Thermal fatigue analysis of structures subjected to liquid metal jets at different temperatures in the Gen-IV nuclear energy system

In the Generation-IV (Gen-IV) nuclear reactor system, the liquid metal cooled fast reactor is regarded as a promising reactor type, especially the sodium-cooled fast reactor (SFR). It is necessary to investigate the thermal striping of liquid metal jets and the thermal fatigue behavior of adjacent structures at the core outlet of a liquid metal cooled fast reactor where coolant at different temperatures is mixed and causes thermal fatigue of adjacent structures. In this work, a fluid-structure coupling model and thermal fatigue assessment methodology are proposed and employed to study the thermal fatigue of structures subjected to liquid mental jets at the core outlet of the SFR. The temperature field and velocity distribution of the fluid, as well as the deformation and thermal stress of structures are obtained. The transient load and thermal fatigue damage of the structure at different locations are also calculated and analyzed. The fatigue damage factor of the structure is less than 1.0. The max deformation is predicted and a relatively large von Mises stress is located in the junction of central column and control rod guide tube, as well as the area of geometric structure mutation.