Preliminary Mechanical Design of FHX for PGSFR

In this paper, more specific data from analysis and mechanical method of approach to design will be addressed. Especially, frame of tube bundle and housing of FHX. Heretofore, it is concept design by mechanical basic knowledge and research of various structures that are activating in realities. Especially, to reduce thermal stress, we have planning to attach insulations inside the housing. In as much as FHX is as important on SFR as the other part, hereafter, we will develop FEM to check feasibility of the FHX's housing design in order to perform static and thermal analysis as well as bucking, seismic and so on. The Forced-draft sodium-to-air Heat Exchanger system (FHX) (employed in the Active Decay Heat Removal System (ADHRS) is a shell-and-tube type counter-current flow heat exchanger with serpentine finned-tube arrangement. Liquid sodium flows over the finned tubes. The unit is placed above the reactor building and has function of dumping the system heat load into the final heat sink, i. e., the atmosphere. Heat is transmitted from the primary hot sodium pool into the ADHRS sodium loop via Decay Heat Exchanger (DHX), and a direct heat exchange occurs between the tube-side sodium and the shell-side air through the FHX sodium tube wall. Cold atmospheric air is introduced into the air inlet duct at the lower part of the unit by using an electrically driven air blower. Air flows across the finned tube bank rising upward direction to make uniform air flow with perfect mixing across the tubes. The finned tube bundle is placed inside a well-insulated casing. The air heated at the tube bank region is collected at the top of the unit and then is discharged through the air stack above the unit. Although a blower supplies atmospheric air into the FHX unit, a tall air stack is also provided to secure natural draft head of natural circulation air flow against a loss power supply. The stack also has rain protecting structures to prevent inflow of rain drops or undesired harmful objects. To place this FHX tube assembly on the SFR, the housing in necessary. FHX's specific tube bundle dimensions have already deducted by analysis