Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Mo/
Tc generator by (n,
) method, 2Fujita, Yoshitaka; Seki, Misaki; Namekawa, Yoji*; Nishikata, Kaori; Kato, Yoshiaki; Sayato, Natsuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; Hori, Junichi*; et al.
KURNS Progress Report 2019, P. 157, 2020/08
no abstracts in English
Hiraiwa, Kenichi*; Hirai, Kazuhide*; Sano, Tadashi*; Osawa, Hideaki; Sato, Toshinori; Aoyagi, Yoshiaki; Fujita, Tomoo; Aoyagi, Kazuhei; Inagaki, Daisuke*
JAEA-Technology 2015-033, 50 Pages, 2015/11
JAEA-Technology-2015-033.pdf:12.6MB
Japan Atomic Energy Agency (hereinafter referred to as JAEA) has been conducted a geoscientific research and development project at the Mizunami Underground Research Laboratory and the Horonobe Underground Research Laboratory in order to construct scientific and technological basis for geological disposal. As a collaborative research between JAEA and Tokyo Sokki Kenkyujo Co., Ltd. (hereinafter referred to as TML), we focused on the fiber-optic crack detection sensor developed by TML as a method to detect cracks in the support system that may affect the stability of rock cavern during the operation. To verify long-term safety performance of the sensor for decades, "Evaluation test of long-term durability of fiber-optic crack detection sensor and the support system" at the Mizunami Underground Research Laboratory and "Performance evaluation test of fiber-optic crack detection sensor for in-situ crack detection" at the Horonobe Underground Laboratory Research Laboratory were conducted. As the result, we understand that fiber-optic crack detection sensor is applicable measurement method to promptly detect the cracks in the support system.
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：16 Percentile：79.46(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; 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
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
Sugita, Yutaka*; Takahashi, Yoshiaki*; Uragami, Manabu*; Kitayama, Kazumi*; Fujita, Tomoo; Yui, Mikazu
JAEA-Research 2007-023, 70 Pages, 2007/03
JAEA-Research-2007-023.pdf:26.16MB
The sealing performance of a repository is very important for the safety assessment of the geological disposal system for high-level radioactive waste. NUMO and JAEA set up a technical commission to investigate sealing technology in a repository in 2004 following a cooperation agreement between these two organisations. The objectives of this commission were to present a concept of sealing performance required in the disposal system and to direct future R&D for design requirements of closure components (backfilling material, clay plug, etc.). Hydraulic analyses on tunnel intersections were carried out during the first year in 2004. This was expanded into a hydraulic analysis of a complete disposal panel with all tunnels during the second year in 2005. Since the model structure in 2005 was more complicated than the one used in 2004, the concept of equivalent permeability was adopted in and around each tunnel in the hydraulic analyses. Parameters used in the hydraulic analyses were installation positions of clay plugs, permeability of the backfilling material, permeability of disposal tunnel and directions of hydraulic gradient to estimate influences to the analytical results preliminary. Analytical results showed that flow rate in a disposal tunnel was influenced by directions of hydraulic gradient, installation of the clay plug at the both ends of each disposal tunnel and permeability of the main tunnel.
Sugita, Yutaka; Fujita, Tomoo; Takahashi, Yoshiaki*; Kawakami, Susumu; Umeki, Hiroyuki; Yui, Mikazu; Uragami, Manabu*; Kitayama, Kazumi*
Physics and Chemistry of the Earth, 32(1-7), p.32 - 41, 2007/00
Times Cited Count：6 Percentile：20.74(Geosciences, Multidisciplinary)The H12 repository concept for vitrified high-level radioactive waste was developed based on a multi-barrier system with the emphasis on robust engineered barrier performance to ensure its feasibility for a wide range of geological conditions typically observed in Japan. The buffer is clay-based and plays a very important role in the engineered barrier system (EBS). The decision to use a volunteer siting process requires maximum flexibility of the repository concept to allow it to be adapted to potential sites and hence a wide range of variants of the basic H12 repository design has been developed. In order to evaluate the feasibility and the applicability of different repository options to specific siting environments, NUMO has established a set of "design factors" which classify the aspects that need to be considered when evaluating the pros and cons of different repository options. A Na-type bentonite from Japan is used as the reference material for all clay-based repository components (buffer, backfill, clay plug, etc.). The characteristics of this bentonite (thermal, mechanical, chemical, hydraulic) have been examined with consideration of various practical constraints (limitation on the repository footprint, the influence of saline water, the interaction of hyperalkaline leachates and practical working environment, etc.). Clay-based seals, which close off the tunnels after emplacement of the EBS, may also be key components for assessment of the repository. Full analyses considering all engineered barrier components (buffer, backfill, clay plug, concrete lining, tunnel, concrete plug, host rock) that may be used in a repository will be an essential future task. As a first step towards this goal, a numerical analysis focusing on hydraulic behaviour at the intersections of the disposal tunnels and the main tunnel is presented to illustrate how the design requirements of clay-based seals can be determined.
Fujita, Tomoo; Sugita, Yutaka*; Takahashi, Yoshiaki*
Australian Geomechanics, 41(4), p.89 - 95, 2006/12
In this study, three-dimensional simulations of groundwater flow are conducted to investigate the sealing performance of clay-based backfill and plug at the tunnel intersection for given hydraulic conditions around the tunnels. In the analytical results, it is found that the direction of hydraulic gradient, hydraulic conductivities of concrete and backfilling materials and the position of clay plug had impact on flow condition around the EBS.
