Nu-HOPE (Nuclear-Highly Optimized Prandtl number Experiment facility) is a newly built facility in UNIST to simulate molten salt reactor. Due to the high-temperature corrosion and toxicity issue, the heat transfer phenomena of molten salt are studied under similarity technique with high-Prandtl number simulant fluid. 12-meter-high Nu-HOPE was designed for the study of both natural and forced circulation of high-Prandtl number fluid. Experimental results of natural and forced circulation can give the evaluation of heat transfer characteristics and fluid stability model for the simulant molten salt. In this paper, design of Nu-HOPE based on numerical approach to developing heat transfer model of high-Prandtl number fluid is suggested.