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Sato, Hiroyuki; Nishida, Akemi; Ohashi, Hirofumi; Muramatsu, Ken*; Muta, Hitoshi*; Itoi, Tatsuya*; Takada, Tsuyoshi*; Hida, Takenori*; Tanabe, Masayuki*; Yamamoto, Tsuyoshi*; et al.
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04
JAEA, in conjunction with Tokyo City University, The University of Tokyo and JGC Corporation, have started development of a PRA method considering the safety and design features of HTGR. The primary objective of the project is to develop a seismic PRA method which enables to provide a reasonably complete identification of accident scenario including a loss of safety function in passive system, structure and components. In addition, we aim to develop a basis for guidance to implement the PRA. This paper provides the overview of the activities including development of a system analysis method for multiple failures, a component failure data using the operation and maintenance experience in the HTTR, seismic fragility evaluation method, and mechanistic source term evaluation method considering failures in core graphite components and reactor building.
Matsuda, Kosuke*; Muramatsu, Ken*; Muta, Hitoshi*; Sato, Hiroyuki; Nishida, Akemi; Ohashi, Hirofumi; Itoi, Tatsuya*; Takada, Tsuyoshi*; Hida, Takenori*; Tanabe, Masayuki*; et al.
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04
This paper proposes a set of procedures for accident sequence analysis in seismic PRAs of HTGRs that can consider the unique accident progression characteristics of HTGRs. Main features of our proposed procedure are as follows: (1) Systematic analysis techniques including Master Logic Diagrams are used to ensure reasonable completeness in identification of initiating events and classification of accident sequences, (2) Information on factors that govern the accident progression and source terms are effectively reflected to the construction of event trees for delineation of accident sequences, and (3) Frequency quantification of seismically-initiated accident sequence frequencies that involve multiplepipe ruptures are made with the use of the Direct Quantification of Fault Trees by Monte Carlo (DQFM) method by a computer code SECOM-DQFM.
Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Togashi, Tadashi*; Fukami, Kenji*; et al.
Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164006_1 - 164006_6, 2013/08
Times Cited Count:3 Percentile:19.06(Optics)By introducing 13th- (61.7 nm) and 15th-order harmonics (53.4 nm) of femtosecond laser pulses at 800 nm into an undulator of SCSS (SPring-8 Compact SASE Source) test accelerator at RIKEN, these harmonic pulses were amplified by a factor of more than 10 with a high contrast ratio through the interaction between accelerated electron bunches and the harmonic pulses. From numerical simulations of the amplification processes of high-order harmonic pulses in the undulator, optimum conditions of the electron bunch duration interacting with the high-order harmonic pulses were investigated for generating full-coherent and intense pulses in the extreme ultraviolet wavelength region.
Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Okino, Tomoya*; Yamanouchi, Kaoru*; et al.
Optics Express (Internet), 19(1), p.317 - 324, 2011/01
Times Cited Count:96 Percentile:96.45(Optics)The 13th harmonic of a Ti:sapphire (Ti:S) laser in the plateau region was injected as a seeding source to a 250-MeV free-electron-laser (FEL) amplifier. When the amplification conditions were fulfilled, strong enhancement of the radiation intensity by a factor of 650 was observed. The random and uncontrollable spikes, which appeared in the spectra of the Self-Amplified Spontaneous Emission (SASE) based FEL radiation without the seeding source, were found to be suppressed drastically to form to a narrow-band, single peak profile at 61.2 nm. The properties of the seeded FEL radiation were well reproduced by numerical simulations. We discuss the future precept of the seeded FEL scheme to the shorter wavelength region.
