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Journal Articles

Routing study of above core structure with mock-up experiment for ASTRID

Takano, Kazuya; Sakamoto, Yoshihiko; Morohoshi, Kyoichi*; Okazaki, Hitoshi*; Gima, Hiromichi*; Teramae, Takuma*; Ikarimoto, Iwao*; Botte, F.*; Dirat, J.-F.*; Dechelette, F.*

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 8 Pages, 2019/05

ASTRID has the objective to integrate innovative options in order to prepare the 4th generation reactors. In ASTRID, large number of tubes are installed above each fuel subassembly to monitor the core. These instrumentations such as thermocouples (TC) and Failed Fuel Detection and Location (FFDL) systems are integrated into Above Core Structure (ACS) with various sizes tubes. In the present study, the routing study for TC tubes and FFDL tubes was performed with 3D modeling and mock-up experiment of the ACS designed for ASTRID with 1500 MW thermal power in order to clarify the integration process and secure the design hypotheses. Although some problems on fabricability were found in the mock-up experiment, the possible solutions were proposed. The present study gives manufacturing feedback to design team and will contribute to increase the knowledge for ACS design and fabricability.

Journal Articles

Progress of design and related researches of sodium-cooled fast reactor in Japan

Kamide, Hideki; Sakamoto, Yoshihiko; Kubo, Shigenobu; Oki, Shigeo; Ohshima, Hiroyuki; Kamiyama, Kenji

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Next Generation Nuclear Systems for Sustainable Development (FR-17) (USB Flash Drive), 10 Pages, 2017/06

Development of a sodium-cooled fast reactor has been implemented in Japan from the viewpoint of severe accident countermeasures in order to strengthen safety of a fast reactor since the Great East Japan Earthquake. This paper describes the progress of design study and research and development related to safety enhancement and the severe accident countermeasures. For the purpose of strengthening of decay heat removal function, several researches have been carried out on the decay heat removal in a core disruptive accident (CDA), diversity and applicability of decay heat removal systems, and thermal hydraulic evaluation methods. In order to elucidate the behavior of molten fuel during CDA, some in-pile and out-of-pile tests has been performed by international collaboration including basic experiments. Core design was also improved from the viewpoint of preventing the occurrence of severe accident.

Journal Articles

Progress of divertor simulation research toward the realization of detached plasma using a large tandem mirror device

Nakashima, Yosuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Oki, Kensuke*; Sakamoto, Mizuki*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; Imai, Tsuyoshi*; et al.

Journal of Nuclear Materials, 463, p.537 - 540, 2015/08

 Times Cited Count:17 Percentile:88.2(Materials Science, Multidisciplinary)

Journal Articles

Design study for reactor system of fast reactor JSFR; Concept of reactor system

Kawasaki, Nobuchika; Sakamoto, Yoshihiko; Eto, Masao*; Taniguchi, Yoshihiro*; Kamishima, Yoshio*

Proceedings of 2015 International Congress on Advances in Nuclear Power Plants (ICAPP 2015) (CD-ROM), p.760 - 769, 2015/05

The Japan Sodium-cooled Fast Reactor, JSFR, is currently under conceptual study. The concept of JSFR's reactor system is a compact reactor system to avoid excessive increase of reactor vessel diameter with structural and fluid integrities. To realize this concept, single rotating plug with advanced refueling system is adopted. Advanced refueling system consists of column type Upper Internal Structure and pantograph type Fuel Handling Machine. To realize structural and fluid integrities, top entry piping, sodium dam and flow block/guide structures are adopted. Structural integrities against seismic displacement or thermal stress and fluid integrities against vortex cavitations or cover gas entrainment can be ensured with these designs.

Journal Articles

Development of divertor simulation research in the GAMMA 10/PDX tandem mirror

Nakashima, Yosuke*; Sakamoto, Mizuki*; Yoshikawa, Masayuki*; Oki, Kensuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; et al.

Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10

JAEA Reports

Preliminary conceptual design of the secondary sodium circuit-eliminated JSFR (Japan Sodium Fast Reactor) adopting a supercritical CO$$_{2}$$ turbine system, 2; Turbine system and plant size

Kisohara, Naoyuki; Sakamoto, Yoshihiko; Kotake, Shoji*

JAEA-Research 2014-016, 60 Pages, 2014/09

JAEA-Research-2014-016.pdf:22.38MB

JAEA has performed a design study of an S-CO$$_{2}$$ gas turbine system applied to the JSFR. In this study, the S-CO$$_{2}$$ cycle turbine system was directly connected to the primary sodium system of the JSFR to eliminate the secondary sodium circuit, aiming for further economical improvement. This report describes the system configuration, heat/mass balance, and main components of the S-CO$$_{2}$$ turbine system, based on the JSFR specifications. The layout of components and piping in the reactor and turbine buildings were examined and the dimensions of the buildings were estimated. The study has revealed that the reactor and turbine buildings could be reduced by 7% and 40%, respectively, in comparison with those in the existing JSFR design with the secondary sodium circuit employing the steam turbine. The cycle thermal was also calculated as 41.9-42.3%, which is nearly the same as that of the JSFR with the water/steam system.

JAEA Reports

Preliminary conceptual design of the secondary sodium circuit-eliminated JSFR (Japan Sodium Fast Reactor) adopting a supercritical CO$$_{2}$$ turbine system, 1; Sodium/CO$$_{2}$$ heat exchanger

Kisohara, Naoyuki; Sakamoto, Yoshihiko; Kotake, Shoji*

JAEA-Research 2014-015, 33 Pages, 2014/09

JAEA-Research-2014-015.pdf:27.33MB

JAEA has performed a design study of an S-CO$$_{2}$$ gas turbine system applied to the JSFR. In this study, the S-CO$$_{2}$$ cycle turbine system was directly connected to the primary sodium system of the JSFR to eliminate the secondary sodium circuit, aiming for further economical improvement. The Na/CO$$_{2}$$ heat exchanger is one of the key components, and this report describes its structure and the safety in case of CO$$_{2}$$ leak. A Printed Circuit Heat Exchanger (PCHE) is employed to the heat exchanger. A SiC/SiC ceramic composite material is used for the PCHE to prevent crack growth and to reduce thermal stress. The Na/CO$$_{2}$$ heat exchanger has been designed in such a way that a number of small heat transfer modules are combined in the vessel in consideration of manufacture and repair. CO$$_{2}$$ leak events in the heat exchanger have been also evaluated, and it revealed that no significant effect has arisen on the core or the primary sodium boundary.

Journal Articles

ESR studies on decay of radicals induced in irradiated foods

Kaimori, Yoshihiko; Sakamoto, Yuki*; Kawamura, Shoei*; Kishida, Keigo*; Kikuchi, Masahiro; Nakamura, Hideo*; Kobayashi, Yasuhiko; Ukai, Mitsuko*

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 79, 2013/01

no abstracts in English

Journal Articles

Selection of sodium coolant for fast reactors in the US, France and Japan

Sakamoto, Yoshihiko; Garnier, J.-C.*; Rouault, J.*; Grandy, C.*; Fanning, T.*; Hill, R.*; Chikazawa, Yoshitaka; Kotake, Shoji*

Nuclear Engineering and Design, 254, p.194 - 217, 2013/01

 Times Cited Count:10 Percentile:67.43(Nuclear Science & Technology)

This trilateral study confirms that the fundamental mission of the fast reactor is to achieve significant uranium utilization and waste management goals. Thus, fast spectrum reactor concepts are vital for nuclear fuel cycle sustainability goals. The trilateral countries agree that SFR, GFR and LFR are capable to achieve the goals. However SFR is the most matured technology from the view point of industrial deployment while GFR and LFR still require long term development before a test reactor project could begin. The trilateral common view supports fast reactor project situations in each country.

Journal Articles

Modifications to the edge radial electric field by angular momentum injection in JT-60U and their implication for pedestal transport

Kamiya, Kensaku; Honda, Mitsuru; Miyato, Naoaki; Urano, Hajime; Yoshida, Maiko; Sakamoto, Yoshiteru; Matsunaga, Go; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka; et al.

Nuclear Fusion, 52(11), p.114010_1 - 114010_12, 2012/10

 Times Cited Count:10 Percentile:45.75(Physics, Fluids & Plasmas)

Depending on the direction of the external tangential momentum input, substantial changes in not only toroidal but also poloidal flows for the carbon impurity ions are observed at around the $$E$$$$_{r}$$-well region. The shear in the edge $$E$$$$_{r}$$ becomes wider in the co-NBI case, while the edge $$E$$$$_{r}$$-well becomes deeper in the counter-NBI case.

