LAUSR

Abstract It is a critical safety issue of thermal fatigue in the core outlet of sodium cooled fast reactors (SFRs) due to the mixing phenomenon of coolant with different temperatures flowing from different assemblies. In this paper, the large eddy simulation (LES) method was employed to study the coolant mixing phenomenon of a simplified assembly head model of SFR. The coolant velocity and temperature fields with vortices of different scales were obtained and analyzed. It shows that the lateral velocity is more sensitive to the inlet velocity than to the inlet temperature difference. In addition, the normalized parameters of temperature in axial and radial measuring lines and temperature fluctuations at specific points were obtained. Results show that there is no obvious dominant frequency of the temperature fluctuations with the energy of temperature fluctuations distributed in the frequency range of 0–100 Hz. The results would be beneficial for the design and structure optimization of SFRs.