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Journal Articles

Transient response of LWR fuels (RIA)

Udagawa, Yutaka; Fuketa, Toyoshi*

Comprehensive Nuclear Materials, 2nd Edition, Vol.2, p.322 - 338, 2020/08

Journal Articles

A Conceptual design study of pool-type sodium-cooled fast reactor with enhanced anti-seismic capability

Kubo, Shigenobu; Chikazawa, Yoshitaka; Ohshima, Hiroyuki; Uchita, Masato*; Miyagawa, Takayuki*; Eto, Masao*; Suzuno, Tetsuji*; Matoba, Ichiyo*; Endo, Junji*; Watanabe, Osamu*; et al.

Mechanical Engineering Journal (Internet), 7(3), p.19-00489_1 - 19-00489_16, 2020/06

The authors are developing the design concept of pool-type sodium-cooled fast reactor (SFR) that addresses Japan's specific siting conditions such as earthquakes and meets safety design criteria (SDC) and safety design guidelines (SDGs) for Generation IV SFRs. The development of this concept will broaden not only options for reactor types in Japan but also the range and depth of international cooperation. A design concept of 1,500 MWt (650 MWe) class pool-type SFR was thought up by applying design technology obtained from the design of advanced loop-type SFR, named JSFR, equipped with safety measures that reflect results from the feasibility study on commercialized fast reactor cycle systems and fast reactor cycle technology development, improved maintainability and repairability, and lessons learned from the Fukushima Daiichi Nuclear Power Plants accident.

Journal Articles

A Conceptual design study of pool-type sodium-cooled fast reactor with enhanced anti-seismic capability

Kubo, Shigenobu; Chikazawa, Yoshitaka; Ohshima, Hiroyuki; Uchita, Masato*; Miyagawa, Takayuki*; Eto, Masao*; Suzuno, Tetsuji*; Matoba, Ichiyo*; Endo, Junji*; Watanabe, Osamu*; et al.

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05

The authors are developing the design concept of pool-type sodium-cooled fast reactor (SFR) that addresses Japan's specific siting conditions such as earthquakes and meets safety design criteria (SDC) and safety design guidelines (SDGs) for Generation IV SFRs. The development of this concept will broaden not only options for reactor types in Japan but also the range and depth of international cooperation. A design concept of 1,500 MWt (650 MWe) class pool-type SFR was thought up by applying design technology obtained from the design of advanced loop-type SFR, named JSFR, equipped with safety measures that reflect results from the feasibility study on commercialized fast reactor cycle systems and fast reactor cycle technology development, improved maintainability and repairability, and lessons learned from the Fukushima Daiichi Nuclear Power Plants accident.

Journal Articles

Validation and verification for the melting and eutectic models in JUPITER code

Chai, P.; Yamashita, Susumu; Nagae, Yuji; Kurata, Masaki

Proceedings of 9th Conference on Severe Accident Research (ERMSAR 2019) (Internet), 14 Pages, 2019/03

In order to obtain a precise understanding of molten material behavior inside RPV and to improve the accuracy of the SA code, a new computational fluid dynamics (CFD) code with multi-phase, multi-physics models, which is called JUPITER, was developed. It optimized the algorithms of the multi-phase calculation. Besides, the chemical reactions are also modeled carefully in the code so that the melting process could be treated precisely. A series of verification and validation studies are conducted, which show good agreement with analytical solutions and previous experiments. The capabilities of the multi-physics models in JUPITER code provide us another useful tool to investigate the molten material behaviors in the relevant severe accident scenario.

Journal Articles

Report on the Twentieth International Conference on Grey Literature

Kumazaki, Yui

Karento Aweanesu-E (Internet), 364, p.E2108_1 - E2108_2, 2019/02

no abstracts in English

Journal Articles

Validation of free-convective heat transfer analysis with JUPITER to evaluate air-cooling performance of fuel debris in dry method

Uesawa, Shinichiro; Yamashita, Susumu; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Mechanical Engineering Journal (Internet), 5(4), p.18-00115_1 - 18-00115_13, 2018/08

Journal Articles

Experimental and statistical study on fracture boundary of non-irradiated Zircaloy-4 cladding tube under LOCA conditions

Narukawa, Takafumi; Yamaguchi, Akira*; Jang, S.*; Amaya, Masaki

Journal of Nuclear Materials, 499, p.528 - 538, 2018/02

 Times Cited Count:3 Percentile:38.72(Materials Science, Multidisciplinary)