Journal Articles

Analysis of radicals induced in irradiated foods

Kishida, Keigo*; Kaimori, Yoshihiko*; Kawamura, Shoei*; Sakamoto, Yuki*; Nakamura, Hideo*; Kikuchi, Masahiro; Shimoyama, Yuhei; Kobayashi, Yasuhiko; Ukai, Mitsuko*

Shokuhin Shosha, 47(1), p.1 - 5, 2012/09

no abstracts in English

Journal Articles

Initial decay process of radicals induced in irradiated food

Kaimori, Yoshihiko*; Sakamoto, Yuki*; Kikuchi, Masahiro; Kobayashi, Yasuhiko; Ukai, Mitsuko*

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 82, 2012/01

no abstracts in English

Journal Articles

JSFR design study and R&D progress in the FaCT project

Aoto, Kazumi; Uto, Nariaki; Sakamoto, Yoshihiko; Ito, Takaya*; Toda, Mikio*; Kotake, Shoji*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 11 Pages, 2012/00

In the FaCT project, SFR with 1,500 MWe is a target for the commercialization. R&D on innovative technologies to achieve the economic competitiveness and enhance the reliability and safety is carried out. A compact RV without wall-cooling layer is pursued in consideration of seismic reliability. For a two-loop cooling system with shortened high chromium steel piping, studies on the hydraulics in the pipe elbow and the fabrication capability of the pipes are being performed. A double-walled straight tube SG is investigated to enhance the reliability against sodium/water reaction, and developmental works are progressing including the thermal-hydraulic design and trial manufacturing for components. SASS is being developed with safety analysis of the applicability for JSFR and experimental demonstration in JOYO. An advanced fuel handling system is also pursued. Discussion on whether the innovative technologies can be adopted for JSFR is in progress to be finalized in 2010.

Journal Articles

Conceptual design study of JSFR, 2; Reactor system

Eto, Masao*; Kamishima, Yoshio*; Okamura, Shigeki*; Watanabe, Osamu*; Oyama, Kazuhiro*; Negishi, Kazuo; Kotake, Shoji*; Sakamoto, Yoshihiko; Kamide, Hideki

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 10 Pages, 2012/00

In the JSFR design, the diameter of the Reactor Vessel (RV) shall be minimized and the reactor internal structures shall be simplified for reduction in construction cost. The reduction in the RV diameter is achieved by adopting an advanced refueling system and the hot RV with high temperature wall. The flow velocity in the reactor upper plenum increases because the diameter of the RV is decreased. As the result, the coolant flow field in reactor upper plenum is severe. The optimization of the coolant flow field in the reactor upper plenum was carried out for prevention the cover gas entrainment and the vortex cavitations at the hot leg intake. In addition, structural integrities for seismic loadings and thermal loadings were evaluated because the design seismic loading was highly increased and the vessel wall is directly exposed to the thermal transients of the upper plenum. This paper describes the characteristics and the results of the design study of the reactor system.

Journal Articles

Seismic isolation design for JSFR

Okamura, Shigeki*; Eto, Masao*; Kamishima, Yoshio*; Negishi, Kazuo; Sakamoto, Yoshihiko; Kitamura, Seiji; Kotake, Shoji*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 10 Pages, 2012/00

This paper describes the seismic design of JSFR, which includes the seismic condition, the seismic isolation system and the seismic evaluation of primary component. JSFR employs a seismic isolation system to mitigate the earthquake force. The design seismic loading is made more severe than ever since Niigata-ken Chuetsu-oki Earthquake in 2007. The earthquake force loaded on the primary components has to be mitigated more than that of the previous seismic isolation system. We examined the advanced seismic isolation system by optimizing the performance of the previous seismic isolation system considering the natural frequency of the primary components. The advanced seismic isolation system for SFR was adopted laminated rubber bearings which are thicker than that of the previous, as well as oil dampers. The seismic evaluation of nuclear reactor components under applying the advanced seismic isolation system was performed; the performance of the system was confirmed.

