Thesis

Predicting the seismic behavior of liquid-filled reactor vessels

The purpose of this Graduate Project is to investigate two methods used by the nuclear industry in predicting the seismic behavior of liquid-filled Reactor Vessels. The two methods that will be examined are (1) dynamic testing of a scaled model and (2) dynamic analysis using finite element methods. In the first part of this report, an introduction to dynamic testing establishes basic principles of test program planning, test procedures, and representation of the seismic environment. The latter part of this report presents a procedure, using the finite element method, for determining the dynamic response of a fluid contained within a vessel. A modal and spectrum analysis was performed on a scale test model reactor vessel as an example. Results of the finite element analysis indicate that fluid mode shapes, frequencies, and fluid slosh height due to a seismic excitation can be predicted by the finite element method. The fluid natural frequency and slosh height computed by the dynamic analysis, compared well with those results calculated by simplified equations found in literature. The analysis also determined that the sloshing motion is dominated by the fundamental mode. Results of the shake test indicate that fluid submerged components experience a reduced dynamic response due to the virtual mass effect of the contained fluid.

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