Experimental study on combustion characteristics of mixed sodium fire in a well-ventilated environment compared with confined space

Abstract

The accident caused by the leakage and combustion of liquid sodium is common and frequent in the operation of the sodium-cooled fast reactor. In the actual situation, sodium fire caused by sodium leakage accidents often take place in a well-ventilated environment due to the need for fire ventilation, and multiple types of fire often occur simultaneously. In this paper, an experiment of mixed sodium fire in a well-ventilated environment was carried out. The data of temperature, pressure and oxygen concentration were collected and analyzed, and compared to those in the sodium fire experiments conducted in confined space to study the influence of the well-ventilated environment on the combustion characteristics of mixed sodium fire. It is found that the main combustion product in a well-ventilated environment is sodium peroxide, rather than sodium oxide in confined experiments. During the columnar and spray fire stage, the combustion region limits in the vicinity of the axis, and the peak temperature is close to that in the confined experiments, while the corresponding time is much earlier and it has less effect on the temperature of the distant region. In the later stages of combustion, the pool fire would last a much longer time, and the space temperature was higher due to sufficient oxygen, while the peak temperature was relatively lower due to continuous environmental air. This study could provide technical support for simulation research and prevention measures of sodium fire.