Seismic Analysis of a Turbine on a Spring Isolated Pedestal

Paper deals with the detailed seismic analysis of powerful high-speed Russian turbine of Nuclear Power Plant. Dozens of patterns of such turbine work reliably since 70’s worldwide. Until last decade only simplified structural analyses were available due to a complicated overall structure and internals of such turbines. The current analysis considers detail geometry of the turbine itself as well as vibration and seismic isolation system within turbine’s pedestal and full range of operational, accident and seismic loads. To solve the problem of the turbine seismic and dynamic qualification the following steps have been done. On the first step detailed finite element models of turbine’s high and low pressure parts and rotor system with bearings were created. Using such models corresponding simplified models were developed to be included into the coupled model of the system: “Building – Vibroisolation Pedestal – Turbine” (BVT). The second step was the analysis of that coupled system. Soil-structure interaction was considered using actual soil conditions. Three components of time history acceleration were used to define seismic excitation. As the result of BVT system analysis a full picture of time history displacements and loads were determined. At the same time a non-linear problem of rotor’s axial and radial bearings behavior and gaps in the system was solved. On the final step determined loads were applied to the detailed model of turbine for seismic and dynamic qualification of the whole structure.