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Journal Articles

Emergent spin-1 Haldane gap and ferroelectricity in a frustrated spin-$$frac{1}{2}$$ ladder

Ueda, Hiroshi*; Onoda, Shigeki*; Yamaguchi, Yasuhiro*; Kimura, Tsuyoshi*; Yoshizawa, Daichi*; Morioka, Toshiaki*; Hagiwara, Masayuki*; Hagiwara, Masato*; Soda, Minoru*; Masuda, Takatsugu*; et al.

Physical Review B, 101(14), p.140408_1 - 140408_6, 2020/04

 Times Cited Count:2 Percentile:44.66(Materials Science, Multidisciplinary)

Journal Articles

Progress in developments of an EMAT based on a Halbach magnet system for FBR vessel

Yamaguchi, Toshihiko; Mihalache, O.; Ueda, Masashi

International Journal of Applied Electromagnetics and Mechanics, 59(4), p.1469 - 1477, 2019/03

 Times Cited Count:4 Percentile:51.67(Engineering, Electrical & Electronic)

Journal Articles

A Consideration on the use of shear waves to improve the sensitivity of an optical ultrasonic sensor for under-sodium viewers

Saruta, Koichi; Shirahama, Takuma*; Yamaguchi, Toshihiko; Ueda, Masashi

E-Journal of Advanced Maintenance (Internet), 10(2), p.1 - 8, 2018/08

Journal Articles

Thermal management of heat resistant FBG sensing for high temperature industrial plants

Nishimura, Akihiko; Takenaka, Yusuke*; Furusawa, Akinori; Torimoto, Kazuhiro; Ueda, Masashi; Fukuda, Naoaki*; Hirao, Kazuyuki*

E-Journal of Advanced Maintenance (Internet), 9(2), p.52 - 59, 2017/08

no abstracts in English

Journal Articles

R&D of multi-frequency ECT algorithms for FBR SG tubes

Mihalache, O.; Yamaguchi, Toshihiko; Shirahama, Takuma; Ueda, Masashi

E-Journal of Advanced Maintenance (Internet), 9(2), p.60 - 65, 2017/08

Journal Articles

R&D of multi-frequency ECT algorithms for FBR SG tubes

Mihalache, O.; Yamaguchi, Toshihiko; Shirahama, Takuma; Ueda, Masashi

Proceedings of 3rd International Conference on Maintenance Science and Technology (ICMST 2016) (Internet), 2 Pages, 2016/11

Journal Articles

Journal Articles

Experimental measurements and simulations of ect signal for ferromagnetic SG tubes covered by a sodium layer

Yamaguchi, Toshihiko; Mihalache, O.; Ueda, Masashi

Electromagnetic Nondestructive Evaluation (XVII), p.144 - 154, 2014/00

 Times Cited Count:3 Percentile:90.06

For a Fast Breeder Reactor (FBR) cooled by liquid sodium, the wall of steam generator tubes (SG) is the only barrier between sodium in the tubes vessel and water inside of tubes. By using eddy currents, the SG tube integrity is usually assured during the In-Service Inspection (ISI). During this procedure, the 500 degrees sodium is drained and then SG tubes cooled down slowly in 2 weeks to room temperature. After sodium draining, sodium adheres to SG tubes and other structures in the SG vessel in thin layers. Experimental data shows that sodium drops also appear in specific areas along tubes or tube support plates. The high electrical conductivity of sodium adhering to the outer SG tube surface influences the ECT signal according to sodium layer thickness or sodium deposits located on the outer SG tube surface. The sodium adhering properties depends on several factors among them being the surface roughness of tube material, sodium temperature and wetting time. The ECT effect of sodium adhering to the outer SG tube surface was measured using a small mock-up tank in which were introduced SG tubes similar with the ones in FBR (2.25Cr-1Mo alloy). Defects and support plates were added to tubes and ECT signal was measured before and after sodium draining. Variations in the sodium layer thickness and consequently its ECT effect were measured by filling and draining the tank three times in order to recreate each time new layers of sodium. The paper describes the experimental conditions for defects, SG support plates signal before and after draining of sodium. Additionally, sodium structures were visualized using a CCD camera, confirming the recorded ECT signals. The paper presents details about sodium layer measurements for several parts of the SG tubes by scratching and collecting the sodium on small areas 10x10 square mm. Numerical 3D simulations are performed using a 3D FEM code developed in our laboratory in order to validate the performance of the ECT sensors detection.

