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Journal Articles

Molecular gyrotops with a five-membered heteroaromatic ring; Synthesis, temperature-dependent orientation of dipolar rotors inside the crystal, and its birefringence change

Masuda, Toshiyuki*; Arase, Junko*; Inagaki, Yusuke*; Kawahara, Masatoshi*; Yamaguchi, Kentaro*; Ohara, Takashi; Nakao, Akiko*; Momma, Hiroyuki*; Kwon, E.*; Setaka, Wataru*

Crystal Growth & Design, 16(8), p.4392 - 4401, 2016/08

 Times Cited Count:24 Percentile:90.91(Chemistry, Multidisciplinary)

Journal Articles

Metabolic alterations in leaves of oxalate-rich plant ${it Rumex obtusifolius}$ L. irradiated by $$gamma$$ rays

Kitano, Sayaka*; Miyagi, Atsuko*; Ono, Yutaka; Hase, Yoshihiro; Narumi, Issey*; Yamaguchi, Masatoshi*; Uchimiya, Hirofumi*; Kawai, Maki*

Metabolomics, 11(1), p.134 - 142, 2015/02

 Times Cited Count:8 Percentile:32.49(Endocrinology & Metabolism)

Journal Articles

Corrosion resistance of structural materials in high-temperature aqueous sulfuric acids in thermochemical water-splitting iodine-sulfur process

Kubo, Shinji; Futakawa, Masatoshi; Ioka, Ikuo; Onuki, Kaoru; Yamaguchi, Akihisa*

International Journal of Hydrogen Energy, 38(16), p.6577 - 6585, 2013/05

 Times Cited Count:18 Percentile:45.19(Chemistry, Physical)

Very harsh environments exist in the iodine-sulfur process for hydrogen production. Structural materials for sulfuric acid vaporizers and concentrators are exposed to high-temperature corrosive environments. Immersion tests were carried out to evaluate the corrosion resistance of ceramics and to evaluate corrosion-resistant metals exposed to environments of aqueous sulfuric acids at temperatures of 320, 380, and 460$$^{circ}$$C, and pressure of 2 MPa. The aqueous sulfuric acid concentrations for the temperatures were 75, 85, and 95 wt%, respectively. Ceramic specimens of silicon carbides (SiC), silicon impregnated silicon carbides (Si-SiC), and silicon nitrides (Si$$_{3}$$N$$_{4}$$) showed excellent corrosion resistance from weight loss measurements after exposure to 75, 85, and 95 wt% sulfuric acid. High-silicon irons with silicon content of 20 wt% showed a fair measure of corrosion resistance. However, evidence of crack formation was detected via microscopy. Silicon enriched steels severely suffered from uniform corrosion with a corrosion rate in 95 wt% sulfuric acid of approximately 1 gm$$^{-2}$$h$$^{-2}$$. Among the tested materials, the ceramics SiC, Si-SiC, and Si$$_{3}$$N$$_{4}$$ were found to be suitable candidates for structural materials in direct contact with the considered environments.

Journal Articles

Adaptability of Metallic Structural Materials to gaseous HI decomposition environment in thermochemical water-splitting iodine-sulfur process

Kubo, Shinji; Futakawa, Masatoshi; Onuki, Kaoru; Yamaguchi, Akihisa*

Corrosion Engineering, 62(3), p.104 - 111, 2013/03

The iodine-sulfur thermochemical cycle for hydrogen production takes place in very harsh environments. Structural metallic materials for the hydrogen iodide decomposition are exposed in a high temperature halogen corrosion and hydrogen embrittlement environment. To evaluate adaptability of the materials, the corrosion rates and mechanical properties (the yield strength, the tensile strength, and the elongation) were measured. Prepared test specimens were exposed to ambient gas consisting of HI, I$$_2$$, H$$_2$$O, and H$$_2$$ (molar fraction of 1:1:6:0.16) at 450$$^{circ}$$C for 1000 h at atmospheric pressure. After the exposure, the corrosion rates were obtained by the weight loss of each specimen. Nickel-based alloys (Hastelloy C-276, MAT21, Inconel 625) exhibited appropriate corrosion resistance ($$<$$ 0.03 g m$$^{-2}$$ h$$^{-1}$$. In addition, no degradations of the mechanical properties for the MAT21 and the Inconel 625 were observed. The specimens of tantalum and titanium showed hydrogen embrittlement; the specimens of zirconium and niobium exhibited poor corrosion resistance. The specimens of molybdenum (Mo) exhibited good corrosion resistance; however, the strength degradation of Mo is cause for concern. As the results show, the nickel-based alloys are well suited for the structural materials within this environment from the viewpoint of the corrosion resistance. MAT21 among them is an outstanding material with an eye to its corrosion resistance and mechanical properties.

