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Journal Articles

The Examination of advanced analysis method on unsteady gas entrainment vortex applying AMR method

Matsushita, Kentaro; Fujisaki, Tatsuya*; Ezure, Toshiki; Tanaka, Masaaki; Uchida, Mao*; Sakai, Takaaki*

Keisan Kogaku Koenkai Rombunshu (CD-ROM), 26, 6 Pages, 2021/05

For the gas entrainment vortex at the free surface in sodium-cooled fast reactors, development of the numerical analysis method to evaluate amount of the gas entrainment from the free surface has been developing. In this paper, the automatic creation of analysis meshes which can suppress the calculation cost while maintaining the prediction accuracy of the vortex shape is investigated, and the adaptive mesh refinement (AMR) method is examined to the creation of analysis mesh applying to the unsteady vortex system. The refined mesh based on the criterion evaluated by vorticity, Q-value as second invariant of the velocity and the discriminant for the eigen equation of the velocity gradient tensor is considered, and it found that the AMR method based on Q-value can refine the analysis meshes most efficiently.

Journal Articles

Study on evaluation method for entrained gas flow rate by free surface vortex

Ito, Kei*; Ito, Daisuke*; Saito, Yasushi*; Ezure, Toshiki; Matsushita, Kentaro; Tanaka, Masaaki; Imai, Yasutomo*

Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.6632 - 6642, 2019/08

In this paper, a mechanistic model is proposed to calculate the entrained gas flow rate by a free surface vortex. The model contains the theoretical equation of transient gas core elongation and the empirical equation of critical gas core length for gas bubble detachment. Based on those two equations, the entrained gas flow rate is calculated as the portion of the gas core elongated beyond the critical gas core length per unit time. Then, the mechanistic model was applied to the calculation of the entrained gas flow rate in a simple water experiment. As a result, it is confirmed that the entrained gas flow rate grows rapidly when the liquid (water) flow rate, which determine the strength of a free surface vortex, exceeds a certain threshold value.

Journal Articles

Study on analysis method for inert gas behavior in liquid metal flow with considering dissolution and entrainment at free surface

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

Dai-24-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (USB Flash Drive), 5 Pages, 2019/06

In the design study on a sodium-cooled fast reactor (SFR), a numerical simulation code named SYRENA has been developed in Japan Atomic Energy Agency to analyze the behavior of gas bubbles and/or dissolved gas in the primary coolant system. In the present study, the effect of the non-condensable gas entrainment at the free surface on the bubble and the dissolved gas behavior in the primary coolant system were investigated for a typical pool type reactor, and also effect of a dipped-plate (D/P) installed below the free surface in the reactor vessel to suppress the gas bubble entrainment into the primary coolant system was especially investigated. It was clarified that the D/P was influential to the non-condensable gas behavior and the molar flow rate of gas bubbles in the primary coolant system varies depending on the relationship between the gas entrainment rate at the free surface and the exchange flow rate through the D/P.

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

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

Preparation of fullerenes by arc discharge method; Effects of deposition temperature

Otsuki, Ryusei*; Nasu, Shoichi*; Matsushita, Masaki*; Fujii, Kimio; Ohashi, Kentaro*; Yamamoto, Ryoichi*

Funtai Oyobi Fummatsu Yakin, 51(8), p.633 - 634, 2004/08

We examined effects of deposition temperatures and collector radii onthe yields of fullerenes by arc discharge. Yields of fullerenes were 7-10%, 4-6% and 0.5-1% in the liquid nitrogen-cooling, water-cooling, non-cooling, respectively, and were better with a collector radius of 50mm than with that of 30mm. The weight ratios of C$$_{60}$$/C$$_{70}$$ are about one for all runs of experiments.

Oral presentation

Soft X-ray natural circular dichroism of amino acids

Nakagawa, Kazumichi*; Tanaka, Masahito*; Izumi, Yudai*; Agui, Akane; Yokoya, Akinari; Fujii, Kentaro; Muro, Takayuki*; Matsushita, Tomohiro*

no journal, , 

no abstracts in English

Oral presentation

Development of simulation code of bubble and dissolved gas behavior in sodium-cooled fast reactor primary coolant system, 1; Study on analytical model for tank type reactor

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.

Oral presentation

Study on bubble and dissolved gas behavior in liquid sodium; Modeling and evaluation of gas behavior in pool type sodium-cooled fast reactors

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.

Oral presentation

Development of evaluation method for the non-condensable gas behavior in primary coolant system of sodium-cooled fast reactor; Effect of dipped-plate on bubble behavior in pool type reactor

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.

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