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Journal Articles

Parametric analysis of bubble and dissolved gas behavior in primary coolant system of sodium-cooled fast reactors

Matsushita, Kentaro; Ito, Kei*; Ezure, Toshiki; Tanaka, Masaaki

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 9 Pages, 2019/05

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 of SYRENA to a hypothetical pool type reactor was developed and the non-condensable gas behavior was investigated through the comparison with that in the loop type reactor. The effect of the dipped-plate (D/P) tentatively introduced into the pool-type reactor on the gas behavior was investigated through the parametric analyses about the sodium exchange flow rate through the D/P and the gas entrainment rate at the free surface. It was suggested that the increase in the exchange flow rate through the D/P doesn't always work to decrease the bubble volume in the primary coolant system.

Journal Articles

Physics-basis simulation of bubble pinch-off

Ito, Kei; Koizumi, Yasuo; Ohshima, Hiroyuki; Kawamura, Takumi*

Mechanical Engineering Journal (Internet), 3(3), p.15-00671_1 - 15-00671_9, 2016/06

Journal Articles

Physics-basis simulation of bubble pinch-off

Ito, Kei; Koizumi, Yasuo*; Ohshima, Hiroyuki; Kawamura, Takumi*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05

The authors are developing a high-precision CFD code with an interface tracking method to simulate the gas entrainment (GE) phenomena in sodium-cooled fast reactors (SFRs), which might be caused by a highly-intensified free surface vortex. The GE in SFRs is characterized by an elongated interfacial dent along the vortex core and the bubble pinch-off at the tip of the dent. To simulate this complicated phenomenon, our simulation code has physics-basis algorithms which model accurately the interfacial dynamic behavior, the pressure jump condition at an interface and the surface tension. Several verification problems have been already solved and the accuracy of each individual algorithm is confirmed. In this paper, a basic experiment of the GE is simulated to validate the developed code. The simulation result of the entrained flow rate shows comparable value to the experimental data, that is, our simulation code is considered applicable to the evaluation of the GE in SFRs.

Journal Articles

Evaluation of gas entrainment flow rate using numerical simulation with interface-tracking method

Ito, Kei; Ohno, Shuji; Koizumi, Yasuo*; Kawamura, Takumi*

Proceedings of 10th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-10) (USB Flash Drive), 10 Pages, 2014/12

Journal Articles

Development of vortex model with realistic axial velocity distribution

Ito, Kei; Ezure, Toshiki; Ohshima, Hiroyuki

Nihon Kikai Gakkai Rombunshu (Internet), 80(818), p.FE0299_1 - FE0299_9, 2014/10

A vortex is considered as one of significant phenomena which may cause gas entrainment (GE) and/or vortex cavitation in sodium-cooled fast reactors. In this study, a new vortex model with realistic axial velocity distribution is proposed. As the verification, the new vortex model is applied to the evaluation of a simple vortex experiment, and shows good agreements with the experimental data in terms of the circumferential velocity distribution and the free surface shape. In addition, it is confirmed that the Burgers vortex model fails to calculate accurate velocity distribution with the assumption of uniform axial velocity. However, the calculation accuracy of the Burgers vortex model can be enhanced close to that of the new vortex model in consideration of the effective axial velocity which is calculated as the average value only in the vicinity of the vortex center.

Journal Articles

Effect of physical properties on gas entrainment rate from free surface by vortex, 2

Koizumi, Yasuo*; Ote, Naosuke*; Kamide, Hideki; Ohno, Shuji; Ito, Kei

Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 7 Pages, 2014/07

JAEA Reports

Plate-out distribution of iodine in a high temperature gas cooling in-pile loop facility

Matsumoto, Mikio; Endo, Yasuichi; ; Itabashi, Yukio; ; Yokouchi, Iichiro; Ando, Hiroei

JAERI-M 92-212, 62 Pages, 1993/01

JAERI-M-92-212.pdf:2.09MB

no abstracts in English

Oral presentation

Observation of gas entrainment from free surface by vortex and measurement of entrained gas flow rate

Ote, Naosuke*; Koizumi, Yasuo*; Kamide, Hideki; Ohno, Shuji; Ito, Kei

no journal, , 

Oral presentation

Verification of a high-precision numerical method for interfacial flows

Ito, Kei; Kunugi, Tomoaki*; Ohno, Shuji; Kawamura, Takumi*

no journal, , 

The method of manufactured solution (MS) is well known as a verification method of numerical simulation algorithms. In this study, the authors develop a new MS with dynamic interfacial deformation due to a vortex, which is a simplified model of the gas entrainment (GE) behavior in sodium-cooled fast reactors and is necessary for the verification of a high-precision numerical method developed for the simulation of the GE. The MS is considered on an axisymmetric system and radial, circumferential and axial velocities and pressure are formulated to satisfy the continuity equation and the boundary condition on an interface. Preliminary calculations are performed on five meshes with various resolutions and the calculation error decreases with mesh resolution. Such an appropriate result implies the developed MS is a good problem to verify the high-precision numerical method.

Oral presentation

Evaluate in liquid properties and observation in gas entrainment from the free surface by vortex

Ote, Naosuke*; Koizumi, Yasuo*; Kamide, Hideki; Ohno, Shuji; Ito, Kei

no journal, , 

A sodium-cooled fast breeder reactor is now at the development stage in Japan. One concern for safety is cover gas entrainment into the sodium coolant. The gas entrainment rate into liquid by the vortex formed on the free surface was examined experimentally. Liquid flowed into a cylindrical vessel from a wall tangentially. Swirl flow was formed in the vessel, and then liquid drained from the bottom outlet of the vessel. A hollow vortex was formed on the free surface in the test vessel. The air was entrained under the free surface of the vortex and carried away from the bottom of the vessel. The flow state of the gas entertainment was visually observed by using a high speed video camera. The gas entrainment rate into liquid was measured. In the previous study, test fluid was water. Kerosene and 20 cSt silicone oil were newly introduced as the test fluid to examine the effect of the physical properties on the gas entertainment phenomena.

Oral presentation

Verification of high-precision volume-tracking method with Manufactured Solution

Ito, Kei; Kunugi, Tomoaki*; Ohshima, Hiroyuki

no journal, , 

In this study, the authors develop a new manufactured solution with dynamic interfacial deformation due to a vortex, which is a simplified model of the gas entrainment behavior in a nuclear reactor. The manufactured solution is considered on an axisymmetric system and radial, circumferential and axial velocities and pressure are formulated to satisfy the continuity equation and the boundary condition on an interface. The interfacial dent grows with time and a gas bubble is generated when the lower part of the interfacial dent is pinched off. A preliminary simulation is performed on a coarse mesh to investigate the dynamic interfacial deformation on the velocity field given by the manufactured solution. As a result, a reasonable interfacial shape is simulated at each elapsed time, which implies the developed manufactured solution is a good problem to verify an interface-tracking method.

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