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Journal Articles

Torsion test technique for interfacial shear evaluation of F82H RAFM HIP-joints

Nozawa, Takashi; Ogiwara, Hiroyuki*; Kannari, Jun*; Kishimoto, Hirotatsu*; Tanigawa, Hiroyasu

Fusion Engineering and Design, 86(9-11), p.2512 - 2516, 2011/10

 Times Cited Count:14 Percentile:76.2(Nuclear Science & Technology)

A hot isostatic press (HIP) process is a key technology to fabricate a first wall of the blanket system utilizing a reduced-activation ferritic/martensitic (RAFM) steel such as F82H. A primary objective of this study is to characterize interfacial properties of HIPed F82H joints by torsion to identify the feasibility of this test method. It is apparent that the absorption energies of the HIP joints varied by the processing conditions, although the maximum shear strength was not much different. According to the fracture surfaces, it is indicated that the reduction of the absorption energy was due to the oxide formed on the interface of the HIP joint and this was consistent with the results of charpy impact tests. In conclusion, the torsion test method enables to precisely evaluate the shear properties of the HIPed joint interface and becomes one of promising powerful techniques for inspection of the HIP joints.

Journal Articles

Fabrication of first wall component of ITER test blanket module by HIPping reduced activation ferritic/martensitic steel

Hirose, Takanori; Enoeda, Mikio; Ogiwara, Hiroyuki*; Tanigawa, Hiroyasu

Advances in Technology of Materials And Materials Processing Journal, 13(1), p.34 - 38, 2011/00

Journal Articles

Interfacial properties of HIP joints between beryllium and reduced activation ferritic/martensitic steel

Hirose, Takanori; Ando, Masami; Ogiwara, Hiroyuki*; Tanigawa, Hiroyasu; Enoeda, Mikio; Akiba, Masato

Fusion Engineering and Design, 85(5), p.809 - 812, 2010/08

 Times Cited Count:2 Percentile:19.27(Nuclear Science & Technology)

In this work, the interfacial properties of Be-reduced activation ferritic/martensitic steel (RAFMs) joints were investigated for the first wall of an ITER test blanket module (TBM). The joints were produced by the solid state hot isostatic pressing (HIP) method. Chromium (Cr) was used as a diffusion barrier with a thickness of 1 micron or 10 microns, formed by plasma vapor deposition on the Be surface. The HIPping was conducted at 1023 K and 1233 K. The temperatures are standard normalizing and tempering temperatures of F82H. EPMA showed the Cr layer effectively worked as a diffusion barrier at 1023 K. However, for the F82H/Be interface which underwent HIP at 1233 K followed by tempering a Be rich layer was formed. Bend tests revealed that a thin Cr layer and low temperature HIP is preferable.

Journal Articles

Compact DEMO, SlimCS; Design progress and issues

Tobita, Kenji; Nishio, Satoshi; Enoeda, Mikio; Kawashima, Hisato; Kurita, Genichi; Tanigawa, Hiroyasu; Nakamura, Hirofumi; Honda, Mitsuru; Saito, Ai*; Sato, Satoshi; et al.

Nuclear Fusion, 49(7), p.075029_1 - 075029_10, 2009/07

 Times Cited Count:125 Percentile:98.18(Physics, Fluids & Plasmas)

Recent design study on SlimCS focused mainly on the torus configuration including blanket, divertor, materials and maintenance scheme. For vertical stability of elongated plasma and high beta access, a sector-wide conducting shell is arranged in between replaceable and permanent blanket. The reactor adopts pressurized-water-cooled solid breeding blanket. Compared with the previous advanced concept with supercritical water, the design options satisfying tritium self-sufficiency are relatively scarce. Considered divertor technology and materials, an allowable heat load to the divertor plate should be 8 MW/m$$^{2}$$ or lower, which can be a critical constraint for determining a handling power of DEMO (a combination of alpha heating power and external input power for current drive).

Journal Articles

R&Ds of a Li$$_2$$TiO$$_3$$ pebble bed for a test blanket module in JAEA

Tanigawa, Hisashi; Hoshino, Tsuyoshi; Kawamura, Yoshinori; Nakamichi, Masaru; Ochiai, Kentaro; Akiba, Masato; Ando, Masami; Enoeda, Mikio; Ezato, Koichiro; Hayashi, Kimio; et al.

Nuclear Fusion, 49(5), p.055021_1 - 055021_6, 2009/05

 Times Cited Count:20 Percentile:64.19(Physics, Fluids & Plasmas)

This paper presents recent achievements of the research activities for the TBM being developed in JAEA, focusing on the pebble bed of the tritium breeder materials and tritium behaviour. For the breeder material, the chemical stability of Li$$_2$$TiO$$_3$$ has been improved by Li$$_2$$O additives. In order to analyze the pebble bed behaviour, thermo-mechanical properties of the Li$$_2$$TiO$$_3$$ pebble bed has been experimentally obtained. In order to verify nuclear properties of the pebble bed, the activation foil method has been proposed and a preliminary experiment has been conducted. For the tritium behaviour, the chemical densified coating method has been well developed and tritium recovery system has been modified taking account of the design change of the TBM.