Journal Articles

Validations of multifrequency ECT algorithms for helical SG tubes of FBR

Mihalache, O.; Yamaguchi, Toshihiko; Ueda, Masashi

Electromagnetic Nondestructive Evaluation (XVII), p.109 - 119, 2014/00

 Times Cited Count:3 Percentile:90.06

Journal Articles

Functional test of the ISI system for pipes of MONJU primary heat transfer system

Maeda, Yukihiro; Yamaguchi, Toshihiko; Ueda, Masashi; Fujiki, Kazunari*

Nihon Hozen Gakkai Dai-10-Kai Gakujutsu Koenkai Yoshishu, p.599 - 601, 2013/07

An inspection system was developed for in-service inspection (ISI) of pipes in the primary heat transfer system of MONJU FBR. The system was updated and modified based on experience from the pre-service inspection and related tests. This paper describes the results of the functional tests of the new inspection system on a mockup and in MONJU, which confirmed it can satisfy the expected performance.

Journal Articles

EMAT simulations based on a two-dimensional FEM coupled electro-mechanical formulation

Garcia Rodriguez, D.; Mihalache, O.; Ueda, Masashi

Proceedings of 16th International Symposium on Applied Electromagnetics and Mechanics (ISEM 2013), p.219 - 220, 2013/07

Journal Articles

Perpendicular magnetic anisotropy with enhanced orbital moments of Fe adatoms on a topological surface of Bi$$_2$$Se$$_3$$

Ye, M.*; Kuroda, Kenta*; Takeda, Yukiharu; Saito, Yuji; Okamoto, Kazuaki*; Zhu, S.-Y.*; Shirai, Kaito*; Miyamoto, Koji*; Arita, Masashi*; Nakatake, Masashi*; et al.

Journal of Physics; Condensed Matter, 25(23), p.232201_1 - 232201_5, 2013/06

 Times Cited Count:11 Percentile:50.94(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Large scale 3D FEM electromagnetic simulations and validations for FBR steam generator tubes

Mihalache, O.; Yamaguchi, Toshihiko; Ueda, Masashi

Abstracts of Electromagnetic Nondestructive Evaluation Series, p.42 - 43, 2012/07

Journal Articles

Quasiparticle interference on the surface of Bi$$_{2}$$Se$$_{3}$$ induced by cobalt adatom in the absence of ferromagnetic ordering

Ye. M.*; Eremeev, S. V.*; Kuroda, Kenta*; Krasovskii, E. E.*; Chulkov, E. V.*; Takeda, Yukiharu; Saito, Yuji; Okamoto, Kazuaki*; Zhu, S. Y.*; Miyamoto, Koji*; et al.

Physical Review B, 85(20), p.205317_1 - 205317_5, 2012/05

 Times Cited Count:54 Percentile:90.06(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

R&D on maintenance technologies for FBR plants in JAEA; The Status quo and the future plan

Tsukimori, Kazuyuki; Ueda, Masashi; Miyahara, Shinya; Yamashita, Takuya

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 10 Pages, 2012/00

Journal Articles

Development of an ISI robot for the fast breeder reactor MONJU primary heat transfer system piping

Tagawa, Akihiro; Ueda, Masashi; Yamashita, Takuya; Narisawa, Masataka*; Haga, Koichi*

