Study on Multi-Objective Optimization Design of LP Section for 1000MW Class Nuclear Turbines

With the development of nuclear reactors, the domestic market demand for high-capacity nuclear power turbines is also growing. Low pressure (LP) section (include LP inner casing and LP outer casing) is one of the important components of nuclear steam turbine, which are mainly welded by plates and rods. The increasing size of LP section leads more vacuum load, more self-weight, more stress, more deformation and so on. Therefore, the traditional design methods can no longer adapt to this situation very well. In this paper, the stress, deformation, buckling behaviors and seismic loadcase of the LP section of steam turbine are evaluated by the numerical finite element analysis. Then, the multi-objective optimization (include size optimization and topology optimization) design of the LP section is done, so that the structural efficiency and performance of LP section is achieved. The performance of all aspects of the optimized LP section has been greatly improved. On the basis of a small improvement in stress and deformation, the self-weight of the LP section is greatly reduced. At the same time, the optimization boundaries, the choice of the model and the process are discussed. This study proposes a more optimized design method of LP section of steam turbines, and it offers considerable economic benefits.