Application of CFD code to conceptual T/H design of a new research reactor

For the thermal-hydraulic conceptual design of a new research reactor, a commercial 3-dimensional CFD(Computational Fluid Dynamics) code has been applied to the flow analysis of the tubular fuel and the lower plenum of the core, and to the heat transfer analysis of core aluminium structure as well. 3-dimensional model including receptacle and other structures was developed to find out flow characteristics such as average velocity in each channel, pressure drop, in the tubular type fuel assembly that was under conceptual design. From the analysis results, some considerations were suggested to modify conceptual design of the tubular fuel. The influence of changing outermost channel width on the flow of the other channels was also examined. Temperature distribution in core aluminum block, which generates heat by r-ray heating, was calculated for various heating rates by CFD code . The temperature variation of Al-block is linearly proportional to volumetric heat generation rate. The maximum temperature of Al-block can be maintained below recommended temperature of 80 .deg. C when the coolant temperature is 60 .deg. C. Flow analysis for the flow in the lower plenum of the reactor core showed that there may be large scale vortices, which may cause fretting wear of the fuel assembly due to the flow induced vibration just like in the HANARO. Based on the results of flow analysis, a flow skirt or a flow straightener has been suggested to install in the inlet plenum to prevent the formation of vortices. The CFD flow analysis has predicted that large scale vortices in the inlet plenum are satisfactorily reduced