Stress Analysis For MnMoNi Tube Sheet Of Nuclear Steam Generator

The tube plate of steam generator is an important component of the nuclear steam generator. There are tens of thousands of pipes in the tube plate and the tube plate supports the whole pipes. The stress analysis for steam generator tube plate is very complex, because of the severe condition for tube plate, such as high pressure, high temperature and temperature variety.Based on equivalent solid sheet theory and principle of equal area, tube plate FE model was simplified by two simplifying methods. The whole numerical analysis process was simulated by ANSYS FE analysis softwear, and then the results of temperature field and stress field were gained. Finally did some research on expansion gap.One thickness model for verifying the equivalent solid sheet theory was established by ANSYS. The effective elastic constants were chosen form literatures. Equivalent solid sheet model was established according to the equivalent solid sheet theory.Chose specific nodes and compared the equivalent solid sheet model to validation tubesheet model with the nodal von Mises stress and the strain results. Research results show that average deviation of nodal displacement within 15%. the average deviation of nodal von Mises stress is less than 5%. The feasibility of the equivalent solid sheet theory was verified.The validation model was simplified by using triangular and hexagonal simplified methods. The simplification modles were established by ANSYS. Compared the simplified model with the validation model, the nodal von Mises stress and the strain were investigated. Research results show that average deviation of nodal displacement within 15%, the average deviation of the nodal von Mises stress is less than 5%, and verified the correctness of the simplified methods.The tubesheet model of steam generator which was simplified by using triangle simplified method was established by ANSYS. The distribution of temperature field and stress field were gained. The expansion gap model used to analyze the thermal stress was established. The results indicated that the thermal stress causes the maximum von Mises stress of nodes to be larger than yield strength. Take the expansion gap can effectively reduce the thermal stress of generation, and the size of the expansion gap and the nodal von Mises stress have positive linear relationship. The size of the expansion gap should be between 5.5mm to 7.87mm.