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Yoshida, Shuhei*; Fu, R.*; Gong, W.; Ikeuchi, Takuto*; Bai, Y.*; Feng, Z.*; Wu, G.*; Shibata, Akinobu*; Hansen, N.*; Huang, X.*; et al.
IOP Conference Series; Materials Science and Engineering, 1249, p.012027_1 - 012027_6, 2022/08
Times Cited Count：0 Percentile：0.00(Metallurgy & Metallurgical Engineering)
neutron diffraction study on the deformation of a TRIP-assisted multi-phase steel composed of ferrite, austenite and martensiteLavakumar, A.*; Park, M. H.*; Gao, S.*; Shibata, Akinobu*; Okitsu, Yoshitaka*; Gong, W.; Harjo, S.; Tsuji, Nobuhiro*
IOP Conference Series; Materials Science and Engineering, 580, p.012036_1 - 012036_6, 2019/09
Times Cited Count：3 Percentile：80.98(Engineering, Mechanical)Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Kawakami, Yoshihiko
IOP Conference Series; Materials Science and Engineering, 101, p.012108_1 - 012108_8, 2015/12
Times Cited Count：0 Percentile：0.00(Thermodynamics)Supercritical hydrogen with a temperature of less than 20 K and a pressure of 1.5 MPa is used as moderator material at J-PARC. Total nuclear heating of 3.75 kW is generated by three moderators for a 1-MW proton beam operation. We have developed an orifice-type high-power heater for thermal compensation to mitigate hydrogen pressure fluctuation caused by the abrupt huge heat load and to reduce the fluctuation in the temperature of the supply hydrogen to less than 0.25 K. Through a performance test, we confirmed that the developed orifice-type heater could be heated uniformly and showed fast response, as expected. Furthermore, a simulation model that can describe heater behaviors has been established on the basis of the experimental data. The heater control approach was studied using the aforementioned heater simulation model and a dynamic simulation code developed by the authors.
Tatsumoto, Hideki; Shirai, Yasuyuki*; Shiotsu, Masahiro*; Naruo, Yoshihiro*; Kobayashi, Hiroaki*; Nonaka, Satoshi*; Inatani, Yoshifumi*
IOP Conference Series; Materials Science and Engineering, 101, p.012177_1 - 012177_8, 2015/12
Times Cited Count：0 Percentile：0.00(Thermodynamics)Transient heat transfers from PtCo wire heaters inserted into vertically-mounted pipes, through which forced flow subcooled liquid hydrogen was passed, were measured by increasing the exponential heat input with various time periods at a pressure of 0.7 MPa and inlet temperature of 21 K. The flow velocities ranged from 0.3 to 7 m/s. The PtCo wire heaters had a diameter of 1.2 mm and lengths of 60 mm, 120 mm and 200 mm and were inserted into the pipes with diameters of 5.7mm, 8.0 mm, and 5.0 mm, respectively. With increase in the heat flux to the onset of nucleate boiling, surface temperature increased along the curve predicted by the Dittus-Boelter correlation for longer period, where it can be almost regarded as steady-state. For shorter period, the heat transfer became higher than the Dittus-Boelter correlation. In nucleate boiling regime, the heat flux steeply increased to the transient critical heat flux (CHF), which became higher for shorter period. Effect of flow velocity, period, and heated geometry on the transient CHF was clarified.
Tatsumoto, Hideki; Otsu, Kiichi; Aso, Tomokazu; Kawakami, Yoshihiko
IOP Conference Series; Materials Science and Engineering, 101, p.012109_1 - 012109_8, 2015/12
Times Cited Count：1 Percentile：49.66(Thermodynamics)The J-PARC cryogenic hydrogen system provides supercritical cryogenic hydrogen to the moderators at a pressure of 1.5 MPa and temperature of 18 K and removes 3.8 kW of nuclear heat from the 1 MW proton beam operation. We prepared a heater for thermal compensation and an accumulator, with a bellows structure for volume control, to mitigate the pressure fluctuation caused by switching the proton beam on and off. In this study, a 1-D simulation code named DiSC-SH2 was developed to understand the propagation of pressure and temperature propagations through the hydrogen loop due to on and off switching of the proton beam. We confirmed that the simulated dynamic behaviors in the hydrogen loop for 300-kW and 500-kW proton beam operations agree well with the experimental data under the same conditions.
Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Kawakami, Yoshihiko; Aoyagi, Katsuhiro; Muto, Hideki
IOP Conference Series; Materials Science and Engineering, 101, p.012107_1 - 012107_8, 2015/12
Times Cited Count：0 Percentile：0.00(Thermodynamics)The Japan Proton Accelerator Research Complex (J-PARC) cryogenic hydrogen system was completed in April 2008. The proton beam power was gradually increased to 500 kW. A trial 600-kW proton beam operation was successfully completed in April 2015. We achieved long-lasting operation for more than three months. However, thus far, we encountered several problems such as unstable operation of the helium refrigerator because of some impurities, failure of a welded bellows of an accumulator, and hydrogen pump issues. Furthermore, the Great East Japan Earthquake was experienced during the cryogenic hydrogen system operation in March 2011. In this study, we describe the operation characteristics and our experiences with the J-PARC cryogenic hydrogen system.
