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Yamaguchi, Toshihiko; Mihalache, O.
Nuclear Engineering and Design, 401, p.112084_1 - 112084_14, 2023/01
Times Cited Count：1 Percentile：31.61(Nuclear Science & Technology)Yamaguchi, Toshihiko; Mihalache, O.; Ueda, Masashi
International Journal of Applied Electromagnetics and Mechanics, 59(4), p.1469 - 1477, 2019/03
Times Cited Count：5 Percentile：33.23(Engineering, Electrical & Electronic)Saruta, Koichi; Shirahama, Takuma*; Yamaguchi, Toshihiko; Ueda, Masashi
E-Journal of Advanced Maintenance (Internet), 10(2), p.1 - 8, 2018/08
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)Mihalache, O.; Yamaguchi, Toshihiko; Shirahama, Takuma; Ueda, Masashi
E-Journal of Advanced Maintenance (Internet), 9(2), p.60 - 65, 2017/08
Yamaguchi, Mika; Hidaka, Akihide; Ikuta, Yuko; Murakami, Kenta*; Tomita, Akira*; Hirose, Hiroya*; Watanebe, Masanori*; Ueda, Kinichi*; Namaizawa, Ken*; Onose, Takatoshi*; et al.
JAEA-Review 2017-002, 60 Pages, 2017/03
JAEA-Review-2017-002.pdf:9.41MB
Since 2010, IAEA has held the NEM School to develop future leaders who plan and manage nuclear energy utilization in their county. Since 2012, JAEA together with Japan Nuclear HRD Network, University of Tokyo, Japan Atomic Industrial Forum and JAIF International Cooperation Center have cohosted the school in Japan in cooperation with IAEA. Since then, the school has been held in Japan every year. In 2006, Japanese nuclear technology and experience, such as lessons learned from the Fukushima Daiichi Nuclear Power Plant accident, were provided to offer a unique opportunity for the participants to learn about particular cases in Japan. Through the school, we contributed to the internationalization of Japanese young nuclear professionals, development of nuclear human resource of other countries including nuclear newcomers, and enhanced cooperative relationship with IAEA. Additionally, collaborative relationship within the network was strengthened by organizing the school in Japan.
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
Saruta, Koichi; Yamaguchi, Toshihiko; Ueda, Masashi
E-Journal of Advanced Maintenance (Internet), 7(4), p.NT75_1 - NT75_8, 2016/02
Saruta, Koichi; Yamaguchi, Toshihiko; Ueda, Masashi
EUR-27790-EN, p.209 - 214, 2016/00
Yamaguchi, Toshihiko; Mihalache, O.; Ueda, Masashi
Electromagnetic Nondestructive Evaluation (XVII), p.144 - 154, 2014/00
Times Cited Count：3 Percentile：86.04(Engineering, Electrical & Electronic)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.
Mihalache, O.; Yamaguchi, Toshihiko; Ueda, Masashi
Electromagnetic Nondestructive Evaluation (XVII), p.109 - 119, 2014/00
Times Cited Count：3 Percentile：86.04(Engineering, Electrical & Electronic)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.
Mihalache, O.; Yamaguchi, Toshihiko; Ueda, Masashi
Abstracts of Electromagnetic Nondestructive Evaluation Series, p.42 - 43, 2012/07
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.
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.
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.
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.
Mihalache, O.; Yamaguchi, Toshihiko; Ueda, Masashi; Yamashita, Takuya; Date, Koji*
Dai-9-Kai Hyomen Tansho Shimpojiumu Koen Rombunshu, p.57 - 62, 2006/02
no abstracts in English
Sakakibara, Yasuhide; IKEDA, Hiroshi; Yokota, Yoshio; Kitabata, Takuya; Yamaguchi, Toshihiko
JNC TN4200 2004-001, 317 Pages, 2004/08
JNC-TN4200-2004-001.pdf:24.97MB
None
Mihalache, O.; Yamaguchi, Toshihiko; Ueda, Masashi; Yamashita, Takuya; Date, Koji*
no journal, ,
The paper presents the experimental measurements of detection of small defects in magnetic steam generator (SG) tubes using new designed remote field eddy current (RFEC) multiple vertical and horizontal coils. The coils geometrical characteristics were previously optimized based on three-dimensional numerical simulations of small defect detection using RFEC. During measurements the detection capabilities of the new multiple coils and of the old type Bobbin coil design are compared.