Journal Articles

The Safety design guideline development for Generation-IV SFR systems

Nakai, Ryodai

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

The GIF Safety Design Criteria Task Force (SDC TF) has been developing a set of safety design guidelines (SDG) to support practical application of SDC since the completion of the "SDC Phase I Report" that clarifies safety design requirements for Gen-IV SFR systems. The main objective of the SDG development is to assist SFR developers and vendors to utilize the SDC in their design process for improving the safety in specific topical areas including the use of inherent/passive safety features and the design measures for prevention and mitigation of severe accidents. The first report on "Safety Approach SDGs" aims to provide guidance on safety approaches covering specific safety issues on fast reactor core reactivity and on loss of heat removal. The second report on "SDGs on key Structures, Systems and Components (SSCs)" focuses on the functional requirements for SSCs important to safety; reactor core system, reactor coolant system, and containment system.

Journal Articles

Field observations and failure analysis of an excavation damaged zone in the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Ishii, Eiichi; Ishida, Tsuyoshi*

Journal of MMIJ, 133(2), p.25 - 33, 2017/02

In the construction of a deep underground facility, the hydromechanical properties of the rock mass around an underground opening are changed significantly due to stress redistribution. This zone is called an excavation damaged zone (EDZ). In high-level radioactive waste disposal, EDZs can provide a shortcut for the escape of radionuclides to the surface environment. Therefore, it is important to develop a method for predicting the detailed characteristics of EDZs. For prediction of the EDZ in the Horonobe Underground Research Laboratory of Japan, we conducted borehole televiewer surveys, rock core analyses, and repeated hydraulic conductivity measurements. We observed that niche excavation resulted in the formation of extension fractures within 0.2 to 1.0 m into the niche wall, i.e., the extent of the EDZ is within 0.2 to 1.0 m into the niche wall. These results are largely consistent with the results of a finite element analysis implemented with the failure criteria considering failure mode. The hydraulic conductivity in the EDZ was increased by 3 to 5 orders of magnitude compared with the outer zone. The hydraulic conductivity in and around the EDZ has not changed significantly in the two years following excavation of the niche. These results show that short-term unloading due to excavation of the niche created a highly permeable EDZ.

Journal Articles

A Trajectory generation method for mobile robot based on iterative extension-like process

Kawabata, Kuniaki

Artificial Life and Robotics, 21(4), p.500 - 509, 2016/12

In this paper, we propose a trajectory generation method for mobile robot based on iterative extension-like process. Due to use mobile robots in the real world, trajectory generation must be done depending on the faced situation on each occasion. Proposed method enables online iterative trajectory extension process based on a low-order polynomial curve named as trajectory segment. The waypoints on the existing trajectory segment and a waypoint designated every fixed interval are the constraints to trigger the trajectory extension. For maintaining the smooth continuity of the trajectory, the velocity state must be sustained at the connecting point. Resultantly, the trajectory segments are organized into a single smooth trajectory.

JAEA Reports

Development of ITER CODAC compatible gyrotron local control system and its operation

Oshima, Katsumi; Oda, Yasuhisa; Takahashi, Koji; Terakado, Masayuki; Ikeda, Ryosuke; Hayashi, Kazuo*; Moriyama, Shinichi; Kajiwara, Ken; Sakamoto, Keishi

JAEA-Technology 2015-061, 65 Pages, 2016/03

JAEA-Technology-2015-061.pdf:24.28MB

In JAEA, an ITER relevant control system for ITER gyrotron was developed according to Plant Control Design Handbook. This control system was developed based on ITER CODAC Core System and implemented state machine control of gyrotron operation system, sequential timing control of gyrotron oscillation startup, and data acquisition. The operation of ITER 170 GHz gyrotron was demonstrated with ITER relevant power supply configuration. This system is utilized for gyrotron operation test for ITER procurement. This report describes the architecture of gyrotron operation system, its basic and detailed design, and recent operation results.

JAEA Reports

Assessment report of research and development activities in FY2014; Activity "Fusion Research and Development" (In-advance evaluation)

Fusion Research and Development Directorate

JAEA-Evaluation 2016-002, 40 Pages, 2016/03

JAEA-Evaluation-2016-002.pdf:2.66MB

Japan Atomic Energy Agency (hereinafter referred to as "JAEA") asked the assessment committee, "Evaluation Committee of Research and Development Activities for Fusion" (hereinafter referred to as "Committee") for in-advance evaluation of "Research and Development of the technical system for extraction of fusion energy," in accordance with "General Guideline for the Evaluation of Government R&D Activities" by Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology" and "Regulation on Conduct for Evaluation of R&D Activities" by JAEA. In response to the JAEA's request, the Committee assessed the research program of the Fusion Research and Development Directorate (hereinafter referred to as "FRDD") during the period from April 2015 to March 2022. The Committee evaluated the management and research activities of the FRDD based on the explanatory documents prepared by the FRDD, the oral presentations with questions-and-answers by the Director General and the Deputy Director Generals.