Natsume, Kyohei; Murakami, Haruyuki; Kizu, Kaname; Yoshida, Kiyoshi; Koide, Yoshihiko
IOP Conference Series; Materials Science and Engineering, 101(1), p.012113_1 - 012113_8, 2015/12
Times Cited Count：2 Percentile：64.53(Thermodynamics)Futakawa, Masatoshi
IOP Conference Series; Materials Science and Engineering, 74(1), p.012001_1 - 012001_7, 2015/02
Times Cited Count：2 Percentile：64.53(Materials Science, Multidisciplinary)Innovative researches using neutrons are being performed at the Materials and Life Science Experimental Facility, MLF, at the Japan Proton Accelerator Research Complex, J-PARC, in which a mercury target system is installed for MW-class pulse spallation neutron sources. The structural materials of the mercury target are subjected to irradiation damage due to protons and neutrons, very high cycle fatigue damages due to repeated pressure waves caused by the proton beam bombardment in mercury and so-called liquid metal embrittlement. That is, the structural materials must be said to be exposed to the extremely severe environments. In the paper, research and development relating to the material issues in the high power spallation neutron sources that has been performed so far at J-PARC is summarized.
Taguchi, Tomitsugu; Igawa, Naoki; Shamoto, Shinichi
IOP Conference Series; Materials Science and Engineering, 18, p.062020_1 - 062020_4, 2011/10
Times Cited Count：3 Percentile：76.16(Nanoscience & Nanotechnology)SiC nanowires and nanotubes sheathed with BN were synthesized by annealing C-SiC and SiC nanotubes at 1600 and 1700 
C for 5 h with BN powder in Ar gas. According to TEM observation, the BN coating was very thin and the layer number of BN coating was less than 10. The BN coating on the surface of SiC nanotubes was not produced by the heat treatment at 1500 C. This result revealed that BN on the surface of SiC nanomaterials produced by heat treatment of higher than 1600 C. After the heat treatment of higher than 1600 C, many nanotubes transformed to nanowires because the inner space of nanotubes was occluded due to the SiC grain growth by heat treatment.
pellets for production of 
Mo medical isotopeKimura, Akihiro; Sato, Yuichi*; Tanase, Masakazu*; Tsuchiya, Kunihiko
IOP Conference Series; Materials Science and Engineering, 18(4), p.042001_1 - 042001_4, 2011/10
In the medical field, the radioisotopes are indispensable. Especially, 
Tc is most commonly used as a radiopharmaceutical. However, the supply of Mo in Japan depends fully on the import from foreign countries. JMTR has a plan to produce a medical isotope of Mo, the parent nuclide of Tc by the (n,
) method and a part of the import volume can be covered of the home country. In this plan, it is important to develop the production method of the irradiation targets such as the Molybdenum oxide (MoO) pellets. However, MoO is low sublime temperature and it is difficult to produce the pellets with high density. In this study, MoO pellets were produced by two kinds of production methods. As a result, MoO pellet of about 70% TD was obtained by CIP and MoO pellet of over 95% TD was obtained by SPS.
Eto, Motokuni*; Konishi, Takashi*; Shibata, Taiju; Sumita, Junya
IOP Conference Series; Materials Science and Engineering, 18(16), p.162003_1 - 162003_6, 2011/09
Times Cited Count：4 Percentile：86.63(Materials Science, Ceramics)High Temperature Gas-cooled Reactor (HTGR) and Very High Temperature Reactor (VHTR) are attractive nuclear reactors to obtain high temperature helium gas to the reactor outlet. To enhance the thermal efficiency, the core internals of HTGR/VHTR are subjected to the very severe high temperature condition. The carbon fiber reinforced carbon-carbon composite (C/C composite) is one of the advanced material candidates for the control rod sheath of the reactors because of its excellent thermal resistance and stability in the severe condition. The R&Ds on the C/C composite application to HTGR have been carried out since 1990'. JAEA and Toyo Tanso have been in collaboration with each other in the R&Ds. The development of control rod made of C/C composite is recently focused as one of the important subjects to develop the VHTR in the international R&Ds. The scheme of the development of JAEA is categorized as the following phases; (1) Database establishment, (2) Design and manufacturing of component and (3) Demonstration test by HTTR. At the initial stage of the development in 1990' in JAERI, the feasibility of the control rod using C/C composite was demonstrated by a conceptual design. The phase (2) is planned to be completed within 5 years. This paper presents the review of the development of the control rod made of C/C composite and the recent R&D results.