Aihara, Jun; Ueta, Shohei; Yasuda, Atsushi*; Takeuchi, Hitoshi*; Mozumi, Yasuhiro*; Sawa, Kazuhiro; Motohashi, Yoshinobu*
Materials Transactions, 50(11), p.2631 - 2636, 2009/11
Times Cited Count:8 Percentile:45.88(Materials Science, Multidisciplinary)The ZrC coating layer has been fabricated using the bromide process at JAEA. The coated particles with IPyC layers reported in a previous study were annealed at around 1800C for 1h, under which compact sintering will be done in a practical process, in order to study effects of the heat treatment (annealing) on their microstructure evolution. Then the microstructures of the ZrC layers in the cases (batches) of C/Zr = 1.11 and 1.35 were characterized by means of TEM and STEM. Certain changes in the shape and size of voids or free carbons region caused by the heat treatment were found in the cases of both batches. After the heat treatment, the voids or free carbons region have shown a clod like feature with diameters of 50 to 100 nm. The grain growth of ZrC was also observed in both cases: In the ZrC layer with C/Zr = 1.11, the fibrous carbons grew as of to stand from the PyC to ZrC layers on some places in the IPyC/ZrC boundary.
Hasegawa, Shin; Ohashi, Hitoshi; Maekawa, Yasunari; Katakai, Ryoichi*; Yoshida, Masaru
Polymer Journal, 41(7), p.533 - 540, 2009/07
Times Cited Count:3 Percentile:11.53(Polymer Science)We investigated the permeation behavior of Li over Co and Ni ions through thermo- and pH-responsive gel membranes. The gel membranes were synthesized by -ray grafting of pH-responsive poly (acrylic acid) (AAc) onto a thermo-responsive polymer gel of acryloyl-L-proline methyl ester (A-ProOMe). The permeation constant of Li ions is 3.5 and 2.8 times higher than those of Co and Ni ions at 30 C in a pH 6.0. The most appropriate temperature and pH through the 15% grafted membrane were 30 C and pH 6.0. The adjacencies of the carboxyl groups of poly (AAc) surrounded by thermo-responsive poly (A-ProOMe) matrix must be decisive for the selective Li ion permeability. From the microscopic structures using SEM and the distributions of Co and Ni ions by EDS analysis, we confirmed that the structures formed by the flexible grafted chains of the carboxyl groups onto the thermo-response gel membrane are significant for the selective permeation of Li ion.
Yoshikawa, Hiroshi; Sakaki, Hironao; Sako, Hiroyuki; Takahashi, Hiroki; Shen, G.; Kato, Yuko; Ito, Yuichi; Ikeda, Hiroshi*; Ishiyama, Tatsuya*; Tsuchiya, Hitoshi*; et al.
Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.62 - 64, 2007/10
J-PARC is a large scale facility of the proton accelerators for the multi-purpose of scientific researches in Japan. This facility consists of three accelerators and three experimental stations. Now, J-PARC is under construction, and LINAC is operated for one year, 3GeV synchrotron has just started the commissioning in this October the 1st. The completion of this facility will be next summer. The control system of accelerators established fundamental performance for the initial commissioning. The most important requirement to the control system of this facility is to minimize the activation of accelerator devices. In this paper, we show that the performances of each layer of this control system have been achieved in the initial stage.
Motohashi, Masahiro; Kyue, Tadashi; Imamoto, Nobuo; Ichinosawa, Hitoshi; Inanobe, Kazuhide*
Saikuru Kiko Giho, (27), p.96 - 97, 2005/06
The general-condition report of LWTF is carried to
Hasegawa, Shin; Ohashi, Hitoshi; Maekawa, Yasunari; Katakai, Ryoichi*; Yoshida, Masaru
Radiation Physics and Chemistry, 72(5), p.595 - 600, 2005/04
Times Cited Count:16 Percentile:71.86(Chemistry, Physical)Thermo- and pH-responsive gel membranes were synthesized by -ray grafting of pH-responsive poly (acrylic acid) (AAc) onto thermo-responsive polymer gel of acryloyl--proline methyl ester (A-ProOMe). The gel membranes of poly (A-ProOMe) with 15 mol% graft chains of AAc exhibited both thermo- and pH-responses. Under the condition (pH 6.0, 30C) in which the thermo-sensitive unit shrinks and the pH-sensitive unit swells, the selective permeation of Li ion over Co and Ni ions can be achieved.
