An overview of engineering numerical methods for the dynamic analysis of a nuclear reactor with fluid-structure interaction modelling

Abstract

The paper is concerned with the dynamic analysis of a nuclear reactor withfluid-structure interaction modelling. Various fluid-structure interactioneffects (inertial, elasto-acoustic coupling, confinement) are investigatedusing specific mathematical modelling. In particular, modelling of thereactor internal structures is performed using an homogenisation methodwhose numerical basis are exposed in the paper. Influence of fluidstructurecoupling on the dynamic behaviour of the reactor is highlightedwith a modal analysis, on the one hand, and a dynamic analysis in the 0–20Hz and 20–200 Hz frequency range, on the other hand. Modal analysis iscarried out by computing the mode shapes, frequencies and effectivemasses of the reactor with and without fluid-structure interaction. Dynamicanalysis is performed using various engineering methods (temporal andspectral approaches) which are compared and discussed. From theengineering standpoint, the following questions, of paramount interest inpre-design analysis, are addressed: i) What are the predominant couplingeffects in the low frequency range (0–20 Hz)? ii) What are the predominantcoupling effects in the high frequency range (20–200 Hz)? iii) What is theinfluence of the presence of internal structures as far as fluid-structureinteraction is concerned? iv) What is the influence of the static pressureloading on the dynamic behaviour of the nuclear reactor?