東北大学研究者紹介

ハシヅメ　ヒデトシ

橋爪　秀利

Hidetoshi Hashizume

所属

大学院工学研究科　量子エネルギー工学専攻　エネルギー物理工学講座（核融合・電磁工学分野）

職名

教授

学位

工学博士（東京大学）

researchmap

https://researchmap.jp/read0168483

J-GLOBAL ID

200901046135694396

委員歴 3

日本保全学会　会長

2020年6月～継続中
日本保全学会　副編集委員長

2004年4月～継続中
日本保全学会　副編集委員長

2004年4月～継続中

所属学協会 7

日本保全学会
日本AEM学会
低温工学会
プラズマ核融合学会
電気学会
機械学会
原子力学会

︎全件表示 ︎最初の5件までを表示

研究キーワード 2

超伝導工学
核融合炉工学

研究分野 1

エネルギー / 核融合学 / 第一壁工学

受賞 9

審査に対する表彰

2016年9月30日　日本学術振興会　第一段審査に対する表彰
Russell B. Scott Memorial Award

2015年6月30日　Cryogenic Engineering Conference 2013　Best Research Paper
技術進歩賞

2014年11月18日　プラズマ核融合学会　核融合炉マグネットへの適用を目指した100kA 級高温超伝導導体と機械的低抵抗ジョイントの開発
日本保全学会功労賞

2014年7月24日　日本保全学会
論文賞固相接合を用いた電磁非破壊検査のためも模擬応力腐食割れ試験体製作技術

2012年5月28日　日本保全学会
低温工学協会・優良発表賞

2010年11月　低温工学・超電導学会　金属ジャケット付BSCCO2223導体の機械的バットジョントの基礎評価
先行基礎工学研究表彰

2010年7月27日　日本原子力研究開発機構
日本原子力学会熱流動部会・優秀講演賞流入条件によるデュアルエルボの流動構造変化の解明

2010年3月　日本原子力学会　流入条件によるデュアルエルボの流動構造変化の解明
Best Paper Award

2004年4月27日　2nd International Conference on Nuclear Science and Engineering in Iran

︎全件表示 ︎最初の5件までを表示

論文 412

Feasibility Study on Liquid Divertor Using Molten Salt Free Surface Flow with Turbulent Promoters

Takahiro IJIMA, Shota SAKURAI, Fumiya TAKAHASHI, Shinji EBARA, Hidetoshi HASHIZUME

Plasma and Fusion Research　18　2405075-2405075　2023年8月28日
出版者・発行元：Japan Society of Plasma Science and Nuclear Fusion Research
DOI： 10.1585/pfr.18.2405075 　

eISSN：1880-6821
Bending and Twisting Characteristics of REBCO Lap Joint With Indium

Qifan Zhang, Satoshi Ito, Hidetoshi Hashizume

IEEE Transactions on Applied Superconductivity　33　(5)　1-5　2023年8月
出版者・発行元：Institute of Electrical and Electronics Engineers (IEEE)
DOI： 10.1109/tasc.2023.3261841 　

ISSN：1051-8223

eISSN：1558-2515 2378-7074
Evaluation of the Interface Resistance on Heated REBCO Tape

Atake, Y., Ito, S., Takahashi, K., Hashizume, H.

IEEE Transactions on Applied Superconductivity　33　(5)　2023年8月

DOI： 10.1109/TASC.2023.3240387 　

ISSN：1558-2515 1051-8223
Heat Transfer Characteristics Evaluation of Multi-Elbow Cooling System for Fusion Divertor under One-Sided Heating

Shinji EBARA, Kenya MITOBE, Yukinori HAMAJI, Hidetoshi HASHIZUME

Plasma and Fusion Research　18　2405034-2405034　2023年6月5日
出版者・発行元：Japan Society of Plasma Science and Nuclear Fusion Research
DOI： 10.1585/pfr.18.2405034 　

eISSN：1880-6821
Design of a simple side-incident TE11 mode microwave probe for nondestructive pipe inspection

Yijun Guo, Ryo Yoshikawa, Noritaka Yusa, Hidetoshi Hashizume

Measurement Science and Technology　34　(8)　085104-085104　2023年4月27日
出版者・発行元：IOP Publishing
DOI： 10.1088/1361-6501/accca0 　

ISSN：0957-0233

eISSN：1361-6501

詳細を見る詳細を閉じる

Abstract This study proposed a simple side-incident TE11 mode microwave probe for the rapid and long-range inspection of cracks in metallic pipes. The probe feeds the microwaves to a metallic pipe, which works as a waveguide; the reflection signal provoked by a defect is measured for detection and localization. The probe enables the detection of both circumferentially and axially oriented cracks, unlike those reported in earlier studies. To achieve better performance, numerical simulations were conducted to evaluate the conversion efficiency and optimize the insertion length of the coaxial cable and the exposed length of the cable core wire. The simulation results suggest that the optimized probe configuration is feasible for pipes with various diameters by proportionally changing the current probe configuration. Although injected microwaves propagated in two directions, the ratio of microwaves to one direction could be controlled by adjusting the inclination angle and the exposed length of the cable core wire. Subsequently, three TE11 probes fabricated according to the simulation results were used to detect circumferential and axial slits in a brass pipe. The results showed that circumferential slits in the vertical positions (parallel to the nontilted coaxial cable) and axial slits in the horizontal positions (perpendicular to the nontilted coaxial cable) caused large reflections, consistent with the electromagnetic field distribution of the TE11 mode microwaves in a circular waveguide. Further experiments verified the feasibility of the designed probe for pipes with different diameters and for directional pipe inspection.
Localizing, identification and sizing of inner surface pipe wall thinning by means of domain transformation and spectral analysis

Weiying Cheng, Yijun Guo, Hidetoshi Hashizume

Mechanical Systems and Signal Processing　188　110024-110024　2023年4月
出版者・発行元：Elsevier BV
DOI： 10.1016/j.ymssp.2022.110024 　

ISSN：0888-3270
Mechanism of Recovery Performance Improvement With Porous-Stabilized REBCO Tape for Resistive-Type Superconducting Fault Current Limiters 査読有り

Yuki, K., Ito, S., Hashizume, H.

IEEE Transactions on Applied Superconductivity　33　(5)　2023年

DOI： 10.1109/TASC.2023.3256347 　

ISSN：1558-2515 1051-8223
Evaluation of the applicability of microwave nondestructive testing to crack detection on a pipe inner surface 査読有り

Yijun Guo, Noritaka Yusa, Hidetoshi Hashizume

International Journal of Applied Electromagnetics and Mechanics　71　S1-S9　2022年12月9日
出版者・発行元：IOS Press
DOI： 10.3233/jae-220127 　

ISSN：1383-5416

eISSN：1875-8800

詳細を見る詳細を閉じる

This study explores the applicability of microwave nondestructive testing to detect a metal pipe’s inner crack. Three-dimensional finite element simulations were conducted to study the inspectability of cracks using microwaves in different modes and the dependency of the reflection characteristics of microwaves on crack size. The simulation results showed that microwaves in the TM01 and TE01 modes can detect circumferential and axial cracks, respectively. The positive relationship between crack size and intensity corresponding to the reflected microwaves was obtained in simulations and then verified by experiments. In both simulations and experiments, the axial crack length showed a small influence on the results, especially for shallow crack detection. In the experiments, circumferential and axial cracks with a width of 0.3 mm were detected using microwaves. The experimental results revealed that signal amplitudes decreased when a slit penetrated a pipe wall, probably due to a microwave leakage.
Integration of multiple wall thinning parameters into the probability of detection analysis for long-range pipe inspection using microwaves

Yijun Guo, Takuma Tomizawa, Fanwei Yu, Noritaka Yusa, Hidetoshi Hashizume

NDT & E International　102763-102763　2022年10月
出版者・発行元：Elsevier BV
DOI： 10.1016/j.ndteint.2022.102763 　

ISSN：0963-8695
Evaluation of Magnetic Field Dependence of the Interface Resistivity in REBCO Tape

Yosuke Atake, Satoshi Ito, Kohki Takahashi, Hidetoshi Hashizume

IEEE Transactions on Applied Superconductivity　32　(6)　1-5　2022年9月
出版者・発行元：Institute of Electrical and Electronics Engineers (IEEE)
DOI： 10.1109/tasc.2022.3186268 　

ISSN：1051-8223

eISSN：1558-2515 2378-7074
Impact of Current Transfer to Porous Stabilizer on Recovery Performance of Resistive-Type Superconducting Fault Current Limiters Using REBCO Tapes 査読有り

Yuki, K., Ito, S., Hashizume, H.

IEEE Transactions on Applied Superconductivity　32　(4)　1-7　2022年6月
出版者・発行元：Institute of Electrical and Electronics Engineers ({IEEE})
DOI： 10.1109/TASC.2021.3131539 　

ISSN：1558-2515 1051-8223
Quantitative evaluation of pipe wall thinning defect sizes using microwave NDT

Yijun Guo, Guanren Chen, Takuya Katagiri, Noritaka Yusa, Hidetoshi Hashizume

Nondestructive Testing and Evaluation　1-17　2022年3月9日
出版者・発行元：Informa UK Limited
DOI： 10.1080/10589759.2022.2051505 　

ISSN：1058-9759

eISSN：1477-2671
Multivariate probability of detection (POD) analysis considering the defect location for long-range, non-destructive pipe inspection using electromagnetic guided wave testing

Guanren Chen, Yijun Guo, Takuya Katagiri, Haicheng Song, Takuma Tomizawa, Noritaka Yusa, Hidetoshi Hashizume

NDT & E International　124　102539-102539　2021年12月
出版者・発行元：Elsevier BV
DOI： 10.1016/j.ndteint.2021.102539 　

ISSN：0963-8695
Low-resistance joint development for segment-fabrication of high-temperature superconducting fusion magnets 査読有り

Ito, S., Tamura, H., Yanagi, N., Hashizume, H.

Nuclear Fusion　61　(11)　115002　2021年10月

DOI： 10.1088/1741-4326/ac269e 　

ISSN：1741-4326 0029-5515
Quench Detection Performance of Lowerature Superconducting Quench Detectors for REBCO Tape in Magnetic Fields 査読有り

Hasegawa, S., Ito, S., Nishijima, G. & Hashizume, H

IEEE Transactions on Applied Superconductivity　31　(5)　2021年8月

DOI： 10.1109/TASC.2021.3063645 　

ISSN：1051-8223

eISSN：1558-2515

詳細を見る詳細を閉じる

A quench detection method using a lowerature superconducting quench detector (QD) has been proposed to protect rare-earth barium copper oxide (REBCO) coils at temperatures below 20 K in magnetic fields. In this study, we first conducted an experiment at 4.2 K in 0-9 T using a locally- degraded REBCO tape and Nb-Ti QDs (Nb-Ti/Cu, Nb-Ti/Cu-Ni). Quick quench detection before thermal runaway of the REBCO tape was demonstrated by the Nb-Ti/Cu-Ni QD in 0-9 T, whereas Nb-Ti/Cu QD exhibited quick quench detection only at 9 T. Furthermore, we numerically evaluated the quench detection time of Nb-Ti QDs attached to a REBCO tape with local degradation at 4.2 K in 0-9 T. The simulation reproduced the experimental results. Moreover, the contact resistance between the REBCO tape and QD should be lower than 1.0 × 10-3 m2K/W for quick quench detection.
Effect of Electrical and Thermal Properties of Porous-Stabilized REBCO Tape on Recovery Performance 査読有り

Kohei Yuki, Satoshi Ito, Hidetoshi Hashizume

IEEE Transactions on Applied Superconductivity　31　(5)　1-6　2021年8月
出版者・発行元：Institute of Electrical and Electronics Engineers (IEEE)
DOI： 10.1109/tasc.2021.3058567 　

ISSN：1051-8223

eISSN：2378-7074
Demonstration of detection of the multiple pipe wall thinning defects using microwaves

Takuya Katagiri, Guanren Chen, Noritaka Yusa, Hidetoshi Hashizume

Measurement　175　109074-109074　2021年4月
出版者・発行元：Elsevier BV
DOI： 10.1016/j.measurement.2021.109074 　

ISSN：0263-2241
Experimental investigation on bend-region crack detection using TE11 mode microwaves

Guanren Chen, Takuya Katagiri, Noritaka Yusa, Hidetoshi Hashizume

Nondestructive Testing and Evaluation　1-10　2021年3月14日
出版者・発行元：Informa UK Limited
DOI： 10.1080/10589759.2021.1900847 　

ISSN：1058-9759

eISSN：1477-2671
Frequency properties of a flexible printed circuit coil and inductive measurement of conductivity

Weiying Cheng, Hidetoshi Hashizume

AIP Advances　11　(1)　015133-015133　2021年1月1日
出版者・発行元：AIP Publishing
DOI： 10.1063/9.0000112 　

eISSN：2158-3226
Investigation of the crystallization process of CSD-ErBCO on IBAD-substrate via DSD approach

R. Hayasaka, P. Cayado, M. Erbe, W. Freitag, J. Hänisch, B. Holzapfel, S. Ito, H. Hashizume

Scientific Reports　10　(1)　2020年12月
出版者・発行元：Springer Science and Business Media LLC
DOI： 10.1038/s41598-020-76848-y 　

eISSN：2045-2322

詳細を見る詳細を閉じる

<title>Abstract</title><italic>RE</italic>Ba2Cu3O7-δ (<italic>RE</italic>BCO, <italic>RE</italic>: rare earth, such as Y and Gd) compounds have been extensively studied as a superconducting layer in coated conductors. Although ErBCO potentially has better superconducting properties than YBCO and GdBCO, little research has been made on it, especially in chemical solution deposition (CSD). In this work, ErBCO films were deposited on IBAD (ion-beam-assisted-deposition) substrates by CSD with low-fluorine solutions. The crystallization process was optimized to achieve the highest self-field critical current density (<italic>J</italic>c) at 77 K. Commonly, for the investigation of a CSD process involving numerous process factors, one factor is changed keeping the others constant, requiring much time and cost. For more efficient investigation, this study adopted a novel design-of-experiment technique, definitive screening design (DSD), for the first time in CSD process. Two different types of solutions containing Er-propionate or Er-acetate were used to make two types of samples, Er-P and Er-A, respectively. Within the investigated range, we found that crystallization temperature, dew point, and oxygen partial pressure play a key role in Er-P, while the former two factors are significant for Er-A. DSD revealed these significant factors among six process factors with only 14 trials. Moreover, the DSD approach allowed us to create models that predict <italic>J</italic>c accurately. These models revealed the optimum conditions giving the highest <italic>J</italic>c values of 3.6 MA/cm2 for Er-P and 3.0 MA/cm2 for Er-A. These results indicate that DSD is an attractive approach to optimize CSD process.
Determination of Layers’ Thicknesses by Spectral Analysis of Swept-Frequency Measurement Signals 査読有り

Weiying Cheng, Hidetoshi Hashizume

IEEE Sensors Journal　20　(15)　8643-8655　2020年8月
出版者・発行元：Institute of Electrical and Electronics Engineers (IEEE)
DOI： 10.1109/jsen.2020.2982944 　

ISSN：1530-437X

eISSN：2379-9153
In-depth resistance analysis of REBCO tape joints with indium insert and solders 査読有り

R Hayasaka, S Ito, T Kato, D Yokoe, H Hashizume

Journal of Physics: Conference Series　1559　012034-012034　2020年6月
出版者・発行元：IOP Publishing
DOI： 10.1088/1742-6596/1559/1/012034 　

ISSN：1742-6588

eISSN：1742-6596
Effect of non-uniform proton irradiation on the critical current of REBCO tapes 査読有り

H Yamamoto, S Ito, M Miwa, S Matsuyama, H Hashizume

Journal of Physics: Conference Series　1559　012045-012045　2020年6月
出版者・発行元：IOP Publishing
DOI： 10.1088/1742-6596/1559/1/012045 　

ISSN：1742-6588

eISSN：1742-6596
Joining condition dependency of joint resistance in ultrasonic welding of high-temperature superconducting tapes with indium 査読有り

S Ito, R Hayasaka, K Yuki, Y S Sato, H Hashizume

Journal of Physics: Conference Series　1559　012065-012065　2020年6月
出版者・発行元：IOP Publishing
DOI： 10.1088/1742-6596/1559/1/012065 　

ISSN：1742-6588

eISSN：1742-6596
Investigation of trade-off solution in mechanical edge joint of STARS conductors 査読有り

S Sato, S Ito, H Hashizume

Journal of Physics: Conference Series　1559　012110-012110　2020年6月
出版者・発行元：IOP Publishing
DOI： 10.1088/1742-6596/1559/1/012110 　

ISSN：1742-6588

eISSN：1742-6596
Design of a dual-port, side-incident microwave probe for detection of in-pipe damage 査読有り

Chen, G., Katagiri, T., Yusa, N., Hashizume, H.

Measurement Science and Technology　31　(12)　2020年6月

DOI： 10.1088/1361-6501/ab9acc 　

ISSN：1361-6501 0957-0233
Experimental verification of a TE01 mode converter to locate a crack in a metal pipe 査読有り

Takuya Katagiri, Guanren Chen, Noritaka Yusa, Hidetoshi Hashizume

International Journal of Applied Electromagnetics and Mechanics　2020年4月
Investigation for contact interface of mechanical lap joint fabricated with high-temperature superconducting conductor using X-ray microtomograph 査読有り

Weixi Chen, Satoshi Ito, Noritaka Yusa, Hidetoshi Hashizume

Plasma and Fusion Research　15　(0)　2405014-2405014　2020年3月
出版者・発行元：None
DOI： 10.1585/pfr.15.2405014 　

eISSN：1880-6821
Evaluation of Neutronic and Thermophysical Characteristics of Molten Salts Specialized for Long-Lived Fission Products Transmutation in a Fusion Reactor∗)

KITASAKA, T., SHISHIDO, H., HASHIZUME, H.

Plasma and Fusion Research　15　2020年

DOI： 10.1585/PFR.15.2405077 　

ISSN：1880-6821
In-pipe crack detection for multiple diameters using TE11 mode microwaves 査読有り

Guanren Chen, Takuya Katagiri, Noritaka Yusa, Hidetoshi Hashizume

International Journal of Applied Electromagnetics and Mechanics　2020年
Quantitative evaluation of the delamination length in mechanical lap joints of high-temperature superconducting tapes using Lamb waves 査読有り

Feng, B., Chen, W., Ito, S., Yusa, N., Hashizume, H., Ribeiro, A.L., G. Ramos, H.

Measurement: Journal of the International Measurement Confederation　156　107606　2020年1月

DOI： 10.1016/j.measurement.2020.107606 　

ISSN：0263-2241
Recovery performance of partially-joined porous-stabilized REBCO tape for resistive type superconducting fault current limiters 査読有り

Yuki, K., Ito, S., Hashizume, H.

Superconductor Science and Technology　33　(3)　2020年

DOI： 10.1088/1361-6668/ab669a 　

ISSN：1361-6668 0953-2048
Investigation of the effect of a bend on pipe inspection using microwave NDT 査読有り

Chen, G., Katagiri, T., Song, H., Yusa, N., Hashizume, H.

NDT and E International　110　102208　2020年

DOI： 10.1016/j.ndteint.2019.102208 　

ISSN：0963-8695

詳細を見る詳細を閉じる

This study investigated the effect of a bend on microwave NDT (non-destructive testing) applied for rapid pipe inspections. The factors affecting the mode conversion of microwaves due to a bend were deducted theoretically and verified through numerical simulation. Both theoretical and numerical results revealed that the mode conversion at a bend was actually determined by the frequency normalized by the cut-off frequency of an arbitrary mode (f/fc), the ratio of the curvature radius to the inner diameter of the pipe (r/D) and the bend angle (α). Subsequent experimental evaluations were performed using four groups of pipes with different inner diameters and five different bends. The effect of a bend was quantitatively evaluated by comparing the reflection signals from pipe wall thinning in a straight pipe with those in a bent pipe. The results showed that the presence of a bend led to a decrease in the reflection signal behind the bend, and the extent of decrease also depended on r/D and α of the bend. Furthermore, the length or the depth of the pipe wall thinning did not noticeably affect the decrease in reflection signal, when the bend’s dimensions were certain.
Heat transfer enhancement in MHD free surface flow by controlling the electromagnetic force with fin structure 査読有り

Kawamoto, M., Muraoka, K., Ito, S., Hashizume, H.

Fusion Engineering and Design　146　(B)　2671-2675　2019年9月

DOI： 10.1016/j.fusengdes.2019.04.079 　

ISSN：0920-3796
Effect of coil configuration parameters on the mechanical behavior of the superconducting magnet system in the helical fusion reactor FFHR 査読有り

Tamura, H., Goto, T., Yanagi, N., Miyazawa, J., Tanaka, T., Sagara, A., Ito, S., Hashizume, H.

Fusion Engineering and Design　146　(A)　586-589　2019年9月

DOI： 10.1016/j.fusengdes.2019.01.029 　

ISSN：0920-3796
Bridge-type mechanical lap joint of HTS STARS conductors using an integrated joint piece 査読有り

Ito, S., Hashizume, H., Yanagi, N., Tamura, H.

Fusion Engineering and Design　146　(A)　590-593　2019年9月

DOI： 10.1016/j.fusengdes.2019.01.030 　

ISSN：0920-3796
Evaluation of interface resistance in a rebco tape at different temperatures by contact-probing current transfer length method 査読有り

Hayasaka, R., Ito, S., Hashizume, H.

IEEE Transactions on Applied Superconductivity　29　(5)　9000805　2019年8月

DOI： 10.1109/TASC.2019.2895603 　

ISSN：1558-2515 1051-8223
Investigation of the correlation between the electrical contact resistance and the contact area of mechanical lap joint fabricated with high-temperature superconducting tapes using X-ray microtomography 査読有り

Chen, W., Ito, S., Yusa, N., Hashizume, H.

Fusion Engineering and Design　148　111284　2019年8月

DOI： 10.1016/j.fusengdes.2019.111284 　

ISSN：0920-3796

詳細を見る詳細を閉じる

A mechanical lap joint fabricated with high-temperature superconducting (HTS) tapes is proposed for the application to joint-winding in HTS magnets for fusion reactors. The applicability of the joint has been validated, however, it could not be guaranteed because the joint resistance is unpredictable before the entire conductor is cooled and energized. Identifying the factors that affect the joint resistance is necessary to develop a method to predict this parameter at room temperature. In this report, we evaluated the correlation between the electrical resistance of contact interfaces (contact resistance) and the contact area observed using X-ray computer tomography scan (observed contact area), and discussed appropriate techniques for this prediction. A total of 40 mechanical lap joint samples were prepared. The observed contact areas were segmented from cross-sectional images of contact interfaces using a graph cut image segmentation, while the contact resistances were calculated from measured joint resistances. The correlation indicated that the prediction of contact resistance is more precise when base on the observed contact area compared to the conventional method using the nominal contact area. However, some of dispersive contact resistivity still remained due to inhomogeneous distribution of fine-structure on contact interface.
Comparison of heat assisted lap joints of high-temperature superconducting tapes with inserted indium foils 査読有り

Ito, S., Fujii, H.T., Hayasaka, R., Sato, Y.S., Hashizume, H.

IEEE Transactions on Applied Superconductivity　29　(5)　6600405　2019年8月

DOI： 10.1109/TASC.2019.2892050 　

ISSN：1558-2515 1051-8223
Fundamental Evaluations of Applicability of LTS Quench Detectors to REBCO Pancake Coil

Shin Hasegawa, Satoshi Ito, Gen Nishijima, Hidetoshi Hashizume

IEEE Transactions on Applied Superconductivity　29　(5)　1-5　2019年8月1日
出版者・発行元：None
DOI： 10.1109/TASC.2019.2900633 　

ISSN：1051-8223

eISSN：2378-7074

詳細を見る詳細を閉じる

© 2002-2011 IEEE. Quench detection in a rare-earth barium copper oxide (REBCO) coil is difficult due to the slow normal zone propagation in it. To address this issue, we have proposed a quench detection method using a low temperature superconducting (LTS) wire as a quench detector. A demonstration experiment in our previous research using a REBCO tape showed that the quench detector was able to detect quench in the tape before it burned out. Therefore, to verify the applicability of this method to a real magnet system, we first numerically evaluated the quench detectability of Nb-Ti and Nb3Al detectors attached on stacked REBCO tapes at 4.2 K under magnetic fields up to 20 T assuming the coil excitation process. The results indicated that the detectors were not needed to be placed in each layer of the REBCO coil. Furthermore, we have conducted an experiment using a REBCO single pancake coil with the Nb-Ti quench detector at 4.2 K and self-field. As the results of the experiment, we demonstrated that one Nb-Ti detector was able to detect the quench in the REBCO coil even if there were at least three REBCO tapes and the polyimide tapes between the detector and the hot-spot in the REBCO coil.
Detection of cracks with arbitrary orientations in a metal pipe using linearly-polarized circular TE11 mode microwaves 査読有り

Chen, G., Katagiri, T., Song, H., Yusa, N., Hashizume, H.

NDT and E International　107　102125　2019年7月

DOI： 10.1016/j.ndteint.2019.102125 　

ISSN：0963-8695
Mechanical Design Concept of Superconducting Magnet System for Helical Fusion Reactor 査読有り

Tamura, H., Yanagi, N., Goto, T., Miyazawa, J., Tanaka, T., Sagara, A., Ito, S., Hashizume, H.

Fusion Science and Technology　75　(5)　384-390　2019年4月

DOI： 10.1080/15361055.2019.1603041 　

ISSN：1943-7641 1536-1055
Characterization of multilayered structures by swept-frequency eddy current testing 査読有り

程衛英

AIP Advances　9　(3)　035009-035009　2019年3月
出版者・発行元：None
DOI： 10.1063/1.5079959 　

eISSN：2158-3226
Progress in the Conceptual Design of the Helical Fusion Reactor FFHR-d1 査読有り

Yanagi, N., Goto, T., Miyazawa, J., Tamura, H., Terazaki, Y., Ito, S., Tanaka, T., Hashizume, H., Sagara, A.

Journal of Fusion Energy　38　(1)　147-161　2019年2月

DOI： 10.1007/s10894-018-0193-y 　

ISSN：0164-0313
Proposal of a TEM to TE 01 mode converter for a microwave nondestructive inspection of axial flaws appearing on the inner surface of a pipe with an arbitrary diameter 査読有り

Katagiri, T., Sasaki, K., Song, H., Yusa, N., Hashizume, H.

International Journal of Applied Electromagnetics and Mechanics　59　(4)　2019年

DOI： 10.3233/JAE-171144 　

ISSN：1383-5416
Long-range inspection of a pipe with a bend using microwaves 査読有り

Uoshita, S., Sasaki, K., Katagiri, T., Yusa, N., Hashizume, H.

International Journal of Applied Electromagnetics and Mechanics　59　(4)　2019年

DOI： 10.3233/JAE-171001 　

ISSN：1383-5416
EXPERIMENTAL INVESTIGATION OF INFLUENCE OF TURBULENT NEAR-WALL FLOW ON FLOW ACCELERATED CORROSION BEHIND AN ORIFICE 査読有り

T. Kaneko, S. Ebara, H. Hashizume

Proceedings of The 29th International Symposium on Transport Phenomena　ISTP29-153　2018年11月
Advanced high-temperature superconducting magnet for fusion reactors: Segment fabrication and joint technique 査読有り

Ito, S., Hashizume, H., Yanagi, N., Tamura, H.

Fusion Engineering and Design　136　(A)　239-246　2018年11月

DOI： 10.1016/j.fusengdes.2018.01.072 　

ISSN：0920-3796
Development of a high energy hydrogen beam injection system for divertor plasma simulation experiments on the DT-ALPHA device 査読有り

Boonyarittipong, P., Takahashi, H., Kitajima, S., Okamoto, A., Tobita, K., Kobayashi, T., Saikyo, T., Ishikawa, Y., Ogasawara, K., Hashizume, H.

Plasma and Fusion Research　13　3402102-1-3402102-5　2018年9月

DOI： 10.1585/PFR.13.3402102 　

ISSN：1880-6821
Development of ion sensitive probe and its application to RF plasma device DT-ALPHA 査読有り

Kobayashi, T., Takahashi, H., Kitajima, S., Okamoto, A., Tobita, K., Boonyarittipong, P., Saikyo, T., Ishikawa, Y., Ogasawara, K., Hashizume, H.

Plasma and Fusion Research　13　3401090-1-3401090-7　2018年7月

DOI： 10.1585/PFR.13.3401090 　

ISSN：1880-6821
Experimental verification of long-range microwave pipe inspection of using straight pipes with lengths of 19–26.5 m 査読有り

Kota Sasaki, Takuya Katagiri, Noritaka Yusa, Hidetoshi Hashizume

NDT&E International　96　47-57　2018年6月1日
出版者・発行元：None
DOI： 10.1016/j.ndteint.2018.03.001 　

ISSN：0963-8695
Application of low-frequency eddy current testing to the inspection of a double-walled tank in a reprocessing plant 査読有り

Naoki Tajima, Noritaka Yusa, Hidetoshi Hashizume

Nondestructive Testing and Evaluation　33　(2)　189-197　2018年4月3日
出版者・発行元：Taylor and Francis Ltd.
DOI： 10.1080/10589759.2017.1376057 　

ISSN：1477-2671 1058-9759

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This paper discusses the applicability of simple low-frequency eddy current testing to the detection of deeply embedded flaws. The study specifically considered a double tank in a reprocessing plant for extracting plutonium-uranium from spent nuclear fuels. The tank was modelled by two type 304 austenitic stainless steel plates situated with an air gap of 80 mm, and the change in the thickness of one of the plates was detected through the other plate and the air gap. Axisymmetric two-dimensional finite element simulations were conducted and found that a simple circular coil with a large diameter enabled to detect the thickness based on the magnetic flux density at the centre of the coil although the plates were as thick as 30 mm. The results of the numerical simulations were validated by experiments.
Numerical and Experimental Evaluations of the Quench Detection Performance of an YBCO/Nb-Tid Tape 査読有り

Shin Hasegawa, Satoshi Ito, Hidetoshi Hashizume

IEEE Transactions on Applied Superconductivity　28　(3)　4700605　2018年4月1日
出版者・発行元：Institute of Electrical and Electronics Engineers Inc.
DOI： 10.1109/TASC.2018.2795552 　

ISSN：1051-8223

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Quench detection for the high-temperature superconducting tape, especially rare-earth barium copper oxide (REBCO) tape, is difficult due to the small normal zone propagation velocity in it. To address this issue, we have proposed a novel quench detectable REBCO tape with a low-temperature superconducting wire used as a quench detector, "REBCO/LTSd tape". In this paper, we numerically and experimentally demonstrated the validity of the tape consisting of the yttrium barium copper oxide (YBCO) tape and the Nb-Ti wire used at 4.2 K under no external field. Results of the numerical simulation showed that sufficiently high voltage of 0.1 V can be detected before the maximum temperature of the YBCO tape reaches 50 K with the Nb-Ti wires having high resistance at normal conducting state. Experimental results also demonstrated that the quench in the YBCO was detected with the 1 V scale voltage by using the pure Nb-Ti wire.
Construction of minor actinides reduction scenario in Japan utilizing fusion reactors 査読有り

Yuki Furudate, Hiroki Shishido, Noritaka Yusa, Hidetoshi Hashizume

Progress in Nuclear Energy　103　28-32　2018年3月1日
出版者・発行元：Elsevier Ltd
DOI： 10.1016/j.pnucene.2017.11.003 　

ISSN：0149-1970

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This study demonstrates by numerical simulations how transmuting minor actinides in fusion reactors can contribute to nuclear fuel cycles in Japan. Minor actinides are installed into blankets of a helical-type fusion reactor to transmute them rather moderately so that neither large neutron wall loading nor removal of large heat are required. Neutron transport and burn-up simulations are conducted to optimize the position of minor actinides and the blanket's structure for transmutation. Whereas the ratio of transmuted minor actinides is not large, the total amount of transmuted minor actinides is revealed to be sufficient because of the system's large inventory. The simulations are followed by a plan that introduces fusion reactors intended for transmutation. Discussion based on Japan's present situation confirms that introduction of fusion reactors with a thermal fusion output of 1 GW by the year 2050 would mitigate many issues concerning disposal of high-level radioactive waste.
Development of remountable joints and heat removable techniques for high-Temperature superconducting magnets 査読有り

H. Hashizume, S. Ito, N. Yanagi, H. Tamura, A. Sagara

Nuclear Fusion　58　(2)　26014　2018年2月1日
出版者・発行元：Institute of Physics Publishing
DOI： 10.1088/1741-4326/aa874f 　

ISSN：1741-4326 0029-5515

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Segment fabrication is now a candidate for the design of superconducting helical magnets in the helical fusion reactor FFHR-d1, which adopts the joint winding of high-Temperature superconducting (HTS) helical coils as a primary option and the 'remountable' HTS helical coil as an advanced option. This paper reports on recent progress in two key technologies: The mechanical joints (remountable joints) of the HTS conductors and the metal porous media inserted into the cooling channel for segment fabrication. Through our research activities it has been revealed that heat treatment during fabrication of the joint can reduce joint resistance and its dispersion, which can shorten the fabrication process and be applied to bent conductor joints. Also, heat transfer correlations of the cooling channel were established to evaluate heat transfer performance with various cryogenic coolants based on the correlations to analyze the thermal stability of the joint.
高周波プラズマ源DT-ALPHAにおけるIon sensitive probeによるイオン温度計測査読有り

小林鷹彦, 橋爪秀利, 高橋宏幸, Peerapat Boonyarittipong, 西京毅, 石川裕介, 小笠原健太, 北島純男, 岡本敦, 飛田健次

日本物理学会講演概要集　73　(0)　840-840　2018年
出版者・発行元：一般社団法人日本物理学会
DOI： 10.11316/jpsgaiyo.73.1.0_840 　
Divertor plasma simulation experiment using hydrogen ionizing plasma and helium ion beam in an RF plasma source DT-ALPHA 査読有り

Takahashi, H., Kobayashi, T., Boonyarittipong, P., Saikyo, T., Ishikawa, Y., Ogasawara, K., Okamoto, A., Tobita, K., Kitajima, S., Hashizume, H.

Plasma and Fusion Research　13　3401053　2018年

DOI： 10.1585/PFR.13.3401053 　

ISSN：1880-6821
Proposal of fluid stirring by multi-layered trenches for liquid metal divertor 査読有り

Makoto Kawamoto, Kenta Muraoka, Satoshi Ito, Hidetoshi Hashizume

Fusion Engineering and Design　136　(A)　415-419　2018年
出版者・発行元：Elsevier Ltd
DOI： 10.1016/j.fusengdes.2018.02.065 　

ISSN：0920-3796

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This study proposes ″multi-layered trenches″ as a new liquid metal flow stirring structure for the flowing-type liquid metal divertor to prevent the temperature stratification and the evaporation of liquid metal.Then it investigates the characteristics of the liquid metal flow induced by this structure experimentally and numerically. The proof-of-principal experiment using a torus channel simulating the trenches successfully demonstrated the liquid metal wavy flow where the ratio of meandering component to the main stream was 27% under the magnetic field up to 5 T. The experiment and three-dimensional magnetohydrodynamics flow simulation also proved that magnitudes of the wavy flow and the vorticity increased with a rise in the magnetic field. Moreover, two-dimensional heat transfer model simulation showed the heat transfer enhancement by the wavy flow. Maximum temperature was 26.6 K lower than that in the case without the wavy flow.
Comparison of shear strength and failure mechanisms of lap joint between REBCO tapes bonded by different joining techniques 査読有り

Luis Ernesto Aparicio, Satoshi Ito, Hidetoshi Hashizume

Fusion Engineering and Design　136　(B)　1196-1201　2018年
出版者・発行元：Elsevier Ltd
DOI： 10.1016/j.fusengdes.2018.04.101 　

ISSN：0920-3796

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Lap joints between Rare-Earth Barium Copper Oxide (REBCO) tapes are intended to be employed for segmented fabrication of high-temperature superconducting magnet as innovative design of fusion magnets. This study evaluates the shear strength and failure mechanism of lap joints between commercial REBCO tapes from two different manufacturers while using different mechanical joining procedures or soldering alloys. Additionally, the shear strength along the width direction of the different REBCO tapes was experimentally evaluated. Overall results using REBCO tapes with soldered Cu stabilizer revealed that they are unsuitable for field application due to low shear strength of the tapes. On the other hand, REBCO tapes with electro-plated Cu stabilizer are more versatile soldered lap joints using Pb37Sn63 showed shear strength higher than required value. However, failure mechanism of the soldered joints always involve delamination of the REBCO tape which instantly increase joint resistance. Conversely, mechanical lap joints with indium fabricated using the improved method with heat treatment or indium pre-coating with heat treatment exhibited cohesive failure followed by plastic deformation of indium, which reduces the shear stress while maintaining acceptable joint resistance. This fact makes the mechanical lap joint a more reliable option so far.
Probability of detection analyses of eddy current data for the detection of corrosion 査読有り

Noritaka Yusa, Takuma Tomizawa, Haicheng Song, Hidetoshi Hashizume

Nondestructive Testing and Diagnosis　4　2018年
TE モードのマイクロ波を用いた配管内管軸方向割れの広域一括検出査読有り

片桐拓也, 佐々木幸太, 遊佐訓孝, 橋爪秀利

日本機械学会論文集　84　2018年
Low Frequency Electromagnetic Testing for Evaluating Wall Thinning in Carbon Steel Pipe 査読有り

Haicheng Song, Noritaka Yusa, Hidetoshi Hashizume

Materials Transactions　59　1348-1353　2018年
Experimental Evaluation of Novel Hybrid Microwave/Ultrasonic Technique to Locate and Characterize Pipe Wall Thinning 査読有り

Alobaidi, W.M., Kintner, C.E., Alkuam, E.A., Sasaki, K., Yusa, N., Hashizume, H., S, gren, E.

Journal of Pressure Vessel Technology, Transactions of the ASME　140　(1)　2018年

DOI： 10.1115/1.4038517 　

ISSN：1528-8978 0094-9930
Design modification of structural components for the helical fusion reactor FFHR-d1 with challenging options 査読有り

Tamura, H., Yanagi, N., Goto, T., Miyazawa, J., Tanaka, T., Sagara, A., Ito, S., Hashizume, H.