Sumita, Junya; Shibata, Taiju; Kunimoto, Eiji*; Yamaji, Masatoshi*; Konishi, Takashi*; Sawa, Kazuhiro
IOP Conference Series; Materials Science and Engineering, 18(16), p.162012_1 - 162012_4, 2011/09
Times Cited Count：1 Percentile：51.54(Materials Science, Ceramics)For control rod element of Very High Temperature Reactor, carbon fiber reinforced carbon matrix composite (C/C composite) is one of the major candidate materials for its high strength and thermal stability. The development of a property prediction model of the two-dimensional (2D)-C/C composite is one of the most important subjects for the design methodology for control rod. Since the property of the 2D-C/C composite is strongly dependent on its microstructure, fiber/matrix, it would be possible to evaluate the properties of the 2D-C/C composite from its microstructure. In this study, in order to develop the property prediction model of the 2D-C/C composite base on its microstructure, pore distribution was investigated by using the X-ray computed tomography (X-ray CT) images and developed image based voxcel model. The compressive strength of the 2D-C/C composite was measured and evaluated by the voxcel model. This study shows that the pore distribution in the 2D-C/C composite can be confirmed visually and the volume and shape of the pores can be estimated from X-ray CT images. It is also shown that evaluation of the compressive strength by using the voxel model is useful to simulate the trend of the stress distribution of the 2D-C/C composite. However, it is necessary to characterize the property of the 2D-C/C composite and to set up the appropriate mesh to simulate the absolute stress value precisely.
Nozawa, Takashi; Choi, Y.-B.*; Hinoki, Tatsuya*; Kishimoto, Hirotatsu*; Koyama, Akira*; Tanigawa, Hiroyasu
IOP Conference Series; Materials Science and Engineering, 18, p.162011_1 - 162011_4, 2011/09
Times Cited Count：11 Percentile：97.28(Materials Science, Ceramics)A SiC/SiC composite is one of attractive candidates for fission and nuclear fusion due to the proven irradiation tolerance coupled with the excellent baseline properties as refractory ceramics. Considering the inherent anisotropy of composites due to the variety of fabric architecture, it is required to identify the crack propagation behavior of SiC/SiC composites by various failure modes. This study aims to evaluate crack propagation behavior by the axial and off-axial tensile/compressive tests, Iosipescu test for in-plane shear, double-notch-shear test for inter-laminar shear and diametral compression test for inter-laminar detachment. Preliminary test results identified strength anisotropy maps, implying that the composites failed by the mixed modes. Specifically, it was found that the in-plane/inter-laminar shear modes had significant impacts on the results.
O
Matsumoto, Keisuke*; Koyama, Tsukasa*; Mori, Shigeo*; Yoshii, Kenji; Kambe, Takashi*; Ikeda, Naoshi*
IOP Conference Series; Materials Science and Engineering, 18(9), p.092047_1 - 092047_4, 2011/09
Times Cited Count：1 Percentile：51.54(Materials Science, Ceramics)Changes of charge ordered (CO) structure by partial substitution of Mn for Fe in YbFeO were investigated by a transmission electron microscope (TEM), incombination with conventional dielectric measurement. It is revealed that partial substitution of Mn
for Fe in YbFeO destroyed drastically the CO structure with the wave vector of q=
1/3 1/3 1/2
. Consequently polar clustering structure giving rise to honeycomb-shaped diffuse streaks was found in YbFeMnO. The random distribution of polar clustering structure gives rise to characteristic broad dielectric dispersion.
Sumita, Junya; Fujita, Ichiro; Shibata, Taiju; Makita, Taiyo*; Takagi, Takashi*; Kunimoto, Eiji*; Sawa, Kazuhiro; Kim, W. J.*; Park, J. Y.*
IOP Conference Series; Materials Science and Engineering, 18(16), p.162010_1 - 162010_4, 2011/09
Times Cited Count：1 Percentile：51.54(Materials Science, Ceramics)For control rod element of Very High Temperature Reactor, carbon fiber reinforced carbon matrix composite (C/C composite) is one of the major candidate materials for its high strength and thermal stability. Since the crack propagation of the C/C composite is complicated, the fracture behavior is one of the most important subjects of the design methodology for the control rod with the C/C composite. In this study, in order to assess the Mode-II fracture behavior of the two-dimensional (2D-) C/C composite which has the layer structure of laminas composed of fibers and matrix, bending test with oxidized end notched flexure specimen was carried out. The interlaminar fracture toughness decreased with increasing the oxidation for the 2D-C/C composite. The oxidized matrix causes reduction of fracture toughness and the reduction ratio is dependent on the matrix type. The crack initiates at the boundary between fiber bundles and grows along them without breaking the fiber. It is thought that the cracks which were initiated at the interface between matrix and fiber were gathered into the voids in the boundary between fiber bundles, and then the crack grows up in the matrix.
