Numerical study on sodium-water reaction mechanism in the gas phase using counter-flow reaction region

Abstract

Sodium water reaction (SWR) is a design basis accident of a sodium-cooled fast reactor (SFR). In a steam generator of the SFR, when a heat transfer tube fails, highly pressurized water and/or water vapor will leak into liquid sodium resulting in a chemical reaction between sodium and water or water vapor. In the previous works, mechanisms of the SWR have been researched on surface reaction and gas-phase reaction. The mechanisms, however, are complicated and have not been fully elucidated. The authors have developed a numerical code in which chemical reaction models of sodium and water vapor are coupled with thermal-hydraulics. Experiments of a counter-flow diffusion flame for the gas-phase reaction have also been carried out. In this article, the authors perform numerical simulations based on the experimental conditions to validate two chemical reaction models, the chemical equilibrium model and the Arrhenius model. With respect to the reaction products, the latter model gives more realistic results. In addition, sensitivity analyses are performed for various hydration numbers and main-flow velocities. It is founded that hydration reaction occurs somewhat in the gas-phase reaction and that influences of the main-flow velocity are not negligible mainly from the viewpoint of the reaction surface location. © 2012 Atomic Energy Society of Japan. All rights reserved.