Journal Articles

Adaptability of metallic structural materials to gaseous HI decomposition environment in thermochemical water-splitting iodine-sulfur process

Kubo, Shinji; Futakawa, Masatoshi; Onuki, Kaoru; Yamaguchi, Akihisa*

Zairyo To Kankyo, 62(3), p.122 - 128, 2013/03

The iodine-sulfur thermochemical cycle for hydrogen production takes place in very harsh environments. Structural metallic materials for the hydrogen-iodide decomposition are exposed in the high-temperature halogen corrosion and the hydrogen embrittlement environment. To evaluate adaptability of the materials, corrosion rates and mechanical properties (the yield strength, the tensile strength, and the elongation) were measured. Prepared test specimens were exposed to ambient gas consisting of HI, I$$_{2}$$, H$$_{2}$$O and H$$_{2}$$ (molarfraction, 1:1:6:0.16) at 450$$^{circ}$$C for 1000 hours at the atmospheric pressure. After the exposure, the corrosion rates were obtained by the weight loss of each specimen. Nickel-based alloys (Hastelly C-276, MAT21, Inconel 625) exhibited appropriate corrosion resistance ($$<$$ 0.03 g m$$^{-2}$$ h$$^{-1}$$). In addition, no degradations of the mechanical properties for the MAT21 and the Inconel 625 were observed. The specimens of tantalum and titanium showed the hydrogen embrittlement; the specimens of zirconium and niobium exhibited poor corrosion resistance. The specimens of molybdenum (Mo) exhibited good corrosion resistance, however strength degradation of Mo is causing concern. As the results, the nickel-based alloys are well suited for the structural materials within this environment from the viewpoint of the corrosion resistance. MAT21 among them is the outstanding material with an eye to its corrosion resistance and mechanical properties.

Journal Articles

Quantification of fatigue crack propagation of an austenitic stainless steel in mercury embrittlement

Naoe, Takashi; Yamaguchi, Yoshihito; Futakawa, Masatoshi

Journal of Nuclear Materials, 431(1-3), p.133 - 139, 2012/12

 Times Cited Count:7 Percentile:53.66(Materials Science, Multidisciplinary)

Liquid metals are expected to be used as the nuclear materials because of its good thermal conductivity. However, in specific combinations of the liquid and solid metals, liquid metals have possibility to decrease lifetime of the structural material due to the LME. In this study, the LME in combination between the mercury and an austenitic stainless steel as a target and structural material for the pulsed spallation neutron source was investigated through the fatigue tests with the notched specimen under mercury immersion. The FRASTA method combined with the measurement of the notch opening distance was performed to estimate the fatigue crack growth rate in mercury. The results showed that the fatigue crack growth rate in mercury was slightly higher than that of in air at low cycle fatigue region. It was suggested that the crack propagation accelerated by the mercury immersion.

JAEA Reports

Conceptual design of multipurpose compact research reactor; Annual report FY2010 (Joint research)

Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.

JAEA-Technology 2011-031, 123 Pages, 2012/01

JAEA-Technology-2011-031.pdf:16.08MB

The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.

Journal Articles

Trapping of multiple hydrogen atoms in a tungsten monovacancy from first principles

Osawa, Kazuhito*; Goto, Junya*; Yamakami, Masahiro*; Yamaguchi, Masatake; Yagi, Masatoshi*

Physical Review B, 82(18), p.184117_1 - 184117_6, 2010/11

 Times Cited Count:92 Percentile:94.29(Materials Science, Multidisciplinary)

The configuration of multiple hydrogen atoms trapped in a tungsten monovacancy is investigated using first-principles calculations. Unlike previous computational studies, which have reported that hydrogen in BCC metal monovacancies occupies octahedral interstitial sites, it is found that the stable sites shift towards tetrahedral interstitial sites as the number of hydrogen atoms increases. As a result, a maximum of twelve hydrogen atoms can become trapped in a tungsten monovacancy.

Journal Articles

Bending fatigue strength of austenitic stainless steel SUS316 in mercury

Naoe, Takashi; Yamaguchi, Yoshihito; Futakawa, Masatoshi; Wakui, Takashi

Zairyo, 59(4), p.309 - 314, 2010/04

Liquid mercury target system for spallation neutron source is installed at Materials and Life Science Experimental Facility in J-PARC. Austenitic stainless steel SUS316 for a structural material of the target vessel is contact with mercury, and imposed by cyclic pressure that is induced by pulsed proton beam injection at 25 Hz. Therefore, it is important from the viewpoint of the structural integrity to investigate the effect of mercury on fatigue behavior of the structural material. Bending fatigue tests in mercury and air were performed to evaluate the effect of mercury on fatigue behavior. FRActure Surface Topography Analyses (FRASTA) were carried out to evaluate the change in fracture morphology with mercury. It was confirmed that the fatigue strength was decreased by mercury immersion in low cycle region less than 10$$^{5}$$ cycles and intergranular fracture surface was observed, while in high cycle region the mercury immersion effect was hardly recognized.

