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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

Development of a hybrid ECT sensor for JSFR SG double-wall tubes

Yamaguchi, Toshihiko; Mihalache, O.

Journal of Nuclear Science and Technology, 54(11), p.1201 - 1214, 2017/11

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

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

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

Development of inspection and repair technology for the micro cracks on heat exchanger tubes

Nishimura, Akihiko; Shobu, Takahisa; Oka, Kiyoshi; Yamaguchi, Toshihiko; Shimada, Yukihiro; Mihalache, O.; Tagawa, Akihiro; Yamashita, Takuya

Reza Kako Gakkai-Shi, 17(4), p.207 - 212, 2010/10

A prototype probe system with a hybrid optical fiber scope was designed for inspecting and re-pairing the micro cracks on heat exchanger tubes in fast breeder reactors (FBRs). It comprised a laser processing head combined with an eddy current testing unit. Ultrashort laser pulse ablation was used to remove work-hardened layers. And spot laser welding was used to repair the micro cracks. This system has both safe and economical options for the maintenance of FBRs because it extends the lifetime of the heat exchangers.

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 inspection and repairing technology for FBR heat exchanger tubes, 2; Preparation of operation software and performance check

Nishimura, Akihiko; Oka, Kiyoshi; Yamaguchi, Toshihiko; Akatsu, Tomohiro*; Seki, Takeshi*; Mihalache, O.; Shimada, Yukihiro; Tagawa, Akihiro; Yamashita, Takuya

Nihon Hozen Gakkai Dai-6-Kai Gakujutsu Koenkai Yoshishu, p.250 - 253, 2009/08

In order to maintain FBR heat exchanger tubes, a new probe system was designed. A coupling unit and operational software are key components in the second year. The coupling unit to combine a high energy laser beam and optical fiberscope images was developed. The operational software successfully controlled an eddy current testing device and a laser processing head.

Journal Articles

Inspection of the steam generator heat transfer tubes for FBR Monju restart

Takahashi, Kenji; Shiina, Akira; Onizawa, Takahiro; Ibaki, Shoji; Yamaguchi, Toshihiko; Tagawa, Akihiro

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

Japanese prototype FBR Monju will restart its operation for the first time since the sodium leak accident in 1995. Concerning heat transfer tubes of the steam generator (SG) units, presumable deteriorations were studied and the integrity is confirmed when they have no lack of thickness by corrosion after the long-term suspension. It was impossible to test the tubes directly, then three tests were applied, which were ECT, VT (visual test) and leak test. ECT is to check for the lack of thickness caused by regional corrosion. VT checked for the global corrosion and the bottom of the tube. Leak test checked for pin-holes (penetrating holes). Total evaluation proved no significant lack of thickness and pin-holes in the tube.

Journal Articles

Development of the Kiso river delta during the last 10,000 years based on analyses of sedimentary cores and $$^{14}$$C datings

Ogami, Takashi*; Sugai, Toshihiko*; Fujiwara, Osamu*; Yamaguchi, Masaaki*; Sasao, Eiji

Chigaku Zasshi, 118(4), p.665 - 685, 2009/00

The depositional process of the latest Pleistocene to Holocene shallow marine and fluvial sequences is investigated by using five drill cores from the Kiso river delta, central Japan. Based on facies analysis, the sediments were classified into 5 units; A: basal gravel, B: fluvial to intertidal sand and silt, C: transgressive lag deposit, prodelta mud or sandy silt, D: delta-front-slope sandy silt or sand, delta-front-platform sand, E: delta-plain to fluvial sand and silt. Detailed age-depth curves of each cores are reconstructed based on 107 AMS $$^{14}$$C ages. The curves are divided into four sections; I: mainly consists of unit B with rapid accumulation (7.3-21.4 mm/yr), II: mainly consists of unit C with moderate accumulation (2.4-2.8 mm/yr), III: mainly consists of unit D with rapid accumulation (6.7-17.8 mm/yr), IV: consists of unit D and E with moderate accumulation (1.3-3.9 mm/yr). The section boundaries of I/II and II/III reflect inundation into the bay and achievement of progradational delta-front slope, respectively. The expanding rate of the bay is 10 m/yr during 10,200-7,900 cal yrs BP. The progradation rates of the delta are 3-4 m/yr (6.500-4,100 cal yrs BP), 5 m/yr (4,100-1,300 cal yrs BP), 10 m/yr (1,300 cal yrs BP to the present). These indicate the transition from transgression to regression occurred between 7,800 to 7,300 cal yrs BP. The geological cross section along the Kiso river coupled with isochrones indicates following history. (1) 10,000-7,280 cal yrs BP (K-Ah horizon): During the expansion of the bay, onlap of unit C on unit B is visible, and unit C overlapped all the core sites. (2) 7,280 cal yrs BP to present: Isochrones younger than 6,500 cal yrs BP are similar each other and cross unit boundaries of C/D and D/E. This demonstrates units C, D and E are contemporaneous heterotopic facies formed by progradational delta.

Journal Articles

Operating experience of the J-PARC linac

Hasegawa, Kazuo; Asano, Hiroyuki; Chishiro, Etsuji; Hori, Toshihiko; Ito, Takashi; Kobayashi, Tetsuya; Kondo, Yasuhiro; Namekawa, Yuya; Oguri, Hidetomo; Okoshi, Kiyonori; et al.

Proceedings of 24th International Linear Accelerator Conference (LINAC 2008) (CD-ROM), p.55 - 57, 2009/00

The beam commissioning of the J-PARC linac started in November 2006 and 181 MeV acceleration was successfully achieved in January 2007. The linac has delivered beams to the 3 GeV Rapid Cycling Synchrotron for its commissioning, and then, the subsequent Main Ring Synchrotron and the neutron target commissioning. The linac uses a Cs-free LaB$$_{6}$$-driven ion source and 20 units of 324 MHz klystrons. As of June 2008, the operation times are about 3,000 and 6,000 hours for the ion source and the RF source, respectively. The operating experience of the linac is described.

Journal Articles

High power test of 972 MHz waveguide systems for J-PARC Linac

Hori, Toshihiko; Yamazaki, Masayoshi; Yamaguchi, Seiya*; Hasegawa, Kazuo; Linac RF Group

NIFS-MEMO-55, p.289 - 292, 2008/03

no abstracts in English

Journal Articles

Present status of RF source operation at J-PARC linac

Yamazaki, Masayoshi; Chishiro, Etsuji; Kobayashi, Tetsuya; Hori, Toshihiko; Suzuki, Hiroyuki; Anami, Shozo*; Kawamura, Masato*; Fukui, Yuji*; Nammo, Kesao*; Fang, Z.*; et al.

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.485 - 487, 2008/00

no abstracts in English

Journal Articles

DATA collection using memory area of PLC touch panel for J-PARC linac RF

Suzuki, Hiroyuki; Chishiro, Etsuji; Kobayashi, Tetsuya; Hori, Toshihiko; Yamazaki, Masayoshi; Anami, Shozo*; Yamaguchi, Seiya*; Kawamura, Masato*; Fukui, Yuji*; Fang, Z.*

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.467 - 469, 2008/00

no abstracts in English

77 (Records 1-20 displayed on this page)