Journal Articles

Structural material properties and dimensional stability of components in first wall components of a breeding blanket module

Hirose, Takanori; Enoeda, Mikio; Ogiwara, Hiroyuki; Tanigawa, Hiroyasu; Akiba, Masato

Fusion Engineering and Design, 83(7-9), p.1176 - 1180, 2008/12

 Times Cited Count:16 Percentile:74.37(Nuclear Science & Technology)

This paper summarize the fabrication process of the first wall structure and provides the material properties of the structural material F82H and dimensional stability of the components through whole of the process. A cold-rolling process introduced typical stretched rolling structure and ferrite/martensite dual phase structure, which lead reduction in strength. These anisotropic microstructural features were successfully recovered by optimized HIP process at 1373 K. As for dimensional stability of the components, a full-scale mockup has been developed with F82H tubes and plates. The HIPped mockup demonstrated good accordance with a design drawing. The dimensions of wall thickness and cooling channels were to size even after HIP. According to these results, the fabrication process does not degrade the material properties and demonstrates good dimensional accuracy and stability of the FW structure.

Journal Articles

Extra-irradiation hardening of reduced activation ferritic/martensitic steel by multi-ion irradiation

Ando, Masami; Wakai, Eiichi; Okubo, Nariaki; Ogiwara, Hiroyuki; Sawai, Tomotsugu; Onuki, Somei*

Nihon Kinzoku Gakkai-Shi, 71(12), p.1107 - 1111, 2007/12

 Times Cited Count:1 Percentile:14.26(Metallurgy & Metallurgical Engineering)

no abstracts in English

Journal Articles

Radiation induced phase instability of precipitates in reduced-activation ferritic/martensitic steels

Tanigawa, Hiroyasu; Sakasegawa, Hideo; Ogiwara, Hiroyuki*; Kishimoto, Hirotatsu*; Koyama, Akira*

Journal of Nuclear Materials, 367-370(1), p.132 - 136, 2007/08

 Times Cited Count:30 Percentile:89.28(Materials Science, Multidisciplinary)

It was previously reported that reduced-activation ferritic/martensitic steels (RAFs), such as F82H-IEA and JLF-1, showed a variety of changes in its mechanical property after neutron irradiation at 573K up to 5dpa, and have possible correlation with precipitation. The effects of irradiation on precipitation were also reported previously. In this study, irradiation effects on precipitation were investigated in detail utilizing ion irradiation in which irradiation condition could be controlled with high accuracy. F82H IEA heat, JLF-1 HFIR heat, and aged F82H-IEA (873K$$times$$30k h) were used for experiments. The specimens were irradiated at DuET facility, Inst. of Advanced Energy, Kyoto University up to 10 dpa at 573K with 6.4MeV Fe$$^{3+}$$ ion. Cross sectional TEM thin film specimens of ion irradiated region were made utilizing focused ion beam (FIB) processor with micro-sampling system at JAERI. These thin film specimens were made to contain both irradiated region and non-irradiated region beneath irradiated region. Size distribution and aspect ratio of precipitates were analyzed on each region. It turned out that the finer precipitates were dominant in irradiated region of F82H compared to that in non-irradiated region, but fewer and larger precipitates were dominant in irradiated region of JLF-1. These results confirmed the presence of irradiation effects on precipitate evolution even at 573K, which was observed in neutron irradiated RAFs.

Oral presentation

Clarification of creep mechanism of dual phase 9Cr-ODS steel as a composite material

Sakasegawa, Hideo; Otsuka, Satoshi; Ukai, Shigeharu; Tanigawa, Hiroyasu; Ogiwara, Hiroyuki*; Tamura, Manabu*; Koyama, Akira*; Fujiwara, Masayuki*

no journal, , 

Clarifying creep mehcanism of 9Cr-ODS(9Cr-2W-0.2Ti-Y203) steels to be applied for cladding materials in fast breeder reactors are performed in order to improve mass production material processing procedures and the method of creep life prediction. Conventional studies on microstructures in 9Cr-ODS steels revealed that superior creep properties were due to the dual phase structure, delta-ferrite and tempered martensite. Delta ferrite has very fine oxide particles dispersed in the matrix. In this study, the role of delta-ferrite dual phase 9Cr-ODS steel creep mechanism as a compsite material were studied.

