Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.
Journal of Environmental Radioactivity, 238-239, p.106721_1 - 106721_10, 2021/11
Times Cited Count：11 Percentile：56.59(Environmental Sciences)This study was aimed at analysing performance of models for radiocesium migration mainly in evergreen coniferous forest in Fukushima, by inter-comparison between models of several research teams. The exercise included two scenarios of countermeasures against the contamination, namely removal of soil surface litter and forest renewal, and a specific konara oak forest scenario in addition to the evergreen forest scenario. All the models reproduced trend of time evolution of radiocesium inventories and concentrations in each of the components in forest such as leaf and organic soil layer. However, the variations between models enlarged in long-term predictions over 50 years after the fallout, meaning continuous field monitoring and model verification/validation is necessary.
Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.
High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02
As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950
C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.
Hirota, Noriaki; Kasahara, Seiji; Iwatsuki, Jin; Imai, Yoshiyuki; Ohashi, Hirofumi; Yan, X.; Tachibana, Yukio
Zairyo To Kankyo, 68(6), p.137 - 142, 2019/06
New corrosion test equipment for high temperature gas of decomposed sulfuric acid was manufactured in order to ascertain flow rate of sulfuric acid in the piping, occurrence of sulfuric acid decomposition reaction in the equipment, and temperature distribution inside the furnace tube. The flow rate of the sulfuric acid solution was constantly measured using an ultrasonic flowmeter. The SO
concentration at the inlet of the test equipment was almost the same as that at the inlet of the sulfuric acid decomposer in the hydrogen production plant assuming a high-temperature gas cooled reactor hydrogen-power cogeneration system (GTHTR300C). On the other hand, during a test, leakage of sulfuric acid occurred from the fitting part at the outlet side. Hence the temperature distribution of the fitting part at the outlet side was investigated using fluid analysis. As a result, it was found that the temperature at the fitting was low enough to use fluorine joint grease when the distance was 0.05 m or more away from the outlet side pipe. An improved furnace tube was manufactured and the temperature was measured again at fitting part of the outlet side. The temperature was lower that the temperature limit of the joint grease and almost the same as the temperature distribution in the fluid analysis, and leakage of sulfuric acid has not occurred to date.
Iwatsuki, Jin; Ohashi, Hirofumi; Yan, X.
Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 7 Pages, 2018/10
The HTTR is a 30MW, 950C high temperature engineering test reactor built and operated on the site of the Oarai Research & Development Center of Japan Atomic Energy Agency (JAEA). In the framework of the HTTR project, JAEA has been conducting a research and development on the steam reforming system (CH
+ H
O = 3H + CO). JAEA had constructed a mock-up test facility in 2002, and investigated transient behavior of the hydrogen production system and established system controllability. Based on the results and experience of above, the conceptual design of steam reforming system for hydrogen production connected to HTTR has been studied. The system condition was optimized considering the HTTR specification and the experience on the construction and the operation of the mock-up test facility. The hydrogen production system is heated with about 0.2MW transported from the HTTR to the hydrogen system via a helium loop. The system produces about 70 Nm
/h hydrogen.
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.
Ueta, Shohei; Inoi, Hiroyuki; Mizutani, Yoshitaka; Ohashi, Hirofumi; Iwatsuki, Jin; Sakaba, Nariaki; Sawa, Kazuhiro
Proceedings of 21st International Conference on Nuclear Engineering (ICONE-21) (DVD-ROM), 4 Pages, 2013/07
Japan Atomic Energy Agency (JAEA) has planned to investigate on iodine release behavior from fuel through the testing operation of High Temperature Engineering Test Reactor (HTTR) in order to contribute to the reasonable estimation of the radiation exposure necessary for the realization of HTGR in the future. In this test, the fractional release of iodine will be measured and evaluated by measuring xenon isotopes, the daughter nuclides of iodine isotopes, in the primary coolant sampling under the loss-of-forced cooling (LOFC) test by which the primary coolant circulator is shut down and/or the manual scram test of HTTR. In parallel, the local area of primary coolant circuit where iodine is plated-out will be evaluated. This paper describes the testing plan and the preliminary analytical study on the release behavior of iodine and xenon isotopes through the operation of HTTR.
Pikuz, T.; Faenov, A.*; Fukuda, Yuji; Kando, Masaki; Bolton, P.; Mitorfanov, A.*; Vinogradov, A.*; Nagasono, Mitsuru*; Ohashi, Haruhiko*; Yabashi, Makina*; et al.
Optics Express (Internet), 20(4), p.3424 - 3433, 2012/02
Times Cited Count：27 Percentile：76.85(Optics)Inogamov, N. A.*; Anisimov, S. I.*; Petrov, Y. V.*; Khokhlov, V. A.*; Zhakhovskii, V. V.*; Faenov, A. Ya.*; Pikuz, T.; Fortov, V. E.*; Skobelev, I. Y.*; Kato, Yoshiaki*; et al.
Journal of Optical Technology, 78(8), p.473 - 480, 2011/08
Times Cited Count：6 Percentile：32.94(Optics)Inogamov, N. A.*; Faenov, A. Ya.*; Zhakhovsky, V. V.*; Pikuz, T. A.*; Skobelev, I. Yu.*; Petrov, Y. V.*; Khokhlov, V. A.*; Shepelev, V. V.*; Anisimov, S. I.*; Fortov, V. E.*; et al.
