STUDY OF JET CHARACTERISTICS AND STRUCTURAL FATIGUE IN THE UPPER CHAMBER OF A LEAD-BISMUTH EUTECTIC COOLED REACTOR BASED ON FLUID-STRUCTURE COUPLING METHODS

To evaluate the impact of temperature fluctuations caused by jet mixing in the upper plenum of a lead-bismuth eutectic (LBE) reactor on the fatigue damage of internal structural components, this paper conducts a study on the stress distribution of the operation head and the central column based on a fluid-solid coupling calculation method. On this basis, a fatigue damage assessment method under thermal stress for the solid domain is established. The fatigue damage of the operation head and the central column under typical working conditions, as well as the influence of the flow parameters at the operation head inlet on fatigue damage, are analyzed. The results indicate that the fatigue damage at the monitoring points on the side of the operation head is significantly higher than that in the central column and should be given special attention. Compared to velocity, fatigue damage is more sensitive to temperature distribution, and the degree of fatigue damage decreases with the reduction of temperature difference. The research in this paper can provide reference and guidance for the design and operation of LBE reactors.