Fusion Engineering and Design　124　605-609　2017年11月

DOI： 10.1016/j.fusengdes.2017.03.031 　

ISSN：0920-3796
Development of remountable joints and heat removable techniques for high-temperature superconducting magnets 査読有り

Hashizume, Hidetoshi, Ito, Satoshi, Yanagi, Nagato, Tamura, Hitoshi, Sagara, Akio

Nuclear fusion　2017年10月1日
Heating and Loading Process Improvement for Indium Inserted Mechanical Lap Joint of REBCO Tapes 査読有り

Tatsuki Nishio, Satoshi Ito, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　27　(4)　4603305　2017年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2017.2672691 　

ISSN：1051-8223

eISSN：1558-2515

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A mechanical lap joint of REBCO high-temperature superconducting (HTS) tapes with an indium foil inserted between joint surfaces has been proposed for segment-fabrication of HTS magnet of an advanced fusion reactor and various HTS applications. In a previous study, we successfully achieved a joint resistivity of about 3.5 p Omega m(2) by heat treatment during fabrication of the joint. In this study, improved heat treatment method was developed by controlling contact pressure and combining bake-out process. We evaluated joint resistance and critical current of the joint depending on the heating condition and bake-out condition. The joint resistivity after heat treatment was 2.5 p Omega m2 without decreasing critical current with conditions of heating temperatures of 90-140 degrees C, a heating time of 30 min, a contact pressure of 100 MPa, a bake-out time of 30 min, and a bake-out temperature of 150 degrees C. Owing to applying the contact pressure when the indium becomes softer, the true area of contact increased and the thickness of the indium decreased greater than those in the previous method. In addition, it was shown that voids appearing by heating were removed by bake-out process from thermal desorption spectroscopy test.
Bending Characteristic of a Bridge-Type Mechanical Lap Joint of REBCO Tapes 査読有り

Satoshi Ito, Tatsuki Nishio, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　27　(4)　4600105　2017年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2016.2625748 　

ISSN：1051-8223

eISSN：1558-2515

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This study focuses on bending characteristic of a bridge-type mechanical lap joint of Rare-Earth Barium Copper Oxide (REBCO) tapes, which has been proposed for segment fabrication of high-temperature superconducting magnet especially for a heliotron-type fusion reactor. Previous studies have developed the joint with a straight geometry, showing sufficiently low joint resistance from a view point of electrical power required to run a cryoplant for removing heat from a superconducting magnet, though conductors connected at the joint section are ideally curved to form a helical-shaped coil. In this study, we experimentally evaluated joint resistance as a function of bending strain for a bridge-type mechanical lap joint of REBCO tapes with indium foils inserted between the joint surfaces. The results showed critical bending strain, where joint resistance starts to increase, was almost the same as irreversible strain of the REBCO tape in the case of a 10-mm-long joint. The critical bending strain varied as a function of both joint resistivity and joint length; lower joint resistivity and longer joint can achieve higher critical bending strain. The fabrication process "Joining-then-bending" can be also applied to a curved joint for reactor-scaled helical coils, where 25-mm-long joint is planned to be applied, though "Bending-then-joining" would be needed for the joint of small prototype coils.
The Application of 3D Printing Technology to Fabricate an Imitative Crack for Electromagnetic NDT&E Studies 査読有り

Noritaka Yusa, Weixi Chen, Hidetoshi Hashizume

Studies in Applied Electromagnetics and Mechanics　42　150-156　2017年
出版者・発行元：IOS Press
DOI： 10.3233/978-1-61499-767-2-150 　

ISSN：1879-8322 1383-7281

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This study evaluates the applicability of 3D printing technology for creating artificial flaws that imitate real cracks for the development of electromagnetic nondestructive testing methods. A plate containing an artificial flaw with branching and electrical contact is fabricated using a powderbed-based laser metal additive manufacturing machine. Eddy current testing using an absolute pancake probe is conducted to gather the signals due to the flaw. Subsequent finite element simulations on the basis of the results of destructive testing suggests that one should design a flaw whose signals do not change so significantly even though the profile of the flaw changes almost 0.1 mm.
Non-Destructive Testing Using Microwave in TE Mode for Detecting Axial Cracks in a Metal Pipe 査読有り

Takuya Katagiri, Kota Sasaki, Noritaka Yusa, Hidetoshi Hashizume

Studies in Applied Electromagnetics and Mechanics　42　106-112　2017年
出版者・発行元：IOS Press
DOI： 10.3233/978-1-61499-767-2-106 　

ISSN：1879-8322 1383-7281

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A new mode convertor, which has four coaxial cable connectors and four semi-rigid cables situated circumferentially, was fabricated to propagate TE mode microwaves in a circular pipe in order to detect axial cracks appearing in the inner surface of the pipe. In this study, the reflections were measured using a network analyzer by propagating microwaves as a pulse through the mode convertor into a brass pipe that contains the slit on the inner surface. The reflections were evaluated with different orientations, lengths, and positions of the slit. The experimental results showed a clear difference between the signals with and without the slit.
Low Frequency Eddy Current Testing to Measure Thickness of Double Layer Plates Made of Nonmagnetic Steel 査読有り

Naoki Tajima, Noritaka Yusa, Hidetoshi Hashizume

Studies in Applied Electromagnetics and Mechanics　42　131-138　2017年
出版者・発行元：IOS Press
DOI： 10.3233/978-1-61499-767-2-131 　

ISSN：1879-8322 1383-7281

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This study attempts to apply low frequency eddy current testing to measure the thickness of double-layered plates which consist of two 304 austenitic stainless steel plates with a thickness of about 30 mm and an air gap with a thickness of 80 mm. The results of numerical simulations show that a change in the magnetic flux density due to the thickness change of the plates appears at the center of the coil when the diameter of the exciting coil is as large as 300 mm and the exciting frequency is in the low tens of Hertz. Experimental verifications were conducted using a magneto-impedance sensor whose sensitivity was 1 mV/nT and sensing range was from 0.2 nT to 2000 nT. We used a large diameter pancake exciting coil and a compensating coil to make up for the short of the range of the magnetic sensor during the measurements. The signals of the sensor situated at the center of the exciting coil changed with the thickness of the double-layered plates, which agrees with the result of the simulations.
Current-carrying capability of the 100 kA-class HTS STARS conductor for the helical fusion reactor FFHR-d1 査読有り

Y. Terazaki, N. Yanagi, S. Ito, S. Hamaguchi, H. Tamura, T. Mito, H. Hashizume, A. Sagara

Journal of Physics: Conference Series　871　(1)　012099　2017年

DOI： 10.1088/1742-6596/871/1/012099 　
Numerical investigation of the ability of eddy current testing to size surface breaking cracks 査読有り

Noritaka Yusa, Hidetoshi Hashizume

NONDESTRUCTIVE TESTING AND EVALUATION　32　(1)　50-58　2017年
出版者・発行元：TAYLOR & FRANCIS LTD
DOI： 10.1080/10589759.2015.1135918 　

ISSN：1058-9759

eISSN：1477-2671

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This study attempts to estimate the limitations of eddy current testing for evaluating the depth of a crack with the aid of numerical simulations. Three-dimensional finite element simulations were conducted to obtain eddy current signals resulting from a crack in a plate made of Ni-based alloy. The simulations modelled the crack as a sufficiently long rectangular region with a constant width and depth. A uniform conductivity was given inside the modelled crack because actual cracks do not always behave as electrically insulating walls. The conductivity of the modelled crack was chosen on the basis of a recent study reporting how real cracks can be modelled from the viewpoint of electromagnetic non-destructive evaluation. This study considered three conventional eddy current probes: a pancake probe, a vertical pancake probe and a plus point probe. The results of the simulations reveal that lower frequency does not always enhance the evaluation of a deeper crack if the crack is conductive; moreover, the maximum depth of a stress corrosion crack that conventional eddy current testing can evaluate quantitatively should be limited to a few mm at most. In contrast, the simulations also demonstrate that the ability of eddy current testing to size a fatigue crack would not differ significantly from that to size an artificial slit.
Thermal Design Investigation for a Flinabe Blanket System 査読有り

Hiroki Shishido, Noritaka Yusa, Hidetoshi Hashizume, Yoshiki Ishii, Norikazu Ohtori

FUSION SCIENCE AND TECHNOLOGY　72　(3)　382-388　2017年
出版者・発行元：TAYLOR & FRANCIS INC
DOI： 10.1080/15361055.2017.1330623 　

ISSN：1536-1055

eISSN：1943-7641

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The present study evaluates the thermal design of a blanket system using Flinabe in order to facilitate further discussions on its applicability as a self-cooled liquid blanket system. Molecular dynamics simulations were performed to evaluate the Prandtl number of mixtures in five compositions (LiF-NaF-BeF2 = 31-31-38, 36-27-37, 42-22-36, 49-16-35, and 67-0-33). Thermofluid analysis was carried out to estimate the temperature margin and pressure drop per unit length in a simple geometry model of the blanket system. The Prandtl number of Flinabe is above 100 at 400 degrees C. The present study reveals that Flinabe remarkably relaxes the design conditions compared to Flibe as a coolant owing to its low melting point. In contrast, the pressure drop per unit length of Flinabe is higher than that of Flibe because the viscosity exponentially increases at low temperature. The temperature margin is quite dependent on the heat load on the first wall. If the pressure drop per unit length is around 1.0 MPa/m, the heat load value must be approximately below 0.7 MW/m(2).
Demonstration of the Applicability of Nondestructive Microwave Testing to the Long-Range Inspection of Inner-Surface Cracks in Tubes 査読有り

Kota Sasaki, Takuya Katagiri, Noritaka Yusa, Hidetoshi Hashizume

MATERIALS TRANSACTIONS　58　(4)　692-696　2017年
出版者・発行元：JAPAN INST METALS
DOI： 10.2320/matertrans.M2017008 　

ISSN：1345-9678

eISSN：1347-5320

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This study evaluated the applicability of nondestructive microwave testing method for the long-range detection of inner-surface cracks in metallic tubes. Two seamless straight tubes 7 m in length and 23.0 mm in inner diameter were prepared, and artificial circumferential slits penetrating the tube walls were introduced. A probe to propagate microwave inside the tube, designed based on three-dimensional finite element simulations, was attached to an end of the tube, and the reflections of the microwave propagating inside the tube were measured using a network analyzer. The experiments confirmed clear reflections due to the slits situated 6 m away from the probe. Furthermore, imposing a signal processing method to compensate for the dispersion of the microwave clarified the refiections and enabled the slit to be localized quantitatively from the time-of-flight of the refiections.
Evaluation of Interface and Cohesion Shear Strength of Mechanical Lap-Joint Between HTS Coated Conductors Intended for Segmented HTS Magnet 査読有り

Luis E. F. Aparicio, Satoshi Ito, Hidetoshi Hashizume

FUSION SCIENCE AND TECHNOLOGY　72　(4)　789-795　2017年
出版者・発行元：TAYLOR & FRANCIS INC
DOI： 10.1080/15361055.2017.1350522 　

ISSN：1536-1055

eISSN：1943-7641

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This study evaluates the mechanical strength, failure mechanism and change in electrical resistance under shear stress of a mechanical lap joint of Rare-Earth Barium Copper Oxide high-temperature superconducting (HTS) tapes using indium as bonding material, which has been proposed for "remountable" (demountable) or segmented HTS magnet in future fusion reactors. Results from tensile shear tests using reinforced REBCO tapes along with an analysis on the failure mode demonstrated that contact conductivity is the critical parameter that defines joint's shear strength rather than joint pressure. Additionally, it was concluded that change in joint resistance when failure occur is not abrupt and its behavior as joint displaces depends on the failure mode of the joint.
管側面入射マイクロ波による配管内壁面広域一括探傷技術の検討査読有り

佐々木幸太, 遊佐訓孝, 片桐拓也, 橋爪秀利

日本AEM学会誌　25　(2)　266-272　2017年
出版者・発行元：日本AEM学会
DOI： 10.14243/jsaem.25.266 　

ISSN：0919-4452

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This study proposes long-range nondestructive inspection of the inner surface of a pipe without open end using microwave emitted by a probe attached to the pipe wall. Three-dimensional finite element simulations were conducted to evaluate how to propagate microwave effectively inside a pipe having an inner diameter of 19 mm. The simulations considered a coaxial cable penetrating the pipe wall to emit microwave inside the pipe. Experimental verifications were then carried out using a brass pipe with a total length of 4.5 m and a probe fabricated on the basis of the results of the numerical simulations. The experiment confirmed clear reflections due to artificial wall thinning 1 m away from the probe situated approximately at the center of the pipe. The experiment also revealed that directivity of the microwave depended on the frequency, which agrees with the results of the numerical simulations.
Magnet design with 100-kA HTS STARS conductors for the helical fusion reactor 査読有り

N. Yanagi, Y. Terazaki, S. Ito, H. Tamura, S. Hamaguchi, T. Mito, H. Hashizume, A. Sagara

CRYOGENICS　80　(2)　243-249　2016年12月
出版者・発行元：ELSEVIER SCI LTD
DOI： 10.1016/j.cryogenics.2016.06.011 　

ISSN：0011-2275

eISSN：1879-2235

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The high-temperature superconducting (HTS) option is employed for the conceptual design of the LHD-type helical fusion reactor FFHR-d1. The 100-kA-class STARS (Stacked Tapes Assembled in Rigid Structure) conductor is used for the magnet system including the continuously wound helical coils. Protection of the magnet system in case of a quench is a crucial issue and the hot-spot temperature during an emergency discharge is estimated based on the zero-dimensional and one-dimensional analyses. The number of division of the coil winding package is examined to limit the voltage generation. For cooling the HTS magnet, helium gas flow is considered and its feasibility is examined by simple analysis as a first step. (C) 2016 Elsevier Ltd. All rights reserved.
Flow Field Investigation in a Cooling Channel with Finger-Stacked Structure Using PIV Measurement 査読有り

Shohei YASUNAGA, Shinji EBARA, Hidetoshi HASHIZUME

Proceedings of the 11th International Symposium on Advanced Science and Technology in Experimental Mechanics　57-Shohei YASUNAGA-770.pdf　2016年11月
HEAT TRANSFER CHARACTREISTIC OF SPHERE-PACKED RECTANGULAR CHANNEL FOR HIGH PRANDTL NUMBER FLUID UNDER ONE-SIDED HEATING CONDITION 査読有り

Dorota Smakulska, Shohei Yasunaga, Shinji Ebara, Hidetoshi Hashizume

Proceedings of the 4th International Forum on Heat Transfer　Paper ID IFHT2016-2041　2016年11月
Development of Remountable Joints and Heat Removable Techniques for High-temperature Superconducting Magnets 査読有り

H. Hashizume, S. Ito, N. Yanagi, H. Tamura, A. Sagara

IAEA FEC2016　2016年10月17日
革新的核融合炉実現に向けた分割型高温超伝導マグネットの研究開発〜高温超伝導導体の着脱可能な接合法の開発状況〜招待有り査読有り

伊藤悟, 橋爪秀利, 遊佐訓孝, 柳長門, 田村仁, 相良明男

プラズマ核融合学会誌　92　(8)　623-634　2016年8月
出版者・発行元：プラズマ・核融合学会
ISSN：0918-7928

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Accepted for Publication
Demonstration of probability of detection taking consideration of both the length and the depth of a flaw explicitly 査読有り

Noritaka Yusa, Weixi Chen, Hidetoshi Hashizume

NDT & E INTERNATIONAL　81　1-8　2016年7月
出版者・発行元：ELSEVIER SCI LTD
DOI： 10.1016/j.ndteint.2016.03.001 　

ISSN：0963-8695

eISSN：1879-1174

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This study proposes the construction of the probability of detection (POD) as a function of both the depth and length of a flaw. In addition, this study discusses how to censor signals in constructing the POD. The general effects of the flaw parameters on signals are evaluated by numerical simulations, and the scattering of signals, which is critical to the POD, is estimated by signals obtained in experiments. A new likelihood function is introduced, and the proposed method is demonstrated using eddy current signals caused by various artificial flaws on a flat type 316L stainless steel plate obtained in a laboratory test. The demonstration confirms that the proposed method can provide a reasonable POD with a small amount of experimental signals, and reveals that proper censoring significantly decreases the detrimental effect of noise on the POD. (C) 2016 Elsevier Ltd. All rights reserved.
Modeling of TE mode transducer for nondestructive testing of defects inside a metal pipe using microwave 査読有り

K. Sasaki, T. Katagiri, N. Yusa, H. Hashizume

19th World Conference on Non-destructive Testing (WCNDT2016)　2016年6月13日
Structure and Magnetic Field Dependences of Joint Resistance in a Mechanical Joint of REBCO Tapes 査読有り

Satoshi Ito, Yutaro Seino, Tatsuki Nishio, Hidetoshi Oguro, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　26　(4)　2016年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2016.2539210 　

ISSN：1051-8223

eISSN：1558-2515

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Mechanical joints of rare-earth barium copper oxide (REBCO) tapes and stacked tape conductors have been investigated for segmented fabrication of high-temperature superconducting (HTS) magnets for future fusion reactors. To design the optimized joint, we need to predict joint resistance depending on operating conditions and the conductor's structure. The prediction method was proposed in our previous study, taking into account the model of contact resistance, resistance of constituent materials, and interfaces. However, that was just based on data of mechanical lap joints for one kind of REBCO tape and a magnetic field perpendicular to the tape. Therefore, in this paper, we first evaluated joint resistances in mechanical lap joints of Fujikura's and SuperPower's REBCO tapes as a function of temperature and magnetic field with different orientations. The results showed that the joint resistance significantly increased with an increase in magnetic field parallel to the tape at temperatures of 10 K and lower. In addition, the reduction rate of joint resistance for the SuperPower's tape with a decrease in temperature was lower than that for the Fujikura's tape. Based on experimental results for Fujikura's REBCO tapes with different field orientations, we modified the model of contact resistance. Further improvement of the prediction method is still needed for different stabilizer structures and a temperature range around 10 K.
Reducing Joint Resistance by Heat Treatment During Fabrication of a Mechanical Joint of High-Temperature Superconducting Conductors 査読有り

Tatsuki Nishio, Satoshi Ito, Noritaka Yusa, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　26　(4)　4800505　2016年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2016.2521891 　

ISSN：1051-8223

eISSN：1558-2515

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A mechanical joint of high-temperature superconducting (HTS) conductors has been investigated for segmented fabrication of HTS magnets proposed for a future fusion reactor. In a previous study, joint resistance of 1.8 n Omega at 100 kA was achieved for a large-scale simple-stacked gadolinium barium copper oxide (GdBCO) conductor having a bridge-type mechanical lap joint with indium foils inserted between joint surfaces. The obtained joint resistivity (the product of joint resistance and contact area) was, however, ten times larger than that of a single mechanical lap joint achieved in previous studies, which may be caused by nonuniform distribution of contact pressure. In order to reduce this joint resistance, therefore, we propose a new method by introducing heat treatment in fabricating process of the joint. By applying the method, the joint resistance became the lowest at heating temperatures of 75 degrees C-90 degrees C, which was reduced to 60% of the value obtained without heat treatment. The reduction of joint resistance was due to a decrease in thickness of the inserted indium and an increase in true area of the contact surface. On the other hand, relatively large voids were observed in the indium by X-ray computed tomography when the heating temperature exceeds 120 degrees C. The voids were caused by emission of the gases absorbed in the tape and foil, and the voids decreased by baking the conductor tapes and indium foil before the heat treatment. Applying the heat treatment to a large conductor joint, the voids can be formed due to the temperature exceeding 120 degrees C since the temperature control in the large joint becomes more difficult. Therefore, the baking process before the joint fabrication with heat treatment is one of the options to avoid the void formation.
Structure and Magnetic Field Dependences of Joint Resistance in a Mechanical Joint of REBCO Tapes 査読有り

Satoshi Ito, Yutaro Seino, Tatsuki Nishio, Hidetoshi Oguro, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　26　(4)　4800505　2016年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2016.2539210 　

ISSN：1051-8223

eISSN：1558-2515

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Mechanical joints of rare-earth barium copper oxide (REBCO) tapes and stacked tape conductors have been investigated for segmented fabrication of high-temperature superconducting (HTS) magnets for future fusion reactors. To design the optimized joint, we need to predict joint resistance depending on operating conditions and the conductor's structure. The prediction method was proposed in our previous study, taking into account the model of contact resistance, resistance of constituent materials, and interfaces. However, that was just based on data of mechanical lap joints for one kind of REBCO tape and a magnetic field perpendicular to the tape. Therefore, in this paper, we first evaluated joint resistances in mechanical lap joints of Fujikura's and SuperPower's REBCO tapes as a function of temperature and magnetic field with different orientations. The results showed that the joint resistance significantly increased with an increase in magnetic field parallel to the tape at temperatures of 10 K and lower. In addition, the reduction rate of joint resistance for the SuperPower's tape with a decrease in temperature was lower than that for the Fujikura's tape. Based on experimental results for Fujikura's REBCO tapes with different field orientations, we modified the model of contact resistance. Further improvement of the prediction method is still needed for different stabilizer structures and a temperature range around 10 K.
Design status of the structural components of the helical fusion reactor FFHR-d1 査読有り

Tamura, H., Tanaka, T., Goto, T., Yanagi, N., Miyazawa, J., Masuzaki, S., Sakamoto, R., Sagara, A., Ito, S., Hashizume, H.

Plasma and Fusion Research　11　(Specialissue1)　2405061　2016年5月17日

DOI： 10.1585/pfr.11.2405061 　

ISSN：1880-6821
Fabrication of imitative cracks by 3D printing for electromagnetic nondestructive testing and evaluations 査読有り

Noritaka Yusa, Weixi Chen, Jing Wang, Hidetoshi Hashizume

Case Studies in Nondestructive Testing and Evaluation　5　9-14　2016年5月1日
出版者・発行元：Elsevier Ltd
DOI： 10.1016/j.csndt.2016.03.004 　

ISSN：2214-6571

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This study demonstrates that 3D printing technology offers a simple, easy, and cost-effective method to fabricate artificial flaws simulating real cracks from the viewpoint of eddy current testing. The method does not attempt to produce a flaw whose morphology mirrors that of a real crack but instead produces a relatively simple artificial flaw. The parameters of this flaw that have dominant effects on eddy current signals can be quantitatively controlled. Three artificial flaws in type 316L austenitic stainless steel plates were fabricated using a powderbed-based laser metal additive manufacturing machine. The three artificial flaws were designed to have the same length, depth, and opening but different branching and electrical contacts between flaw surfaces. The flaws were measured by eddy current testing using an absolute type pancake probe. The signals due to the three flaws clearly differed from each other although the flaws had the same length and depth. These results were supported by subsequent destructive tests and finite element analyses.
Characteristics of flow field and pressure fluctuation in complex turbulent flow in the third elbow of a triple elbow piping with small curvature radius in three-dimensional layout 査読有り

Shinji Ebara, Hiroyuki Takamura, Hidetoshi Hashizume, Hidemasa Yamano

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY　41　(17)　7139-7145　2016年5月
出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD
DOI： 10.1016/j.ijhydene.2016.02.068 　

ISSN：0360-3199

eISSN：1879-3487

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In this study, a flow visualization and pressure measurement were conducted by using an experimental setup including test sections of 1/7-scale models of the cold-leg piping of Japan sodium-cooled reactor with high Reynolds number region up to about one million. Regarding the flow field, flow separation appeared in the intrados of the third elbow. However, the separation region was smaller than that observed in the first elbow in the direction normal to the mean flow and was larger in the streamwise direction. This can be considered because of the swirling flow vgenerated downstream of the second elbow which flowed into the third elbow with a little reduction. From the pressure fluctuation test, it was found that prominent frequencies of the pressure fluctuation appeared at about 0.4 in Strouhal number, which corresponds to a nondimensional frequency, in the region from 0 D to 0.4 D downstream of the elbow outlet, where D is the diameter of the piping. And weak peaks of about 0.7 in Strouhal number were observed in the region far 0.75 D downstream of the outlet. The peak values were about 1/4 of those in the first elbow. This means that the excitation source in the third elbow becomes smaller than that in the first elbow for the fully developed inflow case. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Multiscale Stress Analysis and 3D Fitting Structure of Superconducting Coils for the Helical Fusion Reactor 査読有り

Hitoshi Tamura, Nagato Yanagi, Kazuya Takahata, Akio Sagara, Satoshi Ito, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　26　(3)　4202405　2016年4月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2016.2531008 　

ISSN：1051-8223

eISSN：1558-2515

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Conceptual design studies for the Large-Helical-Device-type helical reactor, i.e., FFHR-d1, are being conducted in the National Institute for Fusion Science. Three different cooling schemes and conductor types have been proposed for the superconducting magnet system. A multiscale structural analysis is used to assess the mechanical characteristics of the magnet structure, taking into account the types of cooling schemes and superconductors. Multiscale analysis evaluates both the stress distribution in the coil support structure and local stress in the constituents of the superconductors without rebuilding a finite-element model of the support structure. Concerning a segmented fabrication of the helical coils using a high-temperature superconductor, the feasibility of segment installation is confirmed using a three-dimensional printing model, which identifies the maximum segment length and the necessary gap in the coil casing to install a segment.
Mechanical and Electrical Characteristics of a Bridge-Type Mechanical Lap Joint of HTS STARS Conductors 査読有り

Satoshi Ito, Noritaka Yusa, Nagato Yanagi, Hitoshi Tamura, Akio Sagara, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　26　(2)　4201510　2016年3月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2016.2517197 　

ISSN：1051-8223

eISSN：1558-2515

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Segmented fabrication of high-temperature superconducting (HTS) coils has been proposed for the helical fusion reactor FFHR-d1; the joint-winding and "remountable" (demountable) helical coils concept are the primary and advanced options, respectively. This paper introduces recent research activities on a bridge-type mechanical lap joint of HTS Stacked Tapes Assembled in Rigid Structure (STARS) conductors, particularly to be used for joint winding of the helical coils, and also discusses some technical issues to develop a reliable joint. First, the required joint performance is discussed from the viewpoints of operation cost and mechanical behavior, taking the present design of joint winding of the helical coils for the FFHR-d1 into consideration. Then, mechanical and electrical characteristics of a prototype STARS conductor joint, which achieved a joint resistance of 1.8 n Omega at a current of 100 kA, are analyzed based on small-and large-scale joint tests. It is suggested that the joint performance of the prototype joint can be improved more, according to tests of small-scale conductor joints. Finally, the study introduces a fabrication procedure for a reliable joint. We need to develop nondestructive testing for a joint at room temperature. For this purpose, we also perform an X-ray computed tomography inspection as a first step. The inspection can roughly judge whether a fabricated joint is acceptable.
Evaluation of shear strength in soldered and mechanical lap joints of high-temperature superconducting tapes intended for a remountable magnet 査読有り

Luis Aparicio, Satoshi Ito, Hidetoshi Hashizume

Plasma and Fusion Research　11　(1)　2016年
出版者・発行元：Japan Society of Plasma Science and Nuclear Fusion Research
DOI： 10.1585/pfr.11.2405065 　

ISSN：1880-6821

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This study describes the electro-mechanical response under tensile and shear stresses of the mechanical and soldered lap-joint methods proposed for joining Rare-Earth Barium Copper Oxide (REBCO) high-temperature superconducting (HTS) coated conductors (CCs) in designs of a "remountable" (demountable) HTS magnet and joint-winding of an HTS magnet intended for the helical fusion reactor FFHR-d1. Proper joint of REBCO CCs for the HTS magnets not only requires sufficiently low joint resistance to avoid quench phenomena, but also involves mechanical stability against large electromagnetic forces. Results obtained from tensile test to apply shear stress namely tensile shear tests performed on mechanically jointed REBCO CCs showed that the linear proportionality between shear strength and contact conductivity of the joint is conserved for larger joint section area. An attempt to describe the failure mechanism of mechanical lap-joint revealed that a bending moment is originated at the joint section. Furthermore, results from tensile shear test on soldered joint between REBCO CCs with copper stabilizer showed failure of the REBCO CCs with small axial loads while joint remained intact.
Numerical investigation of the ability of eddy current testing to size surface breaking cracks 査読有り

N. Yusa, H. Hashizume

Nondestructive Testing and Evaluation　2016年
Discussion on the effect of NaF on physical properties of Flinabe in comparison to Flibe from molecular dynamics simulations 査読有り

H. Shishido, N. Yusa, H. Hashizume, Y. Ishii, N. Ohtori

25th International TOKI Conference (ITC-24), Toki, Japan　2015年11月3日
Improving the joint resistance by heat treatment during fabrication of mechanical joint of high-temperature superconducting conductors 査読有り

T. Nishio, S. Ito, N. Yusa, H. Hashizume

International Conference on Magnet Technology 24 (MT-24), Seoul, Korea　2015年10月18日
Proposal of a prediction method for forced convection and nucleate boiling heat transfer characteristics in a cryogenic cooling system using the metal-particle sintered porous medium 査読有り

S. Sasaki, S. Ito, H. Hashizume

nternational Workshop on Cooling-system for HTS Applications 2015 (IWC-HTS 2015), Matsue, Japan　2015年10月14日
Evaluation of Influence of the Inlet Swirling Flow on the Flow Field in a Triple Elbow System 査読有り

J. Mizutani, S. Ebara, H. Hashizume

17th International Conference on Emerging Nuclear Energy Systems (ICENES2015), Istanbul, Turkey　2015年10月4日
Novel divertor design to mitigate neutron irradiation in the helical reactor FFHR-d1 査読有り

Hitoshi Tamura, Teruya Tanaka, Takuya Goto, Junich Miyazawa, Suguru Masuzaki, Tsuguhiro Watanabe, Nagato Yanagi, Akio Sagara, Satoshi Ito, Hidetoshi Hashizume

FUSION ENGINEERING AND DESIGN　98-99　1629-1633　2015年10月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2015.01.025 　

ISSN：0920-3796

eISSN：1873-7196

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The heat flux at the divertor in a fusion reactor is considered to have a peak of >10 MW/m(2). In a design study of the helical reactor FFHR-d1, the feasibility of employing a copper alloy for divertor cooling pipes was investigated; however, radiation in the divertor area would quickly damage the copper alloy. The neutron load on the divertor can be reduced by a blanket arrangement; nevertheless, in the present divertor structure, irradiation damage of materials on the inboard side of the torus remains relatively high. If the divertor could be moved to an area receiving much less radiation, then the lifetimes of divertor materials should increase. In this paper, a novel divertor structure is introduced in which the coil-support structure is modified to create a region receiving relatively low amounts of radiation without changing the geometry of the helical or vertical field coils. Using this proposed design would increase the lifetime of the copper alloy in divertor components to more than an estimated six years. In addition, the divertor could be accessed from either the upper or lower sides of the device, simplifying maintenance. (C) 2015 Elsevier B.V. All rights reserved.
EVALUATION OF PHYSICAL PROPERTIES OF THE MOLTEN SALT MIXTURES FLINABE FOR A FUSION BLANKET SYSTEM USING MOLECULAR DYNAMICS SIMULATION 査読有り

Hiroki Shishido, Noritaka Yusa, Hidetoshi Hashizume, Yoshiki Ishii, Norikazu Ohtori

FUSION SCIENCE AND TECHNOLOGY　68　(3)　669-673　2015年10月
出版者・発行元：AMER NUCLEAR SOC
DOI： 10.13182/FST14-975 　

ISSN：1536-1055

eISSN：1943-7641

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This study evaluates the physical properties of the molten salt Flinabe, using molecular dynamics simulations to discuss its applicability to a fusion blanket system. More specifically, the simulations calculate the density and viscosity of Flinabe to facilitate further discussion of the applicability from the viewpoint of the heat removal of the first wall. The results of the simulations are compared with data reported in earlier publications, which support the validity of the simulations. This study reveals that Flinabe tends to have lower viscosity than Flibe even when they contain almost the same BeF2. Analyzing the results of the simulations confirms that the degree of polymerization in Flinabe correlates with its viscosity, as that in Flibe does. The analyses also revealed, however, that the correlation in the case of Flibe is not directly applicable to the case of Flinabe.
Simulated evaluation of eddy current thermalgraphy for inspection of joint of divertor 査読有り

J. Wang, N. Yusa, H. Hashizume

The 20th International Workshop on Electromagnetic Nondestructive Evaluation, Sendai, Japan　2015年9月21日
Low frequency magnetic field measurement to monitor pipe wall thinning using mi sensor arrays 査読有り

N. Tajima, K. Sasaki, N. Yusa, H. Hashizume, T. Uchimoto, T. Takagi, K. Tanji

The 20th International Workshop on Electromagnetic Nondestructive Evaluation, Sendai, Japan　2015年9月21日
Development of the sided-incidence method in nondestructive testing using microwave for wall thinning inside a metal pipe 査読有り

K. Sasaki, N. Yusa, H. Hashizume

The 20th International Workshop on Electromagnetic Nondestructive Evaluation, Sendai, Japan　2015年9月21日
Impedance measurement for predicting joint resistance of a mechanical lap joint in a high-temperature superconductor 査読有り

W. Chen, S. Ito, N. Yusa, H. Hashizume

The 20th International Workshop on Electromagnetic Nondestructive Evaluation, Sendai, Japan　2015年9月21日
Designing of a fusion blanket system using molten salt flinabe for transmutation of minor actinides 査読有り

H. Shishido, Y. Furudate, N. Yusa, H. Hashizume

GLOBAL2015, Paris, France　2015年9月20日
Applicability of evaluation of non-destructive testing using microwave for a crack on the inner surface of metal tubes 査読有り

K. Sasaki, N. Yusa, H. Hashizume

The 17th International Symposium on Applied Electromagnetics and Mechanics, Kobe, Japan　2015年9月15日
Evaluation of neutronic performance of Flibe+LiI molten salt blanket system for MA transmutation 査読有り

Y. Furudate, H. Shishido, N. Yusa, H. Hashizume

The 17th International Symposium on Applied Electromagnetics and Mechanics, Kobe, Japan　2015年9月15日
STEADY AND TRANSIENT THERMAL ANALYSES ON A SEGMENTED HIGH-TEMPERATURE SUPERCONDUCTING MAGNET WITH POROUS MEDIA-INSERTED CRYOGENIC COOLING 査読有り

Satoshi Ito, Hidetoshi Hashizume

FUSION SCIENCE AND TECHNOLOGY　68　(2)　428-432　2015年9月
出版者・発行元：AMER NUCLEAR SOC
DOI： 10.13182/FST15-104 　

ISSN：1536-1055

eISSN：1943-7641

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This paper discusses thermal design of a segmented high-temperature superconducting (HTS) magnet depending on geometry of HTS conductors, cooling system (indirect cooling or partial forced flow cooling), cooling techniques and joint resistance. For the purpose, three-dimensional heat conduction analysis was carried out with a finite element code, modeling geometry and operating condition of helical coils. in a helical fusion reactor, FFHR as an example. In this analysis, liquid neon was assumed to be used as a coolant at an operating temperature of 25 K. As a heat removal technique for the joint, cooling system of a cryogenic liquid coolant with metal porous media has been proposed and it was also modeled in the heat conduction analysis. The numerical results showed that stainless steel jacket and a low thermal conductivity insulator determine temperature distribution and any cooling techniques cannot contribute to prevent the temperature rise when joint resistance increases in the case of the indirect cooling system. On the other hand, a high performance cooling technique such as metal porous media-inserted channel is effective to reduce temperature rise in the partial force cooling system.
OVERVIEW OF FUSION ENGINEERING IN JAPAN 招待有り査読有り

H. Hashizume, T. Nishitani, S. Konishi, Y. Ueda, S. Fukada, A. Sagara

FUSION SCIENCE AND TECHNOLOGY　68　(2)　201-210　2015年9月
出版者・発行元：AMER NUCLEAR SOC
DOI： 10.13182/FST14-947 　

ISSN：1536-1055

eISSN：1943-7641

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Based on long-term research activities on fusion engineering, eleven key technologies for future fusion reactors, especially for demo reactor, were selected in the Working Group of fusion research under the Council for Science and Technology, MEXT. In this paper, the recent achievement on the following key technologies will be summarized, which are strongly related to the Working Group proposal, 1) Fusion engineering research project in National Institute for Fusion Science, 2) High T-c superconducting magnets, 3) LiPb blanket system 4) Tungsten divertor and 5) Fusion engineering activities under the Broader Approach (BA) framework.
Analysis on Propagation Losses inside a Metal Pipe in Nondestructive Testing Using Microwave for Wall Thinning 査読有り

K. Sasaki, N. Yusa, H. Hashizume

XVIII International Symposium on Theoretical Electrical Engineering(ISTET'15), Kolobrzeg, Poland,　2015年6月7日
Fundamental Investigation on Tensile Characteristics of a Mechanical Lap Joint of REBCO Tapes 査読有り

Satoshi Ito, Hidetoshi Oguro, Hitoshi Tamura, Nagato Yanagi, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　25　(3)　4201205　2015年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2014.2369058 　

ISSN：1051-8223

eISSN：1558-2515

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This paper discusses tensile characteristics of a mechanical lap joint, which has been proposed and tested for joint-winding of a high-temperature superconducting (HTS) helical coil in the Large Helical Device type helical fusion reactor, FFHR-d1. Structural analysis for the helical coils in FFHR-d1 indicates that the maximum tensile strain along the HTS conductors and the maximum shear stress in HTS tapes region are 0.145% and 32 MPa, respectively under electromagnetic forces. Tensile test of the mechanical lap joint using Gadolinium Barium Copper Oxide (GdBCO) tapes with an inserted indium foil showed that the joint having 5-mm length and 5-mm width with a joint pressure of > 11 MPa had tensile strength exceeding that of the GdBCO tape itself, which also allows the tensile strain of 0.145% when used in the helical coil. To tolerate the shear stress of 32 MPa, the joint pressure of > 50 MPa was found to be needed according to the experimental results.
Investigation of Influences of Film Resistance and Magnetic Field on Contact Resistance in a Mechanical Lap Joint of GdBCO Tapes 査読有り

Yutaro Seino, Satoshi Ito, Hidetoshi Oguro, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　25　(3)　6603405　2015年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2014.2376771 　

ISSN：1051-8223

eISSN：1558-2515

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In order to design a remountable (demountable) high temperature superconducting (HTS) magnet of a fusion reactor, it is necessary to predict joint resistance in a mechanical (electrical) joint of HTS conductors as functions of temperature and magnetic field. Holm contact theory explains that the contact resistance consists of the constriction resistance and the film resistance. The film resistance depends on the thickness of oxide layers on contact surface. In this paper, therefore, relationship between influences of the film resistance and surface roughness of the stabilizing copper layer of a gadolinium barium copper oxide tape was investigated using experimentally evaluated joint resistance. Next, dependencies of contact resistance on the temperature and magnetic field were evaluated using the experimentally obtained joint resistance. Then, a new model of contact resistance was suggested based on the results of current distribution analysis. The contact resistance based on the new model shows good agreement for the test results of a 100-kA class HTS conductor, which demonstrates the validity of the model.
Measurement and Analysis of Critical Current of 100-kA Class Simply-Stacked HTS Conductors 査読有り

Y. Terazaki, N. Yanagi, S. Ito, Y. Seino, S. Hamaguchi, H. Tamura, T. Mito, H. Hashizume, A. Sagara

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　25　(3)　4602905　2015年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2014.2377793 　

ISSN：1051-8223

eISSN：1558-2515

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Based on the successful plasma experiments in the Large Helical Device (LHD), design activities of the LHD-type helical fusion reactor FFHR-d1 are progressing at National Institute for Fusion Science (NIFS). A 100 kA current capacity is required for the winding conductor under the maximum magnetic field of similar to 12 T. The high-temperature superconductor (HTS) is a promising option for the helical coil conductor. For the development of such a HTS conductor suitable for the helical fusion reactor, we fabricated 30 kA-class HTS conductor samples, and the excitation tests were successfully carried out. We then fabricated and tested a 100-kA class HTS conductor. The conductor sample is a one-turn short-circuit coil with a race-track shape having a bridge-type mechanical lap joint. The transport current of the sample was induced by changing the external magnetic field, then the critical current of the sample was measured. A numerical analysis of the critical current is being performed by self-consistently solving the spatial distributions of the current density and magnetic field among the simply-stacked HTS tapes to verify the measured critical current of the samples. The critical current characteristics of a single HTS tape is evaluated by the percolation model in the precise analysis.
Design and development of high-temperature superconducting magnet system with joint-winding for the helical fusion reactor 査読有り

N. Yanagi, S. Ito, Y. Terazaki, Y. Seino, S. Hamaguchi, H. Tamura, J. Miyazawa, T. Mito, H. Hashizume, A. Sagara

NUCLEAR FUSION　55　(5)　053021　2015年5月
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.1088/0029-5515/55/5/053021 　

ISSN：0029-5515

eISSN：1741-4326

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An innovative winding method is developed by connecting high-temperature superconducting (HTS) conductors to enable efficient construction of a magnet system for the helical fusion reactor FFHR-d1. A large-current capacity HTS conductor, referred to as STARS, is being developed by the incorporation of several innovative ideas, such as the simple stacking of state-of-the-art yttrium barium copper oxide tapes embedded in a copper jacket, surrounded by electrical insulation inside a conductor, and an outer stainless-steel jacket cooled by helium gas. A prototype conductor sample was fabricated and reached a current of 100 kA at a bias magnetic field of 5.3 T with the temperature at 20 K. At 4.2 K, the maximum current reached was 120 kA, and a current of 100 kA was successfully sustained for 1 h. A low-resistance bridge-type mechanical lap joint was developed and a joint resistance of 2 n Omega was experimentally confirmed for the conductor sample.
Optimized microwave excitation probe for general application in NDT of wall thinning in metal pipes of arbitrary diameter 査読有り

Kota Sasaki, Linsheng Liu, Noritaka Yusa, Hidetoshi Hashizume

NDT & E INTERNATIONAL　70　(2015)　53-59　2015年3月
出版者・発行元：ELSEVIER SCI LTD
DOI： 10.1016/j.ndteint.2014.12.004 　

ISSN：0963-8695

eISSN：1879-1174

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Generalized approaches to developing a microwave NDT for flaws inside an arbitrary diameter pipe through optimizing a microwave-exciting probe were investigated. A microwave probe obtained from a parameter-optimizing scheme based on transmission characteristics is proposed. Three-dimensional finite element simulation of five microwave probes indicates that a larger optimization parameter enables reduced microwave reflection, as well as improved single-mode propagation inside the pipe as compared with conventional probes. Experimental verification, using straight brass pipes of various diameters confirmed that the optimized microwave probe exhibits a larger signal-to-noise ratio for internal flaws when compared with conventional probes, thereby validating the new optimization parameter. (C) 2014 Elsevier Ltd. All rights reserved.
Development of electromagnetic non-destructive testing method for the inspection of heat exchanger tubes of Japan Sodium-Cooled Fast Reactor –Part II Detection of flaws on the inner surface using electromagnetic waves

Kota Sasaki, Noritaka Yusa, Hidetoshi Hashizume

The 19th International Workshop on Electromagnetic Nondestructive Evaluation, Xi’an, China　40　244-251　2015年
出版者・発行元：None
DOI： 10.3233/978-1-61499-509-8-244 　

ISSN：1879-8322 1383-7281
Influence of Piping Layout upon the characteristics of flow separation and pressure fluctuation in the primary cold-leg of sodium cooled fast reactor 査読有り

Jun Mizutani, Shinji Ebara, Hidetoshi Hashizume, Hidemasa Yamano

10th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety　2014年12月14日
Boiling Heat Transfer Characteristics of a Cryogenic Coolant with Metal Porous Media and Thermal Analysis on a Segmented High-Temperature Superconducting Magnet 査読有り

S. Ito, H. Hashizume

21st Topical Meeting on the Technology of Fusion Energy　2014年11月9日
Numerical investigation of the ill-posedness of inverse problems to size a crack from eddy current signals 査読有り

Noritaka Yusa, Hiroki Shishido, Hidetoshi Hashizume

The 2nd International Conference on Maintenance Science and Technology　2014年11月2日
Evaluation of the Applicability of Efficient Nondestructive Testing Using Microwave for Wall Thinning Inside a Long-range Metal Pipe 査読有り

Kota Sasaki, Noritaka Yusa, Hidetoshi Hashizume

The 2nd International Conference on Maintenance Science and Technology　2014年11月2日
Development on Microwave Nondestructive Testing of a Wall Thinning inside a Pipe by Optimizing the Frequency Range of Incident Microwaves 査読有り

Kota Sasaki, Noritaka Yusa, Hidetoshi Hashizume

Eleventh International Conference on Flow Dynamics　2014年10月8日
磁性を有する鋼材に発生した表面開口割れの深さ評価のための渦電流探傷技術の開発査読有り

遊佐訓孝, 橋爪秀利

鉄と鋼　100　(10)　2014年10月

DOI： 10.2355/tetsutohagane.100.1339 　

ISSN：0021-1575
Design prospect of remountable high-temperature superconducting magnet 査読有り

Hidetoshi Hashizume, Satoshi Ito

FUSION ENGINEERING AND DESIGN　89　(9-10)　2241-2245　2014年10月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2013.12.014 　

ISSN：0920-3796

eISSN：1873-7196

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The remountable (mountable and demountable repeatedly) high-temperature superconducting (HTS) magnet has been proposed for huge and complex superconducting magnets in future fusion reactors to fabricate and repair easily the magnet and access inner structural components. This paper summarizes progress in R&D activities of mechanical joints of HTS conductors in terms of the electrical resistance and heat transfer performance at the joint region. The latest experimental results show the low joint resistance, 4n Omega under 70 kA current condition using REBCO HTS conductor with mechanical lap joint system, and for the cooling system the maximum heat flux of 0.4 MW/m(2) is removed by using bronze sintered porous media with sub-cooled liquid nitrogen. These values indicate that there is large possibility to design the remountable HTS magnet for fusion reactors. (C) 2014 Elsevier B.V. All rights reserved.
Numerical study of the MHD flow characteristics in a three-surface-multi-layered channel with different inlet conditions 査読有り

Mitsuhiro Aoyagi, Satoshi Ito, Hidetoshi Hashizume

FUSION ENGINEERING AND DESIGN　89　(7-8)　1227-1231　2014年10月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2014.04.021 　

ISSN：0920-3796

eISSN：1873-7196

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A 3D MHD flow simulation was conducted to clarify the effects of the inlet flow conditions on the results of the validation experiment carried out previously and on the design window of the first wall using a three-surface-multi-layered channel. MHD pressure drop was largely influenced by the inlet condition. The numerical model with turbulent velocity profile showed qualitatively good agreement with the experimental result. The first wall temperature and pressure distributions obtained by the 3D simulation corresponded well to those obtained by the 2D simulation assuming fully developed flow. This suggested that complicated three-dimensional inlet flow condition generated in the L-shape elbow would not affects the existing design window. (C) 2014 Elsevier B.V. All rights reserved.
Visualization experiment of complex flow field in a sphere-packed pipe by detailed PIV measurement 査読有り

Shinji Ebara, Mohammad Reza Nematollahi, Hidetoshi Hashizume

FUSION ENGINEERING AND DESIGN　89　(7-8)　1251-1256　2014年10月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2014.03.079 　

ISSN：0920-3796

eISSN：1873-7196

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A sphere-packed pipe has been proposed as a heat transfer promoter for the first wall cooling in a Flibe blanket. In this study, the flow field in a sphere-packed pipe was well investigated by means of two-dimensional PIV method by matching refractive index of a channel material and working fluid. Three-dimensional flow structure was clarified by integrating the obtained data. The feature of the flow was tortuous high-velocity region formed near pebbles and large velocity fluctuation in the vicinity of the channel wall. And, to apply this flow structure to the actual first wall cooling, a new cooling system using finger-stacked structure was proposed and discussed. (C) 2014 Elsevier B.V. All rights reserved.
Evaluating the Ill-Posedness of inverse problem to size flaws from eddy current NDT signals obtained with an absolute type probe

