Modal Analysis for APR+ Reactor Barrel

Korea Atomic Energy Research Institute (KAERI) is developing an Advanced Power Reactor Plus (APR+) which has several improved safety features. For one of the safety features, four Emergency Core Barrel (ECB) ducts are attached at the outer surface of the reactor barrel to guide well ECC water from the Direct Vessel Injection (DVI) lines to the reactor core if necessary. The main purpose of this study is to identify the vibration characteristic of the APR⁺ barrel, having four ECB ducts, and to compare it with a conventional barrel. For the identification, FE analysis and vibration (modal) test for a 1/5 scale model have been carried out in air and in quiescent water. The collateral purpose of this study is to quantify the effects of fluid in a narrow gap between the barrel and the outer vessel, which are the so-called mass, damping and stiffness effects exerted by the fluid.