Development of multi components and multi phase numerical method with chemical reaction. SERAPHIM: a multi-dimensional sodium water reaction analysis code

In a steam generator using liquid sodium, water intensely reacts with sodium when it leaked out from a heat transfer tube. It is important to evaluate thermal influence of the sodium-water reaction to surrounding tubes and the shell. In the past, evaluations of this phenomenon have been carried out based on experimental evidence. However it is difficult to predict the phenomena in different conditions such as configuration of a heat tube and change of operating condition. Furthermore, experiments using sodium are expensive in general. Hence, the quantification of the sodium-water reaction by a numerical method is desirable. In this study, a multi-dimensional sodium-water reaction analysis code SERAPHIM (Sodium watEr Reaction Analysis : PHysics of Interdisciplinary Multi-phase flow) has been developed. This code has two sodium-water reaction models. One is a surface reaction model, which is assumed that liquid sodium reacts with steam vapor on the surface. The other is a gas-phase reaction, in that vaporized sodium reacts with steam vapor. As a result of preliminary analyses of sodium-water reaction in a steam generator (SG) of LMFR with SERAPHIM code, Surface reaction is dominant within 100msec after steam is leaked. Maximum temperature is approximately 1200degC in analyses. Maximum temperature has little sensitivity on a initial pressure in SG and a heat coefficient between liquid and gas phase. Configuration of the tube and leak ratio have affected with a expansion of gas area. And it has been demonstrated that a sodium-water reaction in SG can be comprehended and integrity of the tube can be estimated by SERAPHIM code. (author)