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Journal Articles

Development of laser welding technology for fully austenite stainless steel

Takano, Katsutoshi; Koizumi, Norikiyo; Serizawa, Hisashi*; Tsubota, Shuho*; Makino, Yoshinobu*

Yosetsu Gakkai Rombunshu (Internet), 33(2), p.126 - 132, 2015/06

A radial plates (RP), which is used in Toroidal field (TF) coil in ITER, is significantly large, such as 13 m height and 9 m wide, but thin, such as 10 cm thick, and are made of full-austenite stainless steel. Even though they are very large structures, high manufacturing tolerances are required. In addition, it is required that each RP is fabricated every three weeks. Therefore, the authors develop efficient manufacturing methods of RP. The laser welding is selected as a welding method of RP. But the development of the high power laser welding technology is necessary to avoid hot cracking of the materials used for RP, namely full austenite stainless steel with high nitrogen content. The authors carried out trial aiming at an application of the laser welding to RP. As a result, it is effective to optimize the angle of inclination of the weld head. It also seems sensitivity of hot cracking can be less by optimizing the chemical composition of materials to use for RP. It was therefore demonstrated that the application of the laser welding technology in the full austenite stainless steel.

Journal Articles

IFMIF; Overview of the validation activities

Knaster, J.*; Arbeiter, F.*; Cara, P.*; Favuzza, P.*; Furukawa, Tomohiro; Groeschel, F.*; Heidinger, R.*; Ibarra, A.*; Matsumoto, Hiroshi*; Mosnier, A.*; et al.

Nuclear Fusion, 53(11), p.116001_1 - 116001_18, 2013/11

AA2013-0294.pdf:2.55MB

 Times Cited Count:62 Percentile:94.3(Physics, Fluids & Plasmas)

The IFMIF/EVEDA project under the Broader Approach Agreement between Japan and EU aims at allowing a rapid construction phase of IFMIF in due time. The three main facilities, (1) the Accelerator Facility, (2) the Target Facility and (3) the Test Facility, are the subject of validation activities that include the construction of either full scale prototypes or smartly devised scaled down facilities that will allow a straightforward extrapolation to IFMIF needs. The installation of a Linac of 1.125 MW (125 mA and 9 MeV) of deuterons started in March 2013 in Rokkasho. The world largest liquid Li test loop is running in Oarai with an ambitious experimental programme for the years ahead. A full scale high flux test module that will house $$sim$$ 1000 small specimens developed jointly in Europe and Japan has been constructed in Germany together with its He gas loop. A full scale medium flux test module to carry out on-line creep measurement has been constructed in Switzerland.

Journal Articles

Variation in the surface morphology of polycrystalline UO$$_{2}$$ powder induced by helium precipitation

Serizawa, Hiroyuki; Matsunaga, Junji*; Shirasu, Noriko; Nakajima, Kunihisa; Kashibe, Shinji*; Kaji, Yoshiyuki

Journal of Asian Ceramic Societies (Internet), 1(3), p.289 - 295, 2013/09

This report addresses the precipitation of helium in polycrystalline UO$$_{2}$$, which deforms the morphology of the grains and their surfaces Helium was injected into pulverized UO$$_{2}$$ particles at 1473 K by hot isostatic pressing (HIP). The specific surface area measured by volumetric gas adsorption instrument implied that small pores should exist on the as-helium-treated sample surface. Field-emission scanning electron microscopy observations showed that numerous shallow basins (approximately 500 nm in radius) with hexagonal fringe were formed on the surface. The basin resembles a ruptured blister whose lid has been forced open. SEM observations showed a uniform polygonal-shaped section of the gas bubble on the fracture surface; this implies that precipitated helium forms a negative crystal in the grain.