JAEA Reports

Assessment report of research and development activities in FY2014; Activity "Fusion Research and Development" (Result evaluation)

Fusion Research and Development Directorate

JAEA-Evaluation 2016-001, 128 Pages, 2016/03

JAEA-Evaluation-2016-001.pdf:33.25MB

Japan Atomic Energy Agency (hereinafter referred to as "JAEA") asked the assessment committee, "Evaluation Committee of Research and Development Activities for Fusion" (hereinafter referred to as "Committee") for result evaluation of "Research and Development of the Technical System for Extraction of Fusion Energy," in accordance with "General Guideline for the Evaluation of Government R&D Activities" by Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology " and "Regulation on Conduct for Evaluation of R&D Activities" by JAEA. In response to the JAEA's request, the Committee assessed the research program of the Fusion Research and Development Directorate (hereinafter referred to as "FRDD") during the period from April 2010 to November 2014. The Committee evaluated the management and research activities of the FRDD based on the explanatory documents prepared by the FRDD, the oral presentations with questions-and-answers by the Director General and the Deputy Director Generals.

Journal Articles

Progress of ITER full tungsten divertor technology qualification in Japan

Ezato, Koichiro; Suzuki, Satoshi; Seki, Yohji; Mori, Kensuke; Yokoyama, Kenji; Escourbiac, F.*; Hirai, Takeshi*; Kuznetsov, V.*

Fusion Engineering and Design, 98-99, p.1281 - 1284, 2015/10

 Times Cited Count:22 Percentile:4.63(Nuclear Science & Technology)

Japan Atomic Energy Agency (JAEA) is now devoting to development of Full-W ITER divertor outer vertical target (OVT), especially, PFU that needs to withstand the repetitive heat load as high as 20MW/m$$^{2}$$. JAEA have succeeded in demonstrating that the soundness of a bonding technology is sufficient for the full-W ITER divertor. For the development of bonding technology, the load carrying capability test on the W monoblock with a leg attachment to an OVT support structure was carried out and shows that the attachment can withstand against the uniaxial load more than 20 kN which is three times higher than the IO requirement. JAEA manufactured 6 small-scale mock-ups and tested under the repetitive heat load of 10 and 20 MW/m$$^{2}$$ to examine the durability of the divertor structure including W tile bonding and the cooling tube. All of the mock-ups could survived 5000 cycles at 10 MW/m$$^{2}$$ and 1000 cycles 20 MW/m$$^{2}$$ with no failure such as debonding of the W tile and water leak from the cooling tube. The number of cycles at 20 MW/m$$^{2}$$ is three times longer than the requirement of ITER divertor.

Journal Articles

Development of instrumentation and control systems for the ITER diagnostic systems in JADA

Yamamoto, Tsuyoshi; Hashimoto, Yasunori*; Kitazawa, Sin-iti; Yatsuka, Eiichi; Hatae, Takaki; Sugie, Tatsuo; Ogawa, Hiroaki; Takeuchi, Masaki; Kawano, Yasunori; Itami, Kiyoshi

Fusion Engineering and Design, 96-97, p.1012 - 1016, 2015/10

 Times Cited Count:4 Percentile:53.79(Nuclear Science & Technology)

Japan Domestic Agency (JADA) is responsible for six diagnostic systems in the ITER project. We have successfully developed an instrumentation and control (I&C) system for the diagnostic systems. The I&C system manages internal operations for measurement such as health checks of sensors, configuration of measurement parameters, and consistency checks between measurement parameters. We developed a conversion tool to convert operational flowcharts to EPICS records. The sequencing management function coordinates the execution of operation steps by monitoring changes in the record values. It was designed so that the relationship between the records and steps is determined automatically according to the flowcharts as much as possible. We validated the performance of the I&C system for the thermocouple measurement system, and are continuing the development of even more complex I&C systems for other JADA diagnostic systems.

