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Journal Articles

Study on surface tension modeling for mechanistic evaluation of vortex cavitation

Ito, Kei; Ezure, Toshiki; Ohshima, Hiroyuki; Kawamura, Takumi*; Nakamine, Yoshiaki*

Proceedings of 9th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-9) (CD-ROM), 6 Pages, 2014/11

The authors have been studied the vortex cavitation in sodium-cooled fast reactors. In this paper, the authors present a modified evaluation method for vortex cavitation, in which a surface tension is modeled mechanistically. Namely, the cavity radius is calculated in consideration of radial pressure distribution, saturated vapor pressure and the pressure jump condition at an interface. As the basic validation of the developed surface tension model, numerical analyses of a simple experiment under various velocity conditions are performed. The evaluation results give qualitatively appropriate tendency, that is, the cavity radius becomes larger with the higher liquid velocity and/or lower reference pressure which cause the larger pressure drop at the vortex. In addition, the authors evaluate the influence of the kinematic viscosity which plays an important role in the vortex cavitation occurrences in the experiments.

Journal Articles

Development of ITER divertor vertical target with annular flow concept,1; Thermal-hydraulic characteristics of annular swirl tube

Ezato, Koichiro; Dairaku, Masayuki; Taniguchi, Masaki; Sato, Kazuyoshi; Suzuki, Satoshi; Akiba, Masato; Ibbott, C.*; Tivey, R.*

Fusion Science and Technology, 46(4), p.521 - 529, 2004/12

 Times Cited Count:6 Percentile:42.52(Nuclear Science & Technology)

Thermal hydraulic tests measuring critical heat flux CHF and pressure drop of an annular tube with twisted fin, "annular swirl tube", have been. This tube consists of two concentric tubes, the outer tube and the inner tube with a twisted fin on its outer surface. Cooling water flows inside of the inner tube first, and then returns into an annulus with a swirl flow at an end-return of the cooling tube. The CHF testing shows the no degradation of CHF of the annular swirl tube in comparison with the conventional swirl tube. A minimum axial velocity of 7.1m/sec is required for 28MW/m$$^{2}$$, the ITER design value. Applicability of the JAERI's correlation for the heat transfer to the annular swirl tube is also demonstrated by the comparison of the experimental results with those of the numerical analyses. The friction factor correlation for the annular flow with the twisted fins is made for the hydraulic designing of the vertical target. The least pressure drop at the end-return is obtained by using the hemispherical end-plug. Its radius is the same as that of ID of the outer cooling tube.

Journal Articles

Experience of HTTR construction and operation; Unexpected incidents

Fujimoto, Nozomu; Tachibana, Yukio; Saikusa, Akio*; Shinozaki, Masayuki; Isozaki, Minoru; Iyoku, Tatsuo

Nuclear Engineering and Design, 233(1-3), p.273 - 281, 2004/10

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

From a viewpoint of heat leakage, there were two incidents during HTTR power-rise-tests. One was a temperature rise of the primary upper shielding, and the other was a temperature rise of the core support plate. Causes of the both incidents were small amount of helium flow in structures. For the temperature rise of the primary upper shielding, countermeasures to reduce the small amount of helium flow, enhancement of heat release and installation of thermal insulator were taken. For the temperature rise of the core support plate, temperature evaluations were carried out again considering the small amount of helium flow and design temperature of the core support plate was revised. By these countermeasures, the both temperatures were kept below their limits.

Journal Articles

Effect of electromagnetic force on the pressure drop and coupling loss of cable-in-conduit conductor

Hamada, Kazuya; Takahashi, Yoshikazu; Matsui, Kunihiro; Kato, Takashi; Okuno, Kiyoshi

Cryogenics, 44(1), p.45 - 52, 2004/01

 Times Cited Count:19 Percentile:59.75(Thermodynamics)

In the ITER Central Solenoid Model Coil (CSMC) and a CS Insert Coil (CSIC) experiment, a pressure drop of the CSIC decreased by about 12% at 40 kA, 10 T and coupling losses indicated an transport current dependence. As a result of pressure drop analysis, an electromagnetic force causes a compressive deformation of cable in a jacket and a new flow passage was generated as a gap between cable and jacket. The cable deformation causes a decrease of a contact electrical resistance between strands and an increase of coupling losses. Taking account of the electromagnetic force dependency of a coupling time constant, calculated coupling losses show a good agreement with measured coupling losses at a pulsed operation of CSMC and CSIC.

