Three-Dimensional Seismic Analysis and Safety Evaluation for Nuclear Pump of Nuclear Power Plant Based on the RCC-M Code

Pumps are important equipments of nuclear power plants. The most significant difference between nuclear power pumps and ordinary pumps is strict requirements on reliability and safety by design codes. The nuclear pumps must keep structural intactness and be able to function what they are designed for under strong earthquakes. In this paper, a three-dimensional model of a nuclear power pump based on real project designs is established by SolidWorks software. Hexahedron-dominated elements are used to mesh the finite element model of the pump by ANSYS to obtain solution of seismic analysis. A static analysis in normal conditions defined by Technical Specification of the pump is performed to determine the distribution of basic initial stress. Then, a modal analysis considering the initial stress is carried out to solve the free vibration of the structure. Afterwards, a spectrum analysis considering two horizontal loads and one vertical load is accomplished to obtain seismic responses of deformation and stress distribution of the pump. A post-procession is performed to get the superposition and linearization of dynamical and static results. Finally, the safety of the pump under seismic circumstance is evaluated through comparison of linearized stress on specific paths with the stress intensity limit urged by the RCC-M Code at the level of the given operating condition. The present analysis ensures that the pump will be safe and be able to fulfill the requirement by the RCC-M Code.