Journal Articles

Formation and growth of image crystals by helium precipitation

Serizawa, Hiroyuki; Matsunaga, Junji*; Haga, Yoshinori; Nakajima, Kunihisa; Akabori, Mitsuo; Tsuru, Tomohito; Kaji, Yoshiyuki; Kashibe, Shinji*; Oishi, Yuji*; Yamanaka, Shinsuke*

Crystal Growth & Design, 13(7), p.2815 - 2823, 2013/07

 Times Cited Count:5 Percentile:42.85(Chemistry, Multidisciplinary)

Since the shape of the negative crystal closely relates to the morphology of the crystal habits, the formation and the growth mechanism is important subject in a field of the physical science. Whereas, the negative crystal formed in a large single crystal mass has been arousing interest as an expensive jewelry because of its mysterious appearance and rarity. However, it is difficult to control the shape of this polyhedral cavity embedded in a solid medium arbitrary. Here we report the recent discovery on the growth process of the negative crystal. We found that precipitated helium forms the negative crystal in UO$$_{2}$$; the shape changes drastically with the condition of the helium precipitation. The transformation mechanism was discussed in this article. Our investigation implies that the shape of the negative crystal can be arbitrary controlled by controlling the precipitation condition.

Journal Articles

Development of lithium target system in engineering validation and engineering design activity of the International Fusion Materials Irradiation Facility (IFMIF/EVEDA)

Wakai, Eiichi; Kondo, Hiroo; Sugimoto, Masayoshi; Fukada, Satoshi*; Yagi, Juro*; Ida, Mizuho; Kanemura, Takuji; Furukawa, Tomohiro; Hirakawa, Yasushi; Watanabe, Kazuyoshi; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(12), p.691 - 705, 2012/12

AA2012-1008.pdf:2.42MB

no abstracts in English

Journal Articles

The Solubility and diffusion coefficient of helium in uranium dioxide

Nakajima, Kunihisa; Serizawa, Hiroyuki; Shirasu, Noriko; Haga, Yoshinori; Arai, Yasuo

Journal of Nuclear Materials, 419(1-3), p.272 - 280, 2011/12

 Times Cited Count:23 Percentile:85.78(Materials Science, Multidisciplinary)

The solubility and diffusion coefficient of helium in the single-crystal UO$$_{2}$$ samples were determined by a Knudsen-effusion mass-spectrometric method. The measured helium solubilities were found to lie within the scatter of the available data, but to be much lower than those for the polycrystalline samples. The diffusion analysis was conducted based on a hypothetical equivalent sphere model and the simple Fick's law. The helium diffusion coefficient was determined by using the pre-exponential factor and activation energy as the fitting parameters for the measured and calculated fractional releases of helium. The optimized diffusion coefficients were in good agreement with those obtained by a nuclear reaction method reported in the past. It was also found that the pre-exponential factors of the determined diffusion coefficients were much lower than those analyzed in terms of a simple interstitial diffusion mechanism.

Journal Articles

Fundamental research on behavior of helium in MA-bearing oxide fuel

Arai, Yasuo; Serizawa, Hiroyuki; Nakajima, Kunihisa; Takano, Masahide; Sato, Isamu; Katsuyama, Kozo; Akie, Hiroshi; Suzuki, Motoe; Shirasu, Noriko; Haga, Yoshinori; et al.

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 8 Pages, 2011/12

High amount of He is generated in MA-bearing fuel during irradiation and storage periods compared with that in U or U-Pu fuel. Laboratory scale experiments, post irradiation examinations and modeling study were carried out in order to understand the He behavior in MA-bearing oxide fuel. Diffusion characteristics of He in single-crystal UO$$_{2}$$ were investigated by the Knudsen effusion mass spectrometry. Effects of the He accumulation on lattice and bulk expansion of oxide pellets were examined by use of alpha-decay of $$^{244}$$Cm. Post irradiation examinations of 0.5%Am-MOX fuel irradiated at a fast test reactor JOYO were carried out, concentrating on the He behavior in the fuel pellets. A model describing the He behavior in MA-MOX fuel was constructed based on the principle processes, such as generation, diffusion, equilibrium and release to outer gaseous phase. By use of the model as a subroutine of a conventional fuel behavior analysis code, the He behavior in MA-MOX fuel for fast reactors was simulated.

