Experimental study on interface characteristics of liquid sodium-water vapor interaction in SWR

Abstract

When the sodium-water boundary in the sodium-cooled fast reactor (SFR) fails, water vapor will enter the liquid sodium and cause the sodium water reaction (SWR) accident. SWR may lead to many serious consequences for power plant. Thus, it is a non-negligible factor to be considered in the design and operation of SFR. In this study, experiments on the interaction between liquid sodium and water vapor were carried out. The reaction phenomena, temperature of liquid sodium, morphology of reaction product and other characteristics of the chemical were summarized and analyzed in this paper. The experiment was conducted under different initial sodium temperatures (300–450 °C) and different mass fraction of water vapor (0.1–0.9 at 200 °C) conditions. Visualization scheme was used in this experiment and the reaction process was recorded by a high-speed camera. The results indicate that both mass fraction of water vapor and initial temperature of liquid sodium are important factors in the reaction process. The mass fraction of water vapor affects the actual reaction rate. The initial temperature determines the form of reaction products (liquid NaOH) on the surface of liquid sodium. For the experiments with initial temperature below 400 °C, the reaction products appear as bubbles and foams. While the initial experiment temperature exceeds 400 °C (including 400 °C), bubbles and foams gone, replaced by a thin film. By analyzing the conditions of bubble generation, the surface tension of liquid NaOH is an important cause, which can be affected by the temperature and bounding water molecules. Furthermore, according to the measurement results of sodium temperature, the reaction products in the form of a large concentration of foams have a strong blocking effect on mass transfer and greatly slow down the actual reaction rate. This research has important reference significance for the study of the mechanism of liquid sodium and water vapor reaction.