Analysis of FIV Characteristics on a Coaxial Double-Tube Type Hot Gas Duct for the VHTR

The Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source of the order of 950°C for nuclear hydrogen generation, which can produce hydrogen from water or natural gas. A primary hot gas duct (HGD) as a coaxial double-tube type cross vessel is a key component connecting the reactor pressure vessel and the intermediate heat exchanger in a VHTR. In this study, a structural sizing methodology for the primary HGD of a VHTR is suggested in order to modulate a flow-induced vibration (FIV). And as an example, a structural sizing of a horizontal HGD with a coaxial double-tube structure was carried out using the suggested method. These activities include a decision of the geometric dimensions, a selection of the material, and a evaluation of the strength of the coaxial double-tube type cross vessel components. Also in order to compare the FIV characteristics of the proposed design cases, a fluid-structure interaction (FSI) analysis on a quarter part of the HGD was carried out using the ADINA code.