Oral presentation

Creep mechanism of 9Cr ODS steel

Sakasegawa, Hideo; Ukai, Shigeharu*; Tamura, Manabu*; Otsuka, Satoshi; Tanigawa, Hiroyasu; Ogiwara, Hiroyuki; Koyama, Akira*; Fujiwara, Masayuki

no journal, , 

no abstracts in English

Oral presentation

Impact properties of reduced activation ferritic/martensitic steel, F82H joined by hot isostatic pressing

Ogiwara, Hiroyuki; Tanigawa, Hiroyasu; Hirose, Takanori; Enoeda, Mikio; Koyama, Akira*

no journal, , 

Reduced-activation ferritic/martensitic steels are leading candidate structural material for the blanket system of fusion reactors. The important issue in current stage is the finalization of detailed manufacturing specification for ITER test blanket module. Hot isostatic pressing (HIP) process is one of the most important methods to fabricate the first wall with cooling channels. The objective of this paper is to optimize HIP condition to obtain the excellent joints mechanical properties. The materials used were F82H steels. The joint was produced by solid state HIP method. Before HIP treatments, specimens were heated in vacuum condition to out-gas. This treatment was conducted to decrease oxidation on the surfaces. HIP treatments were carried out for 2 h at 1100 $$^{circ}$$C - 140 MPa. The specimens were normalized at 960 $$^{circ}$$C for 0.5 h and tempered at 750 $$^{circ}$$C for 1.5 h. The bonding interface was characterized by scanning electron microscope. Charpy impact tests and tensile tests were conducted to evaluate the mechanical properties of HIP joint. Impact tests revealed that there were no significant difference in ductile-brittle transition temperatures of HIP jointed specimens and base metal specimens, but upper-shelf energy (USE) of HIP joint specimens at room temperature was about 10 % of that of base metal specimens. SEM observation on the fracture surface of HIP joint specimen revealed that a large number of oxides were formed on the HIP joint. This result indicates that oxides formed on the HIP joint are the dominant factor of the impact properties. Based on the results, the pre-HIP treatment conditions had been optimized to reduce the number of oxides, and USE of HIP joint specimen become about 50 % of base metal. The detailed analyses on HIP joint microstructure will be reported.

Oral presentation

Phase stablity of precipitate in irradiated reduced activation ferritc/martensitic steels

Tanigawa, Hiroyasu; Sakasegawa, Hideo; Ogiwara, Hiroyuki*; Kishimoto, Hirotatsu*; Koyama, Akira*

no journal, , 

It was previously reported that reduced-activation ferritic/martensitic steels (RAFs), such as F82H-IEA and JLF-1, showed a variety of changes in its mechanical property after neutron irradiation at 573K up to 5dpa, and have possible correlation with precipitation. In this study, irradiation effects on precipitation were investigated in detail with the emphasis on phase stability. It turned out that precipitates in the ion irradiated region become amorphous. Laves phase in aged F82H was also amorphized. An aged Fe-Ta-C model alloy contained a high density of TaC in the matrix, but those TaC precipitates disappeared in the ion-irradiation region after 20 dpa single/dual ion irradiation. This amorphization of precipitates and TaC re-solution in these RAFs was also observed in neutron irradiated RAFs.

Oral presentation

Improvement of HIP joint process on reduced activation ferritic/martensitic steels

Ogiwara, Hiroyuki; Tanigawa, Hiroyasu; Hirose, Takanori; Enoeda, Mikio

no journal, , 

Reduced-activation ferritic/martensitic steels are leading candidate structural material for the blanket system of fusion reactors. The important issue in current stage is the finalization of detailed manufacturing specification for ITER test blanket module. Hot isostatic pressing (HIP) process is one of the most important methods to fabricate the first wall with cooling channels. The objective of this paper is to optimize HIP condition to obtain the excellent joints mechanical properties. Upper-shelf energy (USE) of HIP joints increased with increasing the out-gas temperatures before HIP treatments. Impact tests revealed that USE of HIP jointed specimens were 80 % of base metal specimens at 600 $$^{circ}$$C and 50 % at 400 $$^{circ}$$C. The difference of USE will be related to the Thermal Desorption Spectroscopy spectrum of gasses from F82H because temperatures of desorption peak of CO and CO$$_{2}$$ were between 400 $$^{circ}$$C and 600 $$^{circ}$$C. This result indicated that CO and CO$$_{2}$$ out-gassed from pre-HIP joints are the dominant factor of the impact properties. SEM observation on the fracture surface of HIP joint specimen revealed that a large number of oxides were not formed on the HIP joint. Based on the results, the pre-HIP treatment conditions had been optimized to reduce the number of oxides, and USE of HIP joint specimen become about 80 % of base metal.

