19 th International Conference on Nuclear Engineering Chiba, Japan, May 16-19, 2011 ICONE19-43839 DEVELOPMENT OF A SODIUM-WATER REACTION ANALYSIS TOOL FOR LMFBR BY USING A CFD CODE Kazuo HAGA 1 , Tomomichi Itoh 1 , Hiroshi ENDO 1 , Yoshihisa SHINDO 1 , 1 Japan Nuclear Energy Safety Organization, TOKYU REIT Toranomon Bldg,3-17-1, Toranomon, Minato-ku, Tokyo, 105-0001, Japan Phone: 81-3-4511-1831 Phone: 81-3-4511-1703 Phone: 81-3-4511-1749 Phone: 81-3-4511-1836 haga-kazuo@jnes.go.jp i toh-tomomichi@jnes.go.jp e ndo-hiroshi@jnes.go.jp shindo-yoshihisa@jnes.go.jp Emilio BAGLIETTO 2 , Yasutomo SASAKI 3 , Motoki IRIKURA 4 2 CD-adapco, 60 Broadhollow Road, Melville, NY,11747, USA 3 CD-adapco, 7F Dai 4 Yasuda Bldg, 2-26-2Tsuruyacho, Kanagawa-ku, Yokohama,Kanagawa, 221-0835, Japan 4 Chiyoda Advanced Solutions Co., Technowave 100 Bldg, 1-25, Shin-Urashima-cho, 1-chome, Kanagawa-ku, Yokohama, Kanagawa, 221-0031, Japan emilio.baglietto@us.cd-adapco.com Phone: 81-45-328-3625 yasutomo.sasaki@jp.cd-adapco.com Phone: 81-45-441-1284 Motoki.irikura@chas.chiyoda.co.jp Keywords: LMFBR, steam generator, sodium-water raction, CFD code, overheating tube rupture, homogenous muilti-conponent model ABSTRACT When heat-transfer tube failure occurred in SG of LMFBR and the steam leak rate is medium (some 10s g/s-some kg/s), overheating tube rupture would be caused due to the accelerated high-temperature creep in the heat transfer tubes surrounded by the high temperature products of sodium-water reaction (SWR). However, the detailed analysis code to analyze this phenomenon is not established. Adopting a Computational Fluid Dynamics (CFD) code would be a promising candidate for that perpose. At first in developing the analysis tool using a CFD code, STAR-CCM+ and LHM (Locally Homogeneous Multi-phase) model was adapted considering the appropriateness to SWR and the merits of homogeneous model, that is, the light load of computing resources and the minimum usage of models whose applicability is remained in argument. In the second step, a concept of interfacial area density was introduced to the submerged jet analysis. Furthermore, a sodium-water reaction model was added as an external function of the CDF code. A trial calculation was made to the basic SWR experimental data obtained by Hobbes et al. The analysis of the temperature profile formed in the jet region showed a good agreement with the experiment by properly choosing parameters such as Lewis number and the heat transfer coefficient on the sodium droplet. No marked difference was seen between the two-dimensional analysis and the three-dimensional analysis. 1. INTRODUCTION In liquid-metal cooled fast breeder reactor (LMFBR), steam generator (SG) is only component that has an interface between sodium and water. The failure of heat transfer tubes causes steam leak and sodium-water reaction resulting a high-temperature zone surrounding the steam jet when the leak rate is “medium (some 10s g/s-some kg/s)”. The high temperature may cause another tube failure and the failure might propagate. This phenomenon is called “overheating tube rupture”. Actually a larger numbers of heat transfer tube failed in PFR, the British proto-type LMFBR (Currie, 1990). To protect an LMFBR plant from this type of failure, it is required firstly to know high the reaction zone temperature reaches and the conditions of overheating tube rupture, then provide measures to prevent the plant from this phenomenon. We had prepared a computer code, QUARK-LP, to analyze this heat transfer tube failure propagation accident (Shindo, 2003). Although QUARK-LP showed an excellent achievement in the analysis of the PFR event, some key parameters obtained from experiments of the same geometries of SG of PFR, were used. However, to perform analysis of the overheating rupture phenomenon to general geometries of SG, a new tool that des not based on the “a priori” three reaction zones is required. Adopting a Computational Fluid Dynamics (CFD) code would be a promising candidate for this purpose. Applying CFD code to sodium-water reaction (SWR) has been tried by Kim, et al. (2007) by using a multi-component and a multi-phase Eulerian-Eulerian flow model of CFX code. But the analyzed transient state was only for 0.05 s. It is too short to judge if the results are reasonable for the phenomenon. Another multi-dimensional, multi-component and multi-phase thermal hydraulics simulation method with compressibility was developed and the SERAPHIM code was prepared for SWR by Takata et al. (2009). The validation calculation was made and the maximum gas temperature of approximately 1,573 K, which lies within the range of experiment in a tube bundle geometry, was predicted from the calculation for 0.6 s. Although these previous works show a good achievement, their direct application to the actual situation of SG would face high barriers that exist in the dimension size and calculation resources. To deal with these difficulties, we started to develop an analysis tool for the overheating tube rupture using a CFD code with proper additional models. The developing strategy is as follows. (1) Modeling of non reacting submerged jet (2) Introduction of quantification method for the interface area between steam and sodium droplet (3) Modeling of the sodium-water reaction (4) Unification of above models Copyright ©2011 by JSME The Japan Society of Mechanical Engineers NII-Electronic Library Service