Journal Articles

Study on application of kriging to evaluation of radioactivity concentration for ensuring compliance with the criterion of site release

Ishigami, Tsutomu; Shimada, Taro

Journal of Nuclear Science and Technology, 52(9), p.1186 - 1204, 2015/09

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

In the field of decommissioning of nuclear facilities, a reliable method for ensuring compliance with the criterion of site release is an important technical issue to be resolved in Japan. Considering that kriging can consider the spatial correlation of radioactivity concentrations, we propose a method of applying kriging to ensure compliance with the site release criterion. Estimated radioactivity concentrations exhibit uncertainty, which results in a certain probability of the occurrence of decision errors regarding site release. We describe a method for calculating the uncertainty and establish a minimum number of measurement points required. We applied the proposed method and a conventional statistical method to two sample cases. It was observed that the proposed method appropriately estimated the mean radioactivity concentration and led to an efficient measurement requiring fewer measurement points relative to the conventional method when spatial correlation existed.

Journal Articles

Non-destructive examination of jacket sections for ITER central solenoid conductors

Takahashi, Yoshikazu; Suwa, Tomone; Nabara, Yoshihiro; Ozeki, Hidemasa; Hemmi, Tsutomu; Nunoya, Yoshihiko; Isono, Takaaki; Matsui, Kunihiro; Kawano, Katsumi; Oshikiri, Masayuki; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4200904_1 - 4200904_4, 2015/06

 Times Cited Count:0 Percentile:100(Engineering, Electrical & Electronic)

The Japan Atomic Energy Agency (JAEA) is responsible for procuring all amounts of Central Solenoid (CS) Conductors for ITER, including CS jacket sections. The conductor is cable-in-conduit conductor (CICC) with a central spiral. A total of 576 Nb$$_{3}$$Sn strands and 288 copper strands are cabled around the central spiral. The maximum operating current is 40 kA at magnetic field of 13 T. CS jacket section is circular in square type tube made of JK2LB, which is high manganese stainless steel with boron added. Unit length of jacket sections is 7 m and 6,300 sections will be manufactured and inspected. Outer/inner dimension and weight are 51.3/35.3 mm and around 90 kg, respectively. Eddy Current Test (ECT) and Phased Array Ultrasonic Test (PAUT) were developed for non-destructive examination. The defects on inner and outer surfaces can be detected by ECT. The defects inside jacket section can be detected by PAUT. These technology and the inspected results are reported in this paper.

Journal Articles

Fabrication process qualification of TF Insert Coil using real ITER TF conductor

Ozeki, Hidemasa; Isono, Takaaki; Kawano, Katsumi; Saito, Toru; Kawasaki, Tsutomu; Nishino, Katsumi; Okuno, Kiyoshi; Kido, Shuichi*; Semba, Tomoyuki*; Suzuki, Yozo*; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4200804_1 - 4200804_4, 2015/06

 Times Cited Count:0 Percentile:100(Engineering, Electrical & Electronic)

Journal Articles

Development of ITER equatorial EC launcher components toward the final design

Takahashi, Koji; Kajiwara, Ken; Oda, Yasuhisa; Sakamoto, Keishi; Omori, Toshimichi*; Henderson, M.*

Fusion Science and Technology, 67(4), p.718 - 731, 2015/05

 Times Cited Count:3 Percentile:62.98(Nuclear Science & Technology)

Development of an electron cyclotron (EC) equatorial launcher has been undergoing a series of prototype tests and design enhancements intending to improve reliability and functionality of the launcher. The design enhancements include adaptation of the launcher steering angles such that one of three beam rows of the launcher is necessary flipped to perform counter current drive (to conform to a new ITER physics requirement). Also the top and bottom steering rows have been tilted with angle of 5$$^{circ}$$ so that the top and bottom beam row can access from on axis to near mid-radius. Furthermore, the position of the focusing mirror that forms a quasi-optical in-vessel millimeter wave transmission line is modified to increase the nuclear shielding capability. High power experiment of the mm-wave launching system mock-up fabricated in basis of the design confirmed the successful steering capability of 20$$^{circ}$$$$sim$$40$$^{circ}$$. It was measured that some of stray RF propagated in the beam duct and generated some heat on the duct at a certain condition of mm-wave transmission. Prototype tests also include the fabrication of the blanket shield module and the partial port plug mock-up and have shown no serious technological issue on the fabrication and the cooling functionality.

Journal Articles

Assessment of operational space for long-pulse scenarios in ITER

Polevoi, A. R.*; Loarte, A.*; Hayashi, Nobuhiko; Kim, H. S.*; Kim, S. H.*; Koechl, F.*; Kukushkin, A. S.*; Leonov, V. M.*; Medvedev, S. Yu.*; Murakami, Masakatsu*; et al.

Nuclear Fusion, 55(6), p.063019_1 - 063019_8, 2015/05

 Times Cited Count:22 Percentile:13.18(Physics, Fluids & Plasmas)

1143 (Records 1-20 displayed on this page)