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Hayashi, Masaaki*; Nakahara, Hirotaka*; Abe, Takashi*; Matsunaga, Suhei*; Miyata, Hajime*; Shirakura, Shota*; Yamano, Hidemasa
Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2024/06
This paper describes the study of the performance evaluation technology of a heat exchanger between sodium and molten salt and the confirmation of heat transfer improvement measures effects up to FY2023.
Sakamoto, Kan*; Sakaguchi, Chisato*; Miura, Yusuke*; Yokoyama, Hironori*; Matsunaga, Junji*; Kasahara, Hideyuki*; Miyata, Hajime*; Ioka, Ikuo; Yamashita, Shinichiro; Osaka, Masahiko
Proceedings of 2023 Water Reactor Fuel Performance Meeting (WRFPM 2023), p.20 - 28, 2024/00
An oxide-dispersion-strengthened FeCrAl (FeCrAl-ODS) has been continuously developed in Japan as a promising candidate alloy for the accident tolerant fuel cladding of BWRs (boiling water reactors). This paper will introduce the progress in practical development of accident tolerant FeCrAl-ODS fuel claddings for BWRs in the program fully or partially supported and organized by the Ministry of Economy, Trade and Industry (METI) of Japan. The experimental studies have been conducted to obtain and accumulate key material properties of FeCrAl-ODS fuel claddings to support the evaluations in the analytical studies. For the evaluation at normal operation condition, fatigue test of unirradiated fuel cladding and tensile test of irradiated sheet specimen were conducted. In the fatigue test, a tensile-compressive bending strain was loaded on the C-shaped specimens by cyclic movement of a push-pull rod. Test temperature was 623 K, frequency was 1 Hz, and strain amplitude were 0.27, 0.34 and 0.55 %. The results of fatigue tests demonstrated that cycles to failure of the FeCrAl-ODS cladding were higher than that of the O'Donnell and Langer fatigue curve of Zr-based alloy. The tensile test was conducted in a hot cell using the SS-J2 type specimens at ambient temperature, 573 K and 623 K at a strain rate of 10-3 s-1. The specimens were irradiated up to 7.8 and 13 dpa at 573 K in the High Flux Isotope Reactor at ORNL. The irradiation hardening and ductility loss obtained at 7.8 and 13 dpa were comparable to those at 3.9 dpa.
Urano, Hajime; Fujita, Takaaki*; Ide, Shunsuke; Miyata, Yoshiaki; Matsunaga, Go; Matsukawa, Makoto
Fusion Engineering and Design, 100, p.345 - 356, 2015/11
Times Cited Count：21 Percentile：82.35(Nuclear Science & Technology)The operation scenarios for plasma breakdown and current ramp-up phases in JT-60SA tokamak have been developed. The induced current in the in-vessel conducting elements such as vacuum vessel and stabilizing plate increases to the comparable level of plasma current of 
600 kA during the breakdown phase and thus enhances the strength of error field. The optimized scenarios for half and full pre-magnetization cases satisfied the conditions required for the plasma initiation. At the initial plasma, the vertical magnetic field required to sustain the plasma position was controlled by the outer equilibrium field (EF) coil currents which compensate for a vertical field due to a large eddy current. The condition for the formation of divertor configurations given by the combination of the magnetic flux for plasma and the plasma current enables us to develop the operational scenarios with a smooth transition from a limiter to a divertor configuration.
Miyata, Yoshiaki; Suzuki, Takahiro; Takechi, Manabu; Urano, Hajime; Ide, Shunsuke
Review of Scientific Instruments, 86(7), p.073511_1 - 073511_13, 2015/07
Times Cited Count：8 Percentile：32.53(Instruments & Instrumentation)It is essential for a stable plasma equilibrium control to reconstruct an accurate plasma boundary in tokamak devices. Cauchy Condition Surface (CCS) method is a numerical approach to calculate the spatial distribution of the magnetic flux outside a hypothetical plasma surface and reconstruct the plasma boundary from the magnetic measurements located outside the plasma. It is found that the optimum number of unknown parameters and shape of the CCS for minimizing errors in the reconstructed plasma shape increase in proportion to the plasma size. It is shown that the accuracy of the plasma shape reconstruction greatly improves by using the optimum number of unknown parameters. The assessment of accuracy of plasma shape reconstruction by CCS method in JT-60SA is reported.
