Dynamic characteristics identification of reactor internals in SMART considering fluid–structure interaction

The System-Integrated Modular Advanced ReacTor (SMART) was developed by the Korea Atomic Energy Research Institute (KAERI). It is an integrated pressurized water reactor which includes most components in only one reactor vessel. In the structural reactor design, vibration assessment is one of the important technology validations in order to prevent damage from seismic loads and flow-induced vibration. This analysis is performed using modal analysis, which includes finite element analysis and modal test, in order to identify the dynamic characteristics of the reactor internals. First, the 1/12 scaled-down model of the reactor internals is designed for modal analysis. The three-dimensional finite element model is constructed using the commercial package ANSYS based on this model. It represents the detailed geometric shape of the reactor internals and also considers the fluid–structure interaction effect caused by the reactor coolant. In order to validate the results of the finite element analysis, the modal test with the scaled-down model is performed. We found that the results from the FEA are well matched with the results of the modal test. From the results, we can extract the dynamic characteristics of the totally assembled reactor internals that are in contact with water and verify the validity of the detailed finite element model of the scaled-down model of the reactor internals. The finite element model can be used to predict the dynamic characteristics of the reactor internals and can be utilized in further research such as seismic analysis and postulated pipe rupture analysis. This paper performs a similarity analysis in order to predict the dynamic characteristics of real reactor internals using the NAVMI factor and correction factors. The results of the similarity analysis correspond well with the results of the FEA.