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Segawa, Tomoomi; Fukasawa, Tomonori*; Yamada, Yoshikazu; Suzuki, Masahiro; Yoshida, Hideto*; Fukui, Kunihiro*
Proceedings of Asian Pacific Confederation of Chemical Engineering 2015 (APCChE 2015), 8 Pages, 2015/09
A mixed solution of uranyl nitrate and plutonium nitrate is converted to MOX raw powder by the microwave heating de-nitration method in nuclear reprocessing. Copper oxide synthesized by heating de-nitration was used as a model for the de-nitration process. The microwave heating method (MW) and infrared heating method (IR) were used, and how they and their heating rate influence the obtained particle morphology and size were investigated. The particles obtained by the MW and IR were sufficiently similar in the surface morphology and the mass median diameter was decreased by the increased heating rate. The mass median diameters by the MW were the heating rate and smaller than those obtained by IR. The particle size distribution of the particle obtained by the MW was broader than that by the IR. The relationship of the temperature distribution and particle size distribution by the MW was discussed by the numerical simulation.
Murakami, Haruyuki; Kizu, Kaname; Tsuchiya, Katsuhiko; Kamiya, Koji; Takahashi, Yoshikazu; Yoshida, Kiyoshi
Fusion Engineering and Design, 87(1), p.23 - 29, 2012/01
Times Cited Count：10 Percentile：60.35(Nuclear Science & Technology)The JT-60 is planned to be modified to a full-superconducting tokamak. The maximum temperature of the magnet during its quench might reach the temperature of higher than several hundreds Kelvin that will damage the magnet itself. The high precision quench detection system, therefore, is important in the protection system. The disk-shaped pickup coils are inserted in the CS module for quench detection. Thus we improved the analysis model to evaluate the applicability of the disk-shaped pickup coils to quench detection system during the fast plasma event, such as disruption, by introducing the passive coil series such as vacuum vessel and stabilizer. The analysis results show that the disk-shaped pickup coil is applicable whenever the standard operation and fast plasma event. Additionally, the pickup coil design method is also modified to reduce the total cost of protection system. In this paper, the improved analysis method, modified design method and those results are described.
Takahashi, Yoshikazu; Yoshida, Kiyoshi; Nabara, Yoshihiro; Edaya, Masahiro*; Bessette, D.*; Shatil, N.*; Mitchell, N.*
IEEE Transactions on Applied Superconductivity, 17(2), p.2426 - 2429, 2007/06
Times Cited Count：14 Percentile：58.29(Engineering, Electrical & Electronic)The ITER TF coils consists of 18 D-shape coils. The operating current, the maximum field and the stored magnetic energy are 68 kA, 11.8 T and 41 GJ, respectively. A Nb
Sn cable-in-conduit conductor with a central channel is used, with a cooling length of 380 m. An accurate prediction of the coil performance requires, in addition to assessments of the superconductor behavior, a thermohydraulic analysis of the supercritical He. The overall thermohydraulic conditions were simulated by the full-scale quasi three dimensional code VINCENTA. Analysis of stability and quench was carried out using one dimensional Gandalf electric and thermohydraulic code. An interface was written between these codes. The stability margin against the mechanical disturbance and due to a plasma disruption was estimated. In the quench analysis, the temperature rise during the fast discharge was calculated. According to these results, it is confirmed that the TF coils will be operated with the designed performance.