Journal Articles

Conceptual design study for the demonstration reactor of JSFR, 4; Structural design of reactor vessel

Kawasaki, Nobuchika; Okamura, Shigeki*; Sawa, Naoki*; Sakamoto, Yoshihiko; Negishi, Kazuo

Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 7 Pages, 2011/10

Japan Sodium-Cooled Fast Reactor adopts an compacted hot reactor vessel concept. From the point of structural designs to ensure both seismic design and elevated temperature design is important. In this study, based on a common conservative seismic loading condition considered with the Niigata-ken Chuetsu-oki Earthquake, seismic evaluations were carried out, the thicknesses of reactor vessels of 750 MWe and 500 MWe output plants were determined. For both plants 50 mm was selected as the thickness, and ensured buckling evaluation margins were more than 2.4. From the point of seismic design, the difference of plant output was negligible. With the condition of 50 mm thickness of reactor vessel, thermal integrities were evaluated. For three plant start-up conditions which were 2.2, 3.2, and 4.3 days, thermal ratcheting and creep-fatigue damage were evaluated. As a result plant start-up period needed more than 3.2 days for both 750 MWe and 500 MWe output plants. Caused thermal stress were the nearly same for both plants, therefore from the point of thermal design, the difference of plant output was negligible.

Journal Articles

Initial decay process of radicals induced in irradiated food

Kaimori, Yoshihiko; Sakamoto, Yuki*; Kikuchi, Masahiro; Kameya, Hiromi*; Nakamura, Hideo*; Shimoyama, Yuhei; Kobayashi, Yasuhiko; Ukai, Mitsuko*

Shokuhin Shosha, 46(1), p.13 - 18, 2011/09

Journal Articles

Spatio-temporal structure of the edge radial electric field during H-mode in JT-60U

Kamiya, Kensaku; Sakamoto, Yoshiteru; Matsunaga, Go; Kojima, Atsushi; Urano, Hajime; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka; Ida, Katsumi*; Kurki-Suonio, T.*; et al.

Nuclear Fusion, 51(5), p.053009_1 - 053009_3, 2011/05

 Times Cited Count:12 Percentile:51.33(Physics, Fluids & Plasmas)

We revisited to measure the edge impurity ion dynamic with new CXRS in the hot ion H-mode regime at the high magnetic field having two steps transition where a jump of Ti gradient precedes a jump of impurity Vp. Two discrete phases with different magnitude of Er in the H-phase have been observed. One is the intermediate H-phase having a large Ti gradients without significant Vp of impurity species with moderate magnitude of Er, and the other is the complete H-phase characterized by a large Er.

Journal Articles

Design study and R&D progress on Japan sodium-cooled fast reactor

Aoto, Kazumi; Uto, Nariaki; Sakamoto, Yoshihiko; Ito, Takaya*; Toda, Mikio*; Kotake, Shoji*

Journal of Nuclear Science and Technology, 48(4), p.463 - 471, 2011/04

In the FaCT project, SFR with 1,500 MWe is a target for the commercialization. R&D on innovative technologies to achieve the economic competitiveness and enhance the reliability and safety is carried out. A compact RV without wall-cooling layer is pursued in consideration of seismic reliability. For a two-loop cooling system with shortened high chromium steel piping, studies on the hydraulics in the pipe elbow and the fabrication capability of the pipes are being performed. A double-walled straight tube SG is investigated to enhance the reliability against sodium/water reaction, and developmental works are progressing including the thermal-hydraulic design and trial manufacturing for components. SASS is being developed with safety analysis of the applicability for JSFR and experimental demonstration in JOYO. An advanced fuel handling system is also pursued. Discussion on whether the innovative technologies can be adopted for JSFR is in progress to be finalized in 2010.

JAEA Reports

Experience of secondary cooling system modification at prototype fast breeder reactor MONJU (Translated document)

Kisohara, Naoyuki; Sakamoto, Yoshihiko

JAEA-Review 2010-036, 26 Pages, 2010/09

JAEA-Review-2010-036.pdf:3.05MB

The prototype fast breeder reactor MONJU has been shut down since the secondary sodium leak accident that occurred in December 1995. After the accident, an investigation into the cause and a comprehensive safety review of the plant were conducted, and various countermeasures for sodium leak were examined. Modification work commenced in September 2005. Since sodium is used as coolant in MONJU, the modification work required work methods suitable for the handling of sodium. From this perspective, the use of a plastic bag when opening the sodium boundary, oxygen concentration control in a plastic bag, slightly-positive pressure control of cover gas in the systems, pressing and cutting with a roller cutter to prevent the incorporation of metal fillings, etc. were adopted. Owing to these work methods, the modification work proceeded close to schedule without incident.

121 (Records 1-20 displayed on this page)