Journal Articles

Heat transfer characteristics of the steam reformer in the HTTR hydrogen production system

Takeda, Tetsuaki

Proceedings of 12th International Conference on Nuclear Engineering (ICONE-12) (CD-ROM), 4 Pages, 2004/00

no abstracts in English

JAEA Reports

Quantitative experiments on thermal hydraulic characteristics of an annular tube with twisted Fins

Ezato, Koichiro; Dairaku, Masayuki; Taniguchi, Masaki; Sato, Kazuyoshi; Suzuki, Satoshi; Akiba, Masato

JAERI-Tech 2003-084, 49 Pages, 2003/11

JAERI-Tech-2003-084.pdf:1.94MB

Thermal hydraulic tests measuring critical heat flux CHF and pressure drop of an annular tube with twisted fin, "annular swirl tube", have been. This tube consists of two concentric tubes, the outer tube and the inner tube with a twisted fin on its outer surface. Cooling water flows inside of the inner tube first, and then returns into an annulus with a swirl flow at an end-return of the cooling tube. The CHF testing shows the no degradation of CHF of the annular swirl tube in comparison with the conventional swirl tube. A minimum axial velocity of 7.1m/sec is required for 28MW/m$$^{2}$$, the ITER design value. Applicability of the JAERI's correlation for the heat transfer to the annular swirl tube is also demonstrated by the comparison of the experimental results with those of the numerical analyses. The friction factor correlation for the annular flow with the twisted fins is made for the hydraulic designing of the vertical target. The least pressure drop at the end-return is obtained by using the hemispherical end-plug. Its radius is the same as that of ID of the outer cooling tube.

Journal Articles

Pressure drop characteristics of Nb$$_{3}$$Al cable-in-conduit conductor under electromagnetic force; Relation between pressure drop characteristics and cable stiffness

Hamada, Kazuya; Matsui, Kunihiro; Takahashi, Yoshikazu; Nakajima, Hideo; Kato, Takashi; CS Model Coil Test Group

Teion Kogaku, 38(8), p.417 - 424, 2003/08

As one of the R&D of ITER. a hydraulic performance of Nb$$_{3}$$Al insert coil was measured and compared with other Nb$$_{3}$$Sn conductors. It seems that a longer twist pitch will promote a triangle helium flow space among 4th twist stage cables, jacket and center channel and contribute reduction of pressure drop. Under 500 kN/m of the electromagnetic force, the pressure drop of the Nb$$_{3}$$Al insert decreased by approximately 5%. Nb$$_{3}$$Al conductor indicated quit rigid characteristic under the electromagnetic force and suitable for future magnet with higher magnetic field and current.

Journal Articles

AC loss performance of cable-in-conduit conductor; Influence of cable mechanical property on coupling loss reduction

Matsui, Kunihiro; Takahashi, Yoshikazu; Koizumi, Norikiyo; Isono, Takaaki; Hamada, Kazuya; Nunoya, Yoshihiko; CS Model Coil Test Group

Teion Kogaku, 38(8), p.410 - 416, 2003/08

The test of the ITER Central Solenoid (CS) model coil, CS and Nb$$_{3}$$Al inserts was carried. The AC loss measurement is one of the most important tests to determine coil performance. The coupling losses of CS and Nb$$_{3}$$Al inserts were measured by calorimetric and magnetization methods, respectively. Both coils had coupling losses with many coupling time constant, and induced circulation currents were observed by voltage taps and hall sensors. Coupling losses decreased with exponential decay constants since the electromagnetic force broke weak sinter among the strands. The gap, created between the cable and the conduit by electromagnetic force, is dependent on the pressure drop of the coolant that flows in the conductor. Our analysis shows that the exponential decay constant of coupling losses is dependent on the gap size. If we can evaluate this exponential decay constant and apply the electromagnetic force that corresponds for the exponential decay constant to the conductor before the regular operation, we can use coils of the condition that coupling losses decrease on the operation.

Journal Articles

Hydraulic characteristics of ITER TF insert coil; Electromagnetic force effect on hydraulic performance

Hamada, Kazuya; Kawano, Katsumi; Matsui, Kunihiro; Kato, Takashi; Sugimoto, Makoto; Hara, Eiji*; Okuno, Kiyoshi; Egorov, S. A.*; Rodin, I.*; Sytnikov, V. E.*; et al.

