Dynamic Characteristics of a Perforated Cylindrical Test Structure

The Upper Internal Structure (UIS) of a Sodium-cooled Fast Reactor (SFR) is composed of several important components such as an outer cylinder, a support plate, control rod shroud tubes and instruments guidelines that must be protected from unexpected events such as an earthquake. Therefore, the dynamic characteristic analysis of the UIS is very important for the design of the SFR. However, because the UIS has a very complex shape and is submerged in a surrounding liquid, the realization of boundary conditions exactly the same as those in a real situation is difficult in an experiment. Therefore, the proper experimental test model is required to analyze the dynamic characteristics of the UIS more accurately. In this study, Finite Element (FE) analyses of a perforated cylindrical structure simulating the outer cylinder of the UIS under several conditions were carried out to determine the proper experimental test model. Analyses were conducted by the commercial FE software ANSYS, and the mode shape and natural frequency of the test model having several flow holes were assessed for each case