Oral presentation

Impact properties of reduced activation ferritic/martensitic steel, F82H jointed by hot isostatic pressing

Ogiwara, Hiroyuki; Tanigawa, Hiroyasu; Hirose, Takanori; Enoeda, Mikio

no journal, , 

Reduced-activation ferritic/martensitic steels are leading candidates for the blanket and first wall of fusion reactors. The important issue in current stage is the finalization of detailed manufacturing specification for ITER test blanket module. Hot isostaic pressing (HIP) process is one of the most important methods to fabricate the first wall with cooling channel. The objective is to optimize HIP condition with the excellent joints strength and microstructural evolution. The materials used were F82H steels. The joint was produced by solid state HIP method. Before HIP treatments, the gases in specimens were evaporated in the vacuum. This treatment was conducted to decrease oxidation on the surfaces. HIP treatments were carried out for 2 h at 1100 $$^{circ}$$C - 140 MPa. The specimens were normalized at 960 $$^{circ}$$C for 0.5 h and tempered at 750 $$^{circ}$$C for 1.5 h. The bonding interface was characterized by scanning electron microscope. 1/3 charpy V-notch tests applied to the bonding strength. There were no significant difference in ductile-brittle transition temperatures of HIP jointed specimens and base metal specimens. Upper-shelf energy (USE) of HIP joint specimens at room temperature was lower than that of base metal specimens. The fracture had a large number of oxides. Therefore, the condition before HIP treatment was optimized to reduce the number of oxides. Because the density of oxides on the fracture was low level, its oxides along interface might be effective in the increase of USE. In the HIP process, Oxides along bonding interface are the dominant factor determining the impact properties of HIP jointed F82H steels. In this presentation, HIP processes will be reported that is effective in increasing USE.

Oral presentation

Microstructural development of multi-pass TIG welded F82H steels under dual-ion irradiation

Ogiwara, Hiroyuki; Tanigawa, Hiroyasu; Mizui, Tomohiro*; Kishimoto, Hirotatsu*; Koyama, Akira*

no journal, , 

Reduced-activation ferritic/martensitic steels for first wall and blanket structural component applications in a fusion reactor required joining by welding, and effects of displacement damage and helium production on mechanical properties and microstructures are important to these applications. In the fabrication of blanket modules, the joints of a first wall/side walls will be applied to a multi-pass tungsten inert gas (TIG) welding. The objectives of this work are to clarify the helium effects on swelling behavior and the microstructural evolution in the region welded by a multi-pass TIG welding. F82H steels were irradiated at 470 $$^{circ}$$C up to high dose 20 dpa by using 6.4 MeV Fe$$^{3+}$$ and/or energy-degraded 1.0 MeV He$$^{+}$$. The damage rate is 3.0$$times$$10$$^{-4}$$ dpa/s, and the helium injection rate is 15$$times$$10$$^{-3}$$ appm He/s. Microstructure and Vickers hardness profiles across base metal, heat affected zone (HAZ) and fusion zone (FZ) were examined before irradiation experiments. The amount of hardness in FZ increased in increments of number in welding passes. The swelling resistance varied with the type considered due to the phase transformation that occur during the heating and cooling cycles of the fusion welding process. In dual-ion irradiated FZ, cavities were observed to a region from one pass to fourth passes and not fifth passes, and amount of swelling decreased in increments of number in welding passes. The tempered zone offered the largest amount of swelling across HAZ.

Oral presentation

Interfacial properties of HIP joint between beryllium and reduced activation ferritic/martensitic steel

Ando, Masami; Tanigawa, Hiroyasu; Ogiwara, Hiroyuki; Enoeda, Mikio; Akiba, Masato; Hirose, Takanori

no journal, , 

Dissimilar joint between beryllium and reduced activation ferritic/martensitic steel for ITER test blanket module has been successfully developed with hot isostatic pressing (HIP) method. A chromium insert on the interface effectively suppresses diffusion of beryllium into the steel, and the joint demonstrated good bonding strength. The strength of the joint was as well as a joint for ITER shielding blanket, therefore it is applicable for ITER-TBM application.

Oral presentation

Manufacturing and evaluation technology development for ITER-TBM first-wall fabricated by hot isostatic pressing

Ogiwara, Hiroyuki; Tanigawa, Hiroyasu; Hirose, Takanori; Enoeda, Mikio; Akiba, Masato

no journal, , 

no abstracts in English

Oral presentation

Demonstration of manufacturing process of FW component for ITER-TBM

Ogiwara, Hiroyuki; Enoeda, Mikio; Tanigawa, Hiroyasu; Akiba, Masato; Hirose, Takanori

no journal, , 

no abstracts in English

Oral presentation

Optimization of HIP process to fabricate the first wall

Ogiwara, Hiroyuki; Tanigawa, Hiroyasu; Hirose, Takanori; Enoeda, Mikio; Akiba, Masato

no journal, , 

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.

22 (Records 1-20 displayed on this page)