JAEA Reports

Study on helium behavior in oxide fuel, 1; Deformation of microstructure induced by precipitation of helium (Joint research)

Serizawa, Hiroyuki; Matsunaga, Junji*; Haga, Yoshinori; Nakajima, Kunihisa; Kashibe, Shinji*; Iwai, Takashi

JAEA-Research 2011-025, 32 Pages, 2011/11

JAEA-Research-2011-025.pdf:10.17MB

This report deals with the precipitation of helium in UO$$_{2}$$ matrix to deform the microstructure. The examination was performed using single and polycrystalline UO$$_{2}$$ sample. The helium-treated samples under 900 atm at 1473 K were reheat-treated at much more high temperature, 1573 K or 1973 K to release the infused helium. The microstructure of the sample was examined by FIB, FE-STEM and FE-TEM. It was confirmed that precipitated helium atoms form a negative crystal in the grain or the matrix of the single crystal. At 1573 K, helium can be released without formation of intergranular tunnel since the surface diffusion coefficient of helium is large. However, some open grain boundaries were observed in the sample heat-treated at 1973 K. This might be related to the activity of helium in the grain boundary region. The structure of the negative crystal was analyzed from the view point of the thermodynamics of the surface growth.

Journal Articles

Technical issues of reduced activation ferritic/martensitic steels for fabrication of ITER test blanket modules

Tanigawa, Hiroyasu; Hirose, Takanori; Shiba, Kiyoyuki; Kasada, Ryuta*; Wakai, Eiichi; Serizawa, Hisashi*; Kawahito, Yosuke*; Jitsukawa, Shiro; Kimura, Akihiko*; Kono, Yutaka*; et al.

Fusion Engineering and Design, 83(10-12), p.1471 - 1476, 2008/12

 Times Cited Count:78 Percentile:97.75(Nuclear Science & Technology)

Reduced activation ferritic/martensitic steels (RAFMs) are recognized as the primary candidate structural materials for fusion blanket systems. F82H, which were developed and studied in Japan, was designed with an emphasis on high temperature properties and weldability. The database on F82H properties is currently the most extensive available among the existing RAFMs. The objective of this paper is to review the R&D status of F82H and to identify the key technical issues for the fabrication of an ITER Test Blanket Module (TBM) suggested by recent achievements in Japan.

Journal Articles

Temperature dependence of elastic properties for MgO

Serizawa, Hiroyuki; Fukuhara, Mikio*; Nakajima, Kunihisa; Iwai, Takashi; Arai, Yasuo

Proceedings of 8th Asian Thermophysical Properties Conference (ATPC '07) (CD-ROM), 6 Pages, 2007/08

Longitudinal and transverse wave velocities, five kinds of elastic moduli, Debye temperature and Gruneisen parameter have been simultaneously measured as functions of temperature from 298 to 1764 K in polycrystalline MgO, by help of aluminum couplant. Young, shear, bulk moduli, and Gruneisen parameter and Poisson's ratio decreased and increased monotonically with increasing temperature, respectively, showing a lowering of ionic bonding strength. Lame parameter versus temperature slope is almost zeroing in the whale temperature region. The behavior was interpreted as an interlocking associated with network of short Mg-O bonds, based on three-dimensional volume-nonpreserving shear.

Journal Articles

Research and development of minor actinide-containing fuel and target in a future integrated closed cycle system

Osaka, Masahiko; Serizawa, Hiroyuki; Kato, Masato; Nakajima, Kunihisa; Tachi, Yoshiaki; Kitamura, Ryoichi; Miwa, Shuhei; Iwai, Takashi; Tanaka, Kenya; Inoue, Masaki; et al.

Journal of Nuclear Science and Technology, 44(3), p.309 - 316, 2007/03

 Times Cited Count:29 Percentile:87.27(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Development of minor actinide containing fuel/target for the use in a future integrated system of fast reactor and accelerator driven system

Osaka, Masahiko; Serizawa, Hiroyuki*; Kato, Masato; Inoue, Masaki; Nakajima, Kunihisa*; Tachi, Yoshiaki; Kitamura, Ryoichi; Oki, Shigeo; Miwa, Shuhei; Iwai, Takashi*; et al.

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10

Development of minor actinide containing fuel/target, i.e., (Pu,Am)O$$_{2}$$-MgO, (Pu,Np)O$$_{2}$$-MgO, (U,Pu,Np)O$$_{2}$$, (U,Pu,Np)N and (Pu,Np,Zr)N, for the use in a future integrated system of fast reactor and accelerator driven system is underway as a collaborative work between JAERI and JNC. The present statuses of fabrication test and property measurements are given. Irradiation test in the experimental fast reactor JOYO is also mentioned.