Noritaka Yusa, Hiroki Shishido, Hidetoshi Hashizume

International Conference on Mechanical and Electrical Technology, Bangkok, Thailand　2014年7月17日

DOI： 10.4028/www.scientific.net/AMM.619.337 　
Development of electromagnetic non-destructive testing method for the inspection of heat exchanger tubes of Japan Sodium-Cooled Fast Reactor –Part I Application of remote field eddy current testing

Noritaka Yusa, Hiroki Shishido, Hidetoshi Hashizume

The 19th International Workshop on Electromagnetic Nondestructive Evaluation, Xi’an, China　2014年6月25日
Numerical modeling of thermal fatigue crack from viewpoint of eddy current testing

Jing Wang, Noritaka Yusa, Mika Kemppainen, Iikka Virkkunen, Hidetoshi Hashizume

The 19th International Workshop on Electromagnetic Nondestructive Evaluation, Xi’an, China　2014年6月25日
Critical Current Measurement of 30 kA-Class HTS Conductor Samples 査読有り

Y. Terazaki, N. Yanagi, S. Ito, K. Kawai, Y. Seino, T. Ohinata, Y. Tanno, K. Natsume, S. Hamaguchi, H. Noguchi, H. Tamura, T. Mito, H. Hashizume, A. Sagara

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　24　(3)　4801305-4801305　2014年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2013.2287715 　

ISSN：1051-8223

eISSN：1558-2515

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Design activities on the helical-type fusion DEMO reactor, FFHR-d1, are progressing at NIFS. A 100 kA current-capacity is required for the helical coil conductors under the maximum magnetic field of,,13 T. High-temperature superconducting conductor has been proposed as one of the conductor options for the FFHR-d1 magnet. In this study, a 30 kA class HTS conductor sample has been fabricated and tested. The sample had no current feeders and the current was induced by changing the background magnetic field generated by the 9 T split coils in the cryostat. Rogowski coils and Hall probes were used for the measurement of the transport current of the sample. The critical current of the sample was measured at various temperatures and bias magnetic fields. To verify the self-field effect of the sample, a numerical analysis was performed by considering the current and magnetic field distribution among the tapes self-consistently. The analysis result was compared with the experimental observation.
Progress of the Design of HTS Magnet Option and R boolean AND D Activities for the Helical Fusion Reactor 査読有り

N. Yanagi, Y. Terazaki, S. Ito, K. Kawai, Y. Seino, T. Ohinata, Y. Tanno, K. Natsume, S. Hamaguchi, H. Noguchi, H. Tamura, T. Mito, H. Hashizume, A. Sagara

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　24　(3)　4202805-4202805　2014年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2013.2292775 　

ISSN：1051-8223

eISSN：1558-2515

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The high-temperature superconducting magnet option is being explored in the conceptual design studies of the LHD-type helical fusion reactor FFHR-d1. A 100 kA-class conductor is being developed by simply stacking REBCO tapes in a copper and stainless-steel jacket. One of the design options of the HTS conductor includes internal insulation so that the windings do not require vacuum pressure impregnation process. Innovative winding method of the huge helical coils is being investigated based on the segment fabrication of half-helical-pitch conductors by developing a bridge-type mechanical lap joint. A "30 kA-class" prototype conductor sample was fabricated using GdBCO tapes and successfully tested. The critical current was measured at various temperatures at 4.2-40 K and magnetic field < 8 T. The joint resistance was evaluated by changing the applied stress. These experimental results are boosting the HTS magnet design of FFHR-d1.
Performance of a Mechanical Bridge Joint for 30-kA-Class High-Temperature Superconducting Conductors 査読有り

Satoshi Ito, Kenji Kawai, Yutaro Seino, Tatsuya Ohinata, Yusuke Tanno, Nagato Yanagi, Yoshiro Terazaki, Kyohei Natsume, Shinji Hamaguchi, Hiroki Noguchi, Hitoshi Tamura, Toshiyuki Mito, Akio Sagara, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　24　(3)　4602305-4602305　2014年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2013.2291157 　

ISSN：1051-8223

eISSN：1558-2515

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In this report, we propose segment-fabricated high-temperature superconducting (HTS) magnets as candidates for the FFHR-d1 heliotron-type fusion reactor. The FFHR-d1 requires 100-kA-class superconducting conductors used at 12 T for a pair of helical coils. We fabricated and tested two 30-kA-class GdBCO conductors with bridge-type mechanical lap joints (mechanical bridge joints). This report details the design of the joint section and the experimental results of those samples, especially, those of their joints. We improved the geometry of the joint region in a second sample, based on our results from the first. The second sample has sufficiently low joint resistance (less than 5 nil), and we could apply 70 kA to it without causing quenching at the joint. Its joint resistance was also acceptable for providing the electric power required to run the cryoplant for the segmented HTS helical coils.
Joint Resistance Characteristics of Mechanical Lap Joint of a GdBCO Tape With a Change in Temperature and Magnetic Field 査読有り

Yutaro Seino, Satoshi Ito, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　24　(3)　4602105-4602105　2014年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2013.2289356 　

ISSN：1051-8223

eISSN：1558-2515

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Mechanical joints of a high-temperature superconducting (HTS) conductor has been investigated for a "remountable" (demountable) HTS magnet. In a previous study, prediction method of joint resistance for a large-scale conductor was proposed using experimental data and current distribution analysis. However, the data were obtained by tests conducted at 77 K under self field. The joint resistance consists of contact resistance and resistance of constituted materials of HTS tapes, which depend on temperature and magnetic field. In this paper, therefore, we experimentally and numerically evaluated joint resistance characteristics with changing temperature and magnetic field using mechanical lap joint of a GdBCO tape. The experimentally evaluated joint resistance varied with the temperature and magnetic field as predicted. The joint resistance characteristic also depended on contact materials. The numerically evaluated contact resistance included in the joint resistance depending on temperature shows a tendency similar to the calculated value of the constriction resistance based on the Holm's contact theory.
拡散接合を用いた複雑形状模擬きず製作技術の開発、査読有り

遊佐訓孝, 王昌, 橋爪秀利

非破壊検査　63　((3))　148-152　2014年3月
出版者・発行元：The Japanese Society for Non-Destructive Inspection
DOI： 10.11396/jjsndi.63.148 　

ISSN：0367-5866

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This study demonstrates that an artificial flaw that has an arbitrary boundary profile and the response to non-destructive testing similar to a natural crack can be fabricated by bonding surfaces with artificial grooves using diffusion bonding. Artificial flaws with a small openings and widely spread boundary profiles inside can be realized by bonding Type 316L stainless steel blocks with artificial grooves. The artificial flaw is designed so that its surfaces have a 20% physical contact. The conditions for bonding are based on the results of preliminary experiments. Validations are carried out using two electromagnetic non-destructive testing methods: direct current potential drop and eddy current tests, whose results are well reproduced by finite element simulations. Subsequent destructive testing confirms that the actual profile of the artificial flaw agrees well with the designed one.
Feasibility of HTS Magnet Option for Fusion Reactors, 査読有り

N. Yanagi, S. Ito, Y. Terazaki, K. Natsume, H. Tamura, S. Hamaguchi, T. Mito, H. Hashizume, J. Morikawa, Y. Ogawa, M. Iwakuma, A. Sagara

Plasma and Fusion Research,　9(2014)　1405013-1405013　2014年3月
出版者・発行元：Feasibility of HTS Magnet Option for Fusion Reactors
DOI： 10.1585/pfr.9.1405013 　

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Conceptual design studies are being carried out on the application of high-temperature superconducting (HTS) conductors and coils to the magnet systems of fusion reactors. A 100-kA-class HTS conductor is required to be applied at high magnetic fields of > 12 T. A simple stack of YBCO tapes embedded in copper and stainless-steel jackets is found to be a practical approach to producing large-scale conductors that exhibit high cryogenic stability and mechanical rigidity. The feasibility of the segmented fabrication method for large complex HTS coils, such as the helical coils in the LHD-type helical fusion reactor FFHR-d1, is being investigated by developing mechanical bridge-type lap joint technology of HTS conductors.
Development of a 100-kA-class HTS conductor and its mechanical joint for the helical fusion reactor,

Satoshi Ito, Nagato Yanagi, Akio Sagara, Hidetoshi Hashizume

2nd HTS Fusion Conductor Workshop,　2014年1月23日
Evaluation of the electromagnetic characteristics of type 316L stainless steel welds from the viewpoint of eddy current inspections 査読有り

Noritaka Yusa, Hidetoshi Hashizume, Tetsuya Uchimoto, Toshiyuki Takagi, Kunihiro Sato

Journal of Nuclear Science and Technology　51　(1)　127-132　2014年1月2日

DOI： 10.1080/00223131.2013.851043 　

ISSN：0022-3131

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This study evaluated the electromagnetic characteristics of austenitic stainless steel welds from the viewpoint of eddy current testing. Seven welded plate specimens, which were welded using JIS Z3221:2010 YS316L welding metals, were prepared. Two welding metals and several welding conditions were adopted to discuss the generality. The results of eddy current examination of the specimens using three different types of eddy current probes, that is, an absolute pancake probe, a differential plus-point probe, and a uniform eddy current probe, confirmed that the welds cause a large noise especially when the absolute pancake probe was used. The analysis of the signals through finite element simulations revealed that the magnetic property of the welds is not negligible from the viewpoint of eddy current testing. Complementary experiments were conducted using a vibrating sample magnetometer to validate the results. © 2013 Atomic Energy Society of Japan.
Low Frequency Eddy Current Inspection of Wall-thinning of Large Pipes by Bobbin Coils 査読有り

Jing Wang, Noritaka Yusa, Hiroyuki Fukutomi, Hidetoshi Hashizume

2014 IEEE FAR EAST FORUM ON NONDESTRUCTIVE EVALUATION/TESTING (FENDT)　172-175　2014年
出版者・発行元：IEEE

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This study firstly discussed effect of three coil's orientations on sensitivity of low frequency eddy current testing for inspecting wall-thinning of large pipes through experimental signals. One specimen made of carbon steel was prepared. Hollows with different depth were introduced on the bottom of the specimen. Results of experiments showed that sensitivity of low frequency eddy current testing would be best if axes of bobbin coils are both parallel to surface of a pipe. Further experimental data showed that usage of coils' shield could not improve the sensitivity of inspection. Subsequent simulations were performed to reveal the mechanism.
An arrayed uniform eddy current probe design for crack monitoring and sizing of surface breaking cracks with the aid of a computational inversion technique 査読有り

Yusa, N., Hashizume, H., Urayama, R., Uchimoto, T., Takagi, T., Sato, K.

NDT and E International　61　29-34　2014年

DOI： 10.1016/j.ndteint.2013.09.004 　

ISSN：0963-8695
FEASIBILITY STUDY OF APPLICATION OF A SELF-FORMED FLOW FIELD DOWNSTREAM OF ELBOWS TO DIVERTOR COOLING 査読有り

Shoichi Kodate, Tatsuya Kubo, Shinji Ebara, Hidetoshi Hashizume

PROCEEDINGS OF THE 21ST INTERNATIONAL CONFERENCE ON NUCLEAR ENGINEERING - 2013, VOL 5　1　ICONE21-16105-ICONE21-16105　2014年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS
DOI： 10.1115/ICONE21-16105 　

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In this study, the characteristic of the swirling flow was analyzed in detail in terms of flow field by means of a visualization experiment using matched refractive index PIV measurement to evaluate the applicability of the swirling flow generated downstream of a three-dimensionally connected dual elbow to the divertor cooling. The dual elbow used in the experiment comprises two 90-degree elbows with the same curvature connected directly in three-dimensional configuration. From the experiment, it was found that strong swirling velocity component appears locally near the pipe wall downstream of the second elbow. Moreover, although the strength of the swirling flow changed gradually as it flowed downstream, it attenuated little even 8D downstream of the dual elbow, where D was the diameter of the piping. Therefore, this swirling flow is expected to survive for a considerable distance downstream of the elbow, and the applicability of this flow field to divertor cooling can be promising. Furthermore turbulence quantities such as Reynolds stress were analyzed in terms of heat transfer performance. Since there were some regions where larger Reynolds stress than a developed turbulent pipe flow was observed near the pipe wall, high heat transfer is expected there.
PROPOSAL OF A NOVEL BLANKET SYSTEM USING LiF-BeF2-LiI FOR A FUSION REACTOR 査読有り

Hiroki Shishido, Youngmin Han, Kentaro Matsui, Noritaka Yusa, Hidetoshi Hashizume

PROCEEDINGS OF THE 21ST INTERNATIONAL CONFERENCE ON NUCLEAR ENGINEERING - 2013, VOL 5　2014年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS
DOI： 10.1115/ICONE21-16109 　

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This study proposes LiF-BeF2-LiI as a molten salt for a liquid blanket system of a fusion reactor. Firstly, the melting point of LiF-BeF2-LiI is measured as a function of the molar ratio of LiI. The experimental results confirmed that the melting point decreases to 398.2 degrees C when LiF:BeF2:LiI = 19:9.5:71.5, which is consistent with an earlier report. Experiments to evaluate the density and viscosity of LiF-BeF2-LiI are also carried out. The experiments revealed that the density of LiF-BeF2-LiI increases with the molar ratio of LiI, and the viscosity of LiF-BeF2-LiI (LiF:BeF2:LiI = 2:1:1) is somewhat larger than that of LiF-BeF2 (LiF:BeF2= 2:1) but much smaller than that of LiF-BeF2 (LiF:BeF2= 3:2). Monte Carlo numerical simulations using MVP-2.0 with JENDL-4.0 data library are conducted on the basis of the measured density to discuss the feasibility of a blanket system using LiF-BeF2-LiI. The numerical simulations demonstrate that LiF-BeF2-LiI can realize TBR>1.4, which is required for a fusion blanket system, with Be pebble layer and enriching Li-6.
Modeling of Thermal Fatigue Crack for Enhancement of Electromagnetic Nondestructive Evaluation of Nuclear Power Plant 査読有り

Jing Wang, Noritaka Yusa, Hongliang Pan, Mika Kemppainen, Iikka Virkkunen, Hidetoshi Hashizume

PROCEEDINGS OF THE 21ST INTERNATIONAL CONFERENCE ON NUCLEAR ENGINEERING - 2013, VOL 1　2014年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS
DOI： 10.1115/ICONE21-16033 　

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The present study investigates modeling of thermal fatigue crack by the finite element method from the view point of eddy current testing. Three artificially produced thermal fatigue cracks introduced into Inconel 600 specimens are prepared. Eddy current signals are gathered by a differential type plus point probe with 25 kHz and 100 kHz. Subsequent destructive tests show the profile of these cracks. In the numerical simulation thermal fatigue crack is modeled as a region with constant width, uniform conductivity and real profile. Results of the study combining the previous study on modeling of thermal fatigue crack in type 304 stainless steel specimen reveal that thermal fatigue crack, unlike stress corrosion crack, generally should be modeled as an almost nonconductive region regardless of frequencies. Furthermore the resistance of thermal fatigue crack defined as width divided by conductivity is almost unchanged, even though the appropriate conductivity and width are changing with the frequency.
Characteristic Evaluation of Cooling Technique using Liquid Nitrogen and Metal Porous Media 査読有り

Yusuke Tanno, Satoshi Ito, Hidetoshi Hashizume

ADVANCES IN CRYOGENIC ENGINEERING　1573　597-604　2014年
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.4860756 　

ISSN：0094-243X

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A remountable high-temperature superconducting magnet, whose segments can be mounted and demounted repeatedly, has been proposed for construction and maintenance of superconducting magnet and inner reactor components of a fusion reactor. One of the issues in this design is that the performance of the magnet deteriorates by a local temperature rise due to Joule heating in jointing regions. In order to prevent local temperature rise, a cooling system using a cryogenic coolant and metal porous media was proposed and experimental studies have been carried out using liquid nitrogen. In this study, flow and heat transfer characteristics of cooling system using subcooled liquid nitrogen and bronze particle sintered porous media are evaluated through experiments in which the inlet degree of subcooling and flow rate of the liquid nitrogen. The flow characteristics without heat input were coincided with Ergun's equation expressing single-phase flow in porous materials. The obtained boiling curve was categorized into three conditions; convection region, nucleate boiling region and mixed region with nucleate and film boiling. Wall superheat did not increase drastically with porous media after departure from nucleate boiling point, which is different from a situation of usual boiling curve in a smooth tube. The fact is important characteristic to cooling superconducting magnet to avoid its quench. Heat transfer coefficient with bronze particle sintered porous media was at least twice larger than that without the porous media. It was also indicated qualitatively that departure from nucleate boiling point and heat transfer coefficient depends on degree of subcooling and mass flow rate. The quantitative evaluation of them and further discussion for the cooling system will be performed as future tasks.
Bridge-type mechanical lap joint of a 100 kA-class HTS: Conductor having stacks of GdBCO tapes 査読有り

Satoshi Ito, Yutaro Seino, Nagato Yanagi, Yoshiro Terazaki, Akio Sagara, Hidetoshi Hashizume

Plasma and Fusion Research　9　(2)　2014年
出版者・発行元：Japan Society of Plasma Science and Nuclear Fusion Research
DOI： 10.1585/pfr.9.3405086 　

ISSN：1880-6821

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In this paper, we reported design, fabrication and test of a prototype 100-kA-class high-temperature superconducting (HTS) conductor, especially for joint section, to be used for segmented HTS helical coils in the FFHR-d1 heliotron-type fusion reactor. The conductor has a geometry of three rows and fourteen layers of Gadolinium Barium Copper Oxide HTS (GdBCO) tapes embedded in copper and stainless steel jackets and has a joint section with bridge-type mechanical lap joint. We introduced improved method to fabricate the joint based on pilot experiments and we were able to apply a current of ~ 120 kA at 4.2 K, 0.45 T to the sample without quench at joint. The obtained joint resistance was ~ 2nΩ, which was lower than our previous data. Though joint resistance increased with a rise in current and magnetic field, predicted joint resistance in the environment of actual helical coil in the FFHR-d1 was small enough to properly run the cryoplant of the reactor.
FLOW VISUALIZATION EXPERIMENT OF A SWIRLING FLOW FORMED DOWNSTREAM OF A PIPING WITH SUCCESSIVE THREE ELBOW TO BE APPLIED TO DIVERTOR COOLING 査読有り

Shoichi Kodate, Shinji Ebara, Hidetoshi Hashizume

PROCEEDINGS OF THE 22ND INTERNATIONAL CONFERENCE ON NUCLEAR ENGINEERING - 2014, VOL 6　2014年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS

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As one of potential divertor cooling systems, three-dimensionally connected elbow piping has been proposed. In this study, a visualization experiment was conducted for swirling flows generated downstream of five kinds of piping with successive three three-dimensionally connected elbows in order to evaluate the applicability of these systems to divertor cooling by comparing with the dual elbow case previously obtained in terms of strength of the swirling flow and turbulent statistics. From the experimental results, it was found that the triple elbow piping in which all elbows were connected three dimensionally, referred to as 3D+3D layout, generated strong swirling velocity components than those of the dual elbow case and it became up to 70 % of the mean flow velocity. Moreover, it did not attenuate even 5D downstream of the triple elbow, where D was the diameter of the piping and the applicability of this flow field to divertor cooling can be promising. In addition, when heat transfer was evaluated in terms of turbulent statistics in the 3D+3D layout, heat transfer enhancement is expected because larger turbulent kinetic energy was observed near the pipe wall than a straight piping case.
PROPOSAL OF A NOVEL BLANKET SYSTEM USING LiF-BeF2-LiI FOR A FUSION REACTOR 査読有り

Hiroki Shishido, Youngmin Han, Kentaro Matsui, Noritaka Yusa, Hidetoshi Hashizume

PROCEEDINGS OF THE 21ST INTERNATIONAL CONFERENCE ON NUCLEAR ENGINEERING - 2013, VOL 5　5　V005T14A012　2014年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS
DOI： 10.1115/ICONE21-16109 　

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This study proposes LiF-BeF2-LiI as a molten salt for a liquid blanket system of a fusion reactor. Firstly, the melting point of LiF-BeF2-LiI is measured as a function of the molar ratio of LiI. The experimental results confirmed that the melting point decreases to 398.2 degrees C when LiF:BeF2:LiI = 19:9.5:71.5, which is consistent with an earlier report. Experiments to evaluate the density and viscosity of LiF-BeF2-LiI are also carried out. The experiments revealed that the density of LiF-BeF2-LiI increases with the molar ratio of LiI, and the viscosity of LiF-BeF2-LiI (LiF:BeF2:LiI = 2:1:1) is somewhat larger than that of LiF-BeF2 (LiF:BeF2= 2:1) but much smaller than that of LiF-BeF2 (LiF:BeF2= 3:2). Monte Carlo numerical simulations using MVP-2.0 with JENDL-4.0 data library are conducted on the basis of the measured density to discuss the feasibility of a blanket system using LiF-BeF2-LiI. The numerical simulations demonstrate that LiF-BeF2-LiI can realize TBR>1.4, which is required for a fusion blanket system, with Be pebble layer and enriching Li-6.
Evaluating the III-posedness of inverse problem to size flaws from eddy current NDT signals obtained with an absolute type probe 査読有り

Noritaka Yusa, Hiroki Shishido, Hidetoshi Hashizume

Applied Mechanics and Materials　619　337-341　2014年
出版者・発行元：Trans Tech Publications Ltd
DOI： 10.4028/www.scientific.net/AMM.619.337 　

ISSN：1662-7482 1660-9336

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This study discusses the applicability of eddy current testing to the non-destructive evaluation of the depth of a flaw. Three-dimensional finite element simulations are carried out to calculate eddy current signals due to a flaw, and subsequent calculations correlate the difference between signals due to two flaws with the difference between the depths of the flaws. Standard deviation of the difference between the depths of the flaws is used to discuss the ill-posedness of the problem. A flaw is modeled as a sufficiently long rectangular region with a constant width and uniform electrical conductivity an absolute pancake probe is considered. This study reveals that lift-off and coil diameter do not have a large effect on the ill-posedness, which supports that it is reasonable to decide parameters in actual inspections so that signal-to-noise ratio is maximized. The results obtained also indicate the difficulty in evaluating the depth of a flaw deeper than 1 mm using the signals obtained using an absolute pancake probe. © (2014) Trans Tech Publications, Switzerland.
立体曲り配管内で発生する非対称旋回流を流入条件とするオリフィス下流配管減肉特性の実験的評価査読有り

江原真司, 久保達也, 橋爪秀利

日本機械学会論文集（B編）　79　(88)　2616-2620　2013年12月
出版者・発行元：The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.79.2616 　

ISSN：0387-5016

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Flow visualization experiment and accelerated pipe wall thinning experiment were conducted by applying a swirling flow generated by a piping configuration, three-dimensionally connected dual elbow, to the inlet flow condition of a pipe orifice to investigate pipe wall thinning downstream of an orifice appearing due to the combination of swirling flow and orifice. The flow downstream of the orifice was curved by the action of the swirling flow, and the channel wall where the flow turned off toward underwent a large amount of wall thinning. Profiles of turbulent quantities, such as turbulent kinetic energy and Reynolds shear stress, were compared to those of amount of pipe wall thinning. It was found that the profiles of Reynolds shear stress showed good agreement with those of pipe wall thinning in the case for a large amount of that. However, relatively small amount of pipe wall thinning, any profile related to fluid motion could not explain the profiles of pipe wall thinning.
Numerical evaluation of the effect of the mode of microwave propagating inside a pipe on the detectability of a microwave nondestructive testing method,

Noritaka Yusa, Kota Sasaki, Hidetoshi Hashizume

Tenth International Conference on Flow Dynamics,　2013年11月25日
Experimental evaluation of the applicability of a sided-incidence microwave probe for a microwave nondestructive testing method,

Kota Sasaki, Noritaka Yusa, Hidetoshi Hashizume

Tenth International Conference on Flow Dynamics,　2013年11月25日
Development of 100 kA-class HTS conductor and joint for the helical fusion DEMO reactor,

Nagato Yanagi, Satoshi Ito, Yoshiro Terazaki, Yutaro Seino, Kyohei Natsume, Shinji Hamaguchi, Hiroki Noguchi, Hitoshi Tamura, Toshiyuki Mito, Hidetoshi Hashizume, Akio Sagara

International Symposium on Superconductivity 2013,　2013年11月18日
Measurement and analysis of critical current of a 100 kA-class HTS conductor,

Yoshiro Terazaki, Nagato Yanagi, Satoshi Ito, Yutaro Seino, Kyohei Natsume, Shinji Hamaguchi, Hiroki Noguchi, Hitoshi Tamura, Toshiyuki Mito, Hidetoshi Hashizume, Akio Sagara

23rd International Toki Conference (ITC-23),　2013年11月18日
Evaluation of heat transfer characteristics of a sphere-packed pipe for Flibe blanket 査読有り

Atsushi Watanabe, Shinji Ebara, Akio Sagara, Hidetoshi Hashizume

FUSION ENGINEERING AND DESIGN　88　(9-10)　2357-2360　2013年10月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2013.01.051 　

ISSN：0920-3796

eISSN：1873-7196

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A Flibe blanket has been proposed to be used in FFHR. Since Flibe has poor heat transfer performance, heat transfer promoter is required, and a sphere-packed pipe (SPP) has been proposed to enhance the heat transfer performance in the Flibe blanket. In this paper, the fluid flow and heat transfer characteristics in the SPP is evaluated numerically using a k-epsilon turbulent model for the flow field and an algebraic model for the thermal field. As a result, it was shown that bypass flows in the SPP play a significant role in heat transfer. Also it is thought that the turbulent energy can strongly affect heat transfer performance. (c) 2013 Elsevier B.V. All rights reserved.
DIVERTOR COOLING WITH SUB-CHANNELS-INSERTED METAL POROUS MEDIA (Effects of the Sub-Channel volume and location on Heat Transfer Characteristics) 査読有り

Kazuhisa Yuki, Hidetoshi Hashizume, Saburo Toda, Akio Sagara

FUSION SCIENCE AND TECHNOLOGY　64　(2)　325-330　2013年8月
出版者・発行元：AMER NUCLEAR SOC
ISSN：1536-1055

eISSN：1943-7641

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This study evaluates heat transfer characteristics of a sub-channels-inserted (SCI) porous heat removal device for divertor cooling. It is clarified that increasing the total volume of the sub-channels strongly contributes to the enhancement of phase-change of coolant as well as the vapor discharge. A high heat flux of approximately 25 MW/m(2) is removed at a wall superheat less than 70 K by increasing the number of the sub-channels installed under low flow rate conditions. The results also suggest that the SCI porous heat removal device could be applicable for the divertor cooling by optimizing the sub-channel design. Furthermore, especially for an enlarged heating area, optimizing the location of the sub-channel inlet, that is the interval of each sub-channel inlet, could be essential in order to smoothly discharge the generated vapor outside the porous medium.
A novel side-incidence probe with numerically optimized parameters for online microwave remote NDE of pipe wall thinning,

Kota Sasaki, Linsheng Liu, Noritaka Yusa, Hidetoshi Hashizume

The 18th International Workshop on Electromagnetic Nondestructive Evaluation,　2013年6月25日
Optimization of a Mechanical Bridge Joint Structure in a Stacked HTS Conductor 査読有り

Kenji Kawai, Satoshi Ito, Yutaro Seino, Nagato Yanagi, Hitoshi Tamura, Akio Sagara, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　23　(3)　6409408　2013年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2013.2239335 　

ISSN：1051-8223

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The mechanical bridge joint (bridge-type lap joint) of a stacked high-temperature superconducting conductor has been investigated for a "remountable" or a segment-fabricated high-temperature superconducting magnet. In a previous study, joint resistivities were evaluated experimentally for the bridge joints of single-layer and double-layer stacked GdBCO coated conductors. However, the joint resistivity increased with an increase in the number of layers due to nonuniform contact pressure distribution caused by a gap or misalignment in the joint region. In this study, therefore, we were aiming at the reduction of joint resistance by achieving more uniform contact pressure distribution. In addition, we investigated the effects of temperature while applying pressure to the joint and positioning the joint structure to investigate its application in an actual large-sized magnet. First, we inserted an indium film between the joint surfaces to make contact pressure uniform. Experimental results showed that joint resistivity with the indium film did not depend on the number of layers. In addition, applying force at room temperature was more effective in decreasing joint resistivity than that at 77 K. Finally, we examined the effect of the joint structure with screw bolt tightening. The result showed that the structure of the convex plate has better joint performance than others.
INFLUENCE OF FREQUENCY CHARACTERISTICS OF VELOCITY FLUCTUATIONS IN COMPLEX TURBULENT FLOW DOWNSTREAM OF AN ORIFECE UPON PIPE WALL THINNING 査読有り

S. Ebara, H. Yanai, H. Hashizume

Proceedings of The 15th International Topical Meeting on Nuclear Reactor Thermalhydraulics　1　NURETH15-321-NURETH15-321　2013年5月
EXPERIMENTAL STUDY ABOUT THE INFLUENCE OF LIQUID FILM FORMED JUST DOWNSTREAM OF AN ORIFICE UPON PIPE WALL THINNING 査読有り

M. Umehara, S. Ebara, H. Hashizume

Proceedings of The 15th International Topical Meeting on Nuclear Reactor Thermalhydraulics　1　NURETH15-337-NURETH15-337　2013年5月
Discussion on modeling of thermal fatigue cracks in numerical simulation based on eddy current signals 査読有り

Jing Wang, Noritaka Yusa, Hongliang Pan, Mika Kemppainen, Iikka Virkkunen, Hidetoshi Hashizume

NDT & E INTERNATIONAL　55　96-101　2013年4月
出版者・発行元：ELSEVIER SCI LTD
DOI： 10.1016/j.ndteint.2013.01.012 　

ISSN：0963-8695

eISSN：1879-1174

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This study evaluates modeling of thermal fatigue cracks by the finite element method from the view point of eddy current testing. Five artificial thermal fatigue cracks introduced into type 304 stainless steel plates were prepared for the research. Eddy current signals were gathered by a differential type plus point probe and subsequent destructive tests were performed to confirm the true profiles of the cracks. Numerical simulation based on the results of eddy current testing and destructive tests were carried out to show how the thermal fatigue cracks should be modeled in numerical simulations. The results of the numerical simulations revealed that thermal fatigue cracks tend to be much less conductive than stress corrosion cracks if they are assumed to have uniform conductivity inside. The results also imply that taking consideration of magnetization induced by the thermal fatigue process enables eddy current signals to be analyzed more quantitatively. (C) 2013 Elsevier Ltd. All rights reserved.
マイクロ波入射部最適化によるマイクロ波探傷技術の高度化査読有り

佐々木幸太, 遊佐訓孝, 若井隆純, 橋爪秀利

保全学　12　(1)　81-86　2013年4月
出版者・発行元：日本保全学会
ISSN：1348-7795
Experimental Study of Influence of Elbow Curvature on a Swirling Flow Generated in a Three-Dimensionally Connected Dual Elbow, 査読有り

Tatsuya KUBO, Shinji EBARA, Hidetoshi HASHIZUME

E-Journal of Advanced Maintenance　Vol.5 (1)　34-41　2013年2月
Inspection and modeling of stress corrosion crack by eddy current testing

Wang, J., Yusa, N., Pan, H.-L., Hashizume, H.

Huadong Ligong Daxue Xuebao/Journal of East China University of Science and Technology　39　(5)　2013年

ISSN：1006-3080
3.3 熱流動制御とモデリング(3.第一壁・ブランケットの物質熱輸送に関する研究,日米科学技術協力事業TITANプロジェクト) 査読有り

功刀資彰, 横峯健彦, 植木祥高, 結城和久, 佐竹信一, 江原真司, 橋爪秀利

プラズマ・核融合学会誌　89　(11)　2013年1月
出版者・発行元：社団法人プラズマ・核融合学会
ISSN：0918-7928
Evaluation of Sensitivity of Remote Field Eddy Current Testing and Low-Frequency Eddy Current Testing for Inspecting Grooves of Metal Plate 査読有り

Jing Wang, Noritaka Yusa, Hongliang Pan, Toshiyuki Takagi, Hidetoshi Hashizume

MATERIALS TRANSACTIONS　54　(1)　90-95　2013年
出版者・発行元：JAPAN INST METALS
DOI： 10.2320/matertrans.M2012323 　

ISSN：1345-9678

eISSN：1347-5320

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We compare remote field eddy current testing and low-frequency eddy current testing from the viewpoint of sensitivity to back-side grooves in a metal plate. We carry out experiments using three metal plates with different depths of artificial grooves. A U-shape magnetic shield gives rise to a remote field eddy current as occurs in pipe inspection. The experiments show that the two methods have almost the same sensitivity to back-side grooves if a relatively low frequency and relatively far coil interval are used, which is also validated by three-dimensional finite-element simulations. We conduct numerical investigations to find the reason for this condition.
Structure improvement and joint resistance estimation in demountable butt and edge joints of a stacked rebco conductor within a metal jacket 査読有り

Satoshi Ito, Tatsuya Ohinata, Leslie Bromberg, Hidetoshi Hashizume

IEEE Transactions on Applied Superconductivity　23　(3)　6425423-6425423　2013年

DOI： 10.1109/TASC.2013.2244197 　

ISSN：1051-8223

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Electrical (mechanical) butt and edge joints of a stacked REBCO conductor within a metal jacket have been investigated as candidates for demountable (remountable) electrical joints within demountable high-temperature superconducting magnets. This paper summarizes recent progress in the R&amp D of the two electrical joints. First, we have described recent R&amp D for the butt joint. We have previously established fabrication methods for the butt joint samples. In this paper, we have tried to establish a predictive method of joint resistance for a large-scale stacked REBCO conductor within a metal jacket by using small-scale experiments and current distribution analyses. For this purpose, we evaluated joint resistivity, particularly in the butt joint where an indium film is inserted between joint surfaces. Based on the small-scale experiments and 3-D current distribution analyses, the joint resistivity between the contact surface and the indium film inserted into the joint section is evaluated to be $1.1 \\times 10^{-12}\\ \\Omega\\hbox{m}2. According to the discussion based on the results, the joint resistance for a 100-kA-class REBCO conductor is estimated to be 3.7 n\\Omega$, which is a reasonably acceptable value from the viewpoint of electric power for cooling. Second, we recapitulate present R&amp D for the edge joint. In the case of the edge joint, adequate methods for fabricating samples had not been established because this joint has only been recently proposed. In a previous study, the experimentally measured joint resistance of the edge joint was much higher than predicted. We expect that the reason for the discrepancy is degradation of the conductor edge during the fabrication process and strains due to forces during the joint test. In addition, poor fabrication of the joint faces resulted in limited local area contact across the joint. In this paper, we improved the methods of fabrication and the structure of the test conductors based on numerical analysis. We then carried out a testing program of the edge joint of a stacked GdBCO conductor within a copper jacket fabricated with the improved process. The experimentally evaluated joint resistance agreed with numerical predictions. Therefore, the satisfactory performance of the edge joint was demonstrated in this paper. © 2002-2011 IEEE.
Verification Test of a Three-Surface-Multi-Layered Channel to Reduce MHD Pressure Drop 査読有り

M. Aoyagi, Y. Inage, S. Ito, S. Ebara, Y. Ueki, K. Yuki, F. Li, S. Smolentsev, T. Yokomine, T. Kunugi, T. Sketchley, M. Abdou, H. Hashizume

Proceedings of The Eighth Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety　2012年12月9日
Design Improvement of Three-Surface-Multi-Layered Channel by Reinforceing Inner Metal Layer 査読有り

Y. Inage, M. Aoyagi, S. Ito, H. Hashizume

Proceedings of The Eighth Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety　2012年12月9日
Development on microwave nondestructive testing of a wall thinning inside a pipe by optimizing microwave probe and analyzing wall thinning profile

Kota Sasaki, Linsheng Liu, Noritaka Yusa, Takashi Wakai, Hidetoshi Hashizume

1st International Conference on Maintenance Science and Technology Tokyo 2012 (ICMST-Tokyo 2012)　2012年11月11日
Fabrication of an artificial flaw with an arbitrary profile and non-destructive response for the development of NDT&E techniques

Noritaka Yusa, Kota Sasaki, Hidetoshi Hashizume

1st International Conference on Maintenance Science and Technology Tokyo 2012 (ICMST-Tokyo 2012)　2012年11月11日
Flow Visualization Experiment for Downstream of Orifices with Different Aperture Shapes

Masako KATO, Shinji EBARA, Hidetoshi HASHIZUME

Proceedings of 1st International Conference on Maintenance Science and Technology for nuclear Power Plants　165-166　2012年11月
Experimental Study of Influence of Elbow Curvature on a Swirling Flow Generated in a Three-Dimensionally Connected Dual Elbow

Tatsuya KUBO, Shinji EBARA, Hidetoshi HASHIZUME

Proceedings of 1st International Conference on Maintenance Science and Technology for nuclear Power Plants　115-116　2012年11月
Structure improvement of demountable edge joint of a stacked REBCO conductor within a metal jacket 査読有り

Satoshi Ito, Leslie Bromberg, Hidetoshi Hashizume

Applied Superconductivity Conference 2012 (ASC 2012)　2012年10月7日
Improvement of mechanical butt joint of a stacked REBCO conductor by optimizing conductor structure, 査読有り

Tatsuya Ohinata, Satoshi Ito, Hidetoshi Hashizume

Applied Superconductivity Conference 2012 (ASC 2012),　2012年10月7日
渦電流探傷試験における熱疲労割れの数値モデリング査読有り

遊佐訓孝, 橋爪秀利, Iikka Virkkunen, Mika Kemppainen

保全学　11　(3)　186-198　2012年10月
Flow Visualization and Frequency Characteristics of Velocity Fluctuations of Complex Turbulent Flow in a Short Elbow Piping Under High Reynolds Number Condition 査読有り

Hiroyuki Takamura, Shinji Ebara, Hidetoshi Hashizume, Kosuke Aizawa, Hidemasa Yamano

JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME　134　(10)　101201　2012年10月
出版者・発行元：ASME
DOI： 10.1115/1.4007436 　

ISSN：0098-2202

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Flow visualization was performed on a single short elbow piping by means of two-dimensional particle image velocimetry. The piping was designed as a 1/7-scale model of a section of the cold-leg piping of a Japan sodium-cooled fast reactor. This study characterized the periodic motions and flow structures that appeared in and downstream of the elbow and potentially affected flow-induced vibrations. The flow field that related flow separation and frequency characteristics of the flow velocity fluctuation were explored for Reynolds number from 0.3 x 10(6) to 1.0 x 10(6), which belonged to the post-critical regime. Experimental results show that flow structures are not strongly dependent on Reynolds number in this range. Frequency analysis for the velocity fluctuation in terms of Strouhal number (St) reveals that there exist not only two kinds of vortices with different shedding periods, but also one periodic flow in the circumferential direction. In the flow separation region, vortices are periodically emitted with St approximate to 0.5, while those with about 1.0 are shed in a shear flow region located between the separation region and the pipe center. Moreover, a periodic motion with St approximate to 0.5 appeared in the circumferential direction in the vicinity near the separation region. These values of St were not strongly dependent on Reynolds number in this study. [DOI: 10.1115/1.4007436]
渦電流探傷試験における熱疲労割れの数値モデリング査読有り

遊佐訓孝, 橋爪秀利, Iikka Virkkunen, Mika Kemppainen

保全学　3　(11)　73-78　2012年10月
出版者・発行元：日本保全学会
ISSN：1348-7795
Three-dimensional MHD flow simulation in an L-shape elbow of a three-surface-multi-layered channel, 査読有り

Mitsuhiro Aoyagi, Satoshi Ito, Takeo Muroga, Hidetoshi Hashizume

27th Symposium on Fusion Technology (SOFT 2012)　2012年9月24日
Thermal Analysis on a Remountable High Temperature Superconducting Magnet around Jointing Region

Y. Tanno, S. Ito, H. Hashizume

Proceedings of Ninth International Conference on Flow Dynamics　2012年9月19日
Effect of shape of shield on the sensitivity of remote field eddy current testing for inspecting flaw of large diameter tube 査読有り

Jing Wang, Noritaka Yusa, Hongliang Pan, Hidetoshi Hashizume

Ninth International Conference on Flow Dynamics (ICFD2012)　2012年9月19日
A novel approach of microwaves on remote and nondestructive detection of both gradual and abrupt wall thinning inside a metal pipe

Linsheng Liu, Kota Sasaki, Noritaka Yusa, Hidetoshi Hashizume

Ninth International Conference on Flow Dynamics (ICFD2012)　2012年9月19日
Transverse Stress Effects on Critical Current and Joint Resistance in Mechanical Lap Joint of a Stacked HTS Conductor 査読有り

Satoshi Ito, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　22　(3)　2012年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2011.2176290 　

ISSN：1051-8223

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This paper discussed feasibility of bridge-type and multi-layer mechanical lap joint of a stacked HTS conductor. In the multi-layer mechanical lap joint, a decrease in critical current induced by transverse compressive joint force is one of the important factor to decide joint resistance. In addition, misalignment of joint section could be a problem because respective HTS tapes consisting the stacked HTS conductor could have slightly different thickness. In this study, therefore, transverse stress effect on critical current of stacked BSCCO and GdBCO conductors was experimentally investigated at first. Then, bridge-type mechanical lap joints of single layer and 2-layer HTS conductors were tested to confirm their performance and to consider the misalignment of joint section. Experimental results showed that critical current of the BSCCO conductor decreased at lower stress when the number of layers increased whereas that of the GdBCO conductor was less influenced by the stress. Joint resistance in the bridge-type mechanical lap joint was comparable to those in normal mechanical lap joint and soldered lap joint in the case of the single layer. Joint resistances in the 2-layer lap joint were two or three times larger than those in the single layer lap joint due to the misalignment. To solve this problem, compliant metal layer should be inserted into joint section.
EXPERIMENTAL INVESTIGATION OF INFLUENCE OF INLET FLOW CONDITIONS ON SWIRLING FLOW GENERATED IN A THREE-DIMENSIONALLY CONNECTED DUAL ELBOW

Tatsuya Kubo, Shinji Ebara, Hidetoshi Hashizume

Proceedings of the 15th International Symposium on Flow Visualization　ISFV15　105　2012年6月
FLOW STRUCTURE OF HIGH REYNOLDS NUMBER FLOW IN A DUAL-ELBOW PIPING SIMULATING COLD-LEGS OF JSFR

H. Takamura, S. Ebara, H. Yamano, H. Hashizume

Proceedings of the 15th International Symposium on Flow Visualization　ISFV15　058　2012年6月
Proposal of Electrical Edge Joint for a Demountable High-Temperature Superconducting Magnet 査読有り

Satoshi Ito, Leslie Bromberg, Makoto Takayasu, Joseph V. Minervini, Hidetoshi Hashizume

IEEE TRANSACTIONS ON PLASMA SCIENCE　40　(5)　1446-1452　2012年5月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TPS.2012.2190103 　