Hayashi, Nobuhiko; Honda, Mitsuru; Shiraishi, Junya; Miyata, Yoshiaki; Wakatsuki, Takuma; Hoshino, Kazuo; Toma, Mitsunori; Suzuki, Takahiro; Urano, Hajime; Shimizu, Katsuhiro; et al.
Europhysics Conference Abstracts (Internet), 39E, p.P5.145_1 - P5.145_4, 2015/06
Kurihara, Kenichi; Itagaki, Masafumi*; Miyata, Yoshiaki; Nakamura, Kazuo*; Urano, Hajime
Purazuma, Kaku Yugo Gakkai-Shi, 91(1), p.10 - 47, 2015/01
no abstracts in English
Miyata, Yoshiaki; Suzuki, Takahiro; Ide, Shunsuke; Urano, Hajime
Plasma and Fusion Research (Internet), 9(Sp.2), p.3403045_1 - 3403045_5, 2014/05
The precise control of the plasma position is essential in safe and stable plasma operation. An MHD equilibrium control simulator has been developed in order to study the techniques of plasma equilibrium control for JT-60SA. In this study, the modules of plasma shape reconstruction, power supply, PF and FPPC coils are incorporated in order to simulate the real plasma equilibrium control. The plasma equilibrium control is simulated during Ip ramp-up within the power supply capability using MECS.
Miyata, Yoshiaki; Suzuki, Takahiro; Ide, Shunsuke; Urano, Hajime; Fujita, Takaaki
Plasma and Fusion Research (Internet), 8(Sp.1), p.2405109_1 - 2405109_6, 2013/08
The precise control of the plasma position is a key issue in safe and stable plasma operation. A plasma equilibrium control simulator has been developed in order to study the techniques of plasma equilibrium control for JT-60SA. The simulator consists of an equilibrium solver and controller. The equilibrium solver identifies the plasma equilibrium under the given coil current and unknown eddy current by iteration. The function which calculates the self-consistent 
with magnetic flux consumption has been incorporated in order to simulate the control. The waveforms of JT-60SA plasma operation scenario during the ramp-up and the controllability of the plasma equilibrium control using the equilibrium control simulator were reported.
Ide, Shunsuke; Aiba, Nobuyuki; Bolzonella, T.*; Challis, C. D.*; Fujita, Takaaki; Giruzzi, G.*; Joffrin, E.*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Honda, Mitsuru; et al.
Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03
Suzuki, Takahiro; Hayashi, Nobuhiko; Urano, Hajime; Miyata, Yoshiaki; Honda, Mitsuru; Ide, Shunsuke; JT-60SA Team
Europhysics Conference Abstracts (Internet), 37D, p.P2.136_1 - P2.136_4, 2013/00
no abstracts in English
Miyata, Yoshiaki; Suzuki, Takahiro; Fujita, Takaaki; Ide, Shunsuke; Urano, Hajime
Plasma and Fusion Research (Internet), 7, p.1405137_1 - 1405137_9, 2012/10
The plasma position and shape control is important issue in JT-60SA, ITER and future fusion reactor. In order to study the plasma position and shape control, we have developed a simulator which consists of an equilibrium solver and an "isoflux" controller. It is possible to simulate the position and shape control by using the "isoflux" technique and optimize the control logic of coil current in JT-60SA. It was demonstrated that the simulator can simulate the position and shape control in response to prescribed change in the configuration and internal parameters.
