Experimental Research and Assessment for Thermal Fatigue in T-Junction With Mixing Flows

Thermal fatigue in T-junction with mixing flows has been a grown concern in the wake of the accidents occurring at several nuclear power plants in the world. In this paper, based on highly frequent temperature measurements at the outer pipe wall surface and within the pipe wall from the specially-designed test loop, projected models of turbulence penetration length and temperature distribution were developed. Meanwhile, determining temperature and stress distribution in pipe is the key factor for assessment of thermal fatigue life resulting from hot and cold mixing flows in T-junction. In the paper, the temperature of the inner wall surface was obtained using inverse heat conduction and large eddy simulation based on measurements. Finally, the stress distribution caused by mixing flows was obtained using simplified calculation methods, which were verified by detailed analysis results from the special developed program of inverse function. Such solution methods provide a feasible approach to assess the fatigue life of T-junction in nuclear power plants.