Contributions to Plasma Physics, 51(5), p.419 - 426, 2011/06
Times Cited Count：20 Percentile：64.22(Physics, Fluids & Plasmas)Warm dense matter, arising under the action of ultrashort EUV-FEL pulse onto LiF dielectric crystal, is characterized by high temperature of conduction electrons, with their number density achieving values of the order of atom number density at maximum laser fluences in our experiments. Expansion of matter, heated and pressurized through the electron-ion energy exchange, gives rise to the spallative ablation at small fluences and gaseous outflow from a target in the case of large fluences. Ablation threshold is low in comparison with a longer nanosecond XRL.
-poly (AAc) membrane for selective separation of metal ionsHasegawa, 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.
Sakaba, Nariaki; Tachibana, Yukio; Shimakawa, Satoshi; Ohashi, Hirofumi; Sato, Hiroyuki; Yan, X.; Murakami, Tomoyuki; Ohashi, Kazutaka; Nakagawa, Shigeaki; Goto, Minoru; et al.
JAEA-Technology 2008-019, 57 Pages, 2008/03
JAEA-Technology-2008-019.pdf:8.59MB
The small-sized and safe cogeneration High Temperature Gas-cooled Reactor (HTGR) that can be used not only for electric power generation but also for hydrogen production and district heating is considered one of the most promising nuclear reactors for developing countries where sufficient infrastructure such as power grids is not provided. Thus, the small-sized cogeneration HTGR, named High Temperature Reactor 50-Cogeneration (HTR50C), was studied assuming that it should be constructed in developing countries. Specification, equipment configuration, etc. of the HTR50C were determined, and economical evaluation was made. As a result, it was shown that the HTR50C is economically competitive with small-sized light water reactors.
Kato, Michio; Hayashi, Koji; Aita, Hideki; Ohashi, Hirofumi; Sato, Hiroyuki; Inaba, Yoshitomo; Iwatsuki, Jin; Takada, Shoji; Inagaki, Yoshiyuki
JAEA-Technology 2007-022, 209 Pages, 2007/03
JAEA-Technology-2007-022.pdf:14.46MB
The mock-up test facility was fabricated to investigate performance of the steam generator for mitigation of the temperature fluctuation of helium gas and transient behavior of the hydrogen production system for HTTR and to obtain experimental data for verification of a dynamic analysis code. The test facility has an approximate hydrogen production capacity of 120Nm/h and the steam reforming process of methane; CH+HO=3H+CO, was used for hydrogen production of the test facility. An electric heater was used as a heat source instead of the reactor in order to heat helium gas up to 880 C (4MPa) at the chemical reactor inlet which is the same temperature as the HTTR hydrogen production system. Fabrication of the test facility was completed in February in 2002, and seven cycle operations were carried out from March in 2002 to December in 2004. This report describes the structure and main specifications of the test facility.
-proline methyl ester)--poly(acrylic acid) for selective permeation of metal ionsHasegawa, 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.
Meguro, Yoshihiro; Ogiyanagi, Jin*; Tomioka, Osamu; Imura, Hisanori*; Ohashi, Kozaburo*; Yoshida, Zenko; Nakashima, Mikio
Proceedings of 2nd International Symposium on Supercritical Fluid Technology for Energy and Environment Applications (Super Green 2003), p.175 - 179, 2004/00
One of the most attractive properties of SFE is that changing solvent properties by tuning pressure can control distribution behavior of a metal ion. Distribution ratio (D) of uranium(VI) and plutonium(IV) with tributyl phosphate (TBP) from a nitric acid solution and palladium(II) with 2-methyl-8-qunolinol (HMQ) from a hydrochloric solution were determined in SFE at various pressures. In the extraction system using TBP, a linear relationship between the logarithmic distribution ratio (log D) and the solubility parameter of CO was observed. The solubility parameter is difined based on the regular solution theory and is one of the parameters depending on the pressure. On the other hand, a linear relationship with a positive slope between log D and the solubility parameter was observed in the extraction system using HMQ. Most of the extractant was dissolved in the aqueous phase as HMQ
under the extraction condition examined.
(
,
)
and (,)
reactions for 
=1.5-2.4 GeVZegers, R. G. T.*; Sumihama, Mizuki*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Dat
, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; et al.
Physical Review Letters, 91(9), p.092001_1 - 092001_4, 2003/08
Times Cited Count：128 Percentile：94.9(Physics, Multidisciplinary)no abstracts in English
= +1 Baryon resonance in photoproduction from the neutronNakano, Takashi*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Date, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; Fujiwara, Mamoru; et al.
Physical Review Letters, 91(1), p.012002_1 - 012002_4, 2003/07
Times Cited Count：1006 Percentile：99.86(Physics, Multidisciplinary)no abstracts in English
Inagaki, Yoshiyuki; Hayashi, Koji; Kato, Michio; Fujisaki, Katsuo; Aita, Hideki; Takeda, Tetsuaki; Nishihara, Tetsuo; Inaba, Yoshitomo; Ohashi, Hirofumi; Katanishi, Shoji; et al.
JAERI-Tech 2003-034, 129 Pages, 2003/05
JAERI-Tech-2003-034.pdf:7.62MB
no abstracts in English
Shimizu, Akira; Kato, Michio; Hayashi, Koji; Fujisaki, Katsuo; Aita, Hideki; Takeda, Tetsuaki; Nishihara, Tetsuo; Katanishi, Shoji; Takada, Shoji; Inaba, Yoshitomo; et al.
JAERI-Tech 2003-033, 105 Pages, 2003/03
JAERI-Tech-2003-033.pdf:8.35MB
no abstracts in English
Watanabe, Tadashi; Ito, Goichi*; Nakamura, J.*; Kono, Koji*; Ohashi, H.*
Proceedings of 3rd Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-3), p.146 - 151, 2002/10
no abstracts in English
