Abstract
Molten salt reactors (MSRs) require high-temperature testing of corrosive fluids like FLiBe and FLiNaK, complicating integral and separate effect experiments. To overcome these limitations, this study employs a similarity-based methodology, grounded in the hierarchical two-tier scaling (H2TS) framework to investigate the performance of Therminol-66, DOWTHERM A, and DOWTHERM RP as low-temperature, high-Prandtl-number surrogates for fluoride salts. We first match each simulant’s Prandtl number to its corresponding salt at the reactor’s mean operating temperature, then derive all relevant non-dimensional groups under forced and natural circulation. Applying this to three MSR designs, KP-FHR, FuSTAR, and FUJI-233Um, yields compact, low-power test loops with zero distortion in all primary groups and negligible Biot-number error. Nusselt-number predictions using standard correlations show that heat transfer is replicated to within 1% over the target Re-Pr range. These results establish a practical, safe, and scalable pathway for high-fidelity thermal-hydraulic experiments supporting future MSR developments.