Yoshida, Kiyoshi; Takahashi, Yoshikazu; Iida, Hiromasa
IEEE Transactions on Applied Superconductivity, 16(2), p.775 - 778, 2006/06
Times Cited Count：1 Percentile：11.95(Engineering, Electrical & Electronic)The ITER superconducting coil system consists of 18 TF coils, 6 PF coils, 6 CS modules, 18 Correction Coils and their feeders. An extensive measurement and control system is required to monitor and to control these coils and feeders for safety and optimal operational availability. For each coil, both current and helium are supplied from external systems and are controlled from a central control system that manages flow distribution at each cooling pass to smooth the cryoplant loads by a virtual model of the coil thermo-hydraulic system. Quench detection is provided as stand alone system. Monitoring of the electric insulation system inside the coils is performed to detect incipient problems before serious damage. The ITER will procure directly all sensors, wires, electrical insulation breaks and cryogenic components for all the coils and feeders to a common specification. This will avoid duplication of qualification work and guarantee a common interface. This paper introduces the requirements and specifications of the control and instrumentation for the ITER magnet system.
Takahashi, Yoshikazu; Yoshida, Kiyoshi; Nabara, Yoshihiro; Edaya, Masahiro*; Mitchell, N.*
IEEE Transactions on Applied Superconductivity, 16(2), p.783 - 786, 2006/06
Times Cited Count：9 Percentile：46.66(Engineering, Electrical & Electronic)To investigate the conductor behavior during a quench, quench tests of Center Solenoid (CS) insert coils were carried out with various initial conditions in DC and pulse modes. The conductor has very similar configuration and parameters. The inductive heater, attached at the center of the length, initiated an artificial quench in DC mode. A quench has also occurred during the pulse operation with the ramping rate of 0.4-2 T/s. Simulations of electric, thermal and hydraulic behaviors of the conductor during the quench tests in both modes were carried out by using the thermohydraulic simulation code. The experimental results were compared with the simulation and good agreement was obtained. These results are described and the implication for quench detection in ITER is discussed in this paper. The voltage tap method will be used for the quench detection for the CS, and the sensitivity of the detection and the maximum temperature of the conductor during a quench are described. It is shown that the detection system could be designed with high enough detection sensitivity.
Yoshida, Kiyoshi; Takahashi, Yoshikazu; Isono, Takaaki; Mitchell, N.*
Fusion Engineering and Design, 75-79, p.241 - 247, 2005/11
Times Cited Count：10 Percentile：56.74(Nuclear Science & Technology)The ITER superconducting magnet system stores energy of 50 GJ during plasma operation, and generates an average heat load of 23 kW at 4 K to cryoplant. The helium is distributed to the coil through 30 separate feeder lines. The feeders also contain the electrical supplies to the coil and are integrated into the current lead transition to room temperature. The interface components between the coils and the service facilities (power supply and cryogenic plant) consist of the in-cryostat feeders, the cryostat feedthroughs, and the coil terminal boxes (CTBs). The cryostat feedthroughs with S-bend boxes allow thermal contraction of the magnet system. The layout of the in-cryostat feeders takes into consideration routing restrictions in the cryostat and initial assembly with other Tokamak components. The forced-flow-cooled current leads with a conventional copper heat exchanger in the CTBs are adapted to fit in the limited space in the building. This paper presents the latest design concept and parameters of the feeder components.
Takahashi, Yoshikazu; Yoshida, Kiyoshi; Mitchell, N.*
IEEE Transactions on Applied Superconductivity, 15(2), p.1395 - 1398, 2005/06
Times Cited Count：8 Percentile：43.7(Engineering, Electrical & Electronic)The quench detection is important and necessary for the coil protection. The voltage tape method and the flow meter method are both considered for the ITER Central Solenoid (CS). The voltage tap method is primary due to its quick response. The CS consists of six pancake wound modules, which are operated with individual operating current patterns in ac mode. The induced voltage in the windings must be compensated to detect the voltage due to any normal transition during pulse operation. We have investigated the optimum configuration for pick-up coils (PC) for compensation. The results of simulations show that the compensated voltages are very low (70 mV) compared with the inductive voltage and adequate normal voltage sensitivity is obtained. The hot spot temperature in the CS during the operation was estimated from the simulation and the experimental data of the CSMC quench. The hot spot temperature estimated is about 144 K, lower than the ITER design criterion (150 K). It is shown that the detection system using the PCs could be designed with a high enough detection sensitivity.