ISSN：0093-3813

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Electrical edge joint of a stacked high-temperature superconducting (HTS) conductor is explored for electrical joints for a demountable HTS toroidal field coil. Demountable coils would be very useful in small tokamak plasma-facing component-test machines, such as Vulcan. The demountable concept explored in this paper consists of forcing together the edges of stacked HTS conductor embedded in a conductive or a structural material. We carried out a testing program of the edge joint of a stacked YBCO conductor within a copper jacket. The HTS cable has a critical current of 1600 A at 77 K in self-field. The experimental results showed that joint resistance in the edge joint was higher than expected, as was not reproducible. One potential reason for the larger than expected resistance is the damage to the tape edge in preparation of the joint region due to milling/fabrication. Another potential reason was low accuracy in the fabrication of joint surface; the joint surfaces were not parallel to one another. The joint resistance will be reduced by the sophistication of the fabrication process for the joint surface. We also carried out calculations to determine the joint performance of the edge joint in an ideal condition. In the ideal condition, inserting an indium film between joint surfaces or plating copper layer on joint surfaces can prevent joint resistance from increasing due to the misalignment of the contact surfaces and would provide a compliant layer between joints. The joint resistance of the edge joint can become smaller than that of an electrical lap joint when the number of the stacked HTS tape is large.
An accurately controllable imitative stress corrosion cracking for electromagnetic nondestructive testing and evaluations 査読有り

Noritaka Yusa, Tetsuya Uchimoto, Toshiyuki Takagi, Hidetoshi Hashizume

NUCLEAR ENGINEERING AND DESIGN　245　1-7　2012年4月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.nucengdes.2012.01.022 　

ISSN：0029-5493

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This study proposes a simple and cost-effective approach to fabricate an artificial flaw that is identical to stress corrosion cracking especially from the viewpoint of electromagnetic nondestructive evaluations. The key idea of the approach is to embed a partially-bonded region inside a material by bonding together surfaces that have grooves. The region is regarded as an area of uniform non-zero conductivity from an electromagnetic nondestructive point of view, and thus simulates the characteristics of stress corrosion cracking. Since the grooves are introduced using electro-discharge machining, one can control the profile of the imitative stress corrosion cracking accurately. After numerical simulation to evaluate the spatial resolution of conventional eddy current testing, six specimens made of type 316L austenitic stainless steel were fabricated on the basis of the results of the simulations. Visual and eddy current examinations were carried out to demonstrate that the artificial flaws well simulated the characteristics of actual stress corrosion cracking. Subsequent destructive test confirmed that the bonding did not change the depth profiles of the artificial flaw. (C) 2012 Elsevier B.V. All rights reserved.
Numerical Analysis of Microwave NDT Applied to Piping Inspection 査読有り

Yasutomo Sakai, Noritaka Yusa, Satoshi Ito, Hidetoshi Hashizume

MATERIALS TRANSACTIONS　53　(4)　627-630　2012年4月
出版者・発行元：JAPAN INST METALS
DOI： 10.2320/matertrans.I-M2012805 　

ISSN：1345-9678

eISSN：1347-5320

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Numerical simulations using finite element software were carried out to discuss the physical background of nondestructive inspections of pipes using microwaves. The simulations were conducted using an axisymmetric configuration modeling pipe with wall thinning to evaluate the effect of the profile of the wall thinning on the microwave propagation. Both rectangular and quasi-racetrack wall thinnings were considered. The numerical simulations showed the presence of wall thinning attenuates microwaves at particular frequencies. An empirical formula was proposed to evaluate the profile of wall thinning for the particular frequencies. Although the formula was based on the results of numerical simulations considering only rectangular wall thinning, it is also applicable to the evaluation of quasi-racetrack wall thinning. [doi:10.2320/matertrans.I-M2012805]
Finite element modeling of stress corrosion cracking for electromagnetic nondestructive evaluations

J. Wang, N. Yusa, H. Pan, H. Hashizeume

The 18th Pacific Basin Nuclear Conference (PBNC2012)　2012年3月18日
Na冷却高速炉における大口径配管の流力振動評価に関する研究:（39）コールドレグ1/7縮尺流動試験装置を用いた1段および2段エルボ管内流れPIV計測による複数エルボ効果の検証

高村宏行, 江原真司, 橋爪秀利, 山野秀将

日本原子力学会年会・大会予稿集　2012　265-265　2012年
出版者・発行元：一般社団法人日本原子力学会
DOI： 10.11561/aesj.2012f.0.265.0 　

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Na冷却高速炉の実証炉JSFRは研究開発中にあり、一次冷却系を2系統にする案が採用されている。一次冷却系はこれまでにない大口径配管、低曲率半径比のエルボ、大流量で設計され、エルボ腹側での流れの剥離およびそれに起因する圧力変動と複雑な流動場が想定されている。本研究では一次冷却系コールドレグ配管を模擬したシングルおよびデュアルエルボ体系で高レイノルズ数（～100万）条件のもと2D-PIV計測実験を行い、流れ場の詳細を評価する。剥離域の形成や剥離渦放出挙動に着目するとともに、2つの体系の配管内流動構造を比較することにより複数エルボ効果について解明する。
Fabrication of imitative stress corrosion cracking specimen using lithography and solid state bonding 査読有り

Noritaka Yusa, Hidetoshi Hashizume

International Journal of Applied Electromagnetics and Mechanics　39　(1-4)　291-296　2012年

DOI： 10.3233/JAE-2012-1473 　

ISSN：1383-5416

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This study proposes a method to fabricate artificial flaws whose response to non-destructive testing, especially electromagnetic non-destructive testing, is the same as that of stress corrosion cracking. Stacked metallic films containing through-grooves are sandwiched between metallic blocks and then bonded using solid state bonding. The profiles of the through-grooves are accurately controlled with the aid of the lithography technique, which allows a three-dimensional discontinuity to be embedded inside a material. Since the spatial distribution of the discontinuity is small compared to the spatial resolution of non-destructive testing methods, the method allows the response of stress corrosion cracking to be simulated. Specimens are fabricated using type 316 L austenitic stainless steel, and validated using eddy current testing. © 2012 - IOS Press and the authors. All rights reserved.
Nondestructive evaluation of wall thinning inside a pipe using the reflection of microwaves with the aid of signal processing 査読有り

Yasutomo Sakai, Noritaka Yusa, Hidetoshi Hashizume

NONDESTRUCTIVE TESTING AND EVALUATION　27　(2)　171-184　2012年
出版者・発行元：TAYLOR & FRANCIS LTD
DOI： 10.1080/10589759.2011.633608 　

ISSN：1058-9759

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This study demonstrates that the reflection of microwave propagating inside a pipe enables one to nondestructively detect and locate wall thinnings appearing inside the pipe. A signal processing method is proposed to compensate for the dispersion of microwave and to make the reflection due to a wall thinning clearer. After fundamental characteristics of the microwave signals were evaluated using 3D finite element simulations, verifications were made by both experiments and numerical simulations using straight brass pipes whose outer diameter and wall thickness were 25 and 3 mm, respectively. The verifications revealed that imposing the signal processing method provided a clear indication of the location of wall thinning, and no significant deterioration was observed even when the pipe was as long as 2000 mm. The verifications also showed that the amplitude of reflection signal was almost proportional to the volume of wall thinning, which agreed with another report, and the reflections were sufficiently clear even when the edge of a flaw was not stepwise but curved like actual wall thinnings.
Fundamental evaluation of joint resistance in mechanical butt joint of a stacked GdBCO conductor 査読有り

Tatsuya Ohinata, Satoshi Ito, Hidetoshi Hashizume

Plasma and Fusion Research　7　(1)　2012年

DOI： 10.1585/pfr.7.2405045 　

ISSN：1880-6821

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In this study, joint resistance in mechanical butt joint of a single GdBCO tape was evaluated by experiments and current distribution analyses to apply a remountable HTS magnet for a future fusion reactor. The results showed that thickness of the metal layers of GdBCO tape, cutting angle of the conductor and existence of soldered interface affect the joint resistance. According to discussion based on the results, an optimized joint structure could achieve joint resistance of 0.4 μω for single GdBCO tape, which corresponds to 5 nω for 100 kA class HTS conductor. The resistance has to be reduced almost a half value of the present result to be accepted from the view point of electric power for cooling. © 2012 The Japan Society of Plasma Science and Nuclear Fusion Research.
Measurement of the joint resistance of large-current YBCO conductors 査読有り

Yoshiro Terazaki, Nagato Yanagi, Sai Tomida, Hiroki Noguchi, Kyohei Natsume, Toshiyuki Mito, Satoshi Ito, Hidetoshi Hashizume, Akio Sagara

Plasma and Fusion Research　7　(SPL.ISS.1)　2012年

DOI： 10.1585/pfr.7.2405027 　

eISSN：1880-6821

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Feasibility studies on applying high-temperature superconductors (HTS) to the LHD-type heliotron fusion energy reactor FFHR are being carried out. Because the HTS conductor has high cryogenic stability at elevated temperature operations (e.g. 20K) and the refrigeration power has enough margins, it is considered that Joule heating dissipation generated at joints of conductors is acceptable to facilitate the segmented fabrication of the helical coils of FFHR. In this study, the joint resistance with 10-kA class YBCO conductors has been measured to evaluate the joule heating dissipation in the FFHR magnet. The experiment has been carried out by fabricating a soldered lap joint and a mechanical lap joint. The feasibility of segmented fabrication is examined by the measured results. © 2012 The Japan Society of Plasma Science and Nuclear Fusion Research.
Discussion on distributed conductivity for modeling stress corrosion crack in eddy current testing

Jing Wang, Noritaka Yusa, Hidetoshi Hashizume, Hongliang Pan

2012 6th International Conference on Electromagnetic Field Problems and Applications, ICEF'2012　2012年

DOI： 10.1109/ICEF.2012.6310334 　

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The study discusses a proper numerical modeling of stress corrosion crack (SCC) in finite element simulations, mainly from the viewpoint of the distribution of conductivity along the surface of crack. Two SCCs introduced into austenitic stainless steel plates are studied. SCCs are modeled as a region with a constant width, and non-uniform conductivity along surface of crack in the direction of depth of the SCCs, on the basis of the true profile revealed by destructive tests. Eddy current signals gathered by a differential probe with several frequencies are analyzed. The results show that a more appropriate model of SCC can be obtained by considering non-uniform conductivity. © 2012 IEEE.
Fabrication of imitative stress corrosion cracking specimen using lithography and solid state bonding 査読有り

Noritaka Yusa, Hidetoshi Hashizume

INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS　39　(1-4)　291-296　2012年
出版者・発行元：IOS PRESS
DOI： 10.3233/JAE-2012-1473 　

ISSN：1383-5416

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This study proposes a method to fabricate artificial flaws whose response to non-destructive testing, especially electromagnetic non-destructive testing, is the same as that of stress corrosion cracking. Stacked metallic films containing through-grooves are sandwiched between metallic blocks and then bonded using solid state bonding. The profiles of the through-grooves are accurately controlled with the aid of the lithography technique, which allows a three-dimensional discontinuity to be embedded inside a material. Since the spatial distribution of the discontinuity is small compared to the spatial resolution of non-destructive testing methods, the method allows the response of stress corrosion cracking to be simulated. Specimens are fabricated using type 316 L austenitic stainless steel, and validated using eddy current testing.
Discussion of structural design issues on a remountable high-temperature superconducting magnet

S. Ito, H. Hashizume, H. Tamura, N. Yanagi, S. Imagawa, A. Sagara

21st International Toki Conference (ITC-21)　2011年11月28日
Evaluation of heat transfer performance for a sphere-packed pipe by using molten salt under high heat flux condition

A. Watanabe, S. Ebara, H. Hashizume

21st International Toki Conference (ITC-21)　2011年11月28日
Fundamental evaluation of joint resistance in mechanical butt joint of a stacked GdBCO conductor

T. Ohinata, S. Ito, H. Hashizume

21st International Toki Conference (ITC-21)　2011年11月28日
Comparison between remote field eddy current testing and conventional low frequency eddy current testing for inspecting flaws in large diameter tubes from outside

J. Wang, N. Yusa, H. Pan, H. Hashizume

The Eighth International Conference on Flow Dynamics (ICFD2011)　2011年11月9日
Pressure fluctuation characteristics of complex turbulent flow in a dual elbow with small curvature radius in a three-dimensional layout

H. Konno, S. Ebara, H. Hashizume, H. Yamano, K. Aizawa

The Eighth International Conference on Flow Dynamics (ICFD2011)　2011年11月9日
Four-terminal measurement of the distribution of electrical resistance across stress corrosion cracking 査読有り

Noritaka Yusa, Hidetoshi Hashizume

NDT & E INTERNATIONAL　44　(7)　544-546　2011年11月
出版者・発行元：ELSEVIER SCI LTD
DOI： 10.1016/j.ndteint.2011.06.004 　

ISSN：0963-8695

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This study measures electrical resistance of a stress corrosion crack directly by the four-terminal method to discuss appropriate modeling from the viewpoint of electromagnetic nondestructive evaluation. Two type-316 stainless steel plate specimens containing artificial stress corrosion cracks were prepared, and columnar samples containing penetrating cracks were cut from the plates for the measurements. The results obtained agree with recent reports discussing appropriate numerical modeling of stress corrosion cracking on the basis of finite element simulations. In contrast, this study also reveals that it is not always valid to assume that a stress corrosion crack has uniform conductivity internally. (C) 2011 Elsevier Ltd. All rights reserved.
Improvement of crack radar system to detect flaws in pipes 査読有り

H. Hashizume, N. Yusa, Y. Sakai

he 15th International Symposium on Applied Electromagnetics and Mechanics, Napoli, Italy　2011年9月
Evaluation of advanced Flibe blanket using Cs 査読有り

K. Matsui, N. Yusa, Daisuke Komiyama, Akihiro Suzuki, Akio Sagara, Hidetoshi Hashizume

The 10th International Symposium on Fusion Nuclear Technology, Portrald, USA　2011年9月
Influence of Strain Distribution on Joint Resistance in Mechanical Lap Joint of a Stacked HTS Conductor 査読有り

S. Ito, H. Hashizume

22nd International Conference on Magnet Technology, Marseille, France　2011年9月
FEASIBILITY STUDY OF FLIBE BLANKET WITH Cs 査読有り

Hidetoshi Hashizume, Noritaka Yusa, Kentaro Matsui

FUSION SCIENCE AND TECHNOLOGY　60　(2)　523-527　2011年8月
出版者・発行元：AMER NUCLEAR SOC
ISSN：1536-1055

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The present study clarifies feasibility of a new concept for the Flibe blanket system with Cesium from the thermonuclear viewpoint. Through this study it was revealed at first that the melting temperature of Flibe can be lowered with adding the CsF. And then the tritium breeding ratio when (137)Cs was mixed in the Flibe was evaluated by using the neutron transport calculation code of MVP. The numerical results indicate that the TBR decreases gradually by adding Cs substituted for Beryllium.
Thermo-Fluid Simulation in a Liquid Metal Blanket with Three-Surface- Multi-Layered Channel 査読有り

M. Aoyagi, S. Ito, S. Ebara, T. Muroga, H. Hashizume

Fusion Science and Technology　60　(2)　523-527　2011年8月
HEAT TRASFER EXPERIMENTS USING A HIGH PRANDTL NUMBER FLUID FLOWING IN SPHERE-PACKED CHANNELS FOR FLIBE BLANKET DESIGN 査読有り

Katsuya Shimizu, Shinji Ebara, Hidetoshi Hashizume

FUSION SCIENCE AND TECHNOLOGY　60　(2)　528-532　2011年8月
出版者・発行元：AMER NUCLEAR SOC
ISSN：1536-1055

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Flibe blanket, which uses molten salt Flibe as coolant and tritium breeder, is considered as one of the candidates of advanced liquid blanket for fusion reactors. Although Flibe has low heat transfer performance which comes from high Pr, sufficient heat removal can be achievable by using sphere-packed pipe (SPP) as heat transfer promoter. In this study, heat transfer correlations of SPP which can be available for high Pr fluids are derived from experimental analysis inserting various size and materials of spheres into the pipe. Further, heat transfer performance in a rectangular channel is simulated by using sphere-packed annular channel. Based on these results, heat transfer performance of Flibe blanket is evaluated and some design window with pressure drop of less than 1 MPa/m was confirmed.
STATUS OF HIGH TEMPERATURE SUPERCONDUCTING FUSION MAGNET DEVELOPMENT 査読有り

L. Bromberg, H. Hashizume, S. Ito, J. V. Minervini, N. Yanagi

FUSION SCIENCE AND TECHNOLOGY　60　(2)　635-642　2011年8月
出版者・発行元：AMER NUCLEAR SOC
ISSN：1536-1055

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Since the discovery of high temperature superconductors (HTS) more than 2 decades ago, there has been interest in their use for future fusion machines. Lack of performance of commercially available materials, however, dampened the initial optimism. However, recent advances in HTS materials, mostly second-generation tapes, open attractive topologies. In addition to reduced cryogenic loads and increased superconducting stability, the HTS tapes may allow demountable magnets that could be very helpful in the long term (for reactor maintenance) and in the intermediate term, for component-testing machines which require large access. Tests on joints have demonstrated that the thermal load due to the Joule dissipation in these joints is small, allowing operation with very long pulses without restrictions on cost of electricity or power availability. There are challenges in the use of HTS in magnets in general, and fusion specifically. The excellent properties of HTS materials, e.g., YBCO (YBa(2)Cu(3)O(7-delta)) superconductors operating at elevated temperatures (> 30K) also offer operational advantages for fusion machines, but there are challenges, such as the manufacturing of high current cables and methods of quench protection. In addition to tapes, HTS can be fabricated as monoliths. These monoliths offer the possibility of field control for complex geometries, such as generating stellarator-like fields from simple toroidal fields. This paper summarizes work at MIT and in Japan on concept development and testing, as well as challenges ahead.
SUB-CHANNELS-INSERTED POROUS EVAPORATOR FOR EFFICIENT DIVERTOR COOLING 査読有り

Kazuhisa Yuki, Hidetoshi Hashizume, Saburo Toda

FUSION SCIENCE AND TECHNOLOGY　60　(1)　238-242　2011年7月
出版者・発行元：AMER NUCLEAR SOC
ISSN：1536-1055

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A sub-channels-inserted porous evaporator is proposed as a heat removal device of the divertor with a heat load exceeding 10 MW/m(2). The porous medium is made by sintering copper particles of micro size in diameter and has several sub-channels to enhance discharge of generated vapor outside the porous medium. This porous cooling devise is attached onto the backside of the divertor and remove the heat by evaporating water passing through the porous medium against the heat flow. In order to prove the effect of the sub-channels, the heat transfer characteristics of this porous device are evaluated experimentally using a plasma arcjet as a high heat flux source. The result shows that the heat transfer performance of copper-particles-sintered porous medium with the sub-channels enables to remove much higher heat flux under lower flow rate and lower wall superheat conditions, compared with the normal porous media. The removal heat flux, 8.1 MW/m(2), is 1.8 times as higher than that of the normal porous medium at a wall superheat of 50 degrees (the heat transfer coefficient, 1.6 x 10(5) W/m(2)/K, is 2.4 times as higher). The removal heat flux reaches almost 10 MW/m(2) although the wall superheat exceeds 100 degrees (The wall temperature is approximately 220 degrees C. still in a fully developed boiling regime). In addition, the removal heat flux exceeds 20 MW/m(2) by increasing the number of the sub-channels under lower wall superheat conditions, which proves high potential of the sub-channels-inserted porous evaporator.
MIDTERM SUMMARY OF JAPAN-US FUSION COOPERATION PROGRAM TITAN 査読有り

T. Muroga, D. K. Sze, K. Okuno, T. Terai, A. Kimura, R. J. Kurtz, A. Sagara, R. Nygren, Y. Ueda, R. P. Doerner, J. P. Sharpe, T. Kunugi, N. B. Morley, Y. Hatano, M. A. Sokolov, T. Yamamoto, A. Hasegawa, Y. Katoh, N. Ohno, K. Tokunaga, S. Konishi, S. Fukuda, P. Calderoni, T. Yokomine, K. Messadek, Y. Oya, N. Hashimoto, T. Hinoki, H. Hashizume, T. Norimatsu, T. Shikama, R. E. Stoller, K. A. Tanaka, M. S. Tillack

FUSION SCIENCE AND TECHNOLOGY　60　(1)　321-328　2011年7月
出版者・発行元：AMER NUCLEAR SOC
ISSN：1536-1055

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Japan-US cooperation program TITAN (Tritium, Irradiation and Thermofluid for America and Nippon) started in April 2007 as 6-year project. This is the summary report at the midterm of the project. Historical overview of the Japan-US cooperation programs and direction of the TITAN project in its second half are presented in addition to the technical highlights.
Thermo-fluid simulation in a liquid metal blanket with three-surface-multi-layered channel 査読有り

Aoyagi, M., Ito, S., Ebara, S., Muroga, T., Hashizume, H.

Fusion Science and Technology　60　(1)　283-287　2011年7月

DOI： 10.13182/FST11-A12366 　

ISSN：1943-7641 1536-1055
PIV Measurements of a Complex Turbulent Flow in a Short Elbow Piping under a High Reynolds Number Condition 査読有り

H. Takamura, H. Konno, S. Ebara, H. Hashizume, K. Aizawa, H. Yamano

The 9th International Symposium on Particle Image Velocimetry, Kobe, Japan　2011年7月
Investigation of an Optimum Structure for Mechanical Butt Joint of a Stacked HTS Cable With a Metal Jacket 査読有り

Satoshi Ito, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　21　(3)　1995-1999　2011年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2010.2100346 　

ISSN：1051-8223

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Mechanical butt joint of a high-temperature superconducting (HTS) cable with a metal jacket has been investigated for a remountable HTS magnet where parts can be mounted and demounted iteratively to allow a superconducting magnet for a fusion reactor to be assembled and repaired. In this study, an optimum structure to achieve relatively uniform contact pressure distribution on joint surface in the mechanical butt joint was suggested by structural analysis. Then, joint resistance in mechanical butt joint of a stacked BSCCO 2223 cable with copper jacket was evaluated experimentally using an experimental setup established based on the structural analysis, to confirm effect of decreasing joint resistance by the joint structure. The results showed that the structure can reduce joint resistance to 140 n Omega for the BSCCO 2223 cable having 1 kA of critical current at liquid nitrogen temperature.
Experimental Estimation in Characteristics of Swirling Flow Appearing in a Three-Dimensionally Connected Dual Elbow Layout by Means of Matched Refractive-index PIV Measurement 査読有り

T. Kubo, H. Yanai, S. Ebara, H. Hashizume

The 11th Asian Symposium on Visualization, Niigata, Japan　2011年6月
固相接合を用いた電磁非破壊検査のための模擬応力腐食割れ試験体製作技術査読有り

遊佐訓孝, 内一哲哉, 高木敏行, 橋爪秀利

保全学　10　64-69　2011年4月
Electromagnetic modeling of stress corrosion cracks in Inconel welds 査読有り

H. Huang, N. Yusa, K. Miya, H. Hashizume, T. Sera, S. Hirano

E-Journal of Advanced Maintenance　2　168-180　2011年2月
Numerical evaluation of microwave testing for pipe thinning 査読有り

Yasutomo Sakai, Noritaka Yusa, Hidetoshi Hashizume

Electromagnetic Nondestructive Evaluation (XIV)　259-266　2011年
w PRESSURE MEASUREMENT TEST OF SINGLE ELBOW SIMULATING Na COOLED FAST REACTOR COLD-LEG PIPING 査読有り

Shinji Ebara, Yuta Aoya, Tsukasa Sato, Hidetoshi Hashizume, Kazuhisa Yuki, Kosuke Aizawa, Hidemasa Yamano

PROCEEDINGS OF THE 18TH INTERNATIONAL CONFERENCE ON NUCLEAR ENGINEERING 2010, VOL 4 PTS A AND B　705-+　2011年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS
DOI： 10.1115/ICONE18-29719 　

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Regarding the Japan Sodium-cooled Fast Reactor, a multi-elbow piping system is adopted for its cold-legs. Flow Induced Vibration (FIV) is considered to be caused by complex flow with very high velocity in the elbows. In this study, pressure measurement test of a single elbow flow is conducted to find out pressure fluctuation characteristic which is related to the elbow turbulent flow and lead potentially to the Fly. Two types of experimental loops, that is, 1/7 and 1/15-scale setup simulating the JSFR cold-leg pipings, are used for pressure measurement, and a distinguishing peak can be seen in the power spectrum density profile of pressure fluctuation obtained where flow separation occurs and at the downstream from it. This characteristics of pressure fluctuation is obtained from the two different scale experiments, and the scale effect is not found in terms of the pressure fluctuation.
An eddy current probe suitable to gain information about the depth of near-side flaws much deeper than the depth of penetration 査読有り

Noritaka Yusa, Yasutomo Sakai, Hidetoshi Hashizume

NDT & E INTERNATIONAL　44　(1)　121-130　2011年1月
出版者・発行元：ELSEVIER SCI LTD
DOI： 10.1016/j.ndteint.2010.10.003 　

ISSN：0963-8695

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This study proposes an approach to gain information about the depth of near-side flaws using eddy currents The approach utilizes only two coils one of which works as an exciter and the other as a detector like conventional eddy current testing using a transmitter-receiver probe The uniqueness of this approach is that signals obtained by this approach change significantly with the depth of a flaw even though the flaw is much deeper than the depth of penetration After the physical background of the approach is explained its validity is confirmed in experiments The experiments utilize a 25 mm thick austenitic stainless steel plate with five artificial rectangular slits of 40 mm length 0 5 mm width and 1 5 10 15 and 20 mm depth The experiments confirm clear differences between signals generated by the five slits even although the exciter is driven at 50 kHz at which the depth of penetration is approximately 2 0 mm Subsequent finite element simulations are carried out to confirm the validity of the experimental results and to support discussion about the physical background of the approach (C) 2010 Elsevier Ltd All rights reserved
Proposal of electrical edge joint for a demountable high-temperature superconducting magnet 査読有り

Satoshi Ito, Hidetoshi Hashizume, Leslie Bromberg, Makoto Takayasu, Joseph V. Minervini

2011 IEEE/NPSS 24TH SYMPOSIUM ON FUSION ENGINEERING (SOFE)　23　1446-1452　2011年
出版者・発行元：IEEE
DOI： 10.1109/TPS.2012.2190103 　

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Electrical edge joint of a stacked high-temperature superconducting (HTS) conductor is explored for electrical joints for a demountable HTS toroidal field coil. Demountable coils would be very useful in small tokamak plasma-facing component-test machines, such as Vulcan. The demountable concept consists of forcing together the edges of stacked HTS conductor embedded in a conductive or a structural material. Numerical evaluation showed that inserting an indium film between joint surfaces or plating copper layer on joint surfaces could prevent joint resistance from increasing due to misalignment of the contact surface and would provide a compliant layer between joints. Joint resistance of the edge joint can become smaller than that of electrical lap joint when the number of the stacked HTS tape is large. We carried out a testing program of the edge joint of a stacked YBCO conductor within a copper jacket. The HTS cable has a critical current of 1600 A at 77 K in self field. The experimental results showed that joint resistance in the edge joint was higher than expectation, as was irreproducible. One potential reason for the degradation of HTS material is the damage to the tape edge in preparation of the joint region due to milling. Another potential reason was low accuracy of fabrication of joint surface, the joint surface were not parallel to another one. The joint resistance will be reduced by sophistication of fabrication process for the joint surface.
MHD pressure drop characteristics in a three-surface-multi-layered channel under a strong magnetic field 査読有り

M. Aoyagi, S. Ito, H. Hashizume, T. Muroga

FUSION ENGINEERING AND DESIGN　85　(7-9)　1181-1184　2010年12月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2010.02.036 　

ISSN：0920-3796

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A three-surface-multi-layered channel is one of the possible methods for reducing the magnetohydrodynamic (MHD) pressure drop in a Li/V blanket. In this study, experimental and numerical evaluations of the liquid metal MHD flow in a three-surface-multi-layered channel were conducted to confirm the extent of MHD pressure reduction in the channel. The MHD flow was tested using a Bi-Sn eutectic alloy (MHD liquid) and an open annular channel under up to 5T magnetic field. Experimentally determined pressure drops differed from those predicted by numerical analysis. This may be as a result of an increase in the friction force caused by an oxide appearing on the liquid free surface and a decrease in the electromagnetic force owing to the formation of a contact resistance between the Bi-Sn alloy and the bottom wall of the stainless steel channel. (C) 2010 Elsevier B.V. All rights reserved.
Numerical simulation of turbulent flow in microscopic pore scale of pebble bed by large-eddy simulation 査読有り

S. Ebara, T. Yokomine, A. Shimizu, H. Hashizume

FUSION ENGINEERING AND DESIGN　85　(7-9)　1638-1641　2010年12月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2010.04.065 　

ISSN：0920-3796

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Performance of a fusion reactor using pebble bed in its blanket depends on averaged properties such as packing density of the bed. On the other hand, crucial phenomena that affect safety issues, such as blockage of flow area and the outset of a heat spot caused by thermal creep of constituent particles, depend on local properties of the bed. Conventional researches for pebble bed have been done in terms of average operation or coarse graining of the bed and can never capture the above local phenomena. In this study, the pebble bed is not coarse-grained but is treated such that small scale phenomena are treated as they are. Large-eddy simulation is used for simulation of turbulent flow in microscopic pore scale of pebble bed in the frame of the finite element method. The bed is modeled as one with regular configuration of spherical particles and fluid motion in the pore is simulated in detail. (C) 2010 Elsevier B.V. All rights reserved.
Feasibility of a remountable high-temperature superconducting magnet for a helical fusion reactor 査読有り

S. Ito, H. Hashizume, H. Tamura, N. Yanagi, S. Imagawa, A. Sagara

20th International Toki Conference, Toki　2010年12月
Pressure Fluctuation Characteristics of Complex Turbulent Flow in a Single Elbow With Small Curvature Radius for a Sodium-Cooled Fast Reactor 査読有り

Shinji Ebara, Yuta Aoya, Tsukasa Sato, Hidetoshi Hashizume, Yuki Kazuhisa, Kosuke Aizawa, Hidemasa Yamano

JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME　132　(11)　111102　2010年11月
出版者・発行元：ASME-AMER SOC MECHANICAL ENG
DOI： 10.1115/1.4002813 　

ISSN：0098-2202

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A multi-elbow piping system is adopted for the Japan sodium-cooled fast reactor (JSFR) cold-legs. Flow-induced vibration (FIV) is considered to appear due to complex turbulent flow with very high Reynolds number in the piping. In this study, pressure measurement for a single elbow flow is conducted to elucidate pressure fluctuation characteristics originated from turbulent motion in the elbow, which lead potentially to the FIV. Two different scale models, 1/7- and 1/14-scale simulating the JSFR cold-leg piping, are tested experimentally to confirm whether a scale effect in pressure fluctuation characteristics exists. A distinguishing peak can be seen in each power spectrum density (PSD) profile of pressure fluctuation obtained in and downstream of the flow separation region for both scaled models. When nondimensionalized, the PSD profiles show good correspondence regardless of scale model and even of Reynolds number simulated in this study. [DOI: 10.1115/1.4002813]
PIV measurement for dual elbow flow using 1/7-scale model of cold-leg piping in a sodium-cooled fast reactor 査読有り

S. Ebara, T. Sato, H. Hashizume

7th International Conference on Flow Dynamics (ICFD2010), Sendai　2010年11月
The Effects of wall thinning shapes on microwave testing for piping 査読有り

Y. Sakai, N. Yusa, H. Hashizume

7th International Conference on Flow Dynamics (ICFD2010), Sendai　2010年11月
Heat transfer experiments using a high Pr number fluid flowing in sphere-packed pipe for flibe blanket design 査読有り

K. Shimizu, S. Ebara, H. Hashizume

19th Topical Meeting on the Technology of Fusion Energy, Las Vegas, Nevada, USA　2010年11月
A fundamental research of mechanical lap joint of high-temperature superconducting conductor 査読有り

Y. Uchida, S. Ito, H. Hashizume

19th Topical Meeting on the Technology of Fusion Energy　2010年11月
Status of High Temperature Superconducting Magnet Development 査読有り

L. Bromberg, H. Hashizume, S. Ito, J.V. Minervini, N. Yanagi

19th Topical Meeting on the Technology of Fusion Energy　2010年11月
Analysis of generating mechanism of liquid droplet jet stream at the orifice downstream area 査読有り

M. Umehara, S. Ebara, H. Hashizume

The 8th International Topical Meeting on Nuclear Thermal-Hydraulics, Operation and Safety (NUHTOS-8), Shanghai, China, 2010/10/10-14　N8　P0305　2010年10月
Investigation of influence of inlet flow conditions on flow structure in a dual elbow 査読有り

H. Yanai, S. Ebara, H. Hashizume

The 8th International Topical Meeting on Nuclear Thermal-Hydraulics, Operation and Safety (NUTHOS-8), Shanghai, China, 2010/10/10-14　N8　P0303　2010年10月
Transmutation process of 90Sr with 14 MeV neutron by nuclear fusion 査読有り

K. Matsui, N. Yusa, H. Hashizume

Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2010 (SNA+MC2010)　2010年10月
確率論的安全評価を用いた原子力プラントの長期運転における保全計画評価手法の構築査読有り

白石夏樹, 高橋信, 橋爪秀利, 若林利男, 宮田浩一, 佐藤親宏

保全学　9　(2)　45-52　2010年7月
出版者・発行元：日本保全学会
ISSN：1348-7795
Effect of Thermal Strain on the Mechanical Butt Joint of a Stacked HTS Cable With a Metal Jacket 査読有り

Satoshi Ito, Takeshi Sakashita, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　20　(3)　1747-1750　2010年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2010.2043424 　

ISSN：1051-8223

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A remountable high-temperature superconducting (HTS) magnet where parts can be mounted and demounted is proposed to allow a superconducting magnet for a fusion reactor to be assembled and repaired. A conceptual study of a mechanical butt joint for a stacked HTS cable with metal jacket was carried out. In this study, contact pressure distribution at the joint surface was evaluated by structural analysis to investigate the deformation of the joint region due to the joint force and the influence of the thermal strain on joint performance. Analytical results showed that thermal strain and Young's modulus of the constituent material strongly affect the contact pressure distribution. In addition, combinations of parallel and perpendicular joint forces, and the procedure with which they are applied, have a strong impact on the realization of a remountable joint in a HTS cable.
Improvement of Joint Structure for Mechanical Butt Joint of Stacked BSCCO 2223 Cable 査読有り

Takeshi Sakashita, Satoshi Ito, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　20　(3)　1751-1754　2010年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2010.2043660 　

ISSN：1051-8223

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A concept of remountable HTS magnet has been proposed to simplify fabrication of a superconducting magnet for a fusion reactor and to reduce maintenance cost of the reactor. For realization of the remountable HTS magnet system, mechanical butt joint of a stacked BSCCO 2223 cable has been investigated experimentally with large joint stress. In this study, 10 layered BSCCO 2223 cable with copper jacket is used as a test cable, and the roughness of joint surface is controlled quantitatively by using several different particle sizes of abrasive particles. Then the relation between the joint stress and resistance is evaluated through the mechanical butt joint test of the cable under several experimental conditions. Although dependence of the joint resistance on the joint stress is observed the relationship between roughness and joint resistance is not observed clearly due to not coincidence in surface flatness of the test cables.
Evaluation of microwave in pipes for inspection 査読有り

Y. Sakai, N. Yusa, S. Ito, H. Hashizume

The 15th International Workshop on Electromagnetic Nondestructive Evaluation, Szczecin, Poland, 2010/06/13-16　2010年6月
Fabrication of imitative stress corrosion cracking specimens for electric nondestructive evaluations 査読有り

N. Yusa, T. Uchimoto, T. Takagi, H. Hashizume

The 15th International Workshop on Electromagnetic Nondestructive Evaluation, Szczecin, Poland, 2010/06/13-16　2010年6月
Understanding Key Parameters in Flow Accelerated Corrosion for Advanced Wall Thinning Prediction 査読有り

Hiroshi Abe, Shinji Ebara, Nobuyuki Fujisawa, Hidetoshi Hashizume, Kiwamu Sue, Yutaka Watanabe, Takayuki Yamagata

Proceedings of International Symposium on the Ageing Management and Maintenance of Nuclear Power Plants (ISaG2010)　38-46　2010年5月
Thermohydraulic analysis of high-Prandtl-number fluid in complex duct simulating first wall in fusion reactor 査読有り

Masaaki Satake, Kazuhisa Yuki, Hidetoshi Hashizume

FUSION ENGINEERING AND DESIGN　85　(2)　234-242　2010年4月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2010.01.025 　

ISSN：0920-3796

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For fusion reactors, molten salt is one of the candidates for coolant materials. Molten salt is a high-Prandtl-number fluid: thus, it is necessary to enhance the heat transfer coefficient. It is proposed that rods are inserted into a duct to enhance the heat transfer coefficient. The flow field behind the rod in the duct is visualized to compare experimental data with simulation results. The trends and distributions in the numerical simulation are the same as those in the experiment, and furthermore, the magnitudes of the time and space scales in the numerical simulation are of the same order as those in the experiment. Thermohydraulic numerical analysis confirmed that the heat transfer coefficient is improved by inserting the rod when the fluid is a high-Prandtl-number fluid and the flow field is in the turbulent region. However, it is necessary for the rods to be arranged in the streamwise direction. (C) 2010 Elsevier B.V. All rights reserved.
Proposal of a Micro/Mini Cooling Device using Fins-installed Porous Media for High Heat Flux Removal exceeding 1000W/cm(2) 査読有り

Kazuhisa Yuki, Akira Matsui, Hidetoshi Hashizume, Koichi Suzuki

MNHMT2009, VOL 2　71-82　2010年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS

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Heat transfer characteristics of micro-sized bronze particle-sintered porous heat sinks and copper minichannel-fins heat sinks are experimentally investigated in order to clarify the feasibility of a newly proposed micro/mini cooling device using fins-installed porous media. Regarding the porous heat sinks, fin effect toward more inside of the porous medium is promoted by sintering the porous heat sink on the heat transfer surface, which results in increasing the heat transfer performance up to 0.8MW/m(2)K at heat flux of 8.2MW/m(2) though there still remains a large pressure loss issue. In addition, the results clarify that the heat exchanging area exists only in the vicinity of the heat transfer surface. As to the minichannel-fins heat sinks, the influence of the channel width and the fin thickness are evaluated in detail. As a result, the minichannel-fins heat sink having the narrower channel width (i.e. scale effect) and lower porosity (i.e. thicker fin thickness with larger heat capacity) achieves higher heat transfer performance up to 0.10MW/m(2)K at 8.3MW/m(2). However, rapid increase of pressure loss, which is occasionally observed in a microchannel due to vapor bubbles choking the narrow channel, still remains as an issue under flow boiling conditions in the minichannel. Finally, heat transfer performance of the fin-installed porous heat sink is numerically predicted by the control volume method. The simulation confirms that the heat transfer coefficient at each wall superheat of 0 and 30 degrees has performance 2.5 times and 2.0 times higher than that of the normal fins, which indicates that this heat sink coupling the micro and mini channels has high potential as efficient cooling method under high heat flux conditions exceeding 10MW/m(2).
Numerical simulation of MHD turbulent flow in a rectangular channel with three-surface-coated multi layers 査読有り

Mitsuhiro Aoyagi, Hidetoshi Hashizume, Kazuhisa Yuki, Satoshi Ito, Takeo Muroga

International Journal of Fluid Mechanics Research　37　(5)　447-457　2010年

DOI： 10.1615/InterJFluidMechRes.v37.i5.50 　

ISSN：1064-2277

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A rectangular channel with three-surface-coated multi layers has been proposed to reduce the MHD pressure drop in the liquid metal blanket system. In this study, the turbulent flow and pressure drop characteristics are investigated with changing the orientation of the magnetic field by numerical simulation, where a k-ε model containing the effects of the magnetic field is employed. The simulation is conducted under the conditions the Reynolds number of 4494 and the Hartmann number of 20:9 or 52:2. The inclination of the magnetic field (θ) is changed from 0°to 90°. At an inclination of θ = 45°, turbulence viscosity becomes the highest due to the velocity distributions with more turbulence kinetic energy production. The pressure drop increases when θ is larger than 30°by the electromagnetic force, especially in the case of higher Hartmann number. © 2010 Begell House, Inc.
Key issues to enable high heat flux removal exceeding 10 Mw/m2 by use of metal porous media as a latent heat-transfer device 査読有り

Kazuhisa Yuki, Hidetoshi Hashizume, Saburo Toda

Special Topics and Reviews in Porous Media　1　(1)　1-13　2010年

DOI： 10.1615/SpecialTopicsRevPorousMedia.v1.i1.10 　

ISSN：2151-4798 2151-562X

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Heat transfer characteristics of two-phase flow in particle-sintered porous media are experimentally investigated in order to clarify the key issues to enable extremely high heat flux removal exceeding 10 MW/m2. The porous media experimented on are stainless steel particle-sintered and bronze particle-sintered compacts. The experiments under some heat flux inputs clarify that the effects of porous structure such as pore size and porosity on the heat transfer characteristics highly depend on the level of the heat flux input. The results suggest that liquid-vapor exchange due to capillary and pumping effects works effectively under several MW/m2 in this cooling system. However, under conditions exceeding the heat flux level, permeability for vapor discharge outside the porous medium becomes the most important factor in enabling the heat flux removal of over 10 MW/m2. Furthermore, in order to evaluate what kind of porous material is appropriate for higher heat removal, the two-phase flow characteristics in the porous media are simulated by the two-phase mixture model. The results show that utilizing a higher thermal-conductivity matrix facilitates a delay in the onset of the phase change near the heating wall and leads to much higher heat flux removal, even at the same liquid saturation, compared with the case utilizing a lower thermal-conductivity matrix. Copyright © 2010 Begell House Inc.
Evaluation of stress corrosion cracking as a function of its resistance to eddy currents 査読有り

Noritaka Yusa, Hidetoshi Hashizume

NUCLEAR ENGINEERING AND DESIGN　239　(12)　2713-2718　2009年12月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.nucengdes.2009.08.032 　

ISSN：0029-5493

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This study discusses the equivalent conductivity, the equivalent width, and the equivalent resistance of stress corrosion cracks from the viewpoint of eddy current testing. Four artificial stress corrosion cracks were prepared for this study, and their eddy current signals were gathered using two absolute pancake probes and two differential type plus point probes. Then their numerical models were evaluated using finite element simulations on the basis of the measured eddy current signals and their profiles revealed by destructive tests. The results of this study revealed that whereas the equivalent conductivity and the equivalent width depend on the exciting frequency utilized, the equivalent resistance of a crack has much less dependency, which agrees well with an earlier report. This study also revealed that the resistance of a crack depends on probe utilized. Larger probes tend to lead to smaller crack resistance. Pancake type probes tend to lead to larger crack resistance than plus point probes. Analyzing the results together with earlier reports indicates that cracks with a large equivalent conductivity tend to have large equivalent width, and supports the validity of assuming the minimum resistance of a stress corrosion crack whereas considering the conductivity and the width individually would not be viable. (C) 2009 Elsevier B.V. All rights reserved.
Detection of axial crack in the bend region of a pipe by high frequency electromagnetic waves 査読有り

