Fig. 1. Diagram of the heat removal system of the drain tank

Fig. 2. Schematic illustration of the heat exchanger element (color online)

Fig. 3. Decay heat power of molten salt within the first hour after the completion of the fuel drain process

Fig. 4. Structural diagram of the heat exchanger element model (color online) (a) Low section, (b) Middle section

Fig. 5. Steady-state temperature distribution of the heat exchanger element (color online)

Fig. 6. Distribution of steady-state temperature at a height of 10 mm

Fig. 7. Volume fraction contour of molten salt in the annual gas space (color online)

Fig. 8. Mass flow rate vs. time (color online)

Fig. 9. Vapor volume fraction contour within heat exchanger element (color online)(a) Before leak occurring, (b) After leak occurring

Fig. 10. Molten salt mass flow vs. time at leak location

Fig. 11. Volume fraction distribution of frozen molten salt in the annular gas space

Fig. 12. Temperature distribution when leak occurring (color online)

Fig. 13. Power and mass flow rate vs. the height of leak location (color online)

Fig. 14. Power and mass flow rate vs. pressure difference at a leakage size of 4 mm (color online)

Fig. 15. Variations of power and mass flow rate with leak size in the range of 2~5 mm (color online)

Fig. 16. Mass flow rate vs. time at a leakage size of 7 mm (color online)