In fast breeder nuclear reactors accidental breach in heat transport circuits can cause sodium leaks and resultant fire events may jeopardize the reactor safety. The liquid jet released from the leak location can undergo fragmentation and create numerous spray droplets and their burning in the surrounding air constitutes the sodium spray fire scenario. In this connection, numerical analysis has been carried out for the assessment of spray formation and droplet generation process by liquid jet impingement on an intercepting solid surface. The analysis considered the flow structure of impinging liquid jet over a horizontal surface and subsequent fragmentation of liquid sheet formed. The resultant mean droplet sizes have been evaluated using the linear stability theory based analytical model. The representative mean diameters predicted by the model for various leak conditions have been compared with the benchmark liquid spray experimental results available in the literature. The droplet size distribution estimated by this method can be used in the analysis of sodium spray fire scenarios pertaining to SFR safety evaluation.