Characterization Analysis of Core Outlet Temperature Measurement in Nuclear Power Plants

The core outlet temperature measurement is of great significance for mastering the reactor operation status. This paper analyzed the characterization of the core outlet temperature measurement by computational fluid dynamics (CFD) method. By simulating the structure of the fuel assembly and instrument tube, the coolant flow and temperature distributions in the instrument tube were obtained. The relationship between core outlet temperature characterization and fuel assembly power was obtained through quantitative analysis of core outlet temperature measurement results under 9 typical power distributions. The calculation results show that the average temperature of the measurement point is basically linearly related to the power of the fuel rod, and the temperature value of the measurement point increases with the increase of the power of the fuel rod, while the characterization of the temperature measurement becomes worse with the increase of the power of the fuel rod. The research results provide a certain basis for the calibration of outlet temperature measurement.