Sodium Spray Fire Analysis with Combustion Space Multi-node Model for Sodium-Cooled Fast Reactor

Abstract

Sodium leakage from a pipe will cause a spray fire accident and the high energy released from the combustion of sodium can result in containment failure. Predicting the response of containment during a sodium spray fire accident is one of the key problems in the safety analysis of Sodium-cooled Fast Reactors (SFR). The lumped parameter method, assuming the combustion space only one node, was used to calculate the average temperature and pressure of the whole space in previous studies. The local information on the temperature and pressure in the space still needs to be obtained. In this paper, a multi-node model which divides the combustion space into several parts is developed to improve the prediction effect by calculating the heat release and transfer of sodium combustion in spaces separated by nodes. The energy transfer in each space mainly includes the heat transfer between the falling sodium droplets and the surrounding air and that between the air and the wall, while the energy exchange among the spaces is ignored. The results calculated by the multi-node model show a good agreement with the FAUNA and SNL T3 downward sodium spray fire experiments. The peak temperature and pressure predicted by the multi-node model are close to the experimental values and the location where the peak values reach is obtained. With the increase of the initial temperature of sodium, the highest temperature region in the container is closer to the position of sodium injection in the axial direction.