An Analytical Method for Calculating Vibration Characteristics of PWR FuelAssembly with Reactor End Boundary Conditions Using Fourier Series

摘要

Many reactor components including fuel assembly, heat exchanger tubes and control element assembly aretypically beam-type structures with either classical or non-classical boundary conditions, or both. In such cases, it isquite difficult to evaluate the vibration characteristics of the structures since methods for accurate calculating naturalfrequencies of those structures with complicate restraints are not generally available.In this study, the frequency equations for calculating the natural frequencies of the beams with generallyrestrained boundary conditions by both translational and rotational springs are derived in matrix form using Fouriersine series. In order to show the validation of the solution, numerical results for two degenerate cases are comparedwith existing results for natural frequency obtained by the conventional analysis. And as a specific application, thenatural frequencies of KSNP (The Korean Standard Nuclear Plant) fuel assembly with reactor end conditions arecalculated and compared with the test results.As a result, the frequency equations derived in present study are quite general and useful to solve many differentphysical problems since the identical Fourier series expressions may be used for them.