Journal Articles

Effect of tensile stress on cavitation damage formation in mercury

Naoe, Takashi; Kogawa, Hiroyuki; Yamaguchi, Yoshihito; Futakawa, Masatoshi

Journal of Nuclear Materials, 398(1-3), p.199 - 206, 2010/03

 Times Cited Count:5 Percentile:38.65(Materials Science, Multidisciplinary)

Pressure wave induced cavitation is a critical issue to realize a MW-class mercury target because structural integrity of the target vessel is remarkably degraded by the pitting damage. The target vessel suffers tensile stress by welding residual stress and/or thermal stress due to proton beam injection. In this study, in order to examine the effect of tensile stress on pitting damage formation, cavitation erosion test was performed using an ultrasonic homogenizer in mercury. The result showed that the damaged area was increased with increasing in tensile stress. The depth and diameter of pits were larger than that of no-stressed specimen, and the eroded area was increased. Indentation tests under tensile stress were carried out to quasi-statically simulate impact load. Vickers hardness was slightly decreased. Threshold stress of the deformation, i.e. pitting damage formation, was decreased by tensile stress.

JAEA Reports

Assessment on long-term safety for geological disposal of high level radioactive waste; Application of probabilistic safety assessment methodology to uncertainties in hypothetical geological disposal system (Contract research)

Takeda, Seiji; Yamaguchi, Tetsuji; Nagasawa, Hirokazu; Watanabe, Masatoshi; Sekioka, Yasushi; Kanzaki, Yutaka; Sasaki, Toshihisa; Ochiai, Toru; Munakata, Masahiro; Tanaka, Tadao; et al.

JAEA-Research 2009-034, 239 Pages, 2009/11

JAEA-Research-2009-034.pdf:33.52MB

In safety assessment for geological disposal of high level radioactive waste, it is of consequence to estimate the uncertainties due to the long-term frame associated with long-lived radionuclides and the expanded geological environment. The uncertainties result from heterogeneity intrinsic to engineered and natural barrier materials, insufficient understanding of phenomena occurring in the disposal system, erroneous method of measurement, and incomplete construction. It is possible to quantify or to reduce the uncertainties according to scientific and technological progress. We applied a deterministic and a Monte Carlo-based probabilistic method simulation techniques to the uncertainty analysis for performance of hypothetical geological disposal system for high level radioactive waste. This study provides the method to evaluate the effects of the uncertainties with respect to scenarios, models and parameters in engineering barrier system on radiological consequence. The results also help us to specify prioritized models and parameters to be further studied for long-term safety assessment.

Journal Articles

Corrosion rate evaluations of structural materials for a iodine-sulfur thermochemical water-splitting cycle

Kubo, Shinji; Futakawa, Masatoshi; Tanaka, Nobuyuki; Iwatsuki, Jin; Yamaguchi, Akihisa*; Tsukada, Ryuji*; Onuki, Kaoru

Proceedings of 2006 International Congress on Advances in Nuclear Power Plants (ICAPP '06) (CD-ROM), 6 Pages, 2006/06

no abstracts in English

Journal Articles

Mechanical property evaluation of surface layer corroded in thermochemical-hydrogen-production process condition

Futakawa, Masatoshi; Kubo, Shinji; Wakui, Takashi*; Onuki, Kaoru; Shimizu, Saburo; Yamaguchi, Akihisa*

Jikken Rikigaku, 3(2), p.109 - 114, 2003/06

Micro-indentation technique was applied to evaluate the mechanical properties of corroded surface layers of Ni-alloy, 316SS, Ti and Ta, which were exposed into the corrosive gaseous environment consisting of HI+I$$_{2}$$+H$$_{2}$$O+H$$_{2}$$. The corrosion condition was chosen so as to simulate one of the environments in the thermochemical hydrogen production, IS process, where the degradation due to the corrosion attack by HI and the hydrogen embrittlement is a key issue from the viewpoint of material integrity. The micro-indentation tests using a spherical indenter and the inverse analysis with Kalman filter were performed to quantitatively estimate material constants of corroded surface layer. Ni-alloy exhibited good corrosion resistance and Ta was remarkably influenced by the hydrogen embrittlement.