Sugita, Yutaka*; Fujita, Tomoo; Takahashi, Yoshiaki*; Kawakami, Susumu; Umeki, Hiroyuki; Yui, Mikazu; Uragami, Manabu*
JNC TN8400 2005-016, 49 Pages, 2005/09
JNC-TN8400-2005-016.pdf:5.45MB
The sealing performance of a repository should be considered in the safety assessment of the geological disposal system of the high level radioactive waste. Nuclear Waste Management Organization of Japan and Japan Nuclear Cycle Development Institute are examining the sealing performance of the closure components (backfilling material and clay plug) to present the concept on the sealing performance required to the disposal system, and to develop the direction for the future R&D programme for the design requirements of the closure components of the presented concepts.The first step of this examination reviewed the current status of the domestic and the international sealing technologies, summarized the repository components and the repository environments, and performed the hydraulic analysis considering components on the intersections of a main tunnel and a disposal tunnel in a disposal panel and in and around the engineered barrier system (EBS). Since all tunnels connect in the underground facility, understanding of hydraulic behaviour at the intersections of the tunnels is the important issue to estimate migration of radionuclides from the EBS, and to evaluate the required sealing performance for the disposal system. The considering components in the analysis model are the intersections of the disposal tunnel and the main tunnel, the waste package, the EBS, the backfilling material, the clay plug, the concrete plug, the excavated disturbed zone, the tunnel lining and the host rock. Alteration of the concrete material (tunnel lining and concrete plug) is described as variation of the hydraulic conductivity of it. Sites of emplacement of the clay plug are the disposal tunnel and the main tunnel. No clay plug condition is also analysed. Effect of the clay plug is discussed by the results of these analyses.
Am from 0.003eV to 10keV using lead slowing-down spectrometer, thermal neutron facility and time-of-flight methodKai, Tetsuya; Kobayashi, Katsuhei*; Yamamoto, Shuji*; Cho, H.*; Fujita, Yoshiaki*; Kimura, Itsuro*; Okawachi, Yasushi*; Wakabayashi, Toshio*
Annals of Nuclear Energy, 28(8), p.723 - 739, 2001/05
Times Cited Count：7 Percentile：48.68(Nuclear Science & Technology)no abstracts in English
Fujita, Mitsutane*; Kinugawa, Junichi*; Tsuji, Hirokazu; Kaji, Yoshiyuki; Tachi, Yoshiaki*; Saito, Junichi*; Shimura, Kazuki*; Nakajima, Ritsuko*; Iwata, Shuichi*
Fusion Engineering and Design, 51-52, p.769 - 774, 2000/11
Times Cited Count：1 Percentile：12.1(Nuclear Science & Technology)no abstracts in English
Kinugawa, Junichi*; Fujita, Mitsutane*; Noda, Tetsuji*; Tsuji, Hirokazu; Kaji, Yoshiyuki; Sakino, Takao*; Tachi, Yoshiaki*; Kaneda, Kenichiro*; Mashiko, Shinichi*; Shimura, Kazuki*; et al.
Proceedings of 9th German-Japanese Workshop on Chemical Information, p.134 - 135, 2000/00
no abstracts in English
Kaji, Yoshiyuki; Tsuji, Hirokazu; Sakino, Takao*; Fujita, Mitsutane*; Kinugawa, Junichi*; Tachi, Yoshiaki*; Saito, Junichi*; Kano, Shigeki*; Shimura, Kazuki*; Nakajima, Ritsuko*; et al.
JAERI-Tech 99-007, 32 Pages, 1999/02
no abstracts in English
Tsuji, Hirokazu; ; Fujita, Mitsutane*; Kano, Shigeki*; Tachi, Yoshiaki*; Shimura, Kazuki*; Nakajima, Ritsuko*; Iwata, Shuichi*
Advances in Science and Technology, 24, p.417 - 424, 1999/00
no abstracts in English
Tsuji, Hirokazu; ; Fujita, Mitsutane*; Kurihara, Yutaka*; Kano, Shigeki*; Tachi, Yoshiaki*; Shimura, Kazuki*; Nakajima, Ritsuko*; Iwata, Shuichi*
Journal of Nuclear Materials, 271-272, p.486 - 490, 1999/00
no abstracts in English
Nakajima, Ritsuko*; Shimura, Kazuki*; Fujita, Mitsutane*; Tsuji, Hirokazu; ; Tachi, Yoshiaki*; Kano, Shigeki*; Iwata, Shuichi*
Joho Chishiki Gakkai Dai-6-Kai Kenkyu Hokokukai Koen Rombunshu, p.43 - 46, 1998/00
no abstracts in English
Tsuji, Hirokazu; ; Fujita, Mitsutane*; Kano, Shigeki*; Tachi, Yoshiaki*; Shimura, Kazuki*; Nakajima, Ritsuko*; Iwata, Shuichi*
Materials for Advanced Power Engineering 1998, p.1739 - 1745, 1998/00
no abstracts in English
Shimura, Kazuki*; Nakajima, Ritsuko*; Fujita, Mitsutane*; Kurihara, Yutaka*; Tsuji, Hirokazu; ; Tachi, Yoshiaki*; Kano Shigeki*; Iwata, Shuichi*
JAERI-Tech 97-047, 22 Pages, 1997/10
no abstracts in English
