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Ono, Ayako; Yoshida, Hiroyuki; Suzuki, Takayuki*
no journal, ,
The behavior of bubbles and the process of coalescence are simulated by a computational multi-fluid dynamics (CMFD) simulation code TPFIT, which will contribute to develop the prediction method of critical heat flux based on the liquid-layer evaporation model. In this study, the calculation results in various pressure condition will be shown and the effect of the pressure on the behavior of bubbles will be discussed.
Matsushita, Kentaro; Ito, Kei*; Ezure, Toshiki; Tanaka, Masaaki
no journal, ,
In a sodium-cooled fast reactor, from the viewpoint of prevention of core reactivity disturbance, it is important to evaluate the bubbles and dissolved gas behavior in the primary coolant system due to gas entrainment. For this reason, a numerical simulation code SYRENA for bubble and dissolved gas behavior analysis in the fast reactor primary coolant system has been developed in JAEA. In this study, a flow network model of SYRENA for tank type reactor was constructed and numerical simulations aiming to compare the bubble behavior characteristics in the loop type reactor and the tank type reactor was performed as a part of the fundamental validations of the flow network model of SYRENA. As the result, it was clarified that the differences regarding the bubbles and dissolved gas behavior between two different type reactors were indicated.
Ono, Ayako; Uesawa, Shinichiro; Shibata, Mitsuhiko; Yoshida, Hiroyuki; Koizumi, Yasuo
no journal, ,
The boiling behavior was observed up to under 2MPa condition by high-speed camera, where was on the vertical surface in pool boiling, in order to grasp the mechanism of boiling including the bubble coalescence behavior and establish the model to predict the critical heat flux (CHF) under the high pressure condition. From these observations, the differences on the boiling behavior between under the atmospheric condition and higher pressure conditions were pointed out, and the phenomena and parameters to consider under the high pressure condition were considered in order to establish the CHF which was applicable to various pressure conditions.
Matsushita, Kentaro; Ito, Kei*; Ezure, Toshiki; Tanaka, Masaaki
no journal, ,
A numerical simulation code named SYRENA has been developed in JAEA to analyze the behavior of entrained bubbles and dissolved gas in the primary coolant of sodium-cooled fast reactor (SFR). In the present study, a flow network model for a pool-type SFR was newly developed in SYRENA and the non-condensable gas behavior in the pool type SFR was analyzed. A dipped-plate (D/P) model was introduced into the flow network to investigate influences of D/P installation on the non-condensable behavior in the pool-type reactor. A parametric study was performed on the exchange flow rate through the D/P and the gas entrainment rate at the free surface existing above the D/P. The non-condensable gas behavior under various flow conditions, e.g. gas entrainment rate condition, was obtained. Especially, it was observed that the bubble volume in the primary coolant system changed with the exchange flow rate though the change ratio is dependent on the gas entrainment.
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.
Ono, Ayako; Yamaguchi, Manabu*; Sakashita, Hiroto*; Uesawa, Shinichiro; Shibata, Mitsuhiko; Yoshida, Hiroyuki
no journal, ,
The establishment of the evaluation method of the critical heat flux for light water reactors is needed. However, the boiling phenomena under high pressure remain to be clarified. The measurement system based on detecting the electric capacitance has been developed, which detects the liquid-vapor behavior vicinity of the heating surface in order to clarify the mechanism of the critical heat flux under the higher pressure region. In this study, the detail of the measurement system and the result to confirm the validity of the measurement system are reported.
Furuya, Masahiro*; Ono, Ayako; Yoshida, Hiroyuki
no journal, ,
The establishment of the evaluation method of the critical heat flux for light water reactors is needed. However, the boiling phenomena under high pressure remain to be clarified. The bubble growth process was investigated with a time-series of the identified bubbles on the basis of the developed feature extraction method for the video-recoded frames of boiling bubbles on the heat transfer surface under high pressure and temperature. The applied semantic segmentation algorism is known as a proven machine learning technology for an autonomous driving system as well.