Research Of Hydraulic Expansion Technology In Nuclear Steam Generator

Nuclear steam generator is not only the device for generating steam but also the barrier for the first loop and the second loop, which is very important for the safe running of whole nuclear equipment. At present, tube-to-tubesheet joints are always connected by hydraulic expansion technology for steam generator. As an application of technology, hydraulic expansion is already very mature in technology, equipments and operations. However, up to now, there are no specific standards or norms to guide enterprises to select the appropriate parameters before manufacturing. For realizating industrial applications of hydraulic expansion technology, it is very meaningful to study the series of tube-to-tubesheet joints which are used the technology.The whole numerical simulation course of hydraulic expansion between the tube and the tubesheet is solved by ANSYS software. At the base of the suitable simplifying of the U-tube and tubesheet in one steam generator, the Equivalent double-tube model is used to replace porous tube plate,and the finite element models of tube-to-tubesheet joints have been established. Test bed which is used to measure stress-strain curve along the loop of tube specimen is set up. The instantaneous expansion course is simulated by ANSYS, and the simulation results of different expansion parameters are gained. The results include the remnant stress and residual contact pressure distribution on the face of the contact region, the effect of different expansion parameters and grooves geometry, etc.The paper has analyzed the simulation results integrated with the material specialty, and obtained a series of optimized results. It has provided academic and technical basis for not only the determination of the optimal expansion parameters but also the confirming of the enterprise standard for hydraulic expansion technology.