DEVELOPMENT AND AUTOMATION OF MEASUREMENT AND REGULATION OF FLOW IN THE HEAT-RELEASING ELEMENT CELL OF FUEL ASSEMBLIES

The article presents the results of the development of a formula for determining the flow rate in the fuel element cells, taking into account the real velocities distribution in the flow cross section (average velocity deficit); the functional diagram of the system for monitoring and controlling the flow rates in the fuel element cell and the algorithm of the program of the flow control system at the experimental stands with spills or blowdowns of bundles of heat-releasing element cell simulators. Automation of flow control is carried out on the basis of the previously obtained semiempirical relationship between the volumetric flow rate of the coolant in the fuel element cell, the maximum flow rate in the flow on the cell axis and friction pressure losses along the length of the stabilized flow section; and also on the basis of the dependence of the average speed on the maximum speed and the coefficient of friction resistance. The formula used in the program code makes it possible to determine the coolant flow rate in a tightly packed fuel element cell with an accuracy of up to 2% of the nominal flow rate. The results presented in the article are of practical value for experimenters who investigate the heat transfer (or heat transfer) coefficients of model fuel assemblies, as well as fuel bundles with a limited number of fuel rod simulators, including life tests on full-scale fuel assemblies.