Masahiro, Motohashi,; Tadashi, Kyue,; Imamoto, Nobuo; Ichinosawa, Hitoshi; Inanobe, Kazuhide*
Saikuru Kiko Giho, (26), p.131 - 132, 2005/00
The general-condition report of LWTF is carried to "JNC Technical Review No.26 2005.3"
Masahiro, Motohashi,; Tadashi, Kyue,; Kiyonori, Ishii,; Ichinosawa, Hitoshi; Inanobe, Kazuhide*
Saikuru Kiko Giho, (22), 114- Pages, 2004/00
None
Masahiro, Motohashi,; Tadashi, Kyue,; Kiyonori, Ishii,; Ichinosawa, Hitoshi
Saikuru Kiko Giho, (23), 130- Pages, 2004/00
"JNC Technical Review " The general-condition report of LWTF is carried to No. 23.
Masahiro, Motohashi,; Tadashi, Kyue,; Imamoto, Nobuo; Ichinosawa, Hitoshi; Inanobe, Kazuhide*
Saikuru Kiko Giho, (24), p.82 - 83, 2004/00
The general-condition report of LWTF is carried to "JNC Technical Review No.24 2004.9"
Masahiro, Motohashi,; Tadashi, Kyue,; Imamoto, Nobuo; Ichinosawa, Hitoshi; Inanobe, Kazuhide*
Saikuru Kiko Giho, (25), 132- Pages, 2004/00
The general-condition report of LWTF is carried to "JNC Technical Review No.25 2004.12"
Motohashi, Masahiro; Kyue; Ishii; Ichinosawa, Hitoshi
Saikuru Kiko Giho, (19), 94- Pages, 2003/00
None
Chen, J.; Hasegawa, Shin; Ohashi, Hitoshi; Maekawa, Yasunari; Yoshida, Masaru; Katakai, Ryoichi; Tsubokawa, Norio*
Macromolecular Rapid Communications, 23(2), p.141 - 144, 2002/01
Times Cited Count:9 Percentile:33.27(Polymer Science)no abstracts in English
Aihara, Jun; Ueta, Shohei; Yasuda, Atsushi; Takeuchi, Hitoshi; Sawa, Kazuhiro; Motohashi, Yoshinobu*
no journal, ,
We report in this study the microstructural change of the ZrC coating layers with annealing. We already reported the microstructures of as-fabricated ZrC coating layers last year. ZrC coated particles were annealed at about 1800 C for 1 hour to simulate the sintering process of the real HTGR fuel. With annealing, ZrC grains were slightly grown especially near the surface regions and kept their orientation. The free carbons and/or voids cohered at the grain boundaries. The cohered free carbons and/or voids were appeared to form the clods of the free carbon ribbons. In addition, IPyC/ZrC boundary structure changed. Fibrous carbon texture was found at IPyC/ZrC boundary even in the specimen of the batch of which that texture was not observed in the as-fabricated specimen.
Nagasono, Mitsuru*; Harries, J.; Iwayama, Hiroshi*; Togashi, Tadashi*; Tono, Kensuke*; Yabashi, Makina*; Semba, Yasunori*; Ohashi, Haruhiko*; Tanaka, Hitoshi*; Ishikawa, Tetsuya*; et al.
no journal, ,
Honda, Yuki; Sato, Hiroyuki; Ohashi, Hirofumi; Nishida, Akemi; Muta, Hitoshi*; Muramatsu, Ken*; Itoi, Tatsuya*; Tanabe, Masayuki*
no journal, ,
We have been conducting a source term evaluation method development for high temperature gas-cooled reactors considering structural failures in the major components. We will present the outline of evaluation method and results of transient analysis for unprotected depressurized loss-of-forced cooling accident which may be initiated by Beyond-Design-Basis Earthquake.
Muramatsu, Ken*; Muta, Hitoshi*; Matsuda, Kosuke*; Sato, Hiroyuki; Nishida, Akemi; Ohashi, Hirofumi; Itoi, Tatsuya*; Tanabe, Masayuki*
no journal, ,
As part of PRA method development for High temperature Gas-cooled Reactor, domestic and international PRA standards are investigated to identify requirements related to accident scenario assessment and reliability database development. It was concluded that there are three key thing to note for the PRA method development, that is, detail analysis for passive components, integration of mechanistic source term evaluation and supplementation of reliability data.