrast tracer into one of the loops of the model. Propane was used as a passive tracer. Tracer concentration at the inlet core simulator allowed to evaluate the degree of flow mixing and thereby studied the direction of coolant flow. As a result of the studies, the spatial distribution of the tracer concentration in the coolant flow in the lower annular channel, as well as in the lower pressure chamber, was determined. It was shown that in the lower pressure chamber, an axial central vortex influences the mixing intensity. The estimation of the parameters of mixing of the passive tracer in the model of reactor pressure was given.