Kavoos Abbasi, Nasrin Hosseini Motlagh, Mohammad Reza Neamatollahi, Hidetoshi Hashizume

INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING　86　(11)　764-768　2009年11月
出版者・発行元：ELSEVIER SCI LTD
DOI： 10.1016/j.ijpvp.2009.07.006 　

ISSN：0308-0161

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High frequency electromagnetic guided waves are used to detect axial narrow slit or crack in bend-section of the U-shape pipe. In the previous studies performed by the authors, electromagnetic waves (EM-waves) of TM(01)- and TE(11)-modes have used to detect circumferential and axial crack in straight section of a pipe, appropriately. In this paper to show potential of this technique for detection of any shape of piping system, especially bend-section of the steam generator (SG) and feeder pipe of pressurized water reactor (PWR), axial crack in bend-section is investigated. Due to axial orientation of the TE(11)-mode, a suitable mode for detection of axial crack is implied for this purpose. To excite TE(11)-crack, mode in the test pipe, microwave signals generated by the network analyzer, are sent to the inspected pipe by a coaxial line and a mode converter. Presence of the crack causes change in the reflection coefficient of the reflected signals from the crack. The behavior of the crack characteristic signals as a function of time is studied to estimate time of flight of the reflected wave and consequently crack position. Suitable frequency range is chosen in order to generate only TE(11)-mode in the test pipe. To show effect of frequency range of the electromagnetic waves to the crack, crack positions are also evaluated for several smaller frequency ranges. Two crack positions were examined and comparisons of measurement results with theoretical calculations indicate that the microwave guided waves technique has high capability to detect defect in bend-section of a piping systems. (C) 2009 Elsevier Ltd. All rights reserved.
FEASIBILITY STUDY FOR FLIBE TBM BASED ON THERMOFLUID ANALYSIS 査読有り

H. Hashizume, K. Yuki, N. Seto, A. Sagara

FUSION SCIENCE AND TECHNOLOGY　56　(2)　892-896　2009年8月
出版者・発行元：AMER NUCLEAR SOC
ISSN：1536-1055

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By changing the composition ratio in Flibe to decrease its melting temperature, it becomes possible to design the TBM under the temperature design limits for ferritic steel. The accompanied demerit due to the increase in viscosity and degradation in heat transfer performance is overcome by introducing sphere-packed pipe as the first wall. The empirical correlation for heat transfer performance is derived for several sizes and materials of the spheres. Through the present analysis, there exist design windows for the Flibe TBM This possibility is strongly linked to the demo reactor development since the structural material development for higher temperature condition can lead to the usage of Flibe with higher melting temperature and better heat transfer performance, which could be available under higher heat flux in the demo reactor.
Mechanical Butt Joint of Laminated HTS Cable With Metal Jacket for Remountable HTS Magnet 査読有り

Satoshi Ito, Takayuki Kato, Hidetoshi Hashizume

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY　19　(3)　1536-1539　2009年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TASC.2009.2019057 　

ISSN：1051-8223

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The remountable HTS magnet was proposed to allow a superconducting magnet for a fusion reactor to be assembled and to allow a failed part of the magnet to be replaced or repaired. In this study, joint resistance was evaluated in a mechanical butt joint of a stacked BSCCO 2223 cable with a copper jacket. The fabricated cables could reduce joint resistance to be 400-500 n Omega with a silver-plated layer or an indium-film applied to the joint surface. The experimental results also showed that parallel joint force is required to reduce joint resistance more without deformation of the joint surface configuration.
Experimental Investigation of Flow Field Structure in Mixing Tee 査読有り

Seyed Mohammad Hosseini, Kazuhisa Yuki, Hidetoshi Hashizume

JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME　131　(5)　2009年5月
出版者・発行元：ASME-AMER SOC MECHANICAL ENG
DOI： 10.1115/1.3112383 　

ISSN：0098-2202

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T-junction is one of the familiar components in the cooling system of power plants with enormous capability of high-cycle thermal fatigue. This research investigates the structure and mixing mechanism of turbulent flow in a T-junction area with a 90 deg bend upstream. According to the wide distribution of turbulent jets in the T-junction, a re-attached jet was selected previously as the best representative condition with the highest velocity fluctuation and the most complex structure. For considering the mixing mechanism of re-attached jet, T-junction is subdivided into few lateral and longitudinal sections, and each section is visualized separately by particle image velocimetry technique. Corresponding to the experimental data, the branch flow acts as a finite turbulent jet, develops the alternative type of eddies, and causes the high velocity fluctuation near the main pipe wall. Three regions are mainly subject to maximum velocity fluctuation: the region close to the jet boundaries (fluctuation mostly is caused by Kelvin-Helmholtz instability), the region above the jet and along the main flow (fluctuation mostly is caused by Karman vortex), and the re-attached area (fluctuation mostly is caused by changing the pressure gradient in the wake area above the jet). Finally, the re-attached area (near the downstream of wake area above the jet) is introduced as a region with strongest possibility to high-cycle thermal fatigue with most effective velocity fluctuation on the main pipe wall above the branch nozzle. [DOI: 10.1115/1.3112383]
Magneto-Hydro-Dynamic-Simulation of Square Duct Flow with Three-Surface-Coated Multi Layers 査読有り

Kazuhisa Yuki, Taiji Kobayashi, Mitsuhiro Aoyagi, Hidetoshi Hashizume

International Journal of Fluid Mechanics Research　36　(5)　473-487　2009年
出版者・発行元：Begell House
DOI： 10.1615/interjfluidmechres.v36.i5.70 　

ISSN：1064-2277
DEPENDENCE OF HEAT TRANSFER COEFFICIENT ON POROUS STRUCTURE IN POROUS MEDIA 査読有り

Akira Matsui, Kazuhisa Yuki, Hidetoshi Hashizume

HT2008: PROCEEDINGS OF THE ASME SUMMER HEAT TRANSFER CONFERENCE - 2008, VOL 2　299-307　2009年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS

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Detailed heat transfer characteristics of particle-sintered porous media and metal foams are evaluated to specify the important structural parameters suitable for high heat removal. The porous media used in this experiment arc particle-sintered porous media made of bronze and SUS316L, and metal foams made of copper and nickel. Cooling water flows into the porous medium opposite to heal flux input loaded by a plasma arcjet. The result indicates that the bronze-particle porous medium of 100 mu m in pore size shows the highest performance and achieves heat transfer coefficient of 0.035MW/m(2)K at inlet heat flux 4.6MW/m(2). Compared with the heat transfer performance of copper fiber-sintered porous media, the bronze particle-sintered ones give lower heat transfer coefficient. However, the stable cooling conditions that the heat transfer coefficient does not depend on the flow velocity, were confirmed even at heat flux of 4.6MW/m(2) in case of the bronze particle-sintered media, while not in the case of the copper-fiber sintered media. This signifies the possibility that the bronze-particle sintered media enable much higher heat flux removal of over 10MW/m(2), which could be caused by higher permeability of the particle-sintered pore structures. Porous media with high permeability provide high performance of vapor evacuation, which leads to more stable heat removal even under extremely high heat flux. On the other hand, the heat transfer coefficient of the metal foams becomes lower because of the lower capillary and fin effects caused by too high porosity and low effective thermal conductivity. It is concluded that the pore structure having high performance of vapor evacuation as well as the high capillary and high fin effects is appropriate for extremely high heat flux removal of over 10MW/m(2).
Advanced cryogenics cooling technique using metal porous media with liquid nitrogen 査読有り

S. Ito, K. Yuki, H. Hashizume

Proceedings of ICEC 22-ICMC　2009年
Prove the ability of microwave nondestructive method combined with signal processing to determine the position of a circumferential crack in pipes 査読有り

Abbasi, K., Ito, S., Hashizume, H.

International Journal of Applied Electromagnetics and Mechanics　28　(4)　429-439　2008年12月

DOI： 10.3233/jae-2008-995 　

ISSN：1383-5416
Heat transfer enhancement in sphere-packed pipes under high Reynolds number conditions 査読有り

Nao Seto, Kazuhisa Yuki, Hidetoshi Hashizume, Akio Sagara

FUSION ENGINEERING AND DESIGN　83　(7-9)　1102-1107　2008年12月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2008.07.044 　

ISSN：0920-3796

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Flow analysis in sphere-packed pipes (SPP) for different pipe to sphere diameter ratios was experimentally performed in order to clarify a relationship between the heat transfer and pressure drop characteristics. The experiments, using water as a working fluid, were carried out with Re(D) = 2000-33,000 and Pr = 5.0-6.0. Experimental results of the pressure drop characteristics were compared with the Ergun's and Drag model correlations. Empirical correlations for the averaged Nusselt number are proposed, and SPP heat transfer performance is compared with that of the swirl flow. Furthermore, the applicability of the SPP system to the first wall cooling is also discussed from the temperature distribution aspect of the heating wall. (C) 2008 Elsevier B.V. All rights reserved.
Flow Visualization and Heat Transfer Characteristics for Sphere-Packed Pipes 査読有り

Kazuhisa Yuki, Masumi Okurnura, Hidetoshi Hashizume, Saburo Toda, Neil B. Morley, Akio Sagara

JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER　22　(4)　632-648　2008年10月
出版者・発行元：AMER INST AERONAUT ASTRONAUT
DOI： 10.2514/1.30141 　

ISSN：0887-8722

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Particle image velocimetry visualization to identify the complex flow structures in a sphere-packed pipe is carried out by using a matched refractive-index method with a sodium iodide solution as the working fluid. The following three flows were confirmed as representative flow structures in the pipe: a meandrous bypass flow with a high-How velocity due to the wall effect, two pairs of unstable twin vortices accompanied by a strong impinging How to the pipe wall, and a spouting flow from the central area of the pipe. In an experiment on heat transfer using water as the working fluid, the wall-temperature distribution is measured with thermocouples and infrared thermography, which makes clear a relation between the flow structures and the local heat transfer performance. Though an area with a high wall temperature is formed by the flow stagnation located at a contact point between the sphere and the heating wall, the colliding effect of the high velocity and of the meandrous bypass flow with the spheres significantly affects the heat transport from the stagnation areas. On the other hand, the heat transfer performance is quite high in a large gap area between the upstream and downstream spheres because of the influence of the strong impinging flow and the vortices that are both induced by the meandrous bypass flow.
Visualization of supersonic gas-liquid two-phase flow affecting wall thinning events in the downstream straight and curved pipes of an orifice 査読有り

Yuko ABE, Kazuhisa YUKI, Hidetoshi HASHIZUME, Saburo TODA

Proceedings of the 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety NUTHOS-7　1-4　2008年10月
Matched refractive-index PIV measurement of complex flow structure in a two-dimensional dual elbow 査読有り

Kazuhisa YUKI, Kazuhiro YOSHIDA, Hidetoshi HASHIZUME, Saburo TODA

Proceedings of the 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety NUTHOS-7　1-4　2008年10月
Mechanical Butt Joint of HTS Cable with DFRP for Remountable HTS Magnet 査読有り

S. Ito, H. Hashizume

Proceedings The 16th Pacioc Basin Nuclear Conference　2008年10月
Classification of turbulent jets in a T-junction area with a 90-deg bend upstream 査読有り

Seyed Mohammad Hosseini, Kazuhisa Yuki, Hidetoshi Hashizume

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER　51　(9-10)　2444-2454　2008年5月
出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD
DOI： 10.1016/j.ijheatmasstransfer.2007.08.024 　

ISSN：0017-9310

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Many nuclear power plants report high cycle thermal fatigue in their cooling system, which is caused by temperature fluctuation in a non-isothermal mixing area. One of these areas is the T-junction, in which fluids of various temperatures and velocities blend. The objective of this research is to classify the turbulent jet mechanics in order to examine the flow-field structure under various operating conditions. Furthermore, this research discovers the optimum operating conditions of the mixing tee in this piping system. An experimental model, including the T-junction with a 90-deg bend upstream, is operated to analyze this mixing phenomenon based on the real operation design of the Phenix reactor. The temperature and velocity data show that a 90-deg bend has a strong effect on the fluid mixing mechanism and the momentum ratio between the main velocity and the branch velocity of the T-junction, which could be an important parameter for the classification of the fluid mixing mechanism. By comparing their mean velocity distributions, velocity fluctuations, and time-series data, the behavior of the branch jet is categorized into four types of turbulent jets; sorted from the highest to the lowest momentum ratios, the jets are categorized as follows: the wall jet, the re-attached jet, the turn jet, and the impinging jet. Ultimately, the momentum ration of the turn jet was selected as the optimum operating condition because it has the lowest velocity and the lowest temperature fluctuations near the wall of the mixing tee. (c) 2007 Elsevier Ltd. All rights reserved.
国際コンピテンシー人材育成教育プログラム招待有り査読有り

岡田益男, 橋爪秀利, 長坂徹也, 中島美樹子

工学教育　56　(3)　118-122　2008年3月
出版者・発行元：Japanese Society for Engineering Education
DOI： 10.4307/jsee.56.3_118 　

ISSN：1341-2167
Numerical investigation of thermofluid flow characteristics with phase change against high heat flux in porous media 査読有り

Kazuhisa Yuki, Jun Abei, Hidetoshi Hashizume, Saburo Toda

JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME　130　(1)　2008年1月
出版者・発行元：ASME
DOI： 10.1115/1.27801751 　

ISSN：0022-1481

eISSN：1528-8943

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This study numerically evaluates thermofluid flow characteristics in porous medium by a newly developed "modified two-phase mixture model" applying Ergun's law and a two-energy model instead of a one-energy model. In a single-phase flow case, thermal nonequilibrium between a solid phase and a fluid phase is observed in the area where imposed heat conducts from a heating wall and further convective heat transfer is more active. The degree of thermal nonequilibrium has a positive correlation with the increase inflow velocity and heat flux input. In the case of two-phase flow, the thermal nonequilibrium is remarkable in the two-phase region because the solid-phase temperature in this region is far beyond saturation temperature. A difference between these two models is obvious especially in the two-phase flow case, so that the numerical simulation with the modified two-phase mixture model is indispensable under the high heat flux conditions of over 1 MW/m(2).
Microwave nondestructive detection of longitudinal crack in pipe with U-bend and prediction of its location by signal processing 査読有り

K Abbasi, S Ito, H Hashizume

Studies in Applied Electromagnetics and Mechanics　31　154-161　2008年

DOI： 10.3233/978-1-58603-896-0-154 　
Microwave Detection of Longitudinal Crack and Identification of Its Location in Straight Pipe 査読有り

Kavoos ABBASI, Satoshi ITO, Hidetoshi HASHIZUME

Journal of Power and Energy Systems　2　(2)　538-544　2008年
出版者・発行元：The Japan Society of Mechanical Engineers
DOI： 10.1299/jpes.2.538 　

ISSN：1881-3062

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A microwave NDT method based on guided electromagnetic wave is described in order to detect longitudinal crack and evaluate its location in steel pipe. To detect longitudinal crack in pipe, suitable guided-mode should be propagated in the inspected pipe with crack. For this purpose, first and dominant circular TE11-mode is sent to the system by using a mode-converter. Mode-converter is used to convert rectangular TE10-mode to the circular TE11-mode. A network analyzer, which is a generator and receiver of the microwaves designed to process the magnitude and phase of the reflected and transmitted waves was used to generate continues signal and to measure the amplitude of reflection coefficient. The goal of this investigation is to demonstrate the capability of this technique for detecting longitudinal cracks in piping system with high speed. More emphasis is put on the evaluation of crack location by measuring time of flight (TOF) of the reflected waves from the crack. The results for two crack locations at several plunger positions either in frequency domain or time domain for measuring TOF of the waves are presented. The experimental results of TOF are compared with calculations to show that by knowing TOF of the reflected wave, it is possible to predict crack locations. The evaluated results of TOFs are shown to agree well with the calculated ones and crack locations can be estimated with error less than 0.13%.
Influence of secondary flow generated in a 90-deg bend on the thermal-hydraulic characteristics in a mixing tee 査読有り

Kazuhisa Yuki, Yoshimasa Sugawara, Seyed Mohammad Hosseini, Hidetoshi Hashizume, Saburo Toda, Masa-Aki Tanaka, Toshiharu Muramatsu

Nuclear Science and Engineering　158　(2)　194-202　2008年
出版者・発行元：American Nuclear Society
DOI： 10.13182/NSE08-A2746 　

ISSN：0029-5639

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Th is study aims at clarifying a relationship between nonisothermal fluid mixing in a T-junction area with a 90-deg bend upstream and temperature fluctuations induced by the unstable mixing, by visualizing the flow fields with particle image velocimetry and measuring fluid-temperature fluctuation in the vicinity of a wall. From the visualization, it is clarified that a high-temperature jet flowing out from a branch pipe swings and sways near the wall, though the mixing patterns are basically classified into the same ones without the 90-deg bend upstream. Furthermore, there are cautionary conditions in which the temperature fluctuation is maximized in a transition regime between a stratified flow and a turn-jet flow. It seems that the principal cause is repetitional generation and disappearance of a circulating flow formed behind the jet due to an interaction between unsteady behavior of a secondary flow in a decay process after the bend and the wakes formed behind the jet, which leads to the vigorous oscillation of the jet near the wall.
SPECIFICITY OF FLOW STRUCTURE IN A DUAL ELBOW AND ITS VISUALIZATION BY PIV MEASUREMENT 査読有り

Kazuhiro Yoshida, Yuki Kazuhisa, Hidetoshi Hashizume, Saburo Toda

ICONE16: PROCEEDING OF THE 16TH INTERNATIONAL CONFERENCE ON NUCLEAR ENGINEERING - 2008, VOL 3　293-299　2008年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS
DOI： 10.1115/ICONE16-48231 　

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A large number of pipe failures caused by wall thinning have been reported in nuclear power plants, some of which occur in a dual elbow or the vicinity of it. These pipe failures could be influenced by complex flow induced in the elbow. This study, therefore, aims at predicting the whole flow structure in the dual elbow as the first step by taking a secondary flow after the elbow by PIV measurement. A test section consists of two elbows that are 2-dimentionally connected with/without a straight pipe. They are made of acrylic resin. The diameter of the elbow is 56mm and the curvature radius ratio is 1.5. Reynolds number in this experiment is 4x 10(4). It is confirmed that the flow structure in the dual elbow has specificity depending on the inlet flow condition to the elbow and that the secondary flow itself has swirling motion in a streamwise direction. The dual elbow seems to generate more complex and unstable flow field even when the flow field at the inlet of the elbow slightly changes from a fully developed flow. However, there is a strong possibility that putting a straight pipe between the two elbows makes it ease the occurrence of the complex flow field.
Heat transfer performance for high Prandtl and high temperature molten salt flow in sphere-packed pipes 査読有り

Tomoaki Satoh, Kazuhisa Yuki, Shin-ya Chiba, Hidetoshi Hashizume, Akio Sagara

FUSION SCIENCE AND TECHNOLOGY　52　(3)　618-624　2007年10月
出版者・発行元：AMER NUCLEAR SOC
ISSN：1536-1055

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Heat transfer performance for high Prandtl number and high temperature molten saltflow in a circular pipe and in sphere-packed pipes are evaluated with modified Tohoku-NIFS Thermofluid Loop (TNT loop) using high-temperature molten salt HTS (KNO3: NaNO2: NaNO3 = 53: 40: 7), as a stimulant of Flibe (LiF: BeF2 = 66: 34). The modified TNT loop has much longer entrance region to develop a thermal boundary layer, which enable us to obtain more precise heat transfer data. In the modified TNT loop experiments, the heat transfer characteristics in a circular pipe flow have good agreements with the representative correlations. It is obvious that the analogy for heat and momentum transfer is also valid for high-temperature and high-Prandtlnumber molten saltflow. It is also confirmed that the heat transfer performance of sphere-packed pipes increases up to about 4 times higher than that of circular pipe, in case of relatively low flow rate. This can be effective in the Flibe blanket system from the viewpoints of moderating MHD effect and electrolysis.
Reproduction of behavior of 2-D channel flow with two rods by using k-ε model 査読有り

Satake, M., Yuki, K., Hashizume, H.

Fusion Science and Technology　52　(4)　817-820　2007年10月

DOI： 10.13182/fst07-a1593 　

ISSN：1536-1055
Heat removal performance of particle-sintered porous media counter to heat flux input and its phase change characteristics 査読有り

Kazuhisa Yuki, Akira Matsui, Hidetoshi Hashizume

Second international conference on porous media and its applications in science, engineering and industry　2007年6月
Control Technique of High-Cycle Thermal Fatigue at a Mixing Tee With a 90-degree Bend Upstream by Changing its Location 査読有り

Hiroshi Ohara, Kazuhisa Yuki, Seyed Mohammad Hoseini, Hidetoshi Hashizume, Masaaki Tanaka

15th International Conference on Nuclear Engineering, ICONE15　2007　(15)　"ICONE1510296-1"-"ICONE1510296-11"　2007年4月
出版者・発行元：一般社団法人日本機械学会

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In nuclear and various power plants, there are many mixing tees at which different temperature fluids are mixed. At this kind of mixing tee, temperature fluctuation in fluids due to the unstable mixing is transported to the surrounding wall, which leads to high-cycle thermal fatigue of structural materials. Depending on the amplitude and frequency of the temperature fluctuation, it could induce cracks on the pipe surface and in the worst case lead to coolant leakage. For pipe maintainability and its reliability improvement in the future power plans, therefore, it becomes important to control the high-cycle thermal fatigue. Particularly in the case of the mixing tee with a 90-degree bend upstream, an unsteady secondary flow arises in the 90-degree bend, and then strongly affects the fluid mixing. Furthermore, the unsteady secondary flow has the tendency to change its velocity distribution after the bend outlet. Therefore, the location of the mixing tee is one of the important parameters to characterize the mixing structure and the temperature fluctuation near the wall. In this study, the temperature fluctuation and its intensity, including frequency analysis, and the fluid mixing structure above the mixing tee are investigated experimentally in different cases of location of the mixing tee from the 90-dgree bend outlet. In case of closer location of the mixing tee from the 90-degree bend, the fluid mixing area tends to shift to the inward side of the bended pipe. As a result, the temperature fluctuation intensity becomes lower and decays faster in the streamwise direction. This result means that the location of the mixing tee strongly affects the fluid mixing and the temperature fluctuation near the wall. Experimental results suggest that changing the location of the mixing tee closer to the 90-degree bend could be an effective control technique for the high-cycle thermal fatigue.
Effect of surface angle on mechanical jointing of HTS 査読有り

Yuko Yamamoto, Shohei Takami, Satoshi Ito, Kazuhisa Yuki, Hidetoshi Hashizume

INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS　25　(1-4)　257-260　2007年
出版者・発行元：IOS PRESS
ISSN：1383-5416

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For realization of a commercial fusion power plant, the remountable HTS magnet was proposed as one of the technologies to reduce both construction and maintenance costs. The butt joint of HTS cable has been investigated for the concept. In this study, the joint performance is evaluated with changing joint area, normal stress and shear stress on the joint surface to investigate an optimum joint condition. The experimental results show that the joint performance is improved by forming the optimum joint surface configuration where the normal stress becomes large while the shear stress is suppressed to be smaller than the normal stress.
Evaluation of HTS butt-jointing performance, focusing on the joint stress distribution 査読有り

Shohei Takami, Hidetoshi Hashizume, Satoshi Ito, Yuko Yamamoto

INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS　25　(1-4)　281-286　2007年
出版者・発行元：IOS PRESS
ISSN：1383-5416

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As a basic research for development of the remountable HTS magnet, experimental evaluation of the butt-jointing method with BSCCO 2223 HTS cable under the large joint stress is performed. In this experiment an optimum joint stress value, which makes joint resistance minimum, is obviously confirmed at each applied current value. In addition, numerical structural analysis is performed to clarify the stress distribution at the joint surface of HTS cable under the experimental condition. From these experimental and numerical results, the efficient jointing condition is considered to reduce the joint resistance.
Evaluation of circumferential crack location in pipes by electromagnetic waves 査読有り

Abbasi, K., Ito, S., Hashizume, H., Yuki, K.

Studies in Applied Electromagnetics and Mechanics　28　117-124　2007年
出版者・発行元：Studies in Applied Electromagnetics and Mechanics
ISSN：1383-7281 1879-8322
Characteristic evaluation of mechanical jointed HTS cable for remountable HTS magnets 査読有り

Satoshi Ito, Shohei Takami, Hidetoshi Hashizume, Yuko Yamamoto, Kazuhisa Yuki, Akio Sagara

Fusion Science and Technology　52　(4)　1070-1074　2007年
出版者・発行元：American Nuclear Society
DOI： 10.13182/FST07-A1638 　

ISSN：1536-1055

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Remountable HTS magnets are suggested for as a method to reduce the construction and maintenance costs of a fusion reactor. Butt joints of BSCCO 2223 HTS cable, where cross-sections of the cable are jointed mechanically, have been researched for the new concept. In a previous study, stress distribution on the joint surface in the butt joint was evaluated by numerical analysis. The result showed the importance of obtaining homogeneous stress distribution on the joint surface to reduce the joint resistance. In this study, therefore, the relations between the joint resistance and the stress distribution inside the HTS cable is evaluated for several loading systems by structural analysis and experiment. Based on the result, an efficient loading system is suggested, which can achieve the uniform stress distribution on the joint surface and can avoid the stress concentration.
Experimental investigation of flow field structure in non-isothermal mixing tee 査読有り

Seyed Mohammad Hosseini, Kazuhisa Yuki, Hidetoshi Hashizume

FEDSM 2007: PROCEEDINGS OF THE 5TH JOINT AMSE/JSME FLUIDS ENGINEERING SUMMER CONFERENCE VOL 1, PTS A AND B　131　(5)　155-163　2007年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS
DOI： 10.1115/1.3112383 　

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T-junction is one of familiar components in the cooling system of power plants with enormous capability to high-cycle thermal fatigue. This research tries to investigate fluid mixing mechanism in non-isothermal T-junction area with 90-degree bend upstream. Classification of turbulent jet and effects of 90-degree bend were evaluated previously and re-attached jet was selected as complicated mixing structure with highest velocity fluctuation [4]. For considering the mixing mechanism of re-attached jet, T-junction area is visualized in various lateral and longitudinal sections. The measuring data show the flow of branch pipe acts as turbulent jet in finite space and interaction between the jet and main flow can create various eddies and develops high velocity fluctuation area near the main pipe wall as well as temperature fluctuation. Three regions are more affected by maximum velocity fluctuation in T-junction area near the main pipe wall; the region close to the jet surface (fluctuation mostly is caused by Kelvin-Helmholtz instability), the region above the jet and along the main flow (fluctuation mostly is caused by Karman vortex) and re-attached area (fluctuation mostly is caused by moving the jet body with pressure gradient). Finally, the re-attached area is selected as region with strongest possibility to high cycle thermal fatigue with effective velocity fluctuation on the main pipe wall above the branch nozzle as well as temperature fluctuation.
Conceptual design activities and key issues on LHD-type reactor FFHR 招待有り査読有り

A. Sagara, O. Mitarai, S. Imagawa, T. Morisaki, T. Tanaka, N. Mizuguchi, T. Dolan, J. Miyazawa, K. Takahata, H. Chikaraishi, S. Yamada, K. Seo, R. Sakamoto, S. Masuzaki, T. Muroga, H. Yamada, S. Fukada, H. Hashizume, K. Yamazaki, T. Mito, O. Kaneko, T. Mutoh, N. Ohyabu, N. Noda, A. Komori, S. Sudo, O. Motojima

FUSION ENGINEERING AND DESIGN　81　(23-24)　2703-2712　2006年11月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2006.07.057 　

ISSN：0920-3796

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An overview of conceptual design activities on the LHD-type helical reactor FFHR is presented, mainly focusing on optimization studies on the reactor size and the proposal of a long-life blanket. A major radius of around 15 m is the present candidate under the constraints of the energy confinement achieved in LHD, a maximum magnetic field around 13 T with a current density around 30 A/mm(2) and a neutron wall loading around 1.5 MW/m(2). R&D on super-conducting magnet systems of large scale, high field and high current-density are new challenging targets based on the LHD. The development of new design tools has been started aiming at establishing a virtual power plant (VPP) and a virtual reality system for 3D design assisting. Next design issues are mainly on engineering optimization of the first wall thickness, the detailed 3D blanket system, and unscheduled replacements of breeder blankets. (c) 2006 Elsevier B.V. All rights reserved.
Overview of fundamental study on remountable HTS magnet 査読有り

S. Ito, H. Hashizume

FUSION ENGINEERING AND DESIGN　81　(20-22)　2527-2533　2006年11月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2006.07.005 　

ISSN：0920-3796

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A remountable HTS (high temperature superconducting) magnet was proposed for one of the future designs of fusion reactors. It can facilitate the fabrication of the magnet itself and the replacement of failed parts and of the inner structural material components in the maintenance phase. The butt joint of HTS cable was investigated for the concept. At first, performance of the butt joint of BSCCO 2223 tape was evaluated by experiments and numerical analyses to clarify the basic property of the butt joint. Then experimental evaluation of the butt joint of laminated BSCCO 2223 cable was carried out to prove robustness against heat generation at jointing parts at liquid nitrogen temperature and several hundred amperes. Based on the proof, the prototype of the remountable HTS magnet by using the butt joint was fabricated and the performance was evaluated to suggest some issues for the future development. The above fundamental studies on the remountable HTS magnet are summarized in this paper. (c) 2006 Elsevier B.V. All rights reserved.
Development of an Advanced Cooling Device Using Porous Media with Active Boiling Flow Counter to High Heat Flux 査読有り

S. Toda, K. Yuki, S. Ebara, Y. Kunikata, J. Abei, H. Hashizume

International Heat Transfer Conferences IHTC13　boi-58　2006年8月
Experimental Investigation of Thermal-Hydraulic Characteristics at a Mixing Tee 査読有り

Seyed Mohammad Hoseini, Kazuhisa Yuki, Yoshimasa Sugawara, Hidetoshi Hashizume, Masaaki Tanaka

International Heat Transfer Conferences IHTC13　fcv-17　2006年8月
Advanced Heat Removal System with Porous Media for Electronic Devices 査読有り

Takayuki Yao, Kazuhisa Yuki, Shingo Takiguchi, Hidetoshi Hashizume

9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference　Tracking No. 55838　2006年7月
Numerical analysis of MHD flow structure behind a square rod 査読有り

M Satake, K Yuki, S Chiba, H Hashizume

FUSION ENGINEERING AND DESIGN　81　(1-7)　525-532　2006年2月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2005.08.028 　

ISSN：0920-3796

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In a liquid blanket system, the large MHD pressure drop for liquid lithium and/or LiPb makes it difficult to remove high heat load. Since the MHD pressure drop is proportional to the flow velocity, it is necessary to remove the high heat load under low velocity conditions. Meanwhile, in case of molten salt Flibe, which is a high Prandtl number fluid, it is also important to enhance the heat transfer performance. In this study, MHD flow structure behind a square rod inserted in a parallel channel to enhance the heat transfer is simulated numerically to clarify the interaction between the flow structure and the magnetic field by using a low-Reynolds number k-epsilon turbulent model and including MHD effects. The laminar flow analysis indicates that the disappearance of twin vortices and the change of the Karman's vortex street to the twin vortices occur around a Ha/Re-h ratio of 0.7 and 0.07-0.09, respectively. The turbulent flow analysis confirms that installing the rod near the heating wall contributes to enhancing the heat transfer even in the presence of a magnetic field, although the turbulent kinetic energy decreases with increasing Hartmann number. (c) 2005 Elsevier B.V. All rights reserved.
Numerical research on heat transfer enhancement for high Prandtl-number fluid 査読有り

SY Chiba, K Yuki, H Hashizume, S Toda, A Sagara

FUSION ENGINEERING AND DESIGN　81　(1-7)　513-517　2006年2月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2005.08.046 　

ISSN：0920-3796

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The molten salt, Flibe, has been recommended as a candidate coolant material in the blanket system of the FFHR fusion reactor though it is high Pmadtl-number (Pr) fluid that leads to low heat transfer performance. This paper, describes the results of numerical simulations performed in order to estimate the effects of cylinders as obstructions for heat-transfer enhancement in high-Pr fluid duct flow. Two-dimensional thermofluid simulations were performed for cases with 44, 24 and 48 cylinders, respectively, inserted perpendicularly to the fluid flow, and acting as heat transfer enhancers between parallel plates. From these analyses, the flow contraction created by the cylinders causes a high-vorticity around the heated wall. This high-vorticity plays an important role in the heat-transfer enhancement. In the high-vorticity region, the momentum perpendicular to a wall has a large gradient along the stream direction. In fact, the fluid flows down while rotating and "washing" the heated wall. This effect is also governed by the arrangement of cylinders. A staggered arrangement is adopted in the case with 44 cylinders, while square arrangement is employed in the cases with 24 and 48 cylinders. The enhancement of perpendicular flow is very effective when using a staggered arrangement, procuring a higher heat transfer downstream of the cylinders. The estimated pressure drop for high-Pr fluid flow was larger for the with 44 cylinders than for the cases with 24 and 48 cylinders. This result indicates that the heat transfer of high-Pr fluid flow strongly depends on the effect of flow stirring caused by obstructions. (c) 2005 Elsevier B.V. All rights reserved.
Butt jointing performance for remountable HTS magnet by improving contact surface condition 査読有り

S Ito, H Hashizume, K Yuki, S Takami, Y Yamamoto

FUSION ENGINEERING AND DESIGN　81　(8-14)　1491-1496　2006年2月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2005.08.062 　

ISSN：0920-3796

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The remountable HTS magnet, which can facilitate the fabrication of the magnet itself and the replacement of failed parts and of inner structural component, was proposed by the authors, especially for helical reactors and Spherical Tokamak. Through the previous researches, it has been clarified that the butt joint of HTS cable is a suitable joint method for the remountable magnet. In this study, the butt jointing performance of BSCCO 2223 cable is evaluated when the contact surface is metal-electroplated or coated with nano-carbon particles. The results show that electroplating of silver can reduce the joint resistance. The joint resistance obtained by this experiment is small enough to prevent significant resistance increase below 500 A. It is proved that the HTS cable has enough robustness against heat generation in the butt joint under liquid nitrogen temperature below 500 A, which shows future feasibility of the remountable HTS magnet. (c) 2005 Elsevier B.V. All rights reserved.
Numerical and experimental research to solve MHD problem in liquid blanket system 招待有り査読有り

H Hashizume

FUSION ENGINEERING AND DESIGN　81　(8-14)　1431-1438　2006年2月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.fusengdes.2005.08.086 　

ISSN：0920-3796

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Thermofluid research issues relating to self-cooling liquid blanket system for fusion reactors are discussed to find ways to realize the system. In this paper, liquid Li and Flibe molten salt are chosen as the blanket coolants. For the Li blanket system, there exists some possibility to overcome MHD problem by using three-surface coated channel with multi-layer structure. The material properties in terms of electrical conductivity required for the innermost metal layer seems achievable together with new concept that the coated material works as the structural component of the innermost thin layer. In the case of Flibe coolant, which shows very small MHD pressure drop, electrolysis occurs to result in generation of fluorine and tritium. The numerical results show that this electrolysis can be suppressed by optimizing the channel geometry. Numerical and experimental results indicate that heat transfer enhancement using pebble beds is expected when the flow velocity is relatively small to reduce the MHD effect. (c) 2005 Elsevier B.V. All rights reserved.
Engineering design and control scenario for steady-state high-beta operation in National Centralized Tokamak

Tsuchiya, K., Akiba, M., Azechi, H., Fujii, T., Fujita, T., Fujiwara, M., Hamamatsu, K., Hashizume, H., Hayashi, N., Horiike, H., Hosogane, N., Ichimura, M., Ida, K., Ikeda, Y., Imai, T., Inoue, N., Ishida, S., Itoh, S., Kamada, Y., Kawashima, H., Kikuchi, M., Kimura, A., Kizu, K., Kubo, H., Kudo, Y., Kurihara, K., Kurita, G., Kuriyama, M., Masaki, K., Matsukawa, M., Matsuoka, M., Miura, Y., Miura, Y.M., Miya, N., Morioka, A., Nakamura, K., Ninomiya, H., Nishimura, A., Okano, K., Okuno, K., Sagara, A., Sakamoto, M., Sakurai, S., Sato, K., Shimada, R., Shimizu, A., Suzuki, T., Takahashi, H., Takase, Y., Takechi, M., Tamai, H., Tanaka, S., Tsutsui, H., Uesugi, Y., Yatsu, K., Yoshida, N.

Fusion Engineering and Design　81　(8-14 PART B)　2006年

DOI： 10.1016/j.fusengdes.2005.08.066 　

ISSN：0920-3796
Carbon tiles as spectral-shifter for long-life liquid blanket in LHD-type reactor FFHR 査読有り

Sagara, A., Imagawa, S., Tanaka, T., Muroga, T., Kubota, Y., Dolan, T., Hashizume, H., Kunugi, T., Fukada, S., Shimizu, A., Terai, T., Mitarai, O.

Fusion Engineering and Design　81　(8-14 PART B)　1299-1304　2006年

DOI： 10.1016/j.fusengdes.2005.09.067 　

ISSN：0920-3796
Critical heat flux of mist-cooling under high heat flux condition and its enhancement with surfactant 査読有り

Kazuhisa Yuki, Atsushi Kamahora, Hidetoshi Hashizume, Saburo Toda

The Sixteenth International Symposium on Transport Phenomena (ISTP-16)　TPF-P4　2005年9月
The Three-Dimensional Study of Flow Mixing Phenomenon in a T-Junction Area with 90-Degree Bend Upstream 査読有り

Seyed Mohammad Hoseini, Kazuhisa Yuki, Hidetoshi Hashizume, Masaaki Tanaka

International Conference Nuclear Energy for New Europe 2005　2005年9月
Joint performance of HTc superconductor for remountable magnet system 査読有り

H Hashizume, S Ito, S Takami, A Sagara

FUSION SCIENCE AND TECHNOLOGY　47　(4)　901-905　2005年5月
出版者・発行元：AMER NUCLEAR SOCIETY
ISSN：1536-1055

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A butt joint method of HTc superconductor has been investigated for a concept of remountable superconducting (SC) magnets in fusion reactors. Through numerical analysis of the present study, it is clarified that the degradation of SC tape near the surface had influences on the joint performance. This degradation of SC tape gives the relationship that the resistance in the butt joint increases when the transport current increases in the butt joint. And through the experiment, the optimum stress, which gives the minimum resistance at the joint, is determined for the butt joint of SC cable composed of ten of SC tapes. The joint resistance of a butt cable shows a larger value than predicted from the experiment using a single layer SC tape.
Heat transfer enhancement technique with copper fiber porous media 査読有り

H Togashi, K Yuki, H Hashizume

FUSION SCIENCE AND TECHNOLOGY　47　(3)　740-745　2005年4月
出版者・発行元：AMER NUCLEAR SOCIETY
ISSN：1536-1055

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In a fusion reactor, almost 30% of fusion energy is deposited on plasma facing components. In the divertor region, it is, however, difficult to utilize this energy with conventional cooling techniques based on high velocity flow with highly subcooled cooling. From this viewpoint, the authors have been developing a cooling technique with metal porous media. In this study, in order to attain both the higher cooling performance and the acquisition of high density energy, high heat removal experiments are performed by using homogeneous and functionally graded porous media to estimate their fundamental heat transfer performances. From the experiments with the homogeneous porous media, it is clarified that the cooling performance is not always improved by using finer pore size media. The functionally graded porous media can reduce a pressure loss. Additionally, in case of the functionally graded porous media with the finer pore, the heat transfer coefficient is higher than that obtained in the homogeneous case. As for the optimal design, it is important to consider the degree of vapor development near a heated surface in the porous media and an effective discharge of vapor from the heated region.
Experimental research on heat transfer enhancement for high Prandtl-number fluid 査読有り

SY Chiba, M Omae, K Yuki, H Hashizume, S Toda, A Sagara

FUSION SCIENCE AND TECHNOLOGY　47　(3)　569-573　2005年4月
出版者・発行元：AMER NUCLEAR SOCIETY
ISSN：1536-1055

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The experimental research on heat-transfer enhancement for such high Prandtl-number fluid as Flibe has been performed with a large molten salt circulating experimental loop named as "TNT loop" (Tohoku-NIFS Thermofluid loop). Through the experiments, a packed-bed tube is employed as the enhanced for molten salt. It is clarified that the enhancement of packed-bed tube is superior to that of turbulent heat transfer from the viewpoint of the same flow rate. Also, the 1/4-diameter bed is superior to the 1/2-diameter one at the same flow rate. Furthermore, at low flow rate, a little differences of heat transfer performance can be seen between the stainless-steel bed and copper bed. At high flow rate, however, the heat-transfer coefficient ratio strongly depends on the flow rate in the case of the 1/4-diameter copper bed only. As a result, it is considered that the thermal energy is expanded from a heated wall deeply and fast through packed bed at low flow rate. On the contrary, it is also considered that the convective heat transfer in the vicinity of a heated wall is strong at high flow rate. The evaluation from the viewpoint of the pressure drop shows that the turbulent heat transfer is superior to that with packed bed However, the ratio of heat transfer with bed to turbulent one is steeply improved at low flow rate. Taking account of MHD effect, avoidance of erosion and electrolysis of Flibe, the enhancement under low flow-rate condition can be suitable in a fusion reactor.
Experimental study on NDT method using electromagnetic waves 査読有り

T Shibata, H Hashizume, S Kitajima, K Ogura

JOURNAL OF MATERIALS PROCESSING TECHNOLOGY　161　(1-2)　348-352　2005年4月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/j.jmatprotec.2004.07.049 　

ISSN：0924-0136

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The NDT method using electromagnetic waves has strong possibility to detect defects in large structures, or large pipes. The purpose of this study is to control the electromagnetic waves of circular TM01-mode near the cut-off frequency for detecting defects inside the pipes, and to obtain the information in order to develop the device for the defect detection with high speed and high accuracy. The experiment is carried out with mode converter, which can convert the rectangular TE01-mode to circular TM01-mode microwaves. It is confirmed that the circular TM01-mode is converted from the rectangular TE01-mode, and is generated inside the circular waveguide on some optimum conditions. It also becomes clear that the reflected wave carries a lot of information on crack width, since the obtained signal of reflected wave depends on the crack width. Experimental results strongly suggest that it is useful to apply electromagnetic waves to NDT technique. (c) 2004 Published by Elsevier B.V.
Design study of National Centralized Tokamak facility for the demonstration of steady state high-β plasma operation

Tamai, H., Akiba, M., Azechi, H., Fujita, T., Hamamatsu, K., Hashizume, H., Hayashi, N., Horiike, H., Hosogane, N., Ichimura, M., Ida, K., Imai, T., Ishida, S., Itoh, S., Kamada, Y., Kawashima, H., Kikuchi, M., Kimura, A., Kizu, K., Kubo, H., Kudo, Y., Kurihara, K., Kurita, G., Kuriyama, M., Masaki, K., Matsukawa, M., Matsuoka, M., Miura, Y., Miura, Y.M., Miya, N., Morioka, A., Nakamura, K., Ninomiya, H., Nishimura, A., Okano, K., Okuno, K., Sagara, A., Sakamoto, M., Sakurai, S., Sato, K., Shimada, R., Shimizu, A., Suzuki, T., Takahashi, H., Takase, Y., Takechi, M., Tanaka, S., Tsuchiya, K., Tsutsui, H., Uesugi, Y., Yatsu, K., Yoshida, N.

