Practical modeling of fluid in ABWR suppression pool for seismic analysis using 3D FEM model

Abstract

This paper presents a practical modeling of the fluid in a suppression pool (SP) for seismic analysis by using three-dimensional finite element method (3D FEM) models of the reactor building of an advanced boiling water reactor (ABWR). We performed a seismic analysis considering the fluid-structure interaction by using the virtual mass method in MSC Nastran, which was verified on the basis of vibration tests in this study, and the effects of the fluid on the structures around the SP were evaluated. For the analysis, we developed the following 3D FEM models: a full model, impulsive model, and no-fluid model. The full model considered both the convective and impulsive effects of the fluid, and the impulsive model lacked the convective effects of the full model (modeling the fluid as masses). The no-fluid model removed the impulsive effects from the impulsive model (removing the fluid from the full model). From the analysis, we obtained the maximum acceleration, von Mises stresses, and pressure fluctuations at the structures around the SP. The obtained results were compared with each other. They indicate that the fluid hardly affects the seismic responses of the structures, though some effects of the fluid were found. On the basis of the effects we found, we propose a practical modeling of the fluid and a modeling flowchart to use it. The modeling flowchart enables us to practically model the fluid in the SP for seismic analysis using ABWR 3D FEM models.