Teion Kogaku, 37(10), p.531 - 538, 2002/10

In the Engineering Design Activities of the International Thermonuclear Experimental Reactor (ITER), Toroidal Field (TF) Insert have been developed and tested successfully. In the experiment, pressure drop performance of TF insert was investigated. There were two purposes for the investigation. One is to verify the pressure drop prediction using correlations proposed by various researchers. Second is to observe a behavior of pressure drop under the electromagnetic force. The pressure drops of TF insert decreased by around 12% during current-carrying operation of 46kA at 13T. After several current-carrying operation, the friction factor of TF insert has finally reached a value which is around 12% lower than that of virgin state and was not recovered even if there were zero current. It is considered that a deformation of cable cross section inside the conductor jacket appears due to electromagnetic force and a new flow path in the jacket is generated.

Journal Articles

Electromagnetic force effect on pressure drop and coupling loss of cable in conduit conductor

Hamada, Kazuya; Takahashi, Yoshikazu; Matsui, Kunihiro; Kato, Takashi; Okuno, Kiyoshi

Teion Kogaku, 37(6), p.257 - 264, 2002/06

no abstracts in English

Journal Articles

Experimental results of pressure drop measurement in ITER CS model coil tests

Hamada, Kazuya; Kato, Takashi; Kawano, Katsumi; Hara, Eiji*; Ando, Toshinari; Tsuji, Hiroshi; Okuno, Kiyoshi; Zanino, L.*; Savoldi, L.*

AIP Conference Proceedings 613, p.407 - 414, 2002/00

no abstracts in English

Journal Articles

Selection of filter media used for monitoring airbone alpha-emitting particles in a radiological emergency

Kinouchi, Nobuyuki; Oishi, Tetsuya; Noguchi, Hiroshi; Kato, Shohei; Ishizawa, Masato*

Radioisotopes, 50(9), p.403 - 407, 2001/09

no abstracts in English

Journal Articles

Pressure drop characteristic and flow distribution of ITER CS model coil

Hamada, Kazuya; Kawano, Katsumi; Hara, Eiji*; Kato, Takashi; Shimba, Toru*; CS Model Coil Test Group

Teion Kogaku, 36(6), p.330 - 335, 2001/06

no abstracts in English

Journal Articles

Selection of filter media in alpha air monitors for emergency environmental monitoring

Kinouchi, Nobuyuki; Oishi, Tetsuya; Noguchi, Hiroshi; Kato, Shohei; Ishizawa, Masato*

Proceedings of 10th International Congress of the International Radiation Protection Association (IRPA-10) (CD-ROM), 4 Pages, 2000/05

no abstracts in English

JAEA Reports

Numerical prediction of local transitional features of turbulent forced gas flows in circular tubes with strong heating

*; A.M.Shehata*; Kunugi, Tomoaki; D.M.McEligot*

JAERI-Research 97-029, 36 Pages, 1997/03

JAERI-Research-97-029.pdf:1.61MB

no abstracts in English

Journal Articles

Time dependency of HEPA filter performance during loading with liquid particles

; ; Ikezawa, Yoshio

Hoken Butsuri, 32(2), p.185 - 191, 1997/00

no abstracts in English

Journal Articles

An Experimental study on interfacial friction in wavy-stratified two-phase flow in a horizontal rectangular duct

*; Tsuji, Yoshiyuki*; *; Nakamura, Hideo; ; Kukita, Yutaka

Nihon Genshiryoku Gakkai-Shi, 39(8), p.669 - 680, 1997/00

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Pressure drop characteristic in a cable-in-conduit conductor

Koizumi, Norikiyo; Takahashi, Yoshikazu; Sugimoto, Makoto; ; Kato, Takashi; Tsuji, Hiroshi; Shimamoto, Susumi

JAERI-Research 95-062, 10 Pages, 1995/09

JAERI-Research-95-062.pdf:0.72MB

no abstracts in English

Journal Articles

Performance of improved cellulose-glass fiber filter paper for radioactive aerosol sampling

Kinouchi, Nobuyuki; Onodera, Junichi; Yoshino, Toshiaki; Murata, Mikio; *

Hoken Butsuri, 30, p.309 - 314, 1995/00

no abstracts in English

JAEA Reports

Improvement of pressure drop caluculation model in TRAC-PF1 code

; Abe, Yutaka*; Onuki, Akira; Murao, Yoshio

JAERI-Data/Code 94-006, 40 Pages, 1994/07

JAERI-Data-Code-94-006.pdf:1.26MB

no abstracts in English

39 (Records 1-20 displayed on this page)