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Ito, Kei; Tanaka, Masaaki; Ohno, Shuji; Ohshima, Hiroyuki
JAEA-Research 2014-023, 34 Pages, 2014/11
JAEA-Research-2014-023.pdf:4.48MB
In a sodium-cooled fast reactor, inert gas (bubbles or dissolved gas) exists in the primary coolant system. Such inert gas may cause disturbance in reactivity and/or degradation of IHX performance, and therefore, the inert gas behaviors have to be investigated to ensure the stable operation of a fast reactor. The authors have developed a plant dynamics code SYRENA to simulate the concentration distributions of the dissolved gas and the bubbles in a fast reactor. In this study, the models in SYRENA code are improved to achieve accurate simulations. Moreover, new models are introduced to simulate the various bubble behaviors in liquid metal flows. To validate the improved models and the newly developed models, the inert gas behaviors in the large-scale sodium-cooled reactor are simulated. As a result, it is confirmed that the complicated bubble dynamics in each component can be simulated appropriately by SYRENA code.
Takata, Takashi*; Konaka, Yuji*; Yamaguchi, Akira*; Ito, Kei; Ohno, Shuji; Ohshima, Hiroyuki
Proceedings of 9th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-9) (CD-ROM), 7 Pages, 2014/11
In this paper, a model of bubble transport at entrance nozzle has been developed based on theoretical and computational methods. For this purpose, a three-dimensional analysis of dynamic bubbles behavior has been carried out by using one-way bubble tracking method which is specified to a bubble flow under a low void fraction. A commercial CFD tool, FLUENT Ver. 6.3.26 is used for three-dimensional flow field analyses. Then the gas accumulation at a high pressure plenum (HPP) of sodium-cooled fast rector has been quantitatively-assessed by implementing the developed model in SYRENA code. Furthermore, gas elimination (bubble removal) systems have been considered and the quantitatively-assessment has been carried out in order to investigate the effect of each measure to the accumulation of gas at the HPP.
Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki; Ito, Kei*
no journal, ,
A numerical simulation code named SYRENA has been developed in Japan Atomic Energy Agency to analyze non-condensable gas behavior in primary coolant system. In this study, for a typical pool type reactor with a horizontal plate (dipped-plate:D/P) below the free surface of a hot plenum to suppress bubble entrainment into primary coolant system and to prevent fluctuation of free surface, non-condensable gas behavior in primary coolant system was evaluated with SYRENA. Parametric analyses was performed on sodium exchange flow rate through D/P and Ar bubble entrainment rate at free surface. It was clarified that effect on void fraction at core inlet by change of Ar bubble entrainment rate at free surface is greater than that by exchange flow rate through D/P. It was implied that suppressing Ar bubble entrainment at free surface by D/P suppressed increasing void fraction of the total bubbles in primary coolant system.