Nuclear Fusion　45　(12)　2005年

DOI： 10.1088/0029-5515/45/12/023 　

ISSN：0029-5515 1741-4326
Innovative Liquid Breeder Blanket Design Activities in Japan 招待有り査読有り

Akio Sagara, Teruya Tanaka, Takeo Muroga, Hidetoshi Hashizume, Tomoaki Kunugi, Satoshi Fukada, Akihiko Shimizu

Fusion Science and Technology　47　524-529　2005年
Super-high heat flux removal using sintered metal porous media 査読有り

Kazuhisa Yuki, Jun Abei, Hidetoshi Hashizume, Saburo Toda

Journal of Thermal Science　14　(3)　272-280　2005年
出版者・発行元：Editorial Committee of Journal of Thermal Sciences
DOI： 10.1007/s11630-005-0014-2 　

ISSN：1003-2169

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Heat transfer experiments using various porous materials are performed to verify the possibility of extremely high heat flux removal (several dozens of MW/m2). The porous media introduced in this experiment are bronze particle-sintered ones and copper fibers-sintered ones that have high thermal conductivity, each of which can enhance the thermal diffusion in the porous material. From the heat transfer experiments using a non-transferred type of plasma arcjet as a high heat flux source, the steady heat removal of 66.0 MW/m2 is proved by using the bronze porous medium whose pore size and porosity are 100 μm and 0.38, respectively. Furthermore, as the result of evaluating the heat removal performance for various copper fiber porous media with the porosity from 0.5 to 0.7 and the fiber diameter from 30 to 90 μm, it is clarified that the maximum cooling performance exceeds 70.0 MW/m2 at the porosity of 0.7 and the fiber diameter of 90 μm, and that using the lower porosity material is useful for improving an evaporation rate in the porous media.
Evaluation of flow structure in packed-bed tube by visualization experiment 査読有り

Masumi Okumura, Kazuhisa Yuki, Hidetoshi Hashizume, Akio Sagara

Fusion Science and Technology　47　(4)　1089-1093　2005年
出版者・発行元：American Nuclear Society
DOI： 10.13182/FST05-A832 　

ISSN：1536-1055

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In order to apply Flibe as a liquid blanket material, a heat transfer enhancement system is required because the Flibe is a high Prandtl number fluid. The purpose of this study is to visualize the detailed flow fields in the packed-bed tube, which is expected to be utilized for the heat transfer enhancement. The visualization inside the packed-bed tube from various angles is performed by using a PIV system with a refractive index matching technique. Pressure loss characteristics in the packed-bed tube whose sphere diameter is half the length of tube inside diameter are evaluated and it is found that a drag model could be suitable to estimate the pressure loss of the packed-bed tube.
Effect of nano-scale surface conditions for boiling heat transfer and its enhancement 査読有り

S. Chiba, K. Yuki, H. Hashizume, S. Toda

HT2005: Proceedings of the ASME Summer Heat Transfer Conference 2005, Vol 2　561-569　2005年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS
DOI： 10.1115/HT2005-72758 　

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In this paper, the Leidenfrost phenomena and water mist cooling are described from the viewpoint of surface conditions of heat transfer interfaces. The effect of nano-scale structures on boiling heat transfer phenomena is researched. It is clarified that the Leidenfrost phenomena on a substrate with adhered nano-scale carbons (nano carbons) are different from the one in case of a normal heat transfer interface. The photographs taken by a high-speed camera show that the boiling on a substrate with nano carbons takes the different form in comparison with the one on a normal interface. In case that the surface temperature of a copper substrate is about 140 degree C, a water droplet has a neck of water between itself and the substrate with nano carbons. On the other hand, the nucleate boiling is observed on a normal copper substrate. From the relation between evaporation time and initial surface temperature, heat transfer enhancement can be achieved under the nucleate boiling conditions. Also, the critical heat flux of water mist cooling could be enhanced by adhering nano carbons on heat-transfer interfaces. It is supposed that the wettability between water and copper is improved by the nano carbons.
Numerical investigation of thermofluid flow characteristics with phase change against high heat flux in porous media 招待有り査読有り

K. Yuki, J. Abei, H. Hashizume, S. Toda

HT2005: Proceedings of the ASME Summer Heat Transfer Conference 2005, Vol 2　409-419　2005年
出版者・発行元：AMER SOC MECHANICAL ENGINEERS
DOI： 10.1115/1.2780175 　

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This study numerically evaluates thermofluid flow characteristics in porous media by a newly developed "modified two-phase mixture model" applying a two-energy model instead of an one-energy model. In a single-phase flow case, thermal nonequilibrium between a solid phase and a fluid phase is observed in the area where inlet heat conducts from a heating wall and further convective heat transfer is more active. Though the degree of thermal nonequilibrium has a positive correlation with the increase inflow velociry and inlet heat flux, the degree is very low and can be ignored, from an engineering perspective. In a case of two-phase flow, the thermal nonequilibrium is remarkable in the two-phase region because the solid-phase temperature in this region is far beyond saturation temperature. A difference between these two models is obvious especially in the two-phase flow case, so that the numerical simulation with the two-energy model is indispensable under the high heat flux conditions of over 1 MW/m(2).
HIGH HEAT FLUX REMOVAL BY USING SINTERED METAL POROUS MEDIA 査読有り

K. Yuki, J. Abei, H. Hashizume, S. Toda

6th International symposium on heat transfer　2004年6月
Advanced nuclear engineering research for both fusion and fission reactors 査読有り

H. Hashizume, S. Toda

2nd International Conference on Nuclear Science and Technology　2004年4月
Effect of Curvature Ratio on Thermal Mixing Characteristics in a T-Junction Area Which Has a 90-Degree Bend in the Upstream Area 査読有り

YUKI Kazuhisa, TAJIMA Yu, TODA Saburo, HASHIZUME Hidetoshi, MURAMATSU Toshiharu

Transactions of the Japan Society of Mechanical Engineers Series B　70　(700)　3142-3149　2004年
出版者・発行元：Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.70.3142 　

ISSN：0387-5016

eISSN：1884-8346
New concept of the first wall to reduce MHD pressure drop 査読有り

H Hashizume, Y Usui, S Kitajima, A Sagara

INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS　19　(1-4)　619-623　2004年
出版者・発行元：IOS PRESS
ISSN：1383-5416

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Numerical analysis of MHD flow in rectangular channel is performed to evaluate the performance of remountable first wall with liquid blanket like Li or Flibe, where fabrication and maintenance of the system become extremely simplified. Four-channel model is used to calculate the MHD pressure drop in variously coated channels. The effect of crack existence in the coated layer of flow channel on the MHD pressure drop is also evaluated for real usage. The numerical results indicate that some amount of crack existence is allowable, which shows possibility to apply the first wall concept to future fusion reactor design.
Fundamental study on the NDT method based on electromagnetic waves 査読有り

H Hashizume, S Kitajima, T Shibata, Y Uchigaki, K Ogura

ELECTROMAGNETIC NONDESTRUCTIVE EVALUATION (VIII)　24　263-270　2004年
出版者・発行元：I O S PRESS
ISSN：1383-7281

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It is considered that the NDT method using electromagnetic waves has strong possibility to detect defects in large structures, or large pipes because the electromagnetic waves propagate inside the pipe up to a long distance. The purpose of this study is to experimentally verify the validity of this method. It is confirmed that the microwave of circular TM01-mode, which is necessary to detect the circumferential crack, is converted from the rectangular TE01-mode. It also becomes clear that the reflected wave carries a lot of information on crack width and depth. Experimental results indicate that the NDT method using the electromagnetic waves has excellent prospect.
Proposal of remountable HTS magnet system for fusion reactor 査読有り

S.Ito, S. Takami, Y. Yamamoto, K. Yuki, H. Hashizume

Proceedings of the 8th Japan-China Symposium on Materials for Advanced Energy Systems and Fission and Fusion Engineering　61-66　2004年
Progress in Butt Jointing Perfomance for Remountable HTc SC Magnet 査読有り

S. Takami, H. Hashizume, S. Itoh, K. Yuki

Third JNZ Joint Seminar　27　2004年1月
Depedence of Joinitng Resistance on Trasnport Current in HTc SC Tape 査読有り

S. Itoh, H. Hashizume

Third JNZ Joint Seminar　31　2004年1月
Thermo-fluid analysis of two-phase flow with phase-change against intense heat in porous media 査読有り

J Abei, K Yuki, H Hashizume, S Toda

PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM ON HEAT TRANSFER ENHANCEMENT AND ENERGY CONSERVATION, VOLS 1 AND 2　1　319-327　2004年
出版者・発行元：SOUTH CHINA UNIV TECHNOLOGY PRESS

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A new cooling system using sintered porous media has been proposed to remove high heat flux on plasma facing components in a fusion reactor. By using this system, it is possible to remove the heat flux of several MW/m(2) with high thermal efficiency. It is difficult, however, to elucidate the thermo-fluid mechanism in the porous media experimentally because of its complicated internal structure. For this reason, the present study aims to carry out the thermo-fluid analysis of two-phase flow with phase-change in the porous media, and to elucidate its fundamental flow characteristics under the heat flux mainly of O (0.1) MW/m(2). As a result, in the case that the porous material has lower thermal conductivity, the heat transport by latent heat of vaporization is dominant, but the thermal penetration toward single-phase region behind the two-phase region is a little. On the other hand, in the case of higher thermal conductivity material, the heat transport by sensible heat in the single-phase region as well as by the latent heat in the two-phase region works effectively. As to the heat removal over 10 MW/m(2), it is clarified that the increase of inlet velocity and higher thermal conductivity of porous media could be necessary.
Numerical simulation on heat transfer enhancement in twisted-tape-inserted tubes 査読有り

K Yuki, C Sato, H Hashizume, S Toda

PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM ON HEAT TRANSFER ENHANCEMENT AND ENERGY CONSERVATION, VOLS 1 AND 2　2　787-794　2004年
出版者・発行元：SOUTH CHINA UNIV TECHNOLOGY PRESS

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To clarify the mechanism of heat transfer enhancement in swirl tubes, especially the effect of secondary flow generated in a pipe cross section on temperature field mixing, numerical simulation of swirl flow under the laminar condition including a mixed convection region is performed. As the result of the simulation, the generation and development processes of secondary flow are visualized clearly and it is clarified that these transitional processes depend on a twist ratio of swirl-tape gamma and Re number. Furthermore, these behaviors of secondary flow also contribute to the heat removal performance highly and Nu number becomes higher especially if the secondary flow has some instability like the transition from one vortex to two vortices. Numerical data on the heat transfer performance as well as the flow patterns shows good agreement with conventional experimental results. On the other hand, it is shown that the transition process of secondary flow under a high heat flux condition is strongly affected by gravity effect and its flow pattern and the local Nu number change periodically in a streamwise direction. By summarizing all the numerical data, a new prediction formula for the Nu number is constructed in wide Re, Pr, Gr, and gamma ranges and it is shown that this formula almost corresponds to the conventional experimental results.
Unsteady Decay Behaviour of Secondary Flow Generated in 90-Degee Bends 査読有り

YUKI Kazuhisa, KUMANO Takayasu, TODA Saburo, HASHIZUME Hidetoshi, MURAMATSU Toshiharu

Transactions of the Japan Society of Mechanical Engineers Series B　70　(693)　1163-1170　2004年
出版者・発行元：Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.70.1163 　

ISSN：0387-5016

eISSN：1884-8346
Performance analysis of butt jointing in remountable HTC superconducting magnet 査読有り

S Ito, H Hashizume, T Yamauchi

INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS　19　(1-4)　467-472　2004年
出版者・発行元：IOS PRESS
ISSN：1383-5416

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For a future design of fusion power plant, concept of remountable SC magnet is proposed to improve cost performance. In this concept butt jointing of HTC SC is used as jointing method and contact force can be obtained from electromagnetic force induced by self magnetic field of the magnet. Evaluation of performance of butt jointing with laminated SC tapes is performed to demonstrate feasibility of the remountable SC magnet experimentally. The result shows that the jointing resistance is almost in inversely proportional to the contact area and dependent on transport current. Numerical analysis is carried out to explicate the resistance dependence. The numerical results, however, shows difference from the experimental one. Further, evaluation of electromagnetic force is carried out to prove that the contact stress can be obtained only by electromagnetic force.
New concept of the first wall to reduce MHD pressure drop 査読有り

H Hashizume, Y Usui, S Kitajima, A Sagara

INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS　19　(1-4)　591-595　2004年
出版者・発行元：IOS PRESS
ISSN：1383-5416

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Numerical analysis of MHD flow in rectangular channel is performed to evaluate the performance of remountable first wall with liquid blanket like Li or Flibe, where fabrication and maintenance of the system become extremely simplified. Four-channel model is used to calculate the MHD pressure drop in variously coated channels. The effect of crack existence in the coated layer of flow channel on the MHD pressure drop is also evaluated for real usage. The numerical results indicate that some amount of crack existence is allowable, which shows possibility to apply the first wall concept to future fusion reactor design.
New crack detection method by using electromagnetic wave 査読有り

Hidetoshi Hashizume, Takuya Shibata, Kazuhisa Yuki, Takahiro Yoshioka

American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP　484　229-234　2004年

DOI： 10.1115/PVP2004-2841 　

ISSN：0277-027X

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The NDT method using electromagnetic waves has the possibility to detect widely and quickly inner surface crack existing in large pipes. The purpose of this study is then to demonstrate validity of the method to detect the thin crack introduced by plasma discharge fabrication. Through this study, it has been shown that both reflected and transmitted waves carry a lot of information on existence of the crack. Experimental results indicate that there exists attractive possibility in this new NDT method.
Crack detection method using electromagnetic waves 査読有り

H Hashizume, T Shibata, K Yuki

INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS　20　(3-4)　171-178　2004年
出版者・発行元：IOS PRESS
ISSN：1383-5416

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The NDT method using electromagnetic waves has availability for crack detection in large pipes or structures in nuclear power plants. The purpose of this study is then, to develop a new method to determine the crack size and location with high speed and accuracy. Through this study, it has been shown that the transmitted wave carries a lot of information on crack depth and the obtained signals of reflected wave below the cut-off frequency depend on the crack position. Experimental results indicate that there exists attractive possibility in the new NDT method.
Configuration Effect on LH Transition in Tohoku University Heliac 査読有り

H. Takahashi, S. Kitajima, M. Yokoyama, Y. Tanaka, H. Utoh, H. Hashizume, M. Sasao, M. Takayama

J. of Plasma and Fusion Research　6　366-370　2003年11月
保全を考慮した核融合炉原型炉の経済性評価査読有り

橋爪秀利, 北郷和寿

保全学　2　(1)　43-48　2003年10月
出版者・発行元：日本保全学会
ISSN：1348-7795
Numerical Analysis of MHD turblent Flow using Mixing Length Model 査読有り

H. Hashizume, M. Satake, K. Yuki

ASAEM2003　8　2003年10月
INVESTIGATION OF NON-ISOTHERMAL FLUID MIXING AND WALL TEMPERATURE FLUCTUATION IN AT-JUNCTION WHICH HAS A 90-DEGREE BEND IN THE UPSTREAM AREA 査読有り

K. Yuki, K. Okuyama, S. Toda, H. Hashizume, T. Muramatsu

NURETH-10(CDROM)　1-12　2003年10月
Cost assessment of fusion reactor with external conductor systems 査読有り

H Hashizume, K Kitagoh, S Kitajima, A Sagara

FUSION SCIENCE AND TECHNOLOGY　44　(2)　284-288　2003年9月
出版者・発行元：AMER NUCLEAR SOCIETY
ISSN：1536-1055

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Fusion reactors with external SC (superconducting) magnet systems have the possibility of high beta-value without plasma current for plasma confinement. These reactors, however have complex configurations and systems, which leads to reduction of these plant availabilities together with unstable maintainability. Through this research the influence on the complex system to its availability is evaluated to demonstrate the effect of using remountable systems on COE.
動力炉ブランケットの役割と条件

朝岡善幸, 毛利憲介, 橋爪秀利, 田中知, 上田良夫

プラズマ・核融合学会誌 = Journal of plasma and fusion research　79　(7)　652-662　2003年7月25日
出版者・発行元：The Japan Society of Plasma Science and Nuclear Fusion Research
DOI： 10.1585/jspf.79.652 　

ISSN：0918-7928

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Roles and requirements of the blanket system of the fusion power reactors are discussed from viewpoints of economics, fuel supply, generation system, maintenance, radioactive waste, and interaction with the plasma core. As the blanket system influences the cost of the fusion energy, the blanket system must be designed to minimize the fusion energy cost. Tritium breeding performance of the blanket is indispensable role to show the advantage of fusion energy on energy security. Material development for high temperature use under high neutron flux is one of the key issues of the generation system because the thermal efficiency depends on the coolant temperature of the blanket. Innovative maintenance technologies such as dividable superconducting coil system are very effective to make the fusion power reactor attractive. From viewpoints of natural resources and waste management, materials used in the fusion reactors should be recycled. Material selection is also of a large importance on the cost of radioactive waste disposal. Finally, it must be paid a careful attention that the design of the blanket system is inseparable from the achievement of a high performance plasma core.
Radial Electric Field Control by Biased Hot Cathode in Tohoku University Heliac 査読有り

S. Kitajima, H. Takahashi, Y. Tanaka, H. Hashizume, M. Sasao

Proc. 2003 IEEE International Conference on Plasma Science　2003年6月
Proposal of mechanically jointed superconducting magnet using high critical temperature superconductors 査読有り

H Hashizume, S Ito, K Yagi, S Kitajima

FUSION ENGINEERING AND DESIGN　63-64　449-454　2002年12月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/S0920-3796(02)00271-5 　

ISSN：0920-3796

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For future design of fusion reactors, development of the remountable superconducting magnet can become one of the important technical issues, which will bring huge benefit to reduce both costs of reactor construction and maintenance. In the conventional design, however, there is a fatal problem of heat generation occurring at the joints, which causes quenching of the magnet. On the other hand HT(c) superconductors, which has large specific heat, are now being used for magnets. In the previous research [International Journal of Applied Electromagnetics and Mechanics, IOS Press, in press. Joint Conference of the 12th International Toki Conference on Plasma Physics and Controlled Nuclear Fusion and The Third General Scientific Assembly of Asia Plasma Fusion Association, Toki. 200 1, in press], the butt jointing method of HT(c) S.C. tapes had been proposed and its contact performance had been reported to be relatively excellent. In this research, therefore, the current distributions in the tape are calculated by numerical analysis and then the heat generations in the jointing region are estimated to evaluate the difference of contact performance in some jointing cases. The results show that the contact performance does not dependent on relative location of each S.C. filaments. (C) 2002 Elsevier Science B.V. All rights reserved.
Numerical analysis of MHD flow in remountable first wall 査読有り

H Hashizume, Y Usui, S Kitajima, Y Hida, A Sagara

FUSION ENGINEERING AND DESIGN　61-62　251-254　2002年11月
出版者・発行元：ELSEVIER SCIENCE SA
DOI： 10.1016/S0920-3796(02)00172-2 　

ISSN：0920-3796

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New concept of remountable first wall using liquid flow has been proposed as a different approach of liquid wall concepts like APEX (Abdou, the APEX team, Fusion Eng. Des. 54 (2001) 181). In this study, the numerical analysis of MHD flow has been carried out to evaluate effect of coating on the MHD pressure drop. In the proposed concept the liquid layer is sandwiched by two metal plates with two side ribs to compose the flow channel. The numerical results indicate that coating the whole rib surface has good performance as three surface coating to reduce the MHD pressure drop. In both cases of flibe and lithium coolants, the solid metal (HT-9) wall can be used by coating with the insulator whose electric conductivity ratio (sigma(coating)/sigma(HT-9)) is less than 10(-6) under 6 T. (C) 2002 Elsevier Science B.V. All rights reserved.
Advanced fusion reactor design using remountable HTc S.C. magnet 査読有り

H.Hashizume, S. Kitajima, S.Ito, K. Yagi, Y. Usui, Y. Hida

J. Plasma Fusion Res. SERIES　5　532-536　2002年6月
Equilibrium Calculation of Tohoku University Heliac 査読有り

K. Harada, S. Kitajima, H. Hashizume

J. Plasma Fusion Res. SERIES　5　500-504　2002年
New model for two-dimensional analysis of electromagnetic field in high TC supercondcuting tapes 査読有り

H.Hashizume, M.Suzuki, S.Toda

Internation Journal of Applied Electromagnetics and Mechanics　14　81-84　2001年12月
HEAT TRANSFER WITH PHASE CHANGE IN POROUS MEDIA EXPOSED TO HIGH HEAT LOAD 査読有り

S. Ebara, S. Toda, H. Hashizume, A. Shimizu, T. Yokomine

Proceedings of 2nd International Symposium on Advances in Computational Heat Transfer　2　985-992　2001年5月
Study on mechanical jointing of high temperature superconductors 査読有り

S.Ito, H.Hashizume, S.KItajima

JSAME Studies in Apllied Electromagnetics and Materials　9　283-284　2001年5月
New model for two-dimensional analysis of electromagnetic field in high critical temperature superconducting filament 査読有り

H Hashizume, M Suzuki, S Toda

INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS　14　(1-4)　81-84　2001年
出版者・発行元：IOS PRESS
ISSN：1383-5416

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A new two-dimensional model for electromagnetic field analysis is proposed to evaluate the current distributions in high critical temperature superconducting filament. The model is based on the results calculated by exact three-dimensional analysis. By using the new model, quench propagation is evaluated, which shows more robustness against the quench propagation.
Radial Electric Field Control with a Biased Hot Cathode in the Tohoku University Heliac 査読有り

S.Kitajima, S.Nakanishi, K.Harada, K.Sugawara, H.Hashizume

J. Plasma Fusion Res. SERIES　4　391-394　2001年
Development of NDT method using electromagnetic waves 査読有り

K Sugawara, H Hashizume, S Kitajima

APPLIED ELECTROMAGNETICS (III)　10　313-316　2001年
出版者・発行元：JAPAN SOCIETY APPLIED ELECTROMAGNETICS & MECHANICS
ISSN：1343-2869

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To detect defects dig can occur in a large structure, or large pipes, a method using electromagnetic waves can be one of the candidates. Analyses of electromagnetic waves am performed to investigate propagation of waves inside of pipes. Numerical results indicate it possible to detect the defect by using TM01 mode.
Characteristics of magnetic surface quantities in the heliac plasma 査読有り

K Harada, S Kitajima, H Hashizume

APPLIED ELECTROMAGNETICS (III)　10　428-431　2001年
出版者・発行元：JAPAN SOCIETY APPLIED ELECTROMAGNETICS & MECHANICS
ISSN：1343-2869

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Characteristics of magnetic surface quantities in Tohoku University Heliac are calculated by using VMEC code. Magnetic surface quantities are investigated both under vacuum and finite beta conditions. It is clarified that well depth becomes deeper as beta does larger in a configuration including rational surface and that the configuration having magnetic well without the plasma is more stable for high beta plasmas than that having magnetic hill.
Study on mechanical jointing of high temperature superconductors 査読有り

S Ito, H Hashizume, S Kitajima

INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS　14　(1-4)　85-88　2001年
出版者・発行元：IOS PRESS
ISSN：1383-5416

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In the present design, the superconducting magnets can not be separated into several parts of the magnet, because of problems caused by heat generation and electromagnetic force. For the future commercial fusion reactor, however, the mountable magnets are desired to make the reactor maintenance and repair easy. In this research, therefore, a study on mechanical jointing of HTc S.C. will be performed to clarify its possibility. Two methods of the jointing are employed to compare the results. In the first method a piece of S.C. tape is put on another tape where the stress between two tapes is controlled. In the second method cross sections of two S.C. tapes are directly jointed. The voltage drop is measured to estimate the resistance in those regions and the possibility of jointing is discussed.
Radial electric field control by electron injection in tohoku university heliac 査読有り

S Kitajima, S Nakanishi, H Hashizume

INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS　13　(1-4)　381-385　2001年
出版者・発行元：IOS PRESS
ISSN：1383-5416

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In this paper, we present experimental results of improvement for plasma confinement by controlling electric field with electron injection [1]. In order to generate the negative radial field, we inserted a hot cathode into the plasma and then biased negative voltage. We observed the plasma parameter changes after the hot cathode biasing: the increase of line density, the fluctuation suppression, the negative radial electric field formation, the plasma rotation, and the increase of the energy confinement time. These results suggest that the improvement of plasma confinement by the formation of negative radial electric field is achieved.
APPLICATION OF POROUS MEDIA TO HIGH HEAT FLUX REMOVAL OF PLASMA FACING COMPONETNS OF FUSION REACTOR 査読有り

S. Ebara, S. Toda, H. Hashizume

Proceedings of 2nd Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety　151-157　2000年10月
Application of porous matrix to high heat load removal system 査読有り

S Ebara, S Toda, H Hashizume

HEAT AND MASS TRANSFER　36　(4)　273-276　2000年7月
出版者・発行元：SPRINGER-VERLAG
DOI： 10.1007/s002310000088 　

ISSN：0947-7411

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In a future design of a compact fusion reactor with enhanced power density, how to remove heat from high heat flux components and to get higher temperature operating fluid for power generation will inevitably play an important role. In the present work, we propose a new cooling system, using sintered metal porous media. For the purpose of developing this cooling system, heat removal experiments were performed with varying geometrical parameters mainly this time. It is feasible for the proposed cooling system to remove heat flux up to 1.3 MW/m(2) at the present step, and there seems to be a great possibility of the enhancement of the heat removal capacity of this cooling system.
Design and development of the Flibe blanket for helical-type fusion reactor FFHR 査読有り

A. Sagara, H. Yamanishi, S. Imagawa, T. Muroga, T. Uda, T. Noda, S. Takahashi, K. Fukumoto, T. Yamamoto, H. Matsui, A. Kohyama, H. Hasizume, S. Toda, A. Shimizu, A. Suzuki, Y. Hosoya, S. Tanaka, T. Terai, Dai-Kai Sze, O. Motojima

Fusion Engineering and Design　49-50　661-666　2000年

DOI： 10.1016/S0920-3796(00)00360-4 　

ISSN：0920-3796

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Blanket design is in progress in helical-type compact reactor FFHR-2. A localized blanket concept is proposed by selecting molten-salt Flibe as a self-cooling tritium breeder from the main reason of safety: low tritium solubility, low reactivity with air and water, low pressure operation, and low MHD resistance which is compatible with the high magnetic field design in force-free helical reactor (FFHR). Numerical results are presented on nuclear analyzes using the MCNP-4B code, on thermal and stress analyzes using the ABAQUS code, and heat exchange efficiency from Flibe to He. R&amp D programs on Flibe engineering are also in progress in material dipping-tests and in construction of molten salt loop. Preliminary results in these experiments are also presented.
Vibration characteristic of heated rod induced by subcooled flow boiling 査読有り

MR Nematollahi, S Toda, H Hashizume, K Yuki

JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY　36　(7)　575-583　1999年7月
出版者・発行元：TAYLOR & FRANCIS LTD
DOI： 10.1080/18811248.1999.9726241 　

ISSN：0022-3131

eISSN：1881-1248

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A subcooled boiling loop with annular flow channel on an electrically heated rod at the channel axial center was used to make an experimental approach to investigate the vibration characteristic induced by subcooled flow boiling. The experiments were carried out to measure vibration induced in the rod under different conditions of incoming coolant subcooling temperature of 10-80 K, coolant flow rates of 0.1-0.35 x 10(-3) m(3)/s and imposed linear power densities of 17-600 W/cm. Distilled water was used as coolant in the loop. The vibration behavior of the rod was measured hy using an accelerometer. Also: a high-speed motion analyzer system was used to analyze the bubble behaviors in the, different subcooled boiling conditions. The results show the intensive SBIV (subcooled boiling-induced vibration) which highly depends on dynamic force generated by rapid growth and collapse of vapor hubbies under high heat flux loading whilst they still attach to the heating surface. These behaviors were influenced strongly by the conditions of subcooling temperature: linear power density and flow rate.
Proposal of a new superconducting wire for high field usage 査読有り

H Hashizume, S Toda

FUSION ENGINEERING AND DESIGN　41　283-290　1998年9月
出版者・発行元：ELSEVIER SCIENCE SA
ISSN：0920-3796

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A new superconducting (S.C.) wire for fusion reactors is proposed, which employs both high and low Te S.C. materials. As the low Tc S.C., NbTi, which is commonly used in S.C. magnets, is chosen as S.C. cable for transport currents, while the high Tc material works as the shielding conductor protecting the low Tc S.C. inside it from the magnetic field generated by other transport currents. Simple evaluation indicates that it is possible to shield approximately 20 T magnetic field. Numerical analysis also indicates that the effect of cracking in the high Tc S.C. on the shielding performance can be reduced by introducing multilayer high Tc S.C. materials. (C) 1998 Elsevier Science S.A. All rights reserved.
Proposal of a new superconducting wire for high field usage 査読有り

H. Hashizume, S. Toda

Fusion Engineering and Design　41　(1-4)　283-290　1998年9月1日
出版者・発行元：Elsevier BV
DOI： 10.1016/S0920-3796(98)00101-X 　

ISSN：0920-3796

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A new superconducting (S.C.) wire for fusion reactors is proposed, which employs both high and low Tc S.C. materials. As the low Tc S.C., NbTi, which is commonly used in S.C. magnets, is chosen as S.C. cable for transport currents, while the high Tc material works as the shielding conductor protecting the low Tc S.C. inside it from the magnetic field generated by other transport currents. Simple evaluation indicates that it is possible to shield approximately 20 T magnetic field. Numerical analysis also indicates that the effect of cracking in the high Tc S.C. on the shielding performance can be reduced by introducing multilayer high Tc S.C. materials. © 1998 Elsevier Science S.A. All rights reserved.
Electromagnetic thermal analysis of low/high Tc superconducting wire 査読有り

H Hashizume, S Toda

IEEE TRANSACTIONS ON MAGNETICS　34　(5)　3016-3019　1998年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
ISSN：0018-9464

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A new scheme Is proposed, which can treat electromagnetic field of the type-II superconductor under transient temperature field. In the analysis, one of the critical state models, the Bean model was employed to determine the current distribution in the superconductors and effect of magnetic flux flow was also taken into account. We chose both low and high Tc superconducting materials. Numerical results indicate that the flux flow strongly affects the stability against the quench in both materials.
Interfilament coupling loss for protection of superconducting multicoil magnets 査読有り

K Takeuchi, YK Kang, H Hashizume, Y Iwasa

CRYOGENICS　38　(4)　367-376　1998年4月
出版者・発行元：ELSEVIER SCI LTD
DOI： 10.1016/S0011-2275(98)00003-4 　

ISSN：0011-2275

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We present experimental and analytical results of quenching for three-coil systems wound with multifilamentary Nb-Ti composites, demonstrating that AC loss, due mostly to interfilament coupling in the composite during quenching, promotes normal-zone propagation (NZP). The experiment used two three-coil systems, each comprised of inner, middle, and outer coils connected in series and shunted with resistors. Both systems shared the same outer and middle coils. Two versions of the inner coil were used, both versions wound with composites that were otherwise identical except for twist pitch lengths. One composite's twist pitch length was chosen sufficiently short to make the interfilament coupling loss to be negligible during quenching, while the other composite's twist pitch length was chosen sufficiently long to make the loss significant. Our model for quenching analysis includes the coupling loss and has been used to simulate the experiment. Agreement between experiment and simulation is excellent. The computed temperature distributions during quenching show a clear effect of heating by coupling loss in the inner coil wound with a composite having a long twist pitch length and virtually no effect of heating in the inner coil wound with a composite having a short twist pitch length. The difference in quenching behaviors between the two systems, different only in twist pitch length in the composites for the inner coils, is so compelling that we conclude that interfilament coupling loss is the key to this difference, We may further conclude that coupling loss may be used to benefit protection of multicoil systems. The twist pitch length that controls this coupling loss is thus a key design parameter; it is best determined through simulation. (C) 1998 Elsevier Science Ltd. All rights reserved.
Molecular dynamics study of heat and mass transfer for disruption erosion 査読有り

H Nakadate, S Toda, H Hashizume

HEAT TRANSFER 1998, VOL 4　4　271-275　1998年
出版者・発行元：TAYLOR & FRANCIS LTD

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In order to decide the life time of the divertor plate, it is necessary to estimate the erosion loss during a plasma disruption. However, in order to realistically simulate the effects of a plasma disruption on the plasma facing components, several physical processes should be taken into account. The molecular dynamics method is one of the effective numerical methods of analyzing non-equilibrium phase change problems. In this study, a numerical method based on molecular dynamics has been investigated with divided time interval, in order to simulate a system which contains a few atoms of high energy in most of slow atoms. Non-equilibrium evaporation processes are simulated by this method. Velocity distributions of evaporating atoms are analyzed.
Fundamental study on high heat flux removal system using evaporated fluid in metal porous media 査読有り

S Toda, S Ebara, H Hashizume

HEAT TRANSFER 1998, VOL 4　4　503-508　1998年
出版者・発行元：TAYLOR & FRANCIS LTD

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In a future design of a compact fusion reactor with enhanced power density, how to remove of heat from high heat flux components and to get higher temperature operating fluid for power generation will inevitably play an important role. In the present work, we propose a new cooling system using sintered metal porous media. In the porous media subjected to high heat load, however, such complex thermohydraulic phenomena as not easily predicted by the previous macroscopic analysis can be expected to occur. Therefore, the purpose of the present work is to investigate numerically and experimentally the basic characteristics of heat and mass transfer in the proposed porous system under high heat load.
Unsteady heat transfer of steam flow with condensation in porous media 査読有り

S Toda, WS Hsu, H Hashizume, T Kawaguchi

HEAT TRANSFER 1998, VOL 6　6　463-468　1998年
出版者・発行元：TAYLOR & FRANCIS LTD

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A fundamental study is performed experimentally and theoretically to evaluate the transient heat transfer fbr a steam flow injected into a porous medium with condensation and re-evaporation. A porous plane board made of calcium silicate was used. Transient changes of the temperature distributions on the surface of porous board are measured by the infrared ray therm,graph. The board temperature at the opposite surface of the steam impinging point increases with increasing the steam pressure, however, no obvious influences is not bund by changing the nozzle diameter. A three dimensional numerical analysis is performed: Momentum equation for steam based on Darcy's model is employed. By introducing an enthalpy transforming scheme, energy equation is converted into a non-linear equation with the enthalpy being single dependent variable. The three dimensional model to treat the diffusion of condensed water affecting porous material properties is newly developed to estimate the saturation of condensed water. The SIMPLE algorithm is used. Both experimental and numerical results show good agreement in terms of temperature transients induced by steam flow with phase change in the porous media.
ONCEPT OF HIGH HEAT REMOVAL DEVICE USING EVAPORATION IN POROUS MEDIA 査読有り

S. Toda, S. Ebara, H. Hashizume

Proceedings of 2nd Japanese-German Symposium on Multi-Phase Flow　133-144　1997年9月
Experimental Research of Water Ingress Event into a Vacuum Vessel of a Nuclear Fusion Reactor 査読有り

A.Jinzu, H.Hayakawa, H.Hashizume, S.Toda

Eighth International Topical Meeting on Nuclear Reactor Thermal-Hydraulics　3　1328-1331　1997年9月
A New Approach of Molecular Dynamics Method with a Divided Time Interval 査読有り

S.Toda, H.Nakadate, H.Hashizume

Proceedings of the Tenth International Conference for Numerical Methods in Thermal Problems　283-289　1997年6月
Molecular dynamics simulation on vapor shielding under high heat load 査読有り

S.Toda, H.Nakadate, H.Hashizume

International Symposium on Advances in Comutaional Heat Transfer　1　119-123　1997年5月
Molecular dynamics study on surface melting and evaporation under high enryg particle flex 査読有り

H.Nakadate, S.Toda, H.Hashizume

International Symposium on Advances in Comuational Heat Transfer　1　487-491　1997年5月
Gas Entrainment Induced by Vortex behaind an Obstacle 査読有り

T.Kumazawa, S.Ebara, H.Hashizume, S.Toda

Eighth International Topical Meeting on Nuclear Reactor Thermal-Hydraulics　3　1742-1746　1997年4月
Fundamental Study on Thermal Hydraulics across the Two-phase Interface with Melting and Gas Releasing in MCCI

Yukihiro Katsumura, Saburo Toda, Hidetoshi Hashizume

Proceedings of JAPAN-U.S. Seminar on Two-Phase Flow Dynamics　15-20　1996年7月
自由界面を伴う流体と溶融する固体面の熱伝達数値解析

勝村幸博, 橋爪秀利, 戸田三朗

第３３回日本伝熱シンポジウム講演論文集　2　697-698　1996年5月
Numerical analysis of fluid flow with free surface and phase change under electromagnetic force 査読有り

Y Katsumura, H Hashizume, S Toda

IEEE TRANSACTIONS ON MAGNETICS　32　(3)　1002-1005　1996年5月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.497409 　

ISSN：0018-9464

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In this study, fluid flow of liquid metal with free surface and melting of metal under electromagnetic force was investigated numerically. The computational code was developed by the authors based upon a finite difference method to simulate the free surface how and the eddy current simultaneously. The VOF method was introduced to treat the free surface, and magnetic vector potential was used for eddy current analysis. The free surface shape predicted by the code agreed with that obtained experimentally. Furthermore, the code was improved to calculate the phase change (melting) of solid metal by Joule heating due to eddy current. Numerical results of melting of metal were also demonstrated.
Numerical evaluation of electromagnetic force induced in high T-c superconductor with grain boundary 査読有り

H Hashizume, S Toda, K Maeda

IEEE TRANSACTIONS ON MAGNETICS　32　(3)　1148-1151　1996年5月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.497446 　

ISSN：0018-9464

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This paper describes a new method to calculate electromagnetic force acting between high T-c superconducting material and permanent magnet, where the effect of grain boundary in the high T-c superconductor is taken into account. The results show that hysteresis of the electromagnetic force is strongly affected by existence of the grain boundary.
Three dimensional evaluation of the current distribution in twisted superconductors 査読有り

H Hashizume, S Toda

IEEE TRANSACTIONS ON MAGNETICS　32　(3)　1152-1155　1996年5月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.497447 　

ISSN：0018-9464

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A new method to calculate three dimensional current distributions in twisted superconductors is proposed in this paper by Introducing the twisted coordinates together with periodic boundary conditions. Numerical analysis is performed based on the critical state model, by which the current distributions in type-ii superconductors can be calculated. Numerical results indicate that the longitudinal currents are induced in the normal conductor region when the relatively large longitudinal magnetic flux is applied.
UV resonant Raman spectra of nitrobenzene adsorbed on Ni(111)

Sakamoto, K., Hashizume, H., Nagafusa, M., Sato, H., Ushioda, S.

Surface Science　368　(1-3)　1996年

DOI： 10.1016/S0039-6028(96)01064-3 　

ISSN：0039-6028
Influence of obstructions on the initiation of subcooled boiling in an annular channel 査読有り

S Toda, H Hashizume, Y Fujiwara, J Ogawa, M Mori

CONVECTIVE FLOW BOILING　79-84　1996年
出版者・発行元：TAYLOR & FRANCIS LTD
Numerical Simulation of Fluxoid Dynamics by Molecular Dynamics Method 査読有り

H. Hashizume, S. Toda, T. Kurusu, K. Maeda

JSAEM Stuedies in Applied Electromagnetics　4　96-102　1996年
MHD Behavior of Liquid Metal under Transient Magnetic Fields 査読有り

H. Hashizume, S. Toda, K. Mano

JSAEM Studies in Applied Electromagnetics　4　103-110　1996年
自由界面と相変化を伴う流体の熱流動解析

勝村幸博, 橋爪秀利, 戸田三朗

第３２回日本伝熱シンポジウム講演論文集　2　409-410　1995年5月
Fundamental Study on Heat Transfer across the Interface with Melting and Gas Releasing in Molten Core/Concrete Interaction 査読有り

Yukihiro Katsumura, Saburo Toda, Hidetoshi Hashizume

Proceedings of the ASME/JSME Thermal Engineering Joint Conference 1995　4　483-490　1995年3月
Influence of Current Distribution on Quench Process in Non-insulated AC Multi-strand Superconducting Cables

Tsuda, M., Okazaki, K., Hashizume, H., Ishiyama, A.