Journal of Nuclear Science and Technology, 48(4), p.504 - 509, 2011/04

This paper describes the development of a new inspection robot for the in-service inspection of the heat transfer system of the fast breeder reactor MONJU. The inspection was carried out using a tire-type ultrasonic sensor for volumetric tests at high temperature (atmosphere, 55 $$^{circ}$$C; piping surface, 80 $$^{circ}$$C) and radiation exposure condition (dose rate, 10 mGy/h; piping surface dose rate, 15 mGy/h). An inspection robot using a new tire type for the ultrasonic testing sensor and a new control method was developed. A signal-to-noise ratio S/N over 2 was obtained during the functional test for a calibration defect with a depth of 50%t (from the tube wall thickness). In the automatic inspection test, an EDM slit with a depth of 9% from the pipe thickness was detectable and with an S/N ratio = 4.0 (12.0 dB).

Journal Articles

3D RFEC simulations for the in-service inspection of steam generator tubes in fast breeder reactors

Mihalache, O.; Yamaguchi, Toshihiko; Ueda, Masashi; Miyahara, Shinya

International Journal of Applied Electromagnetics and Mechanics, 33(3-4), 6 Pages, 2010/00

In FBR, one of the techniques used in the ISI of magnetic steam generator (SG) tubes is the remote field eddy current technique (RF-ECT). The SG tubes, made of 2.25Cr-1Mo alloy, are very long, including several parts with helical, bent and straight shape. The longer parts of these tubes are fixed in a helical shape-structure using multiple support plates (SP) which are also ferromagnetic. The complicated shape of the SP and multiple connections of several tubes to the SP can be quantitatively analyzed only by a 3-dimensional analysis, in order to evaluate the influences in the ECT signal due to the close proximity of the SG tubes. Also, the tube curvature and additionally the presence of sodium on the outer tube surface induces supplementary effects. The paper presents 3D finite element simulations of the SG inspection using RF-ECT. It is evaluated the influences of the SG tubes curvature on the eddy current sensor signal.

Journal Articles

Development of a SH wave single unit electromagnetic acoustic transducer (EMAT) for MONJU reactor vessel in-service inspection

Xu, Y.*; Tagawa, Akihiro; Fujiki, Kazunari*; Ueda, Masashi; Yamashita, Takuya

Proceedings of 17th International Conference on Nuclear Engineering (ICONE-17) (CD-ROM), 9 Pages, 2009/07

In-service inspection is carried out to confirm the integrity of the main components of "MONJU". The ambient temperature during the inspection is 200 $$^{circ}$$C and the irradiation field is 10 Gy/hr. A Periodic Permanent Magnet (PPM) structure has been used for electromagnetic acoustic transducer (EMAT). The PPM structure is the structure of putting in order alternately the S pole and N pole laterally magnetized magnets. A Halbach magnet structure is the structure which sandwiched the longitudinally magnetized magnets between each magnet of PPM structure. Thereby, magnetic flux density is improved 1.4 times. Moreover, it also checked aiming at 4 times as many improvement in detection sensitivity as this by a new signal processing method. The high temperature characteristic and high temperature durability of Halbach type EMAT in 200 hours which corresponds the twice of inspection time under the 200 $$^{circ}$$C inspection environment are reported.

Journal Articles

The Pipe health monitoring method by Hybrid measurement using ultrasonic

Tagawa, Akihiro; Ueda, Masashi; Miyahara, Shinya; Yamashita, Takuya

Nihon Hozen Gakkai Dai-5-Kai Gakujutsu Koenkai Yoshishu, p.470 - 472, 2008/07

This paper describes the development of a new sensor for the pipe health monitoring. The Hybrid measuring using EMAT was made as a trial. It examined and checked that it could measure. The result confirmed that the high accuracy of 200 $$^{circ}$$C at high temperature was acquired in pipe surface temperature, pipe wall thinning, and water temperature.

73 (Records 1-20 displayed on this page)