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Journal Articles

Development of inspection and repair techniques for reactor vessel of experimental fast reactor "Joyo"; Replacement of upper core structure

Takamatsu, Misao; Kawahara, Hirotaka; Ito, Hiromichi; Ushiki, Hiroshi; Suzuki, Nobuhiro; Sasaki, Jun; Ota, Katsu; Okuda, Eiji; Kobayashi, Tetsuhiko; Nagai, Akinori; et al.

Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(1), p.32 - 42, 2016/03

In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly of "MARICO-2" (material testing rig with temperature control) had been broken and bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). This paper describes the results of the in-vessel repair techniques for UCS replacement, which are developed in Joyo. UCS replacement was successfully completed in 2014. In-vessel repair techniques for sodium cooled fast reactors (SFRs) are important in confirming its safety and integrity. In order to secure the reliability of these techniques, it was necessary to demonstrate the performance under the actual reactor environment with high temperature, high radiation dose and remained sodium. The experience and knowledge gained in UCS replacement provides valuable insights into further improvements for In-vessel repair techniques in SFRs.

Journal Articles

Replacement of upper core structure in experimental fast reactor Joyo, 1; Existing damaged upper core structure jack-up test

Ito, Hiromichi; Suzuki, Nobuhiro; Kobayashi, Tetsuhiko; Kawahara, Hirotaka; Nagai, Akinori; Sakao, Ryuta*; Murata, Chotaro*; Tanaka, Junya*; Matsusaka, Yasunori*; Tatsuno, Takahiro*

Proceedings of 2015 International Congress on Advances in Nuclear Power Plants (ICAPP 2015) (CD-ROM), p.1058 - 1067, 2015/05

In the experimental fast reactor Joyo (Sodium-cooled Fast Reactor (SFR)), it was confirmed that the top of the irradiation test sub-assembly had bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). There is a risk of deformation of the UCS and guide sleeve (GS) caused by interference between them unless inclination is controlled precisely. To mitigate the risk, special jack-up equipment for applying three-point suspension was developed. The existing damaged UCS (ed-UCS) jack-up test using the jack-up equipment was conducted on May 7, 2014. As a result of this test, it was confirmed that the ed-UCS could be successfully jacked-up to 1000 mm without consequent overload. The experience and knowledge gained in the ed-UCS jack-up test provides valuable insights and prospects not only for UCS replacement but also for further improving and verifying repair techniques in SFRs.

Journal Articles

Sagittal focusing of synchrotron radiation X-rays using a winged crystal

Nisawa, Atsushi*; Yoneda, Yasuhiro; Ueno, Go*; Murakami, Hironori*; Okajima, Yuka*; Yamamoto, Kenichiro*; Semba, Yasunori*; Uesugi, Kentaro*; Tanaka, Yoshihito*; Yamamoto, Masaki*; et al.

Journal of Synchrotron Radiation, 20(2), p.219 - 225, 2013/03

 Times Cited Count:11 Percentile:56.62(Instruments & Instrumentation)

A Si(111) winged crystal has been designed to minimize anticlastic bending and improve sagittal focusing efficiency. The crystal was thin with wide stiffening wings. The length-to-width ratio of the crystal was optimized by finite element analysis, and the optimal value was larger than the "golden value". The analysis showed that the slope error owing to anticlastic bending is less than the Darwin width. The X-rays were focused two-dimensionally using the crystal and a tangentially bent mirror. The observed profiles of the focal spot agreed well with the results of a ray-tracing calculation in the energy range from 8 to 17.5 keV. X-ray diffraction measurements with a high signal-to-noise ratio using this focusing system were demonstrated for a small protein crystal.

Journal Articles

Radiation response of silicon carbide diodes and transistors

Oshima, Takeshi; Onoda, Shinobu; Iwamoto, Naoya; Makino, Takahiro; Arai, Manabu*; Tanaka, Yasunori*

Physics and Technology of Silicon Carbide Devices, p.379 - 402, 2012/10

SiC is regarded as a promising candidate for electronic devices used in harsh radiation environments because of its high radiation tolerance. Radiation effects on SiC devices are reviewed. Firstly, the Total Ionizing Dose (TID) effect in Metal-Oxide-Semiconductor (MOS) Field Effect Transistors (FETs) is introduced. Then, the radiation hardness of SiC based transistors such as MOSFETs, Metal-Semiconductor (MES) FETs, Static Induction Transistors (SITs) is discussed from the point of view of $$gamma$$-ray irradiation effects. Transient current induced in SiC pn diodes by heavy ions incidence, which is important information on the single event effects (SEEs), is also expressed.

Journal Articles

In-vessel tritium

Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09

no abstracts in English

Journal Articles

Characteristic heavy fermion properties in YbCu$$_2$$Si$$_2$$ and YbT$$_2$$Zn$$_{20}$$ (T: Co, Rh, Ir)

Onuki, Yoshichika; Yasui, Shinichi*; Matsushita, Masaki*; Yoshiuchi, Shingo*; Oya, Masahiro*; Hirose, Yusuke*; Dung, N. D.*; Honda, Fuminori*; Takeuchi, Tetsuya*; Settai, Rikio*; et al.