IEEE Transactions on Applied Superconductivity　5　(2)　1995年

DOI： 10.1109/77.402621 　

ISSN：1558-2515 1051-8223
Numerical evaluation of ac losses in superconductor by introducing twisted coordinates 査読有り

H HASHIZUME, S TODA

ADVANCED COMPUTATIONAL AND DESIGN TECHNIQUES IN APPLIED ELECTROMAGNETIC SYSTEMS　6　375-378　1995年
出版者・発行元：ELSEVIER SCIENCE PUBL B V
電磁場による流れ場の数値解析

勝村幸博, 橋爪秀利, 戸田三朗

日本機械学会熱工学講演会論文集,1994/11/24-25,仙台　137-139　1994年11月
QUASI 3-DIMENSIONAL ANALYSIS OF AC LOSSES IN SUPERCONDUCTOR 査読有り

H HASHIZUME, S TODA

IEEE TRANSACTIONS ON MAGNETICS　30　(5)　3088-3091　1994年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.312590 　

ISSN：0018-9464

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By introducing twisted coordinates, a quasi three-dimensional formulation is performed to evaluate A.C. losses such as hysteresis and coupling losses in type-II superconductors when both transport currents and magnetic field parallel to the currents exist. The numerical results indicate that the hysteresis loss induced in the superconductors increases when the transport current exists, while the coupling loss is not affected by its existence.
流れ場と電磁場の連成問題の数値解析

勝村幸博, 橋爪秀利, 戸田三朗

第６回電磁力関連のダイナミックスシンポジウム講演論文集　173-176　1994年7月
移動境界(自由表面・相変化)を伴う流体の熱流動解析査読有り

勝村幸博, 橋爪秀利, 戸田三朗

日本機械学会論文集Ｂ編　60　(573)　1612-1618　1994年5月
出版者・発行元：The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.60.1612 　

ISSN：0387-5016

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In this study, the process of solidification of fluid with free surface in contact with a solid wall was investigated numerically and experimentally, where temperature of the solid wall was lower than the freezing point of the fluid. In the experiment, we selected a single liquid metal droplet as fluid, and freezing process and transformation of the droplet were observed using a high speed camera. Furthermore, the computer code, which was developed by the authors based on a finite difference method, was employed to analyze the phase change and free surface problems. The numerical results of the transformation of the droplet agreed well with the experimental ones. The analyses showed the intermittent growth of liquid film and the piling steps of solidified layer.
Improvement of numerical scheme to calculate electromagnetic fields in type-II superconductors (quasi 3-D analysis) 査読有り

H. Hashizume, S. Toda

Elsevier Studies in Applied Electromagnetics in Materials　5　293-296　1994年
TRANSIENT THERMAL ELECTROMAGNETIC BEHAVIORS IN TYPE-II SUPERCONDUCTORS DURING QUENCHING 査読有り

H HASHIZUME, T KURUSU, S TODA

HEAT TRANSFER 1994 - PROCEEDINGS OF THE TENTH INTERNATIONAL HEAT TRANSFER CONFERENCE, VOL 3　3　(135)　191-196　1994年
出版者・発行元：INST CHEMICAL ENGINEERS
3-DIMENSIONAL NATURAL CONVECTION HEAT TRANSFER INSIDE A VERTICAL CYLINDER CONTAINING ECCENTRICALLY DISTRIBUTED INTERNAL HEAT SOURCE 査読有り

S TODA, K TAKEUCHI, N NAITOH, H HASHIZUME

HEAT TRANSFER 1994 - PROCEEDINGS OF THE TENTH INTERNATIONAL HEAT TRANSFER CONFERENCE, VOL 3　3　(135)　251-256　1994年
出版者・発行元：INST CHEMICAL ENGINEERS
HEAT-TRANSFER BETWEEN FLUID WITH FREE-SURFACE AND MELTED SOLID WALL 査読有り

S TODA, Y KATSUMURA, H HASHIZUME, M OKUYAMA

NUCLEAR ENGINEERING AND DESIGN　141　(1-2)　47-58　1993年6月
出版者・発行元：ELSEVIER SCIENCE SA LAUSANNE
ISSN：0029-5493

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The heat transfer between a fluid with a free surface and a melted solid wall was investigated basically. Numerical analyses were made by a computational code developed in this study to simulate the phase change and the free boundary problems and to clarify the hydrodynamic behavior of the moving free surface of a droplet impinged upon an ice wall and the heat transfer between them. In order to verify the validity of the code, experiments were performed using water and liquid metal droplets, and ice. Comparisons between numerical analyses and experiments showed a good agreement.
単一液滴の凝固

勝村幸博, 橋爪秀利, 戸田三朗

第３０回日本伝熱シンポジウム講演論文集　3　856-858　1993年5月
溶融炉心/コンクリ-トの熱伝達模擬実験

勝村幸博, 川口孝弘, 橋爪秀利, 戸田三朗

第３０回日本伝熱シンポジウム講演論文集　3　862-864　1993年5月
COUPLED THERMO-ELECTROMAGNETIC ANALYSIS OF TYPE-II SUPERCONDUCTORS 査読有り

T KURUSU, H HASHIZUME, S TODA

IEEE TRANSACTIONS ON MAGNETICS　29　(2)　1550-1553　1993年3月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.250699 　

ISSN：0018-9464

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Using a newly developed computational code, a coupled thermo-electromagnetic analysis of type-II superconductor is performed to evaluate distributions of transport current and temperature in the conductor. Spread of current quenching due to artificial thermal spike and recovery from it are simulated by the code. The numerical results show hysteresis in the current distribution in the superconductor as a consequence of the thermal disturbance.
Study of thermal fluid leaking between piping and insulator : Basic experiment by air 査読有り

S. Toda, W. Hsu, H. Hashizume, Y. Hori

Proceedings of the 2nd. ASME/JSME Nuclear Engineering　131-134　1993年
超電導体における３次元電流分布の解析

橋爪秀利, 戸田三朗

電気学会研究界資料（回転機静止器合同研究会）　RM-93　(57)　9-18　1993年
自由界面をもつ流体と固体面の溶融を伴う熱伝達

戸田三朗, 勝村幸博, 橋爪秀利

第２９回日本伝熱シンポジウム講演論文集　775-776　1992年5月
Numerical analysis of current distribution in type-II superconductors based on T-method 査読有り

H. Hashizume, T. Kurusu, S. Toda

Int. J. Appl. Electromagnetics Mater.　3　(3)　205-213　1992年4月
THERMAL AND STRESS-ANALYSIS OF THE 1ST WALL WITH ASYMMETRICALLY HEATED NONCIRCULAR COOLANT CHANNELS 査読有り

T TAKEDA, M SEKI, H KAWAMURA, H HASHIZUME, K MIYA

FUSION ENGINEERING AND DESIGN　15　(3)　245-253　1992年3月
出版者・発行元：ELSEVIER SCIENCE SA LAUSANNE
DOI： 10.1016/0920-3796(92)90043-4 　

ISSN：0920-3796

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Temperature and thermal stress distributions for a first wall with non-circular coolant channels are calculated without using an empirical heat transfer coefficient. The energy coolant and heat conduction equation are solved simultaneously. The flow is assumed to be laminar; an approximate extension is made to the turbulent flow. The results indicate that the circumferential non-uniformity of the heat transfer coefficient causes thermal stresses that are higher than those predicted by an empirically determined average heat transfer coefficient. The effects of wall thickness and the shape of the coolant channel are discussed.
NUMERICAL-ANALYSIS OF ELECTROMAGNETIC PHENOMENA IN SUPERCONDUCTORS 査読有り

H HASHIZUME, T SUGIURA, K MIYA, S TODA

IEEE TRANSACTIONS ON MAGNETICS　28　(2)　1332-1335　1992年3月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.123937 　

ISSN：0018-9464

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Governing equations to describe electromagnetic phenomena in superconductors were derived by using Helmholtz theorem. The Meissner effect, which is common to type-I and type-II superconductors, is treated by introducing the magnetization vector 'M'. The current flow due to flux invasion into the superconductor, which is a particular phenomenon in the type-II superconductor, is evaluated using current vector potential 'T' together with constitutive equations expressing critical state models. Numerical results based on a two dimensional FEM code, showed excellent agreement with analytical solutions.
NUMERICAL AND EXPERIMENTAL-ANALYSIS OF EDDY-CURRENT TESTING FOR A TUBE WITH CRACKS 査読有り

H HASHIZUME, Y YAMADA, K MIYA, S TODA, K MORIMOTO, Y ARAKI, K SATAKE, N SHIMIZU

IEEE TRANSACTIONS ON MAGNETICS　28　(2)　1469-1472　1992年3月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.123973 　

ISSN：0018-9464

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A new method to calculate impedance signal in Eddy Current Testing(ECT) for a tube with surface cracks is developed using the two dimensional T-method (current vector potential method). Three dimensional current flow around a surface crack is approximated by introducing quasi conductivity in the crack region. Further a final matrix relating the current vector potentials on the crack surface with neighboring potentials is obtained by decreasing the width of the crack to zero and then the elements in the crack region are not necessary any longer. The numerical results show good agreement with the experimental ones, which indicates the validity of the method proposed here and the possibility to design more efficient probe of the ECT using the code.
Numerical simulation of molten flow with free surface under A.C. magnetic field 査読有り

Y. Yoshida, H. Hashizume, K. Miya, T. Nasada

Elsevier Studies in Applied Electromagnetics in Materials　1　59-62　1992年
Numerical and Experimental Analysis of Eddy Current Testing based on T-method 査読有り

Y. Yamada, H. Hashizume, K. Miya, K. Morimoto, K. Satake, N. Shimizu

Elsevier Studies in Applied Electromagnetics in Materials　1　219-222　1992年
超電導体における電磁場・熱場解析(I)-電磁場の解析について-

橋爪秀利, 来栖努, 戸田三朗

電気学会研究会資料（回転機静止器合同研究会）　RM-92　(117)　75-84　1992年
超電導体における電磁場・熱場解析(II)-電磁場と熱場の連成問題-

来栖努, 橋爪秀利, 戸田三朗

電気学会研究界資料（回転機静止器合同研究会）　RM-92　(118)　85-93　1992年
DEVELOPMENT OF PLASMA FACING COMPONENTS AT JAERI 査読有り

M AKIBA, H TAKATSU, T KURODA, H HASHIZUME, M ARAKI, M DAIRAKU, H ISE, S SUZUKI, S TANAKA, K YOKOYAMA, M SEKI

FUSION ENGINEERING AND DESIGN　18　99-104　1991年12月
出版者・発行元：ELSEVIER SCIENCE SA LAUSANNE
DOI： 10.1016/0920-3796(91)90114-6 　

ISSN：0920-3796

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The development and design of the divertor plate in JAERI are presented. Small divertor models are fabricated and tested in an electron beam heating facility in the JAERI. Typical heat load is 10 MW/m2. The divertor models consist of CFC or isotropic graphite/Cu bonded structures. A twisted tape is inserted to enhance heat transfer. It is shown after 1000 thermal cycle tests that CFC-Cu bonded structures can endure against a stationary heat load of 10 MW/m2. A prediction technique, which consists of three analytical steps, is developed to estimate deformation of the divertor plate and stress in the cooling tube. A maximum stress of 350 MPa is obtained for the CFC-Cu divertor plate. Displacement of the divertor plate reduces to +/- 2 mm with supporting structures.
NUMERICAL AND EXPERIMENTAL EDDY-CURRENT ANALYSES OF COMPLEX 1ST WALL COMPONENTS OF A FUSION-REACTOR 査読有り

M TSUCHIMOTO, M FUKAYA, M HASHIMOTO, H HASHIZUME, K MIYA, M SEKI

FUSION ENGINEERING AND DESIGN　16　369-375　1991年12月
出版者・発行元：ELSEVIER SCIENCE SA LAUSANNE
DOI： 10.1016/0920-3796(91)90212-9 　

ISSN：0920-3796

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The eddy current induced in first wall components of a fusion reactor is investigated numerically and experimentally to clarify effects of electromagnetic force on structures branched and with a hole. The eddy current is analyzed by using the current vector potential method (T-method) with an application of finite element method. Partial torus modules of the first wall scaled about 1/20 are made of stainless steel for measurements of the eddy current. The plasma current as a source of the eddy current is simulated by a pulse current from a 16 times turned circular coil. The discharging peak current is 246 kA turns with a period of 1.4 ms and the eddy current is measured with the differential pick-up coil method. Fairly good agreement of numerical and experimental analyses results in validations of both the computational code and the measurement methods. The Lorentz force of the first wall module is also analyzed by the code for an evaluation of the transient electromagnetic force.
NUMERICAL-ANALYSIS OF AC LOSSES IN SUPERCONDUCTORS 査読有り

H HASHIZUME, T SUGIURA, K MIYA, Y ANDO, S AKITA, S TORII, Y KUBOTA, T OGASAWARA

CRYOGENICS　31　(7)　601-606　1991年7月
出版者・発行元：BUTTERWORTH-HEINEMANN LTD
DOI： 10.1016/0011-2275(91)90057-4 　

ISSN：0011-2275

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A two-dimensional computational code to evaluate a.c. losses in superconductors has been developed using the current vector potential method (T-method), where the vector potential T is defined by del x T = J. The current distributions in both superconductors and normal conductors are calculated while changing the conductivity of the superconductor so that the current density never exceeds the critical current density. The hysteresis and coupling losses evaluated by the numerical code agree with analytical solutions, as far as these are available. In order to verify the validity of the code, an experiment to measure the hysteresis and coupling losses was carried out using Nb - Ti/Cu filaments. The total loss evaluated from the numerical code agrees with that from the experiment. The numerical analysis, however, indicates that the hysteresis loss under quasi-steady magnetic field is less than the loss in the superconductor under transient field.
Numerical electromagnetic field analysis of Type-II superconductors 査読有り

Sugiura, T., Hashizume, H., Miya, K.

International journal of applied electromagnetics in materials　2　(3)　183-196　1991年

ISSN：0925-2096
EXPERIMENTS AND NUMERICAL-ANALYSIS OF EDDY CURRENTS IN THE 1ST WALL OF A FUSION-REACTOR 査読有り

M HASHIMOTO, H HASHIZUME, T SUGIURA, T TAKAGI, K MIYA, M SEKI

IEEE TRANSACTIONS ON MAGNETICS　26　(2)　869-872　1990年3月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.106455 　

ISSN：0018-9464
MECHANICAL AND THERMAL-BEHAVIOR OF MULTILAYER PLATES SIMULATING SUPERCONDUCTING LAMINATED STRUCTURE 査読有り

T TAKAGI, Y HAMAOKA, H HASHIZUME, K MIYA, J TANI

MECHANICAL MODELLINGS OF NEW ELECTROMAGNETIC MATERIALS　27-34　1990年
出版者・発行元：ELSEVIER SCIENCE PUBL B V
電磁界解析における積分方程式について

橋爪秀利, 宮健三

電気学会研究会資料（回転機静止器合同研究会）　RM-90　(29)　31-40　1990年
T法に基づいた薄板強磁性体の渦電流解析

槌本昌則, 橋爪秀利, 宮健三

電気学会研究会資料（回転機静止器合同研究会）　RM-90　(47)　107-112　1990年
PROBABILISTIC LIFETIME EVALUATION OF THE FUSION 1ST WALL 査読有り

H OOMURA, T TAKAGI, H HASHIZUME, K MIYA

FUSION ENGINEERING AND DESIGN　9　75-80　1989年5月
出版者・発行元：ELSEVIER SCIENCE SA LAUSANNE
DOI： 10.1016/S0920-3796(89)80013-4 　

ISSN：0920-3796
MAGNETOTHERMOHYDRAULIC BEHAVIOR OF THE MOLTEN LAYER OF A 1ST WALL DUE TO PLASMA DISRUPTION 査読有り

H HASHIZUME, Y YOSHIDA, K MIYA, K IOKI

FUSION ENGINEERING AND DESIGN　9　219-224　1989年5月
出版者・発行元：ELSEVIER SCIENCE SA LAUSANNE
DOI： 10.1016/S0920-3796(89)80037-7 　

ISSN：0920-3796
A conceptual design study of a reversed field pinch fusion reactor

Kondo, S., Tanaka, S., Terai, T., Hashizume, H., Madarame, H., Iwata, S., Shimotohno, H., Iguchi, T., Kamada, H., Suzuki, S.

Fusion Engineering and Design　9　(C)　1989年

DOI： 10.1016/S0920-3796(89)80057-2 　

ISSN：0920-3796
Probabilistic lifetime evaluation of the fusion first wall 査読有り

H. Oomura, T. Takagi, H. Hashizume, K. Miya

Fusion Engineering and Design　9　(C)　69-74　1989年

DOI： 10.1016/S0920-3796(89)80012-2 　

ISSN：0920-3796

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This paper describes a numerical analysis used to evaluate the lifetime of a first wall of a fusion reactor based on a probabilistic approach. Very high heat flux is deposited on the first wall during a major plasma disruption. Melting, evaporation, and resolidification of the material result in metallurgical and mechanical deterioration with high residual stresses and small cracks. It is very important to investigate the severity of the consequences and to evaluate the lifetime of the wall. In this paper, the occurrence of plasma disruptions and the length of resulting cracks are determined by random numbers. More than 400 histories are analyzed to determine the probabilistic distribution of crack length. The prediction of the lifetime of the wall is also presented. © 1989 Elsevier Science Publishers B.V.
Mechanical Design of a Solid Breeder Blanket Canister for ITER. 査読有り

H. Hashizume, A.Y. Ying, A.R. Raffray, M.A. Abdou

Transactions of the 10th International Conference on Structural Mechanics in Reactor Technology, August 14-18, 1989, Anaheim.　N　1-6　1989年
Structural Characteristics and the Influence of Mechanical Disturbance in Superconducting Toroidal Coils. 査読有り

Y. Kannoto, H. Hashizume, M. Minami, K. Hayakawa, T. Takagi, K. Miya

11th International Conference on Magnet Technology (MT-11), August 28-September 1, 1989, Tsukuba.　1　680-685　1989年
ELECTROMAGNETO-THERMOMECHANICAL BEHAVIOR OF THE 1ST WALL 査読有り

H HASHIZUME, K MIYA

FUSION ENGINEERING AND DESIGN　7　(3-4)　293-321　1989年1月
出版者・発行元：ELSEVIER SCIENCE SA LAUSANNE
ISSN：0920-3796
2-STEP PURELY THERMAL ION-EXCHANGE TECHNIQUE FOR SINGLE-MODE WAVE-GUIDE DEVICES IN GLASS 査読有り

M SEKI, H HASHIZUME, R SUGAWARA

ELECTRONICS LETTERS　24　(20)　1258-1259　1988年9月
出版者・発行元：IEE-INST ELEC ENG
ISSN：0013-5194
STUDY ON THE PREDICTION OF QUENCH OCCURRENCE IN SUPERCONDUCTING COILS 査読有り

K MIYA, H YANAGI, H HASHIZUME, Y HAMAOKA

IEEE TRANSACTIONS ON MAGNETICS　24　(2)　1548-1551　1988年3月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.11541 　

ISSN：0018-9464
A conceptual design of RFP fusion power core - REPUTER-I

Madarame, H., Terai, T., Iguchi, T., Kamada, Y., Shimotohno, H., Tanaka, S., Hashizume, H., Sugiura, T., Miya, K., Kondo, S., Suzuki, N.

Fusion Engineering and Design　7　(C)　1988年

DOI： 10.1016/S0920-3796(88)80028-0 　

ISSN：0920-3796
High heat load experiments for first wall materials

Yanagi, H., Sukegawa, T., Kobayashi, K., Madarame, H., Hashizume, H., Miya, K.

Journal of Nuclear Materials　155-157　(PART 1)　1988年

DOI： 10.1016/0022-3115(88)90279-6 　

ISSN：0022-3115
APPLICATION OF T-METHOD TO AC PROBLEM BASED ON BOUNDARY ELEMENT METHOD 査読有り

K MIYA, H HASHIZUME

IEEE TRANSACTIONS ON MAGNETICS　24　(1)　134-137　1988年1月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.43874 　

ISSN：0018-9464
THERMOMECHANICAL BEHAVIOR OF THE 1ST WALL SUBJECTED TO PLASMA DISRUPTION 査読有り

H HASHIZUME, K MIYA, M SEKI, K IOKI

FUSION ENGINEERING AND DESIGN　5　(2)　141-154　1987年7月
出版者・発行元：ELSEVIER SCIENCE SA LAUSANNE
ISSN：0920-3796
THERMOMECHANICAL BEHAVIOR OF THE FUSION 1ST WALL SUBJECTED TO PLASMA DISRUPTION - PREFACE 査読有り

M AKIYAMA, K MIYA

FUSION ENGINEERING AND DESIGN　5　(2)　R1-R1　1987年7月
出版者・発行元：ELSEVIER SCIENCE SA LAUSANNE
ISSN：0920-3796
Three Dimensional Analysis of an Eddy Current by the T-Method. 査読有り

K. Miya, T. Sugiura, H. Hashizume

Electromagnetomechanical Interactions in Deformable Solids and Structures　183-189　1987年
Themomechanical Analysis of a Duplex Plate Subjected to a Plasma Major Disruption. 査読有り

M. Akiyama, K. Miya, H. Hashizume, K. Ioki

Transactions of the 9th International Conference on Structural Mechanics in Reactor Technology, August 17-21, 1987, Lausanne.　N　81-86　1987年
三次元渦電流解析手法T法の高速化と高精度化

宮田浩一, 杉浦壽彦, 橋爪秀利, 宮健三

電気学会研究会資料（回転機静止器合同研究会）　RM-87　(76)　37-46　1987年
三次元渦電流解析手法T法の理論的背景について

宮健三, 橋爪秀利, 杉浦壽彦

電気学会研究会資料（回転機静止器合同研究会）　RM-87　(77)　47-56　1987年
境界要素法を用いたT法による渦電流解析

橋爪秀利, 宮健三

電気学会研究会資料（回転機静止器合同研究会）　RM-87　(78)　57-66　1987年
渦電流探傷法の解析と応用

橋本光男, 宮田浩一, 杉浦壽彦, 橋爪秀利, 宮健三

電気学会研究会資料（回転機静止器合同研究会）　RM-87　(67)　67-76　1987年
超電導マグネットにおける機械的擾乱による熱発生の定量化

浜岡豊, 橋爪秀利, 染谷和良, 高木敏行, 宮健三

電気学会研究会資料（回転機静止器合同研究会）　RM-87　(71)　159-168　1987年
Theoretical and Experimental Study on Magnetically Guided Liquid Metal Flow in a Inertial Fusion Reactor. 査読有り

T. Iizuka, M. Miya, H. Hashizume, K. Someya

4th International Conference on Emerging Nuclear Energy Systems, June 30-July 4, 1986, Madrid.　377-380　1986年
Thermal and Stress Analysis of a Fusion Reactor First Wall with Non-Circular Coolant Channels. 査読有り

M. Seki, T. Takeda, H. Kawamura, H. Hashizume, K. Miya

Proceedings of International conference on Computational Mechanics, May 25-29, 1986, Tokyo.　2　VIII・97-102　1986年
３次元渦電流解析とゲ-ジについて

橋爪秀利, 杉浦壽彦, 宮健三

電気学会研究会資料（回転機静止器合同研究会）　RM-86-41　1-10　1986年
マイクロコンピュ-タを利用した高温クリ-プ条件下におけるC*一定制御実験査読有り

矢川元基, 橋爪秀利, 福田俊彦, 黒沢正蔵

日本機械学会論文集Ａ編　51　(461)　254-257　1985年1月
出版者・発行元：一般社団法人日本機械学会
DOI： 10.1299/kikaia.51.254 　

ISSN：0387-5008

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The C* (modified J-integral) control creep experiment' system was developed using micro-computer. The system was applied to the C*-constant control creep test of type 304 stainless steel CT specimen at 550°C. The test result showd that the C* was successfully controlled in elevated temperature test with the developed system and the crack growth rate was almost constant under the secondary creep region and C* constant condition.

︎全件表示 ︎最初の5件までを表示

MISC 63

次世代核融合装置への適用をめざした大電流高温超伝導導体の開発

柳長門, 小野寺優太, 成嶋吉朗, 寺崎義朗, 平野直樹, 濱口真司, 力石浩孝, 高田卓, 宮澤順一, 伊藤悟, 筑本知子, 川越明史, 田村仁, 橋爪秀利, 高畑一也

プラズマ・核融合学会年会(Web)　38th　2021年
次世代ヘリカル装置の高温超伝導マグネットの工学設計

柳長門, 柳長門, 後藤拓也, 後藤拓也, 三戸利行, 宮澤順一, 宮澤順一, 寺崎義朗, 小野寺優太, 平野直樹, 成嶋吉朗, 成嶋吉朗, 松永信之介, 田村仁, 田村仁, 濱口真司, 高畑一也, 高畑一也, 伊藤悟, 橋爪秀利

プラズマ・核融合学会年会(Web)　37th　2020年
次世代ヘリカル型核融合実験装置への適用をめざした20kA級HTS STARS導体開発の進展

柳長門, 寺崎義朗, 平野直樹, 尾花哲浩, 松永信之介, 三戸利行, 田村仁, 濱口真司, 小野寺優太, 宮澤順一, 成嶋吉朗, 高畑一也, 伊藤悟, 橋爪秀利

低温工学・超電導学会講演概要集　100th　2020年

ISSN：0919-5998
次期ヘリカル型核融合実験装置への適用をめざした20kA級HTS STARS導体の開発

柳長門, 寺崎義朗, 伊藤悟, 松永信之介, 三戸利行, 田村仁, 濱口真司, 小野寺優太, 高畑一也, 橋爪秀利

低温工学・超電導学会講演概要集　98th　2019年

ISSN：0919-5998
ヘリカル型核融合炉FFHRマグネットのHTS設計・開発とLHD次期計画への展開

柳長門, 寺崎義朗, 伊藤悟, 三戸利行, 田村仁, 濱口真司, 小野寺優太, 高畑一也, 橋爪秀利

低温工学・超電導学会講演概要集　97th　2018年

ISSN：0919-5998
放射性廃棄物の核変換処理を目的とした核融合炉溶融塩ブランケット成立性検討(2)分子動力学法を用いたFlinabeの熱物性評価

宍戸博紀, 古館佑樹, 遊佐訓孝, 橋爪秀利, 石井良樹, 大鳥範和

日本原子力学会春の年会予稿集(CD-ROM)　2016　ROMBUNNO.1J13　2016年3月16日
伝熱・MHD特性研究の現状 (小特集液体だけど水じゃない : 次世代ブランケット・ダイバータ研究開発の現状と課題)

横峯健彦, 橋爪秀利

プラズマ・核融合学会誌　92　(2)　125-129　2016年2月
出版者・発行元：プラズマ・核融合学会
ISSN：0918-7928

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液体金属・溶融塩を核融合炉内で使用する場合,磁場の影響は避けられない.この章では,液体金属・溶融塩の基本的な伝熱特性を踏まえつつ,これまでに日米科学協力事業などを通じて明らかになった伝熱流動に関する様々な電磁相互作用を概説する.さらに,流路のMHD圧力損失低減法についても解説する.
F224 液体窒素を用いた除熱システムにおける熱伝達率の金属多孔質体粒径依存性の評価(OS9 熱・流動(5))

佐々木駿介, 伊藤悟, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2015　(20)　383-384　2015年6月7日
出版者・発行元：一般社団法人日本機械学会

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Cryogenic cooling system using a bronze-particle-sintered porous medium has been studied for a remountable high-temperature superconducting magnet. This study evaluates boiling curve of subcooled liquid nitrogen as flowing in a bronze porous medium as a function of the particle diameter of the medium. We obtained Departure from Nuclear Boiling (DNB) point from the boiling curve and discussed growth of nitrogen vapor bubble inferred from measured pressure drop. The pressure drop decreased significantly at wall superheat before reaching the DNB point whereas that slightly decreased after reaching the DNB point compared to the smallest wall superheat. This result could consider DNB rises with an increase in the particle diameter because larger particle makes vapor to move easily from the heated pore region. The influence of the particle diameter on the heat transfer performance is larger than that of coolant's degree of subcooling.
B125 Finger-Stacked Structure流路における内部流動のPIV詳細計測(OS3 軽水炉・新型炉・原子力安全(1))

安永昌平, 江原真司, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2015　(20)　47-48　2015年6月7日
出版者・発行元：一般社団法人日本機械学会

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This study investigates the flow field in a flow channel with finger-stacked structure (FSS), which was proposed as a heat transfer promoter for Flibe blanket, by means of PIV measurement matching refractive indices of the channel material and working fluid. The experimental results revealed that turbulence energy was generated in the large velocity shear regions formed behind the fingers, and transported downstream. Then, when the gap between the fingers and channel wall was adjusted to 1 mm, the stagnant region behind the fingers that appeared in the case of 0 mm gap disappeared. In addition, turbulence energy was newly generated from the tips of the fingers. From these results, high heat transfer promotion is expected in the whole heating surface area of the flow channel with FSS setting small gap.
F134 エルボ下流自己形成流動場のダイバータ冷却への応用に関する基礎研究(OS9 熱・流動(3))

古舘翔一, 服部宗仁, 江原真司, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2015　(20)　171-172　2015年6月7日
出版者・発行元：一般社団法人日本機械学会

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In this study, heat transfer performance downstream of three-dimensionally-connected multi elbows, where a strong swirling flow appear due to the elbow layout, was experimentally studied and compared to that of a swirl tube supposed to be used in the ITER divertor. Dual and triple elbow layouts were tested, and local and averaged Nusselt numbers in the circumferential direction were evaluated from the experiment. The averaged Nusselt numbers of the triple elbow layout were slightly larger than those of the dual one. Although a comparably weak swirling flow was generated in the experiment, the heat transfer rate becomes 0.8 times as large as that of the swirl tube under the condition of single phase flow.
A214 極低周波渦電流探傷法の配管減肉モニタリングへの適用性評価(OS2 保全・設備診断技術(3))

田島直樹, 佐々木幸太, 遊佐訓孝, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2015　(20)　187-188　2015年6月7日
出版者・発行元：一般社団法人日本機械学会

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This paper evaluates the applicability of the extremely low frequency eddy current testing to the monitoring of wall thinning appearing on the inner surface of pipes. Magneto-Impedance sensor arrays are used to detect signals due to wall thinning. Plates made of SS400 with artificial grooves are prepared to simulate wall thinning in a large diameter pipe. We carry out numerical simulations and experiments to evaluate the effect of the depth and width of the grooves on signal. The results show the maximum amplitude and the full width at half maximum of signals correspond approximately to the depth and width of the grooves, respectively.
大型高温超伝導マグネットの開発の現状と展望‐高温超伝導導体の分割製作と接合技術による大型マグネットの開発

橋爪秀利, 伊藤悟, 江原真司, 遊佐訓孝, 柳長門, 寺崎義朗, 田村仁, 相良明男

プラズマ・核融合学会誌　91　(2)　87-96　2015年4月
ヘリカル型核融合炉のマルチスケール構造解析と3Dプリンタを用いた組立検討

田村仁, 柳長門, 高畑一也, 相良明男, 伊藤悟, 橋爪秀利

低温工学・超電導学会講演概要集　92nd　2015年

ISSN：0919-5998
B123 Na冷却高速炉1次系コールドレグにおける配管レイアウトのエルボ下流への影響評価(OS3 軽水炉・新型炉・原子力安全(2))

水谷淳, 江原真司, 橋爪秀利, 山野秀将

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2014　(19)　51-54　2014年6月25日
出版者・発行元：一般社団法人日本機械学会

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It is quite likely that a complex turbulent flow field and large pressure fluctuation induced by separation vortex shed from the intrados of the elbows are seemed to appear in the cold leg piping of the primary cooling system of Japan Sodium-cooled Fast Reactor. This study researched the influence of the inflow condition upon the flow separation especially in the 3rd elbow. In this study, the inflow condition to the 3rd elbow was imposed by changing the distance between the 2nd and 3rd elbows from 6.4D (original design) to 9.4D. The visualization experiment showed that the flow separation appeared in the intrados of the 3rd elbow as was the case with the original design and the separated regions became larger than that in the original one. This is because a swirling flow observed at the inlet of the 3rd elbow became weaker than that in the original case.
B224 FLiNaBe溶融塩ブランケットシステムにおける核転換解析(OS3 軽水炉・新型炉・原子力安全(5))

宍戸博紀, 古館佑樹, 遊佐訓孝, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2014　(19)　255-256　2014年6月25日
出版者・発行元：一般社団法人日本機械学会

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This study evaluates nuclear characteristics of molten salt, namely LiF-NaF-BeF_2 (FLiNaBe), from the viewpoint of its application to a liquid blanket system in a fusion reactor. Monte Carlo numerical simulations using MVP-2.0 with JENDL-4.0 data library and time-dependent nuclear transmutation analysis are carried out to evaluate tritium breeding ratio, change in the compositions of the molten salt. Induced radioactivity of Na contained in FLiNaBe is also evaluated. The results of the numerical analysis reveal that the thermophysical properties of FLiNaBe should vary because the compositions of the molten salt definitely change due to the fusion plasma neutron during power plant operation.
A214 オリフィス下流部に生じる配管減肉の低減に関する研究(OS2 保全設備診断技術(3))

加藤雅子, 江原真司, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2014　(19)　195-196　2014年6月25日
出版者・発行元：一般社団法人日本機械学会

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In this study, two issues related to liquid droplet impingement (LDI) erosion were tackled. As for the LDI erosion just behind an orifice, numerical simulation of single-phase gas flow was conducted and then traces of liquid droplets were simulated on the assumption of point mass approximation with drag force from the flow field for the liquid droplets. The numerical parameters were the size of the liquid droplets and their initial conditions such as position and velocity. As a result, it was found that liquid droplets appearing in the vicinity of the aperture of the orifice did not impinge on the pipe wall just behind the orifice. As for the suppression of the formation of liquid film just behind an orifice, a few orifice with multi-apertures were fabricated and tested experimentally, and the flow fields and behavior of liquid film formed downstream of the orifices were observed. The experiment showed that the apertures in the circumferential direction near the pipe wall were effective to suppress the formation of liquid film.
金属層構造を改善した三面複層コーティング流路におけるMHD流動特性の評価 (強磁場工学、機械的性質及び測定技術に関する研究)

橋爪秀利, 伊藤悟, 一色大地

東北大学金属材料研究所強磁場超伝導材料研究センター年次報告　162-165　2014年
出版者・発行元：東北大学金属材料研究所附属強磁場超伝導材料研究センター
Development of a method to fabricate a simulated flaw with a complicated boundary profile for non-destructive testing and evaluations

Noritaka YUSA, Jing WANG, Hidetoshi HASHIZUME

非破壊検査　2014年
システム統合モデルに関する研究 (プロジェクトレビュー日米科学技術協力事業TITANプロジェクト)

相良明男, 乗松孝好, 橋爪秀利

プラズマ・核融合学会誌　89　(11)　743-748　2013年11月
出版者・発行元：プラズマ・核融合学会
ISSN：0918-7928

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日米TITANプロジェクトのCommon-Taskの役割は,磁場核融合炉と慣性核融合炉設計で共通の,ブランケットでの物質・熱輸送循環システムの構築をめざすタスク1-1から1-3,タスク2-1から2-3までの計6サブタスク構成を縦糸とし,その実験研究成果をシステム統合モデリングの横糸によって連結・統合し,結果を各タスク指針にフィードバックすることである.まず計画前半では,核融合炉ブランケットでの整合性の高いトリチウム・流動システムの構築に向けての要素間の境界条件と,研究課題が整理された.計画後半では,トリチウムとヘリウム複合照射での壁面変質,第一壁トリチウム捕捉と中性子照射効果,伝熱流動と界面物質移動,などの相互関係がモデリングの視点で定量的に評価された.
高速炉冷却系配管における流れの剥離現象に関する基礎研究 : 高レイノルズ数領域におけるマルチエルボ内複雑流動構造の解明 : 先行基礎工学研究に関する平成20年度及び平成21年度共同研究報告書

江原真司, 結城和久, 橋爪秀利

JAEA-research　2013　(11)　巻頭1-2,1-72　2013年10月
出版者・発行元：日本原子力研究開発機構
D112 3次元接続二段エルボ下流に生成する非対称旋回流のオリフィス下流配管減肉への影響(OS6 保全・設備診断技術(2))

久保達也, 江原真司, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2013　(18)　105-108　2013年6月19日
出版者・発行元：一般社団法人日本機械学会

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Flow visualization experiment and accelerated pipe wall thinning experiment were conducted by applying a swirling flow generated by a piping configuration, three-dimensionally connected dual elbow, to the inlet flow condition of a pipe orifice to investigate pipe wall thinning downstream of an orifice appearing due to the combination of swirling flow and orifice The flow downstream of the orifice was curved by the action of the swirling flow, and the channel wall where the flow turned off toward underwent a large amount of wall thinning Profiles of turbulent quantities, such as turbulent kinetic energy and Reynolds shear stress, were compared to those of amount of pipe wall thinning It was found that the profiles of Reynolds shear stress showed good agreement with those of pipe wall thinning in the case for a large amount of that However, relatively small amount of pipe wall thinning, any profile related to fluid motion could not explain the profiles of pipe wall thinning
三面複層コーティング流路を用いた強磁場下におけるMHD流動特性評価 (強磁場工学、機械的性質及び測定技術に関する研究)

橋爪秀利, 伊藤悟, 一色大地

東北大学金属材料研究所強磁場超伝導材料研究センター年次報告　137-140　2013年
出版者・発行元：東北大学金属材料研究所附属強磁場超伝導材料研究センター
大電流容量ReBCO導体の機械的接合試験 (強磁場超伝導の研究 : 高温超伝導体)

伊藤悟, 清野祐太郎, 橋爪秀利

東北大学金属材料研究所強磁場超伝導材料研究センター年次報告　44-47　2013年
出版者・発行元：東北大学金属材料研究所附属強磁場超伝導材料研究センター
I142 ペダル充填管内複雑流動場のPIV詳細計測(OS-16: 多孔質体内の熱物質輸送と応用(4))

江原真司, Nematollahi Mohammad Reza, 橋爪秀利

熱工学コンファレンス講演論文集　2012　287-288　2012年11月16日
出版者・発行元：一般社団法人日本機械学会

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A sphere-packed pipe (SPP) was scrutinized to clarify the complicated turbulent flow field by means of PIV measurement. The geometrically complicated system was visualized by matching refractive index of acrylic resin as the channel material and Sodium Iodide solution as the working fluid. The visualization experiment was conducted with Reynolds number based on the sphere diameter and Darcy velocity of 5,000. As a result, it was found that high velocity regions appeared in the vicinity of packed sphere near penetrating paths formed in the SPP. In addition, it was clarified that turbulence energy was mainly generated in the large velocity shear regions formed near the pipe wall behind the packed spheres.
S083021 JSFRコールドレグ1/7縮尺試験におけるエルポ管内流れのU-RANS解析

金子哲也, 山野秀将, 田中正暁, 江原真司, 橋爪秀利

年次大会 : Mechanical Engineering Congress, Japan　2012　"S083021-1"-"S083021-5"　2012年9月9日
出版者・発行元：一般社団法人日本機械学会

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A study on flow-induced vibration in the primary cooling system of Japan Sodium cooled Fast Reactor (JSFR) has been conducted 111 Japan Atomic Energy Agency (JAEA). The flow-induced vibration in the elbow is an important issue in design study of JSFR consisting of large diameter pipe and elbow with short curvature radius, because it may affect to structural integrity of the pipe. In this study, Unsteady Reynolds Averaged Navier-Stokes equations (U-RANS) approach with the Reynolds Stress Model (RSM) using a commercial CFD code has been applied to the flow through single and double short-elbows under a high Reynolds number condition. This numerical simulation has utilized a 1/7 scaled water experiment of the JSFR cold-leg piping in order to investigate the flow structure in a three-dimensionally connected double elbow. As a result, applicability of the numerical simulation method was confirmed by comparison between the numerical and experimental results. The simulation has also shown that flow fields m the 1st elbow was different from that in the 2nd elbow and pressure fluctuation in the 2nd elbow was larger than that in the 1st elbow because their larger vortex flow structure.
D222 オリフィス下流における配管減肉への乱流速度変動周波数の影響(OS6 保全・設備診断技術)

江原真司, 矢内宏樹, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2012　(17)　371-374　2012年6月20日
出版者・発行元：一般社団法人日本機械学会

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It is very important to clarify the mechanism of Flow-accelerated Corrosion (FAC) from the viewpoint of plant maintenance because of the large potential influence of FAC. From the evidence that the scale of scalloped pattern appearing in the region where FAC occurs is different according to the extent of pipe wall thinning, it can be considered that a scale in the flow, e.g., frequency in the turbulent motion, affetcs the FAC. Experimental data is analyzed in terms of frequency characteristics by using a circular pipe with an orifice. It is shown that Reynolds stress has a lot to do with pipe wall thinning by FAC.
D212 オリフィス背後における高速気液二相流の可視化実験(OS6 保全・設備診断技術)

加藤雅子, 江原真司, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2012　(17)　355-356　2012年6月20日
出版者・発行元：一般社団法人日本機械学会

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Pipe wall thinning caused by erosion and corrosion is one of important problems in thermal and nuclear power plants. In this study, LDI erosion, which is one of the causes of pipe wall thinning especially in steam piping, is focused on. Since LDI erosion which appears downstream of an orifice is considered to depend on the shape of the orifice's aperture, two types of orifice with and without taper are scrutinized by visualization experiments of air-water two-phase flow and only air flow. Some differences are observed in the reattachment point downstream of the orifice, entrainment behavior of liquid phase behind the orifice and shocks formed immediately behind the orifice aperture.
D221 配管減肉に対するマイクロ波探傷法の口径依存性評価(OS6 保全・設備診断技術)

佐々木幸太, 遊佐訓孝, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2012　(17)　367-370　2012年6月20日
出版者・発行元：一般社団法人日本機械学会

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This study develops a methodology to apply a microwave nondestructive inspection technique, which detects and evaluates flaws appearing inner wall of a pipe from the reflection and transmission of microwave propagating inside the pipe, to a pipe with an arbitrary diameter. Three-dimensional finite element simulations are carried out to evaluate the effect of the profile of a microwave probe on the reflection and transmission of the microwave. The results reveal that elliptic microwave probe, which is newly developed in this study, realizes small reflection at the probe as well as single-mode propagation inside the pipe. Experimental validations using a straight pipe with an inner diameter of 39 mm and length of 2 m confirm that the elliptic microwave probe provides much clearer signals due to a wall thinning than conventional one.
津波対策評価ガイドラインの策定 : 福島第一原子力発電所の事故後の対策を受けて

橋爪秀利

日本原子力学会誌 = Journal of the Atomic Energy Society of Japan　54　(4)　250-254　2012年4月1日
出版者・発行元：日本原子力学会
ISSN：1882-2606
Matched refractive-index PIV visualization of complex flow structure in a three-dimentionally connected dual elbow

Kazuhisa Yuki, Shunsuke Hasegawa, Tsukasa Sato, Hidetoshi Hashizume, Kosuke Aizawa, Hidemasa Yamano

Nuclear Engineering and Design　241　4544-4550　2011年11月1日

DOI： 10.1016/j.nucengdes.2010.12.026 　

ISSN：0029-5493

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Flow structure in a three-dimensionally connected dual elbow is visualized using a 1/15-scale experimental apparatus simulating the 1st and 2nd elbows of JSFR cold-leg piping. A matched refractive-index PIV measurement clarifies that a low-velocity region formed on the inner wall side of the 1st elbow develops toward the 2nd elbow. This low-velocity region consists of the following two ones: a flow separation region accompanied mainly with the generation and disappearance of transverse vortices, and a velocity recovery region that has longitudinal vortices with strong unsteadiness. These longitudinal vortices exist as twin vortices in the time-averaged flow field, and their dynamic characteristics highly depend on high-velocity creeping flows generated in the 1st elbow that flow into the velocity recovery region through the side walls. Since the velocity recovery region reaches the 2nd elbow, the geometry of the 2nd elbow has a significant impact on the characteristics of the vortex shedding in the velocity recovery region. On the other hand, obvious flow separation is not observed in the 2nd elbow, whereas high-velocity flow with intense velocity fluctuation is confirmed on the inner wall side. Furthermore, the unsteady vortices shed from the velocity recovery region are transferred to the central area of the 2nd elbow while growing significantly. The visualization of the secondary elbow shortly after the 2nd elbow clarifies that a strong swirling flow is formed in the 2nd elbow. These flow structures are due to the distorted flow formed in the 1st elbow and the shape effect of the 2nd elbow. © 2011 Elsevier B.V. All rights reserved.
C104 固相接合を用いた非破壊検査技術用模擬応力腐食割れ製作技術の開発(OS6 亀裂検査および溶接技術)

遊佐訓孝, 橋爪秀利

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2011　(16)　25-26　2011年6月22日
出版者・発行元：一般社団法人日本機械学会

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This study reports a method to fabricate imitative stress corrosion cracking suitable for the development of nondestructive testing and evaluation methods. The method is to embed a partially-bonded region, which simulates the characteristics of stress corrosion cracking, inside a material by bonding together surfaces having artificial grooves. Since the sizes of the grooves are smaller than the spatial resolution of nondestructive testing method applied, the material property realized can be regarded as uniform as the actual stress corrosion cracking. The grooves are introduced using mechanical machining, which enables one to control the characteristics of the simulated flaw. Four specimens made of type 316L austenitic stainless steel are fabricated. The method is demonstrated by visual and eddy current examinations.
C103 分散補償法によるクラックレーダーの高性能化(OS6 亀裂検査および溶接技術)