Ide, Shunsuke; Hayashi, Nobuhiko; Honda, Mitsuru; Urano, Hajime; Suzuki, Takahiro; Miyata, Yoshiaki; Aiba, Nobuyuki; Shiraishi, Junya; Kurita, Genichi; Fujita, Takaaki
Plasma and Fusion Research (Internet), 7(Sp.1), p.2403131_1 - 2403131_4, 2012/09
no abstracts in English
Suzuki, Takahiro; Miyata, Yoshiaki; Ide, Shunsuke; Urano, Hajime; Fujita, Takaaki
no journal, ,
We have developed an equilibrium control simulator and investigated the JT-60SA operation scenario using the simulator. The simulator consists of an equilibrium construction component that solves temporal evolution of plasma coupled with conducting wall and a controller that controls the plasma current, position and shape via external coil current in the feedback manner. An operation scenario based on the feedback control has been developed, where the plasma current is raised by flux swing in center solenoids and plasma position and shapes are controlled in order to form divertor configuration and apply heating. Results on controllability of the position and shape during heating and flux swing and controllability of the vertical instability are presented as well.
Miyata, Yoshiaki; Suzuki, Takahiro; Fujita, Takaaki; Ide, Shunsuke; Urano, Hajime
no journal, ,
no abstracts in English
Miyata, Yoshiaki; Suzuki, Takahiro; Fujita, Takaaki; Ide, Shunsuke; Urano, Hajime
no journal, ,
The plasma position and shape control is important issue in JT-60SA, ITER and future fusion reactor which has a small number of coils. In order to study the plasma position and shape control, we are developing a simulator which consists of an equilibrium solver and an "isoflux" controller. The controller controls poloidal field (PF) coil currents so as to keep the poloidal flux is equal at all of specified locations. The equilibrium solver identifies an equilibrium under the specified PF coil current and implements the effect of eddy current. The position and shape control has been simulated in response to prescribed change in the poloidal beta and the internal inductance due to heating.
Miyata, Yoshiaki; Suzuki, Takahiro; Ide, Shunsuke; Urano, Hajime; Takechi, Manabu
no journal, ,
It is essential for a stable plasma equilibrium control to reconstruct an accurate plasma boundary in tokamak devices. Cauchy Condition Surface (CCS) method is a numerical approach to calculate the spatial distribution of the magnetic flux outside a hypothetical plasma surface and reconstruct the plasma boundary from the magnetic measurements located outside the plasma. It is found that the optimum number of unknown parameters and shape of the CCS for minimizing errors in the reconstructed plasma shape increase in proportion to the plasma size. It is shown that the accuracy of the plasma shape reconstruction greatly improves by using the optimum number of unknown parameters. The assessment of accuracy of plasma shape reconstruction by CCS method in JT-60SA is reported.
Miyata, Yoshiaki; Suzuki, Takahiro; Urano, Hajime; Takechi, Manabu; Ide, Shunsuke
no journal, ,
In the plasma equilibrium control for tokamak devices, after the plasma shape reconstruction system identifies the plasma quantities from the magnetic measurements such as the magnetic sensor and poloidal magnetic field coil, the plasma equilibrium controller operates the actuator to bring the identified plasma quantities closer to the target ones by feedback control action. The influences of potential magnetic measurement noise on the plasma equilibrium control in JT-60SA is quantitatively evaluated and the techniques for mitigating the influences are reported.
Ide, Shunsuke; Aiba, Nobuyuki; Bolzonella, T.*; Challis, C. D.*; Fujita, Takaaki; Giruzzi, G.*; Joffrin, E.*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Honda, Mitsuru; et al.
no journal, ,
Hayashi, Masaaki*; Nakahara, Hirotaka*; Abe, Takashi*; Endo, Keita*; Miyata, Hajime*; Yamano, Hidemasa
no journal, ,
As part of the development of safety design technologies for sodium-cooled fast reactor coupled to thermal energy storage system with nitrate molten salt heat exchanger, we are considering optimization of heat exchanger type and measures to improve heat transfer. We have confirmed the effect of the heat transfer performance improvement, for which we conducted Computational Fluid Dynamics analyses with the analytical model of the selected heat exchanger type.
