Thermal fatigue analysis of vertical annulus with inner rotating cylinder induced by two temperature fluid mixing

Mechanical seal for nuclear reactor coolant recirculation pump must purge the cold water supply from the outside. The cold purge water is flowing into the hot water zone in the pump through a narrow gap between pump shaft and casing over. On the mixing region of the cold purge water and hot water in the narrow gap, the random level temperature fluctuation occurs on the structural metal surface of casing cover and pump shaft. Then it could lead to cyclic thermal stress and fatigue damage. The experiments and analysis have done, made clear the mechanism of generation of temperature fluctuations. Also, it was studied how to measure the structure of the mixing zone temperature control and how to prevent the occurrence of a large temperature fluctuation. In addition, it is proposed the method of evaluating a random temperature fluctuation by using the envelope curve and its fatigue by OOR counting to applying to the evaluation of the similar random fluid temperature fluctuation problems. (author)