Takahashi, Yoshikazu; Yoshida, Kiyoshi; Mitchell, N.*; Bessette, D.*; Nunoya, Yoshihiko; Matsui, Kunihiro; Koizumi, Norikiyo; Isono, Takaaki; Okuno, Kiyoshi
IEEE Transactions on Applied Superconductivity, 14(2), p.1410 - 1413, 2004/06
Times Cited Count：10 Percentile：48.21(Engineering, Electrical & Electronic)Cable-in-conduit conductors that consist of about 1,000 NbSn strands with an outer diameter of about 0.8mm, have been designed for the TF and CS coils of the ITER. The rated current of these coils is 40 -68kA. Two joint types (Butt and Lap) were developed during the CS Model Coil project. The performance of these joints was evaluated during the operating tests and the satisfied results were obtained. The joints of the TF coils are located outside of the winding in a region where the magnetic field is about 2.1T, a very low value as compared to the maximum field of 11.8T at the winding. The CS joints are located at the coil outer diameter and embedded within the winding pack due to the lack of the space. The maximum fields at the CS joint and winding are 3.5 and 13T, respectively. For the TF coils and the CS, the joints are cooled in series with the conductor at the outlet. The maximum temperature increase due to the joule heating in the joints is set at 0.15K to limit the heat load on the refrigerator. It is shown that both joint types are applicable to the ITER coils.
Yoshida, Kiyoshi; Takahashi, Yoshikazu; Mitchell, N.*; Bessette, D.*; Kubo, Hiroatsu*; Sugimoto, Makoto; Nunoya, Yoshihiko; Okuno, Kiyoshi
IEEE Transactions on Applied Superconductivity, 14(2), p.1405 - 1409, 2004/06
Times Cited Count：16 Percentile：59.99(Engineering, Electrical & Electronic)The ITER Central Solenoid (CS) is 12m high and 4m in diameter. The CS consists of a stack of 6electrically independent modules to allow control of plasma shape. The modules are compressed vertically by a pre-compression structure to maintain contact between modules. The CS conductor is CIC conductor with NbSn strands and a steel conduit. The CS model coil and insert coil test results have shown that the conductor design must be modified to achieve an operation margin. This required either to increase the cable diameter or to use strand with a higher current capability. A bronze-process (NbTi)Sn strand is proposed to achieve a higher critical magnetic field. A square conduit with a high Mn stainless steel is proposed as it can satisfy fatigue requirements. The inlets are in the high stress region and any stress intensification there must be minimized. The pre-compression structure is composed of 9tie plates to reduce the stress on the cooling pipes. These design proposals satisfy all ITER operational requirements.
Shimomura, Yasuo; Tsunematsu, Toshihide; Yamamoto, Shin; Maruyama, So; Mizoguchi, Tadanori*; Takahashi, Yoshikazu; Yoshida, Kiyoshi; Kitamura, Kazunori*; Ioki, Kimihiro*; Inoue, Takashi; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 78(Suppl.), 224 Pages, 2002/01
no abstracts in English
Sn conductor joint for ITER model coilsTakahashi, Yoshikazu; Nunoya, Yoshihiko; Nishijima, Gen; Koizumi, Norikiyo; Matsui, Kunihiro; Ando, Toshinari; Hiyama, Tadao; Nakajima, Hideo; Kato, Takashi; Isono, Takaaki; et al.
IEEE Transactions on Applied Superconductivity, 10(1), p.580 - 583, 2000/03
Times Cited Count：20 Percentile：68.9(Engineering, Electrical & Electronic)no abstracts in English
Sn superconducting wire and large current conductorIsono, Takaaki; Nunoya, Yoshihiko; Matsui, Kunihiro; Sugimoto, Makoto; Yoshida, Kiyoshi; Nishi, Masataka; Takahashi, Yoshikazu; Ando, Toshinari; Tsuji, Hiroshi; Shimamoto, Susumu*
Denki Gakkai Rombunshi, B, 119(11), p.1263 - 1269, 1999/00
no abstracts in English
Takahashi, Yoshikazu; Yoshida, Kiyoshi; Tsuji, Hiroshi; *; *; *; *; *; Takahashi, Ryukichi*; Asano, Katsuhiko*; et al.
