Modal Analysis of a Nuclear Reinforced Concrete Containment Vessel

Modal Analysis of a Nuclear Reinforced Concrete Containment Vessel

In this study, a finite element model of a reinforced concrete containment vessel(RCCV) in an advanced boiling water reactor(ABWR) was constructed using the commercial program ABAQUS ver.6.12. The modal analysis was performed to derive the modal properties of an RCCV, such as the frequency and mode shape of each mode, in order to clarify the dynamic behavior of the RCCV while it is subjected to earthquake excitation. The effect of different mesh sizes and element types on the modal analysis results was examined. The modal frequencies of the first four dominant modes are 7.3Hz, 15.2Hz, 18.2Hz, and 23.6Hz, with the first one representing the horizontal mode, the second being the torsional mode, the third being the inner-shell deformation mode, and the fourth being the vertical mode. It is suggested that the mesh size can be defined as half of the RCCV thickness, and the quadratic element with a reduced integration point can be used to derive accurate results under the limitations of the hardware environment.