Accidental coolant leaks in Sodium-cooled Fast Reactor (SFR) systems can create sodium fire, which is detrimental to safe operation of the reactor because of thermal damage by the fire event and generation of harmful, corrosive reaction products. Hence, in the safety evaluation of SFRs, validated models for the assessment of sodium fire consequences under various postulated leak events is essential. A leaked sodium jet can be subjected to fragmentation because of interfacial instabilities while falling in the air and can generate a large number of droplets of different sizes, and their burning in a reactor cell creates a spray fire scenario. The thermal consequences of spray fire depend on the droplet size distribution (DSD) formed since it determines the surface area of leaked sodium exposed to surrounding air. In accidental sodium sprays, the DSD can vary widely based on the scenario of spray formation, and hence, assessment of appropriate DSD is essential in numerical modeling of sodium spray fire events. The present study considers the underlying fragmentation mechanism of the liquid streams in various configurations envisaged under accidental leak conditions in SFR systems to evaluate the representative mean size of sodium spray droplets generated, using the numerical models and semi-empirical correlations based on the linear stability theory. The mean droplet sizes predicted by the models developed for various leak scenarios have been validated using experimental results available in the literature for liquid sodium and other Newtonian liquid sprays. Liquid stream breakup models have been incorporated into the in-house one-dimensional sodium spray fire analysis code to predict the leak scenario–specific mean size and define the resultant DSD using suitable mathematical functions to simulate benchmark sodium spray fire tests. Comparison of the thermal transients predicted by the revised code and experimental results revealed the efficacy of liquid stream breakup models in predicting the appropriate DSD and resultant sodium spray fire consequences. The physical mechanism–based, configuration-dependent models for defining the accidental sprays improved the sodium fire analysis required in the safety evaluation of SFRs.