Journal Articles

Development of a Method for Evaluation of Pinwise Power Distribution in Fuel Assemblies of Fast Reactors

Yamaoka, Mitsuaki*; Kawashima, Masatoshi*; Yamaguchi, Takashi; Takashita, Hirofumi

Journal of Nuclear Science and Technology, 34(10), p.986 - 991, 1997/10

None

Journal Articles

None

Yamaguchi, Takashi; Kawashima, Masatoshi*

International Conference on Mathmatics and Computations,Reactor Physics,and Environmental Analysis, , 

None

Oral presentation

Development of a retro-reflecting corner cube mirror for JSNS target container monitoring

Teshigawara, Makoto; Wakui, Takashi; Maekawa, Fujio; Futakawa, Masatoshi; Kato, Takashi; Kikuchi, Kenji; Nakamura, Koji*; Fukai, Takashi*; Yoshida, Nobutoshi*; Naoe, Takashi*; et al.

no journal, , 

The spallation neutron source facility (JSNS) in J-PARC project is under construction. Highest neutron intensity, especially peak intensity, is provided to neutron beam users in JSNS. However, the pressure wave caused by the intense pulsed proton beam gives vibration related pitting damage on the target beam window, resulting in a shorter life-time. It is very important to monitor the pitting damage of the target beam window to estimate its life-time. Laser Doppler method is a useful acoustic vibration measurement technique to monitor damage caused by pitting damage. We adopted a retro-reflecting corner cube mirror to enable this measurement. We developed a retro-reflective corner cube mirror with the reflectivity of 12 %, which is made by Ni using electroforming. Finally, we could install the retro-reflective mirror on the real target container with an optimized brazing method (Ag based brazing).

Oral presentation

Effect of tensile stress on pitting damage

Yamaguchi, Yoshihito*; Kogawa, Hiroyuki; Naoe, Takashi; Futakawa, Masatoshi

no journal, , 

High power spallation targets for neutron sources are being developed in the world. A mercury target is being installed in the material and life science facility of J-PARC (Japan Proton Accelerator Research Complex). The mercury target is subjected to pressure waves caused by a proton beam bombardment. The pressure waves load macroscopic stresses on the target vessel and induce the cavitaion in mercury through the pressure wave propagation processes. When cavitation bubbles collapse, the localized impact damages so-called pitting damage, occur on the target vessel. The target vessel is subjected to the pitting damage and macroscopic stress at the same time. It is necessary, therefore, to evaluate the superimposed effect of macroscopic stresses the pitting damage. Pitting damage tests were carried out using a ultrasonic cavitation testing with a static tensile-stress loading unit. The results showed that the damage increased with the imposed tensile stress.

Oral presentation

Effect of liquid metal on fatigue crack propagation

Naoe, Takashi; Wakui, Takashi; Yamaguchi, Yoshihito; Futakawa, Masatoshi

no journal, , 

Liquid mercury was selected as a target material of the high-power spallation neutron source. The target vessel which embrace the mercury receives repeated stress due to the pressure wave and the thermal stress. Then, it is concerned about the Liquid Metal Embrittlement (LME) of the target vessel. In this study, fatigue tests in mercury were performed to investigate the compatibility between mercury and austenitic stainless steel. Furthermore, the effect of liquid metal on fatigue crack propagation was examined by the fracture surface analysis and the opening distance measurement.

Oral presentation

Approach to establishment for systematic safety assessment methodology; Analysis of radionuclides flux out of engineered barrier taking into account linkage of models and parameters

Mukai, Masayuki; Kataoka, Masaharu; Takeda, Seiji; Maeda, Toshikatsu; Iida, Yoshihisa; Watanabe, Masatoshi; Sawaguchi, Takuma; Yamaguchi, Tetsuji; Tanaka, Tadao

no journal, , 

Systematic safety assessment should be carried out taking into account linkage among "Condition Setting", "Safety Function", and "Radionuclide Migration". We have summarized input-output relation among a calculation code coupled mass transport and chemical reaction, models to evaluate performance of each of engineered barriers, and a safety assessment code through the viewpoint of the linkage. As the first step to establish a systematic safety assessment methodology, how to specifically link those codes and models and how to apply a linked calculation process to practical cases of geological disposal conditions have been discussed.

Oral presentation

Effect of $$gamma$$ ray irradiation on ${it Rumex obtusifolius}$

Kitano, Sayaka*; Kawai, Maki*; Miyagi, Atsuko*; Uchimiya, Hirofumi*; Yamaguchi, Masatoshi*; Ono, Yutaka; Hase, Yoshihiro; Narumi, Issei

no journal, , 

no abstracts in English

24 (Records 1-20 displayed on this page)