Igawa, Naoki; Taguchi, Tomitsugu; Hoshikawa, Akinori*; Yamauchi, Hiroki; Birumachi, Atsushi; Ishii, Yoshinobu*
IOP Conference Series; Materials Science and Engineering, 18, p.022021_1 - 022021_4, 2011/05
The neutron scattering length density distributions of Xe deuterohydrate were analyzed by Rietveld and MEM analysis applied to neutron powder diffraction data to clarify the Xe behavior in the temperature range from 10 to 245 K. A spherical positive scattering length density attributed to the Xe atom was observed at the center of the small cage of the hydrate. On the other hand, an ellipsoid shaped scattering length density distribution at the center of the large cage was observed; the major axis of the ellipsoid scattering length density was directed toward the center of a hexagonal facet of the large cage. The distributions of the Xe atom in the both cages were almost the same at any temperature.
Nagatake, Taku; Kunugi, Tomoaki*
IOP Conference Series; Materials Science and Engineering, 10, p.012024_1 - 012024_6, 2010/07
Times Cited Count：3 Percentile：80.37(Materials Science, Multidisciplinary)GPU (Graphics Processing Unit) has been developed for drawing system in computer in order to reduce the CPU (Central Processing Unit) load. The GPU has many processing units and the wide memory bandwidth, because the high performance computing is needed in the graphics processing (ex. 3D video game). Nowadays, the performance of GPU become much higher than that of the CPU, so that the attempt to make use of the GPU for the science calculation and general purpose is performed: This attempt is called "GPGPU" (General Purpose GPU). Now we are developing MARS (Multi-interfaces Advection and Reconstruction Solver) with GPU. The MARS is one of the surface volume tracking methods for multi-phase flows. In this paper, the performance of GPU is compared to the CPU.
Nishi, Tsuyoshi; Takano, Masahide; Ito, Akinori; Miyata, Seiichi; Akabori, Mitsuo; Arai, Yasuo; Minato, Kazuo
IOP Conference Series; Materials Science and Engineering, 9, p.012017_1 - 012017_8, 2010/05
Times Cited Count：2 Percentile：70.44(Chemistry, Inorganic & Nuclear)The thermal diffusivities and heat capacities of transuranium nitride solid solutions, (Np,Am)N and (Pu,Am)N, were measured by using a laser flash method and a drop calorimetry, respectively. The thermal conductivities of these samples were determined from the measured thermal diffusivities, heat capacities and bulk densities. The thermal conductivities of (Np,Am)N and (Pu,Am)N increased with temperature over the temperature range investigated. The increases in the thermal conductivities were probably due to the increase of electrical components. In addition, the thermal conductivities of (Np,Am)N and (Pu,Am)N decreased with increasing Am contents. It could be considered that the decreases in the thermal conductivities correspond to the lowering of electronic contribution.
Metoki, Naoto; Kaneko, Koji; Ikeda, Shugo*; Sakai, Hironori; Yamamoto, Etsuji; Haga, Yoshinori; Homma, Yoshiya*; Shiokawa, Yoshinobu*
IOP Conference Series; Materials Science and Engineering, 9, p.012088_1 - 012088_8, 2010/05
Times Cited Count：1 Percentile：53.83(Chemistry, Inorganic & Nuclear)Inelastic neutron scattering study has been carried out on US. A clear crystalline electric field (CEF) peak has been observed at 7.4 meV, which is consistent with the level scheme obtained from susceptibility data assuming 5f
configuration. The CEF becomes very weak and broad, and a quasi-elastic response emerges above the characteristic temperature 
100 K. It indicates the crossover of the 5f character between localized and itinerant. A quasi-elastic response can be concluded as the hybridization effect of the 5f electrons with ligand p-electrons. Our study suggests that the crossover of the 5f character is the origin of the metal-insulator transition in US.
Kitatsuji, Yoshihiro; Kimura, Takaumi; Kihara, Sorin*
IOP Conference Series; Materials Science and Engineering, 9, p.012078_1 - 012078_7, 2010/05
Times Cited Count：0 Percentile：0.00(Chemistry, Inorganic & Nuclear)The behaviors of reduction of Np(V) by controlled potential electrolysis were studied, and a unique time course of electrolysis current was observed. It was conclude that Np(V) was reduced by two reduction processes that are the chemical reaction with Np(III) and the electrocatalytic reduction by adsorbed hydrogen atom on platinum electrode surface. The time course of current for controlled potential electrolysis of Np(V) under various condition of the solution was investigated, and the effects of the concentration of H
and NO
on electrolysis behaviour were shown.