Journal of the Physical Society of Japan, 80(Suppl.A), p.SA003_1 - SA003_6, 2011/12

Journal Articles

Simulation of dynamics of carbon dust particles in the JT-60U tokamak

Tanaka, Yasunori*; Smirnov, R. D.*; Pigarov, A. Y.*; Takenaga, Hidenobu; Asakura, Nobuyuki; Uesugi, Yoshihiko*; Ono, Noriyasu*

Journal of Nuclear Materials, 415(Suppl.1), p.S1106 - S1110, 2011/08

 Times Cited Count:8 Percentile:58.2(Materials Science, Multidisciplinary)

Dust can be an important contributor to impurity contamination of the core and scrape-off-layer (SOL) plasmas in tokamak fusion devices. This is the first report about investigation of transport of carbon dust particles in case of JT-60U tokamak using the dust transport code (DUSTT). The DUSTT code takes into account various plasma-dust interaction processes. In the present report, background plasma parameters in JT-60U such as densities and temperatures of electron, ion and neutral atom were computed with the UEDGE code. Three dimensional trajectories, temperature evolution, and radius variation of dust particles launched from different positions at the inner divertor, the outer divertor and the dome structure in JT-60U tokamak were simulated numerically to study dynamics and transport of dust particles there. As a result, the lifetime of dust particles is dependent mainly on the ion density in trajectories in final term.

Journal Articles

Ablation of insulators under the action of short pulses of X-ray plasma lasers and free-electron lasers

Inogamov, N. A.*; Anisimov, S. I.*; Petrov, Y. V.*; Khokhlov, V. A.*; Zhakhovskii, V. V.*; Faenov, A. Ya.*; Pikuz, T.; Fortov, V. E.*; Skobelev, I. Y.*; Kato, Yoshiaki*; et al.

Journal of Optical Technology, 78(8), p.473 - 480, 2011/08

 Times Cited Count:5 Percentile:31.11(Optics)

Journal Articles

Development of silicon carbide devices with high radiation resistance

Oshima, Takeshi; Onoda, Shinobu; Tanaka, Yasunori*; Arai, Manabu*

Isotope News, (686), p.8 - 12, 2011/06

no abstracts in English

Journal Articles

Metamagnetic behavior in heavy-fermion compound YbIr$$_2$$Zn$$_{20}$$

Takeuchi, Tetsuya*; Yasui, Shinichi*; Toda, Masatoshi*; Matsushita, Masaki*; Yoshiuchi, Shingo*; Oya, Masahiro*; Katayama, Keisuke*; Hirose, Yusuke*; Yoshitani, Naohisa*; Honda, Fuminori*; et al.

Journal of the Physical Society of Japan, 79(6), p.064609_1 - 064609_15, 2010/06

 Times Cited Count:39 Percentile:84.44(Physics, Multidisciplinary)

Journal Articles

Radiation hardness evaluation of SiC-BGSIT

Tanaka, Yasunori*; Onoda, Shinobu; Takatsuka, Akio*; Oshima, Takeshi; Yatsuo, Tsutomu*

Materials Science Forum, 645-648, p.941 - 944, 2010/04

no abstracts in English

Journal Articles

Heavy fermion state in YbIr$$_2$$Zn$$_{20}$$

Yoshiuchi, Shingo*; Toda, Masatoshi*; Matsushita, Masaki*; Yasui, Shinichi*; Hirose, Yusuke*; Oya, Masahiro*; Katayama, Keisuke*; Honda, Fuminori*; Sugiyama, Kiyohiro*; Hagiwara, Masayuki*; et al.

Journal of the Physical Society of Japan, 78(12), p.123711_1 - 123711_4, 2009/12

 Times Cited Count:37 Percentile:83.56(Physics, Multidisciplinary)

Journal Articles

27th report of ITPA topical group meeting

Osakabe, Masaki*; Shinohara, Koji; Toi, Kazuo*; Todo, Yasushi*; Hamamatsu, Kiyotaka; Murakami, Sadayoshi*; Yamamoto, Satoshi*; Idomura, Yasuhiro; Sakamoto, Yoshiteru; Tanaka, Kenji*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 85(12), p.839 - 842, 2009/12

no abstracts in English

Journal Articles

Tritium science and technology for fusion reactor, 3; Theory and code development for evaluation of tritium retention and exhaust in fusion reactor

Oya, Kaoru*; Inai, Kensuke*; Shimizu, Katsuhiro; Takizuka, Tomonori; Kawashima, Hisato; Hoshino, Kazuo; Hatayama, Akiyoshi*; Toma, Mitsunori*; Tomita, Yukihiro*; Kawamura, Gakushi*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 85(10), p.695 - 703, 2009/10

no abstracts in English

Journal Articles

Current status of the control system for J-PARC accelerator complex

Yoshikawa, Hiroshi; Sakaki, Hironao; Sako, Hiroyuki; Takahashi, Hiroki; Shen, G.; Kato, Yuko; Ito, Yuichi; Ikeda, Hiroshi*; Ishiyama, Tatsuya*; Tsuchiya, Hitoshi*; et al.

Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.62 - 64, 2007/10

J-PARC is a large scale facility of the proton accelerators for the multi-purpose of scientific researches in Japan. This facility consists of three accelerators and three experimental stations. Now, J-PARC is under construction, and LINAC is operated for one year, 3GeV synchrotron has just started the commissioning in this October the 1st. The completion of this facility will be next summer. The control system of accelerators established fundamental performance for the initial commissioning. The most important requirement to the control system of this facility is to minimize the activation of accelerator devices. In this paper, we show that the performances of each layer of this control system have been achieved in the initial stage.

Journal Articles

Relationship between the current direction in the inversion layer and the electrical characteristics of metal-oxide-semiconductor field effect transistors on 3C-SiC

Oshima, Takeshi; Lee, K. K.; Ishida, Yuki*; Kojima, Kazutoshi*; Tanaka, Yasunori*; Takahashi, Tetsuo*; Yoshikawa, Masahito; Okumura, Hajime*; Arai, Kazuo*; Kamiya, Tomihiro

Materials Science Forum, 457-460(Part2), p.1405 - 1408, 2004/06

The electrical characteristics of cubic silicon carbide (3C-SiC) Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) with the current direction in the inversion layer perpendicular to [-110] ([-110]-perpendicular MOSFETs) were compared to those of 3C-SiC MOSFETs with the current direction in the inversion layer parallel to [-110] ([-110]-parallel MOSFETs). The threshold voltage (V$$_{T}$$) for both MOSFETs shows -0.5 V although enhancement type MOSFETs were designed. The values of channel mobility which was estimated from linear region of drain current (I$$_{D}$$) - drain voltage (V$$_{D}$$) curves are 230 cm$$^{2}$$/Vs for [-110]-perpendicular MOSFETs and 215 cm$$^{2}$$/Vs for [-110]-parallel MOSFETs, indicating no significant difference between both MOSFETs. The value of I$$_{D}$$ for [-110]-perpendicular MOSFETs is of order of 10-8 A at V$$_{D}$$ = 10V and gate voltage (V$$_{G}$$) of -2V. However, for [-110]-parallel MOSFETs, I$$_{D}$$ shows of order of -10-6 A at V$$_{D}$$ = 10V and V$$_{G}$$ = -2V.

Journal Articles

The Electrical characteristics of metal-oxide-semiconductor field effect transistors fabricated on cubic silicon carbide

Oshima, Takeshi; Lee, K. K.; Ishida, Yuki*; Kojima, Kazutoshi*; Tanaka, Yasunori*; Takahashi, Tetsuo*; Yoshikawa, Masahito; Okumura, Hajime*; Arai, Kazuo*; Kamiya, Tomihiro

Japanese Journal of Applied Physics, Part 2, 42(6B), p.L625 - L627, 2003/06

 Times Cited Count:37 Percentile:77.51(Physics, Applied)

The n-channel Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) were fabricated on cubic silicon carbide (3C-SiC) epitaxial layers grown on 3C-SiC substrates. The gate oxide of the MOSFETs was formed using pyrogenic oxidation at 1100$$^{circ}$$C. The 3C-SiC MOSFETs showed enhancement type behaviors after annealing at 200$$^{circ}$$C for 30 min in argon atmosphere. The maximum value of the effective channel mobility of the 3C-SiC MOSFETs was 260 cm$$^{2}$$/Vs. The leakage current of gate oxide was of a few tens of nA/cm$$^{2}$$ at an electric field range below 8.5 MV/cm, and breakdown began around 8.5 MV/cm.

JAEA Reports

Evaluation of energy response of neutron rem monitor applied to high-energy accelerator facilities

Nakane, Yoshihiro; Harada, Yasunori; Sakamoto, Yukio; Oguri, Tomomi*; Yoshizawa, Michio; Takahashi, Fumiaki; Ishikura, Takeshi*; Fujimoto, Toshiaki*; Tanaka, Susumu; Sasamoto, Nobuo

JAERI-Tech 2003-011, 37 Pages, 2003/03

JAERI-Tech-2003-011.pdf:1.73MB

no abstracts in English

Oral presentation

Effects of $$gamma$$-ray irradiation on electrical characteristics of SiC schottky barrier diode

Kinoshita, Akimasa*; Tanaka, Yasunori*; Tanaka, Tomoyuki*; Fukuda, Kenji*; Arai, Kazuo*; Oshima, Takeshi; Hishiki, Shigeomi

no journal, , 

no abstracts in English

Oral presentation

Measurements of carbon dust by fast TV camera and YAG Laser scattering in JT-60U

Asakura, Nobuyuki; Hatae, Takaki; Kawashima, Hisato; Nakano, Tomohide; Ono, Noriyasu*; Tanaka, Yasunori*; Uesugi, Yoshihiko*

no journal, , 

no abstracts in English

31 (Records 1-20 displayed on this page)