JAEA Reports

Fabrication of inert-matrix nitride fuel pins for the irradiation test at JMTR

Nakajima, Kunihisa; Iwai, Takashi; Kikuchi, Hironobu; Serizawa, Hiroyuki; Arai, Yasuo

JAERI-Research 2005-027, 42 Pages, 2005/09

JAERI-Research-2005-027.pdf:4.15MB

Nitride fuel pins containing inert matrix such as ZrN and TiN were fabricated for the irradiation test at JMTR, aiming at understanding irradiation behavior of nitride fuel for transmutation of minor actinides. Minor actinides are surrogated by plutonium in the present fuel pin. This report describes the preparation and characterization of fuel pellets, and fabrication of fuel pins. The irradiation for 11 cycles from May 2002 to November 2004 at JMTR was completed without any failure of fuel pins.

Journal Articles

Re-evaluation of the phase relationship between plutonium and zirconium dioxides

Serizawa, Hiroyuki; Nakajima, Kunihisa; Arai, Yasuo; Yamashita, Toshiyuki; Kuramoto, Kenichi; Kinoshita, H.*; Yamanaka, Shinsuke*; Uno, Masayoshi*; Kurosaki, K.*

Progress in Nuclear Energy, 38(3-4), p.237 - 240, 2001/02

 Times Cited Count:5 Percentile:39.04(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Design and installation of high-temperature X-ray diffractometer for transuranium elements and its performance test (Joint research)

Arai, Yasuo; Nakajima, Kunihisa; Serizawa, Hiroyuki; ; Suzuki, Yasufumi; Inoue, Tadashi*

JAERI-Tech 98-022, 21 Pages, 1998/06

JAERI-Tech-98-022.pdf:1.07MB

no abstracts in English

Oral presentation

Technical issues of welding of reduced activation ferritic/martensitic steels at the fabrication of ITER test blanket module

Tanigawa, Hiroyasu; Ogiwara, Hiroyuki; Hirose, Takanori; Shiba, Kiyoyuki; Serizawa, Hisashi*; Kawahito, Yosuke*; Tanaka, Manabu*; Katayama, Seiji*; Mori, Hiroaki*; Nishimoto, Kazutoshi*

no journal, , 

Reduced activation ferritic/martensitic steels (RAFMs) are recognized as the primary candidate structural materials for fusion blanket systems. These steels have been developed based on substantial industrial experience with high chromium heat resistant ferritic/martensitic steels (such as modified 9Cr-1Mo), but with Mo and Nb replaced by W and Ta, respectively. The objective of this paper is to review the R&D status of F82H and to identify the key technical issues for the fabrication of an ITER Test Blanket Module (TBM) suggested by recent achievements in Japan.

Oral presentation

Present status of R&D on breeding functional components in ITER-TBM, 1; Mock-up fabrication of tritium breeding layer for solid breeding ITER-TBM

Hirose, Takanori; Tanigawa, Hiroyasu; Enoeda, Mikio; Kawahito, Yosuke*; Serizawa, Hisashi*; Katayama, Seiji*

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Development of common and fundamental technologies on the evaluation of fuel behavior for realizing MA recycling, 13; The Diffusion coefficients of He in UO$$_{2}$$ and (U$$_{0.3}$$,$$^{238}$$Pu$$_{0.7}$$)O$$_{2}$$

Nakajima, Kunihisa; Shirasu, Noriko; Haga, Yoshinori; Serizawa, Hiroyuki; Arai, Yasuo

no journal, , 

no abstracts in English

Oral presentation

Development of common and fundamental technologies on the evaluation of fuel behavior for realizing MA recycling, 15; Explanation of the formation polyhedral volume defect in UO$$_{2}$$ formed by helium precipitation from the stand point of equilibrium

Serizawa, Hiroyuki; Haga, Yoshinori; Shirasu, Noriko; Nakajima, Kunihisa; Arai, Yasuo

no journal, , 

Helium emitted by $$alpha$$-decay of MA is accumulated in UO$$_{2}$$ and affects on the behavior of the fuel. In the present study, the authors examined the variation of the micro texture of a fuel matrix by the precipitation of helium using single and poly crystalline UO$$_{2}$$. It was found that the precipitated helium form a negative crystal which mainly consists of {111} and {100} crystal planes. The shape of the negative crystal changes depending on the history of the heat treatment.

31 (Records 1-20 displayed on this page)