橋爪秀利, 遊佐訓孝, 酒井康智

動力・エネルギー技術の最前線講演論文集 : シンポジウム　2011　(16)　23-24　2011年6月22日
出版者・発行元：一般社団法人日本機械学会

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This study proposes a signal processing method that significantly enhances the nondestructive evaluation of flaws appearing inside pipe wall from the reflection of microwaves propagating inside the pipe. The signal processing method modifies the phase of incident microwave as a function of frequency so that the reflection due to an anomaly at a certain distance is observed as a pulse. Validations are carried out both by experiments and finite element simulations using a straight brass pipe with a outer diameter of 25mm and a wall thickness of 3mm. This study considered wall thinning artificially introduced into the inner surface of the pipe. The results of the validations demonstrate the effectiveness of the signal processing method even when wall thinning have a complicated boundary profile.
保全学会活動報告原子力発電所のための保全科学と保全技術に関する国際セミナー

高木敏行, 橋爪秀利

保全学　9　(4)　95-99　2011年1月
出版者・発行元：日本保全学会
ISSN：1348-7795
複層コーティングを用いたMHD圧力損失低減化技術の基礎研究 (強磁場工学、機械的性質及び測定技術に関する研究)

橋爪秀利, 伊藤悟, 青柳光裕

東北大学金属材料研究所強磁場超伝導材料研究センター年次報告　168-170　2011年
出版者・発行元：東北大学金属材料研究所附属強磁場超伝導材料研究センター
メタルジャケット付き高温超伝導導体の機械的接合の基礎研究 (強磁場超伝導の研究 : 高温超伝導体)

伊藤悟, 橋爪秀利, 大日方達也

東北大学金属材料研究所強磁場超伝導材料研究センター年次報告　46-49　2011年
出版者・発行元：東北大学金属材料研究所附属強磁場超伝導材料研究センター
Investigation of Application of Remote Field Eddy Current Testing for Inspection Flaws in Large Diameter Tubes from Outside

Jing Wang, Noritaka Yusa, Hongliang Pan, Hidetoshi Hashizume

The 8th International Conference on Flow Dynamics　2011年
A213 球充填環状流路を用いた高Pr数流体の伝熱促進に関する実験(OS-3:多孔質体内の伝熱(I))

清水克矢, 江原真司, 橋爪秀利

熱工学コンファレンス講演論文集　2010　237-238　2010年10月29日
出版者・発行元：一般社団法人日本機械学会

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High Prandtl number (Pr) fluid Flibe, whose Pr varies from 25 to 150 depending on its composition, has been proposed to be used as the cooling and breeding liquid in blanket of fusion reactor. In this study, heat transfer experiments with sphere-packed circular pipes (SPP) and annular channels, which are heat transfer promoter for Flibe, are conducted using silicone oils as working fluids whose Pr are almost 25, 100 and 150. The results show that SPP has a little fin effect and sphere packed annular channels can obtain slightly higher heat transfer performance than circular pipe when comparing in the same pumping power.
金属ジャケット付BSCCO2223導体の機械的バットジョントの基礎評価

伊藤悟, 坂下武志, 橋爪秀利

低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity　81　122-122　2009年11月18日

ISSN：0919-5998
D211 金属多孔質体を用いた高熱流束除去デバイスの工学的課題と展望(多孔質中の熱・物質輸送現象III)

結城和久, 矢内宏樹, 橋爪秀利, 戸田三朗, 鈴木康一

熱工学コンファレンス講演論文集　2009　247-248　2009年11月6日
出版者・発行元：一般社団法人日本機械学会

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Key issues to enable heat removal exceeding 10MW/m^2 of heat flux are evaluated by summarizing experimental and numerical data ever obtained. Porous media focused on are bronze particle-sintered compacts. The experiments clarify that the heat transfer characteristics strongly depend on the level of the heat flux input and suggest that the heat transport by capillary effect works effectively under several MW/m^2. However, under the conditions of over the maximum heat flux transport by the capillary effect, the permeability for the vapor discharge becomes the most important factor to make it possible to remove the extremely high heat flux. In order to evaluate the effect of porous material, the two-phase flow characteristics are simulated by the two-phase mixture model. The results show that applying higher thermal-conductivity matrix leads to delay of onset of the two-phase formation and to much higher cooling performance even at higher liquid saturation.
ヘリカル炉の概念設計における熱流体工学 : 溶融塩 (Flibe) 冷却ブランケットにおける伝熱

相良明男, 橋爪秀利

プラズマ・核融合学会誌 = Journal of plasma and fusion research　85　(8)　561-563　2009年8月25日
出版者・発行元：プラズマ・核融合学会
ISSN：0918-7928

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核融合科学研究所におけるヘリカル炉FFHR設計研究では,溶融塩Flibeを増殖材兼冷却材として用いる液体ブランケットが,その安全性などから採用されている.しかしFlibeは高プラントル数流体であるため熱伝導による除熱は期待できないため,なにがしかの伝熱促進機構を導入しなくてはならず,東北大学TNTループにおいてFlibeの模擬流体としてHTSを用いた除熱性能向上のための実験を行っている.本章ではFFHRブランケットの設計およびFlibeブランケットの実現可能性を議論する.
高速炉冷却系配管における流れの剥離現象に関する基礎研究--高レイノルズ数領域におけるマルチエルボ内複雑流動構造の解明(先行基礎工学研究に関する平成19年度共同研究報告書)

結城和久, 橋爪秀利, 中西繁之

JAEA-research　2009　(17)　1-55,巻頭1〜2　2009年8月
出版者・発行元：日本原子力研究開発機構
核融合炉の除熱技術～実用から先進技術まで～

戸田三朗, 江原真司, 江里幸一郎, 関洋治, 榎枝幹夫, SMOLENTSEV Srgey, 結城和久, 相良明男, 橋爪秀利

プラズマ・核融合学会誌　85　(8)　539-569　2009年8月
出版者・発行元：プラズマ・核融合学会
ISSN：0918-7928
統合モデル

相良明男, 関村直人, 橋爪秀利, 深田智, 森下和功, 田中照也

プラズマ・核融合学会誌 = Journal of plasma and fusion research　85　(5)　276-280　2009年5月25日
出版者・発行元：プラズマ・核融合学会
ISSN：0918-7928

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ブランケットシステムの工学モデル構築には,基礎的知見に基づいたモデル化が必要である.基礎実験による先進的なブランケットシステムの開発を行うとともに,これらに必要な要素モデルをミクロな物理的基盤に基づいた計算機シミュレーションによって構築し,並行して設計データベースの構築を進めた.また,ブランケットシステムの挙動予測をめざして,核融合炉環境でのモデルの階層的および有機的結合と高度化を進め,これを検証する手段を考察した.
メタルジャケット付きBSCCO2223ケーブルのバットジョントの性能評価

坂下武志, 伊藤悟, 橋爪秀利, 西島元

低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity　79　32-32　2008年11月12日

ISSN：0919-5998
コンジット型BSCCO 2223ケーブルの機械的バットジョイントの基礎研究

伊藤悟, 加藤喬之, 橋爪秀利

低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity　78　55-55　2008年5月26日

ISSN：0919-5998
ヘリカル炉FFHRの最適化に向けた設計統合

相良明男, 御手洗修, 深田智, 橋爪秀利, 今川信作, 神前康次, 室賀健夫, 田中照也, 高畑一也, 柳長門, 田村仁, 力石浩孝, 山田修一, 三戸利行, 渡辺二太, IGITKHANOV J.

核融合エネルギー連合講演会予稿集　7th　2008年
三層コーティングを用いたMHD圧力損失低減化技術の基礎研究 (強磁場下の物性の研究--その他)

橋爪秀利, 結城和久, 伊藤悟

東北大学金属材料研究所強磁場超伝導材料研究センター年次報告　2008　156-158　2008年
出版者・発行元：東北大学金属材料研究所附属強磁場超伝導材料研究センター
液体窒素と金属多孔質体を用いた冷却技術の検討

茂庭圭介, 伊藤悟, 結城和久, 橋爪秀利

低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity　77　164-164　2007年11月20日

ISSN：0919-5998
分割型高温超伝導マグネットのためのセルフジョイント法の提案

伊藤悟, 山本裕子, 橋爪秀利, 西島元

低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity　77　165-165　2007年11月20日

ISSN：0919-5998
高温超伝導ケーブルのバットジョイント法における高強度化と接合面の改善

加藤喬之, 伊藤悟, 橋爪秀利

低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity　77　166-166　2007年11月20日

ISSN：0919-5998
分割型高温超伝導マグネットの開発(その1)

橋爪秀利, 伊藤悟, 高見正平, 山本裕子

低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity　74　220-220　2006年5月15日

ISSN：0919-5998
屈折率整合法を適用したペブル充填管内可視化実験(オーガナイズドセッション11 特殊場における伝熱)

奥村真澄, 結城和久, 橋爪秀利, 相良明男

熱工学コンファレンス講演論文集　2004　75-76　2004年11月10日
出版者・発行元：一般社団法人日本機械学会

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In order to apply Flibe as a liquid blanket material, a heat transfer enhancement system is required because the Flibe is a high Prandtl number fluid. The purpose of this study is to visualize the detailed flow fields in the packed-bed tube, which is expected to utilize for the heat transfer enhancement. The visualization inside the packed-bed tube is performed by using a PIV system with a refractive index matching technique. The flow field in the packed-bed tube is visualized from various angles by the PIV system to describe the complicated flow structures in it.
Evaluation of Flow Structure in Pebble Packed Tube by PIV Visualization Experiment

OKUMURA Masumi, YUKI Kazuhisa, HASHIZUME Hidetoshi

Thermal science and engineering　12　(4)　135-136　2004年7月1日

ISSN：0918-9963
みんなが電気を使うとどうなるの?

橋爪秀利

伝熱 : journal of the Heat Transfer Society of Japan　41　(171)　28-29　2002年11月1日

ISSN：1344-8692
26aA25P 東北大学ヘリアック装置における電子注入による径方向電場の制御実験III(ヘリカル・慣性核融合)

北島純男, 高橋裕己, 田中豊, 橋爪秀利

プラズマ・核融合学会年会予稿集　(19)　58-58　2002年
出版者・発行元：プラズマ・核融合学会
高温超伝導テープの直接接合に関する研究

伊藤悟, 橋爪秀利

シンポジウム電磁力関連のダイナミックス講演論文集　13　669-672　2001年6月20日
27pB34P 東北大学ヘリアック装置における電子注入による径方向電場の制御実験II(ヘリカル)

高橋裕己, 原田紘明, 北島純男, 橋爪秀利

プラズマ・核融合学会年会予稿集　(18)　85-85　2001年
出版者・発行元：プラズマ・核融合学会
29pA33P 高温超伝導テープの直接接合に関する基礎研究(加熱/炉設計)

八木賢治郎, 伊藤悟, 北島純男, 秀利秀利

プラズマ・核融合学会年会予稿集　(18)　143-143　2001年
出版者・発行元：プラズマ・核融合学会
高温超伝導体テープにおける新しい電磁場解析手法の提案

鈴木学, 橋爪秀利, 戸田三朗

シンポジウム電磁力関連のダイナミックス講演論文集　12　161-164　2000年6月29日
高温超電導体でのクエンチ伝搬解析

鈴木学, 橋爪秀利, 戸田三朗

シンポジウム電磁力関連のダイナミックス講演論文集　10　211-214　1998年10月23日
第34回日本伝熱シンポジウムを振り返って

戸田三朗, 橋爪秀利

伝熱研究 = News of HTSJ　36　(142)　18-19　1997年7月1日

ISSN：0910-7851
核融合装置における過渡電磁解析II 3. 核融合装置における電磁気解析手法

亀有昭久, 福本英士, 橋爪秀利

プラズマ・核融合学会誌 = Journal of plasma and fusion research　72　(11)　1223-1234　1996年11月25日
出版者・発行元：プラズマ・核融合学会
ISSN：0918-7928

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Methods of electromagnetic analyses in fusion devices are reviewed. Various methods of eddy current analyses are reinvestigated on a basic standpoint. The potential representations (A-φ and T-Ω) of the 3-dimensinal electromagnetic field, the gauge problem and the role of edge elements, and the T-methods and thin conductor approximation are described. Computer Aided Engineering (CAE) systems in eddy current analyses are also explained. New trend of electromagnetics of superconductors is also introduced from the view point of the numerical analysis based on the critical state model.
核融合炉における極限工学課題、高熱流束、電磁構造、材料

戸田三朗, 吉川潔, 高木敏行, 秋場真人, 山崎誠一郎, 関村直人, 橋爪秀利, 上坂充, 高津英幸

日本原子力学会誌　34　(10)　918-930　1992年
出版者・発行元：Atomic Energy Society of Japan
DOI： 10.3327/jaesj.34.918 　

ISSN：0004-7120

︎全件表示 ︎最初の5件までを表示

書籍等出版物 2

計算力学

伊藤耿一, 中橋和博, 橋爪秀利, 山本悟, 吉岡顕

2000年3月
超電導の数理と応用

宮健三, 吉田義勝, 橋爪秀利, 武田信和, 羅雲, 内一哲哉

1997年

講演・口頭発表等 5

Pleanary Session 国際会議

TOFE 2014　2014年11月9日
オリフィス下流における配管減肉への乱流速度変動周波数の影響

江原真司, 矢内宏樹, 橋爪秀利

第17回動力・エネルギー技術シンポジウム　2012年6月21日
The Fukushima Accident 国際会議

Isem2011　2011年9月6日
Numerical and experimental research to solve MHD problem in liquid blanket system 国際会議

ISFNT-7　2005年5月23日
Modeling of Surface Melting and Evaporation under High Heat Load 国際会議

International Symposium on Fusion Nuclear Technology　1997年4月

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(プロシーディング) Fusion Engineering and Design North-Holland 1998

共同研究・競争的資金等の研究課題 20

MHD流動制御による４相連続ダイバータシステムの構築

橋爪秀利

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Scientific Research (A)

研究機関：Tohoku University

2021年4月5日～ 2026年3月31日

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本研究の目的は、従来から考えられている２つの方式であるガスダイバータ（固体壁の表面にガスを噴射する方法）と液体ダイバータ（液体金属を用いる方法）で問題となる、一部の荷電粒子がガス領域を突き抜けてしまうことによる固体壁の重大な損傷の発生・液体の蒸発によるプラズマへの不純分の侵入によるプラズマの不安定化といった工学的課題を解決するため、両者の方法を統合し、世界初の「MHD効果を利用した４相連続型の革新的なダイバータシステム」の基盤研究を遂行することによって、合理的なダイバータの実現に向けたブレイクスルーを示すことである。本年度の研究実績は以下の通りである。 1) 磁場下での液体金属自由表面流における流速分布を評価するための電位プローブユニットを製作し、ナノボルトメータによる電位分布計測系の構築を行った。さらに非一様の0.1 T程度の磁場（東北大学金属材料研究所附属強磁場超伝導材料研究センター）において、液体金属ガリンスタンを用いたMHD自由表面流実験を行い、導電フィン、絶縁フィン、部分導電フィン、部分絶縁フィンの4種類のフィンを流路中に設置した際の流速分布を得てMHD流動制御特性を評価した。 2) 一様磁場下での液体金属自由表面流実験（2年目以降を予定）を行うために、本年度はネオジム系の永久磁石とヨークを合せた磁気回路を有する一様磁場発生装置を製作した。本装置はギャップの幅および高さがそれぞれ90 mmおよび200 mmで、流路方向に200 mm程度に0.8 Tの一様な磁場を発生できるものとした。また本装置に使用する液体金属流動ループ設計に着手した。また、気泡導入部の設計検討のために多孔質体を選定・購入を行った。 3) 自由表面を有する液体金属のMHD流れ、および気泡の影響による電気伝導度の変化を考慮した解析手法の構築に着手した。
超高速中性子と高レベル廃棄物の有効利用による革新的核変換核融合炉の提案

橋爪秀利, 山村朝雄, 染谷洋二, 岡本敦, 金聖潤, 遊佐訓孝, 近藤正聡, 宍戸博紀

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Pioneering)

研究種目：Grant-in-Aid for Challenging Research (Pioneering)

研究機関：Tohoku University

2017年6月30日～ 2020年3月31日

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核融合反応で発生する超高エネルギーの14 MeV中性子と、原子力発電所より生じる使用済み核燃料に含まれる高レベル廃棄物（核分裂生成物やマイナーアクチノイド）を組み合わせたこれまでにないコンセプトを持つ新しい核融合炉の概念設計を行った。マイナーアクチノイド燃料と核変換部の設計、および核分裂生成物の核変換部を含むブランケット設計評価を実施し、当該核融合炉の導入によりこれら高レベル廃棄物の国内における貯蔵量を確実に低減可能となるシナリオを示した。
革新的核融合炉実現へ向けた分割型高温超伝導マグネットの実証と普遍的接合法の創成

橋爪秀利, 田村仁, 江原真司, 伊藤悟, 遊佐訓孝, 柳長門

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)

研究種目：Grant-in-Aid for Scientific Research (S)

研究機関：Tohoku University

2014年5月30日～ 2019年3月31日

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極低温・強磁場環境下でREBCO線材の接合抵抗を予測する手法を確立し、冷却性能予測に不可欠となる金属多孔質体のプール沸騰伝熱相関式の高度化を図った。また、10 kA導体のブリッジ式機械的ラップジョイントにジョイントピースと低温熱処理を導入し、従来の1/6の製作時間、1/3の接合抵抗を実現することに成功した。さらに、臨界状態モデルおよび自己磁場評価に基づいたピン導入実験を陽子線照射により実施し、臨界電流値を制御できることが明らかとなり、超伝導物理に基づく機能分割構造導体の可能性が示された。以上のように革新的核融合炉へ向けた分割型高温超伝導マグネットの実証と普遍的接合法の構築がなされた。
自己形成流動場を利用したダイバータの革新的除熱方法の開発

橋爪秀利

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

研究種目：Grant-in-Aid for Challenging Exploratory Research

研究機関：Tohoku University

2012年4月1日～ 2014年3月31日

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本研究では複数エルボの連続接続配管下流に形成される旋回流特性をダイバータ冷却に応用するために、流れ場の詳細解析を可視化実験により行い冷却に適する配管レイアウトの選定を試みた。まず立体接続2段エルボ体系でエルボ曲率の流れ場への影響を評価し、曲率の小さいショートエルボが強い旋回流を生成することが分かった。次いでショートエルボを用いた5つの3段エルボ体系で流れ場を評価し、1段目-2段目および2段目-3段目エルボが立体接続の時に2段体系より強い旋回流が生成することを明らかにした。乱流エネルギーなどの乱流統計量は2段エルボ体系が一番大きくなり、今後これらの体系の伝熱性能を実験により確認する予定である。
分割型高温超伝導マグネット実用化のための普遍的接合技術の創成と実証

橋爪秀利, 江原真司, 遊佐訓孝, 伊藤悟

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

研究種目：Grant-in-Aid for Scientific Research (A)

研究機関：Tohoku University

2011年4月1日～ 2014年3月31日

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分割型高温超伝導マグネットの普遍的工学手法の創成と実証を目指し、普遍的接合手法の確立、多孔質体を用いた除熱システムの最適化、大型高温超伝導導体および接合部の設計・作製の3点を目的として研究を行った。除熱システムの研究では、金属多孔質体を用いることで、膜沸騰が抑制されることを確認し、本システムが有効であることを示した。また100 kA通電が可能な導体と接合部を開発し、本概念の実証をすることができた。
原型炉を目指した分割型高温超伝導マグネットの実現

橋爪秀利, 結城和久, 伊藤悟

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

研究種目：Grant-in-Aid for Scientific Research (B)

研究機関：Tohoku University

2006年～ 2008年

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核融合炉の実現のために必須である建設コスト・補修費の削減を可能とする技術として、高温超伝導マグネットを分割製造し、機械的に接合して用いる分割型高温超伝導マグネットを我々は提案した。本研究では、本コンセプトの基本技術となる高温超伝導導体の機械的接合の最適化を図れる導体構造・使用温度領域を示し、また、金属多孔質体を用いた極低温冷却技術を適用することが本コンセプトには有用であることを実験的に示した。
トーラスプラズマ閉じ込めにおける分岐現象理論の実験的検証

北島純男, 笹尾真実子, 橋爪秀利, 高山正和, 稲垣滋, 笹尾真実子, 橋爪秀利, 高山正和, 稲垣滋, 小渕隆, 神藤勝啓

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

研究種目：Grant-in-Aid for Scientific Research (B)

研究機関：Tohoku University

2005年～ 2008年

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本補助金により、東北大ヘリアック装置において、プラズマ中に挿入した熱陰極バイアスにより径方向電場分岐実験に成功し、径方向電流と閉じ込め磁場による力、JxBポロイダル駆動力と粘性、摩擦との平衡より粘性を評価すると、理論値と定性的に非常に良く一致した結果が得ることができた。これは核融合を目指した、プラズマ磁気閉じ込めにおけるL-H遷移現象の物理を理解する上で重要なことである。
原型炉を目指した分割型超伝導マグネット・第一壁/液体ブランケット統合システム開発

橋爪秀利, 結城和久

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

研究種目：Grant-in-Aid for Scientific Research (B)

研究機関：Tohoku University

2003年～ 2005年

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核融合炉の超伝導マグネットの製造コストおよび炉内構造物のメンテナンスコストを削減するための新しい核融合炉設計案として分割型高温超伝導マグネットシステムが提案されている。本研究の目的は、高温超伝導ケーブルのバットジョイントにおける基礎特性の把握と液体窒素温度、数百A印加時の高温超伝導ケーブルの発熱耐性の証明を行い、分割型高温超伝導マグネットの実現可能性を実証することである。まず、バットジョイントの基礎特性の把握のために高温超伝導テープのバットジョイントの基礎研究を行った。まず、実験評価により、輸送電流の増加にともない接合抵抗が増加することを確認し、数値解析評価により、この原因が接合部付近の超伝導フィラメントの材料劣化である可能性が高いことを示した。また、数値解析評価により、接合部における超伝導フィラメントの相対位置は接合性能へは影響せず、接触状況が接合性能を決定づけるのに支配的であることを示した。以上の考察により酸化物高温超伝導ケーブルのバットジョイントに共通な基礎特性を把握することができた。加えて、材料劣化の防止、接触状況の改善のために金属メッキが有効であることを示唆した。得られた結果を基に積層型高温超伝導ケーブルのバットジョント試験を行った。まず、金属メッキによる接合面状態の改善および保護が有効であることを確認した。加えて、バットジョイントにおいて液体窒素温度、輸送電流500A以下の場合に接合部での発熱による高温超伝導ケーブルの常伝導転移および臨界電流の低下を防止できることを実験的に確認した、すなわち高温超伝導ケーブルの発熱耐性を実証した。最終年度には、実際に分割型高温超伝導マグネットプロトタイプを製作し、その性能評価を行った。結果を基に今後の開発課題を提示し、また、エネルギー損失評価によって、銅コイルに対する分割型高温超伝導マグネットの優位性を示した。
電磁波を用いた欠陥探傷方法(クラックレーダー)の開発

橋爪秀利, 北島純男

2003年～ 2004年

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電磁波を利用した欠陥検出方法は、電磁波が広く配管内部を伝搬することを利用した全く新しい手法である。本研究では昨年度に引き続き研究を行い、電磁波の配管内伝播実験を実施した。その結果、以下のことが明らかとなった。 1 モード変換器で使用する周波数に合わせてモード変換器のプランジャー位置を調整すれば、広い周波数帯域において透過する入射波強度を高いレベルで維持する事が可能である。 2 理論的に予想していた結果と実験結果は定性的には一致しているものの、定量的にはずれが見られた。この要因として、実験で測定している反射波の共振による影響が考えられる。 3 被測定管部に仮想的に比較的幅の広いき裂を入れ、その幅を変化させると、き裂の幅が大きくなるほど反射波のレベルが大きくなる点が遮断周波数以上の領域に存在し、き裂の検出が可能である。 4 比較的幅の狭いき裂は、遮断周波数以下の領域での差に注目することにより検出できる可能性がある。また、き裂の存在位置と信号の強度にはある程度の相関が見られたが、き裂位置を特定することはかなり困難であると予想される。ことが明らかとなった。以上のように、本手法によってき裂の存在を検出することが可能であるとの結論を得ることができた。また、現有している発振器では周波数の上限が問題となり、今後、より高周波数領域の電磁波を発振できる発振器を導入し、信号強度に加え、位相のずれも測定することにより、き裂の位置を同定できるような高性能化が可能であるとの見通しを得ることもできた。
大型超伝導マグネットモジュール化のための超伝導接合部の電磁・構造最適化の研究

橋爪秀利, 北島純男

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

研究種目：Grant-in-Aid for Scientific Research (C)

研究機関：TOHOKU UNIVERSITY

2000年～ 2002年

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磁場閉じ込め型核融合炉の建設・保守の大きな障害となっている超伝導マグネットをモジュール化するために不可欠となる超伝導線材の直接接合手法の研究を進めるために、高性能電源と製作した試験部からなる実験装置を組み立て、超伝導接合に関する基礎的性能評価試験を実施した。用いた超伝導線材は、ビスマス系高温超伝導線で、臨界電流密度が42MA/m^2(断面約4mmx0.25mm、臨界電流値67A)のものである。接合面は、超伝導線材を重ね被覆材向士が接合する場合と、直接切断面を接合する場合についての電気抵抗値を比較検討した。また、電磁力を模擬するために機械的負荷を与え、負荷の大きさを変え、応力をパラメータとして実験を進めた。その結果、約5mm程度の重ね合わせにより、銅と同程度の電気抵抗値になること、応力を増加させると電気抵抗値は減少するが、漸近値が存在することが明らかとなった。さらに、直接、超伝導テープ断面を接合した場合には、重ね合わせと同程度の性能がでることが明らかとなり、直接接合の可能性が示された。得られた実験結果(超伝導線の切断面を機械的圧縮力によって直接接合する場合についての電気抵抗値が300μΩ)を踏まえ、抵抗値の低減を目的として、接合面の処理方法の検討・接合力の印加方法の検討を行った。まず、ダイヤモンドカッターを用いた切断・ラッピングフィルムによる研磨などにより、抵抗値を60μΩまで改善することに成功した。さらに、機械的圧縮力の印加方法の改善により、抵抗値を5μΩ(電流値60A)まで低減させることに成功した。この値は、超伝導マグネットの分割化のために腰とされる性能とほぼ同程度であり、分割型マグネットの実現可能性を明らかにすることに成功したまた、解析による基礎評価のための超伝導体中の磁場・温度場を連成させ、有限要素法を用い解断コードの整備を行った。特に、高温超伝導線材がテープ状となっているため、超伝導体内部の電流分布を擬3次元的解析から得られた結果に基づき、2次元解析に反映させる方法の検討を行った。
電磁波を用いた欠陥探傷方法の開発競争的資金

制度名：Funded Research

2000年4月～
ライフサイクル健全性監視用分散知能化インタフェース技法研究

北村正晴, 橋爪秀利, 高橋信

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

研究種目：Grant-in-Aid for Scientific Research (A)

研究機関：TOHOKU UNIVERSITY

1997年～ 1999年

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原子力発電所、宇宙ロケット、大型航空機などに代表される大規模機械システムの信頼性,安全性の一層の向上を目的として本研究は1997年から開始された。本研究では、予防保全技術の高度化とりわけライフサイクル全般を視野に入れた状態監視保全の積極的導入がプラント運転安全上一層重視されねばならないとの見解を出発点としている。そして、デークベースによる情報管理と状態監視保全のための情報提供の本質的要素は知的レベルの高いインタフェース技術であるとする基本的な見解に基づき本研究では、状態監視保全高度化を実現するための重要な要素技術集合として (a)状態監視保全用進化型ライフサイクルデータベース技術 (b)予兆監視診断のためのモバイルエージェント技術 (c)知的情報獲得のための目的指向センシング技術を取り上げ、これらの技術開発を行うことを直接の目的として研究を進めた。テーマ(a)では、部分類似度と階層型類似度という自由度の高い事例データ検索方式が導入されこれに基づいて異常診断や保全に関する意思決定を支援でき、さらに組み込み機能を容易に更新できる進化型データベース技術が開発された。テーマ(b)では、このデータベース実装のひとつの形態が分散協調型となることを前提として、その分散データベースと協調して要求されるタスクを非同期的に分散処理するための応用ソフトウエア構築技術がモバイルエージェント技術をベースとして開発された。テーマ(c)では、目的や状況に応じて計測位置や測定対象物理量を変更しそれによって在来計装に対して相補的な役割を果たす移動計測を併用する目的指向センシングという方式を提唱し、ベイジアンネットという事象因果モデル表現を利用してシステム実現を行ってその有効性を検証している。これらの要素技術を統合的に利用することで、本研究が目的とするプラントライフサイクル全体を見通した健全性監視と状態監視保全が実現でき、故障生起の未然防止、ひいては安全性の向上に大きな貢献をできる可能性を確認することが出来た。
耐強磁場ヘリカル炉用高温/低温複合超電導体の研究・開発

橋爪秀利

1997年～ 1998年

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前年度に開発された、傾斜機能的な超電導線材の性能を評価するための解析コードを拡張し、高温超電導体内での温度場解析も同時に可能とした。すなわち、電磁場解析においては、高温超電導体内部に誘起される遮蔽電流を臨界状態モデル・磁束クリープモデルに加え、磁束流モデルも導入して評価した。なお、電磁場解析に関する支配方程式は、導体の存在しない領域で変数を定義する必要のない電流ベクトルポテンシャル法に基づいて導出し、超電導体の電気電導率は、非常に大きな値を初期値として仮定し、反復計算によって値を修正し、電流分布が磁束クリープモデル・磁束流モデルを含む臨界状態モデルと矛盾の無いような結果を得ることに成功した。その結果、高温超電導体内でのクエンチ発生は状況は、低温超電導体のものとは大きく異なり、クエンチの伝播・回復に要する時間が、非常に長くなり、クエンチが伝搬して行く状態なのか、回復状態にあるのかの判断が非常に困難であることが明らかとなった。これは、温度拡散係数が大きいためであり、従来の低温超電導体に適用していたクエンチ対策とは全く別のシナリオが必要となることが分かった。例えば、電圧上昇等によるクエンチ発生が検出された場合に、低温超電導体では、直ちに、電流値低下措置をとる必要性があったが、高温超電導体の場合には、時間的裕度がある。また、この際に急激に電流値を低下させるとそのこと自体が高温超電導体内での熱発生要因になり(ヒステリシス損失・結合損失)逆にクエンチを推進することにも成りうる可能性があることも明らかとなった。さらに、より詳しい電流分布を求めるために、擬3次元コードの整備を進め、3次元電流分布の解析結果が得られるまでに至った。
高粒子ビーム束下の高負荷境界における非平衡熱現象の解明と制御

戸田三朗, 結城和久, 橋爪秀利, 石井慶造, 勝村幸博

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

研究種目：Grant-in-Aid for Scientific Research (A)

研究機関：Tohoku University

1996年～ 1998年

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核融合炉等の高粒子ビーム束下における超高負荷境界の非平衡熱現象を解明するため、以下、高熱流束発生装置としてプラズマ発生装置を用いた固体面へのプラズマ照射実験、プラズマジェットの数値解析、分子動力学を用いた固体面の溶融解析、クエンチ負荷を受ける高温超伝導体内の電磁解析を実施してきた。プラズマ照射実験とプラズマジェットの数値解析購入したプラズマ発生装置により、プラズマジェットを銅ブロックに照射し、銅ブロック内の温度分布さらにプラズマジェットから固体表面への熱負荷と作動流体との相関を明らかにした。本装置を用いることで最大約12MW/m^2の高熱負荷環境が実現可能であることを確認した。さらにプラズマ流と固体表面の相互作用を定性的に評価するため、トーチノズル内部を含めたプラズマ噴流の電磁流体・熱負荷解析コードを作成した。特にノズル内部のプラズマ生成過程のシミュレーションに成功し、プラズマの温度が約10000℃に達することを明らかにした。分子動力学を適用した高負荷を受ける固体表面の溶融・蒸発現象の解明高粒子・熱負荷を受け固体表面が溶融・蒸発する現象を厳密に評価するには、ミクロレベルすなわち分子・原子の運動を厳密に追跡する必要がある。本研究ではまずアルゴン固体壁に高エネルギーのヘリウム粒子を照射する場合の固体表面の溶融・蒸発過程を分子動力学法を用いて解析し、溶融蒸発時の分子速度分布を評価した。また蒸発蒸気による入射粒子の遮蔽効果を明らかにし、次いで核融合炉ダイバーター部に使用されるカーボンの蒸発潜熱を評価した。クエンチ負荷を受ける高温超伝導体内の電磁解析超伝導体におけるクエンチ時にはクエンチフロント周辺で過渡的な熱・電磁負荷が作用する。従来からの実績を踏まえて、高温超電導体における現象に対応できる電磁解析コードの解析を行いその評価に成功した。これらの解析のほとんどは国際学会にて報告、公表された。
革新的核融合炉用高熱流束除熱体EVAPORONの開発

戸田三朗, 結城和久, 橋爪秀利, 石井慶造, 勝村幸博

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

研究種目：Grant-in-Aid for Scientific Research (B)

研究機関：Tohoku university

1996年～ 1998年

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多孔質体内での蒸発現象に注目した高熱除去装置EVAPORON(Evaporated-Fluid-Porous-Themodevice)の開発を進め、その性能試験を進めてきた。この多孔質内での蒸発を利用する、革新的除熱原理による高熱流束除熱体EVAPORONの構造は、片側を液体流に接し、他方を高負荷面に接続する金属多孔質体中で、浸透する液体が高負荷面側より伝熱する熱により蒸発し排出されていく体系を基本としており、除熱熱流束は浸透する液体冷却材流の完全蒸発による潜熱輸送となっている。研究を進めた結果、除熱能力として、すでに2MW/m^2が得られ、数値解析では、さらに1桁の性能向上が可能であると予測され、その性能は実証されつつある。3年間の研究の結果、EVAPORONの除熱性能に関し以下の知見を得た。 (1)蒸発・沸騰による高熱流束の熱吸収がおこなわれている領域は加熱面に接する極く薄い層内であり、そこでの温度分布が急激な変化を示している。 (2)高熱流束熱吸収の層が薄いことから、蒸発蒸気の流出に伴う高温固体面近傍流れは3次元的変化を示し、EVAPORONの除熱性能に大きな影響を持っている。 (3)1次元の熱バランスによる解析と2次元解析の結果、実験結果は数MW/m^2のレベルの高熱流束の除熱性能であったが、EVAPORONの高熱流束熱吸収層の設計、たとえば多孔質の空隙率を径方向・軸方向に分布させ、気液2相流動に対する流動抵抗・平均熱伝導等の最適化による傾斜機能材の開発を行うことで数10MW/m^2以上の高熱流束熱除去の高い可能性が確認できる。 (4)EVAPORONに対する溶融塩FLiBeの適用性を数値的に模索した結果、多孔質体の空隙率等を最適設定することで、高負荷環境下において十分な除熱性能を有することを確認した。以上の知見およびEVAPORONによる蒸発・沸騰二相流冷却の核融合炉高熱流束機器への適用について、他の冷却方式との比較の中で、非常に高い可能性のあることを国際会議における講義の中で公表した。
電磁場・熱場連成解析による超電導体中のクエンチ伝播評価

橋爪秀利

1995年～ 1995年

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一般に用いられている臨海状態モデルに基づく電流分布は、磁束量子が勾配を持って分布し、その結果得られると解釈できる。そこで、分子動力学的手法に基づいて、温度場が変化し磁束流・磁束クリープが存在する場合の磁束量子の分布を求め、その結果を基に温度変化を考慮することの可能なモデルを構築することに成功した。その結果、温度上昇時すなわち臨界電流密度が減少する場合には、従来の臨界状態モデルが適用可能であることが分かったが、逆の場合には、巨視的な電流密度の変化は現れず、電流密度が臨界電流密度より低くなり、臨界状態モデルが適用できないことが明かとなった。次に新たに得られたモデルに基づいて、温度変化が存在し、磁束流・磁束クリープの影響を考慮した場合の巨視的な電流分布を、有限要素法に基づいた電磁場・熱場連成問題解析コードで評価した。すなわち、ヒステリシス損失・磁束流によるエネルギー損失等を求め、熱場解析の熱源として評価し、熱場解析を実施し、得られた温度分布に従い、臨界電流密度・磁束流による等価抵抗・物性値を変化させ、再び電磁場解析を実施した。従って、例えば温度上昇の場合には臨界電流密度が低下し、電磁場解析の結果、磁束流が発生し、更なる温度上昇をまねき、最終的にはクエンチに至るが、この変化の様子を数値解析によって詳細に評価し、クエンチが進展する時とクエンチからの回復が期待できる場合の境界である安定限界を求めた。この結果、印可磁場が比較的小さい場合には従来からの簡単なモデルによる安定限界とほぼ良い一致を示したが、核融合炉条件の強磁場下では、磁束流による発熱が局在化するため、安定限界が非常に低下することが、明らかとなった。
核融合炉超電導マグネットにおけるエネルギー損失評価に関する基礎研究

橋爪秀利

1993年～ 1993年

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第II種超電導体内での電流分布を表す構成方程式を構築し、申請者らがすでに開発している電流ベクトルポテンシャル法に基づく渦電流解析コードを改良して数値解析を実施した。すなわち、超電導体中での電流分布に関しては電流密度が臨界電流を越えないという条件を満足するように数値解析を行い、超電導体中での電磁現象を評価した。さらに、熱場との連成問題を解析するため、新たに、極低温場下での超電導体を取り扱える温度場解析コードを作成し、輸送電流が存在する場合の、非定常磁場下でのエネルギー損失を定量的に評価し、クエンチ伝播の安定限界を詳細に解析した。その結果、クエンチ時の電流分布の変化の様子や、温度場の形成の様子が明かとなった。さらに、従来からの簡易的解析手法では評価することが不可能であった、外部磁場の強さの磁束流による発熱への影響が非常に大きいことが明かとなり、安定限界に関する詳細解析が不可欠であることが分かった。特に、外部磁場が大きいときには、磁束流による発熱が大きくなり、クエンチに対する発熱限界がかなり小さくなることが明かとなった。
磁場の可視化とその応用に関する研究

宮健三, 本間利久, 橋爪秀利, 上坂充, 高木敏行, 槌本昌則, 橋本光男

1990年～ 1991年

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昨年度は、ホ-ル素子を用いた1次元アレイプロ-ブとその制御及び増幅装置を製作し、制御・画像処理の計算機にデ-タを取り込み基本的な可視化像を得ることができた。今年度は、2次元計測の自動化、各種磁場可視化画像の表示方法と計算デ-タのノイズ除去法の開発を行なった。さらに、この装置の応用について検討した。 1)計測の自動システム化:開発したシステムは、3方向成分のホ-ル素子を高密度実装したプロ-ブ、個々の素子の切り替え及び増幅をする制御・増幅装置、プロ-ブの駆動装置、各装置の制御及びデ-タの入力及び画像処理を行う計算機、フルカラ-表示ができるディスプレイにより構成される。プロ-ブの駆動、ゲインやオフセットの設定、計測、及び画像表示は、すべて会話方式で計算機により制御することができる。 2)可視化画像表示の開発:磁場はベクトル量であるため、3成分の情報が入力される。これらのデ-タを基に可視化画像として、(1)カラ-強度表示、(2)ワイヤフレ-ム表示、(3)表示画像化らの磁場計測、(4)ベクトル表示及び、(5)視点を変えた動的表示をそれぞれカラ-グラフィック上に会話方式で表示できるようにした。 3)ノイズ除去法の開発:磁場の連続性を考慮してノイズ除去手法を開発し、弱磁場における計測精度を向上させることができた。 4)非破壊検査への応用:このシステムの応用として、漏洩磁束を検出する非破壊検査法への適用を試みた。この結果、可視化画像から欠陥の大きさ深さを判断できた。開発した磁場可視化システムは、単に磁場分布の計測装置としてだけでなく、非線形に振る舞う磁場を理解しやすくし、さらに非破壊検査における定量的評価を始め各種電磁機器の診断等への応用が期待できることが判った。
ACポテンシャル法に基づいた表面き裂形状認識に関する基礎研究

橋爪秀利

1990年～ 1990年
超電導体内の電磁現象に関する研究競争的資金

制度名：Grant-in-Aid for Scientific Research

1988年4月～

︎全件表示 ︎最初の5件までを表示

社会貢献活動 1

脱原発を問う

2011年8月2日～

その他 5

クラックレーダーの開発とその原子炉配管への適用に関する研究

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「電磁波を利用した欠陥探傷技術に関する基礎研究（平成13年度〜15年度）」により、欠陥の存在による電磁波への影響を検出することがほぼ可能であることが明らかとなった。そこで本研究では、この研究をさらに発展させ、欠陥の存在による電磁波への影響の定量的評価を行い、欠陥の存在と位置同定の手法を数値解析および実験を通して開発する
パルス波を用いたクラックレーダーの開発に関する研究

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電磁波の発信機と計測器を兼ね備えたネットワークアナライザーを用い、精度良く電磁波の周波数を制御し、１０ＭＨｚ〜４０ＧＨｚの電磁波を入射した場合の、各周波数に対する欠陥存在による強度と位相の変化への影響を明らかにし、強度、位相、強度＋位相の情報から欠陥検出可能性を評価する
上流にベンドを有する配管合流領域における非等温流体混合メカニズムの解明とサーマルストライピング緩和・制御法の開発

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上流にベンドを有する配管合流領域における非等温流体混合メカニズムの解明とサーマルストライピング緩和・制御法の開発
電磁波を利用した欠陥探傷技術に関する基礎研究

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原子炉利用期間の長期化に伴う構造健全性確保のためには、複雑な炉内構造物内に発生しうる欠陥の検査技術の開発と合理的な保全シナリオの確立が不可欠である。そこで、本基礎研究では特に、原子炉の安全性向上のための新しい大型配管、複雑構造物内の欠陥探傷技術を開発するために、電磁波を利用した配管内部の欠陥探傷方法に関する基礎研究を進める
渦電流を利用した大型配管中の欠陥探勝技術に関する研究

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原子炉利用期間の長期化に伴う構造健全性確保のためには、複雑な炉内構造物内に発生しうる欠陥の検査技術の開発が不可欠である。そこで、原子炉の安全性向上のための新しい大型配管、複雑構造物内の欠陥探傷技術を開発するために、まず、最先端の技術（Fluxsetセンサー法、Multi-Detector 渦電流プローブ法、リモートフィールド法、SQUID法等）の調査を行い、各手法の比較・検討を行う。その結果に基づいて、将来大型配管内の欠陥探傷技術に発展しうる手法を選択し、基礎的解析を行うことを目的としている