Proc. of 16th Int. Cryogenic Engineering Conf. /Int. Cryogenic Materials Conf., 0, p.811 - 814, 1996/00
no abstracts in English
Sugimoto, Makoto; Isono, Takaaki; Koizumi, Norikiyo; Takahashi, Yoshikazu; Nishi, Masataka; Okuno, Kiyoshi; Yoshida, Kiyoshi; Nakajima, Hideo; Ando, Toshinari; Hosono, Fumikazu*; et al.
IEEE Transactions on Magnetics, 30(4), p.2042 - 2045, 1994/07
Times Cited Count：1 Percentile：24.71(Engineering, Electrical & Electronic)no abstracts in English
Sn demo poloidal coil(DPC-EX)Ando, Toshinari; Nakajima, Hideo; *; Hiyama, Tadao; Takahashi, Yoshikazu; Nishi, Masataka; Yoshida, Kiyoshi; Okuno, Kiyoshi; Kato, Takashi; Sugimoto, Makoto; et al.
Advances in Cryogenic Engineering, Vol.39, 0, p.335 - 341, 1994/00
no abstracts in English
Sn superconducting coils in JAERI Demo Poloidal Coil ProjectOkuno, Kiyoshi; Takahashi, Yoshikazu; Tsuji, Hiroshi; Ando, Toshinari; Nishi, Masataka; Yoshida, Kiyoshi; Sugimoto, Makoto; Koizumi, Norikiyo; Hosono, Fumikazu*; *
IEEE Transactions on Applied Superconductivity, 3(1), p.602 - 605, 1993/03
Times Cited Count：5 Percentile：50.21(Engineering, Electrical & Electronic)no abstracts in English
Takahashi, Yoshikazu; Koizumi, Norikiyo; *; Okuno, Kiyoshi; Nishi, Masataka; Isono, Takaaki; Yoshida, Kiyoshi; Sugimoto, Makoto; Kato, Takashi; *; et al.
IEEE Transactions on Applied Superconductivity, 3(1), p.610 - 613, 1993/03
Times Cited Count：12 Percentile：69.71(Engineering, Electrical & Electronic)no abstracts in English
Hosono, Fumikazu*; Sugimoto, Makoto; Tsukamoto, Hideo*; Oshikiri, Masayuki*; Hanawa, Hiromi*; Seki, Shuichi*; *; Koizumi, Norikiyo; Isono, Takaaki; Takahashi, Yoshikazu; et al.
IEEE Transactions on Applied Superconductivity, 3(1), p.535 - 538, 1993/03
Times Cited Count：1 Percentile：23.77(Engineering, Electrical & Electronic)no abstracts in English
*; Wachi, Y.*; Shimada, M.*; *; *; Hamajima, Takataro*; Fujioka, T.*; Nishi, Masataka; Tsuji, Hiroshi; Ando, Toshinari; et al.
IEEE Transactions on Applied Superconductivity, 3(1), p.480 - 483, 1993/03
Times Cited Count：4 Percentile：45.56(Engineering, Electrical & Electronic)no abstracts in English
Yamamoto, Keiichi*; Yoshida, Kiyoshi; Yasukawa, Yukio*; Tsukamoto, Hideo*; Sasaki, Takashi*; Okuno, Kiyoshi; Nishi, Masataka; Koizumi, Norikiyo; Isono, Takaaki; Sugimoto, Makoto; et al.
Proc. of the 17th Symp. on Fusion Technology, 0, p.971 - 975, 1993/00
no abstracts in English
