When pressurized water or vapor leaks from a failed heat transfer tube in steam generators of sodium-cooled fast reactors, a high-velocity and high-temperature jet with sodium-water chemical reaction may cause tube failure propagation. In this study, a numerical analysis method to predict occurrence of failure propagation by overheating rupture was constructed to expand application range of an existing computer code. Applicability of this method was investigated through the numerical analysis of the experiment on water vapor discharging in liquid sodium. In this experiment, one tube for water vapor discharging and the 91 target tubes were placed in a liquid sodium pool. The numerical analysis showed that the temperature of the target tubes increased by the effect of the reacting jet. Some of them near the initial water leak point resulted in overheating rupture as with the experimental result. Although the proposed analysis method is very helpful for design and safety assessment, this method provides temperature distribution more widely than the real situation. To improve this conservativeness, a Lagrangian particle model for simulating reacting jet was also developed as an alternative method. The numerical results by the program unit of this model showed that the discharged gaseous particles repeated collision with the target tubes and moved along the inverse gravity direction.