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Journal Articles

Quantitative and semi-quantitative analyses using a portable energy dispersive X-ray fluorescence spectrometer; Geochemical applications in fault rocks, lake sediments, and event deposits

Watanabe, Takahiro; Ishii, Chikako; Ishizaka, Chika; Niwa, Masakazu; Shimada, Koji; Sawai, Yuki*; Tsuchiya, Noriyoshi*; Matsunaka, Tetsuya*; Ochiai, Shinya*; Nara, Fumiko*

Journal of Mineralogical and Petrological Sciences, 116(3), p.140 - 158, 2021/00

 Times Cited Count:3 Percentile:38.91(Mineralogy)

A portable energy dispersive X-ray fluorescence spectrometer (potable XRF) can be an effective tool for detecting chemical elements in various materials, such as geological, and environmental samples. In this study, working curves were confirmed using reference materials, such as igneous rocks and other geochemical standards, distributed by national and international organizations. Subsequently, quantification and semi-quantification analyses were performed by the portable XRF for inorganic elements in (A) fault rocks, (B) lake sediments from the middle Japan, and (C) soils with paleotsunami deposits from the Pacific coast of northeast Japan. Twenty-four elements (Mg-U) in these geological samples were measured by potable XRF using our working curves. Measured values by the portable XRF of the samples were good agreement with the reported values in almost cases.

Journal Articles

A Geochemical approach for identifying marine incursions; Implications for tsunami geology on the Pacific coast of northeast Japan

Watanabe, Takahiro; Tsuchiya, Noriyoshi*; Yamasaki, Shinichi*; Sawai, Yuki*; Hosoda, Norihiro*; Nara, Fumiko*; Nakamura, Toshio*; Komai, Takeshi*

Applied Geochemistry, 118, p.104644_1 - 104644_11, 2020/07

 Times Cited Count:9 Percentile:61.97(Geochemistry & Geophysics)

Possible tsunami inundation areas can be predicted from the distribution of paleo tsunami deposits, which are mainly composed of marine-derived sands and muds on land. Such exotic sandy and muddy layers have been identified by multiple approaches. However, there still remain uncertainties and other useful proxies need to be investigated for the identification of tsunami deposits. Here we show the geochemical signatures of modern tsunami deposits from the Pacific coast of Northeast Japan (2011 Tohoku tsunami), as well as those paleo tsunami deposits, which were taken from the Tohoku District (Jogan, ca. 1080 calibrated ages before present [cal BP] and Yayoi, ca. 2000 cal BP). A geochemical ternary diagram (Seawater-Rock-(As+Metals)) enables the weathering trend of tsunami deposits over ca. 2000 years in the Sendai Plain in the Tohoku to be shown. In the paleo tsunami layers from the Tohoku, the Na/Ti atomic ratios markedly increased to 23.4, and the average values were 19.3$$pm$$3.0 (Jogan and Yayoi tsunami deposits), which were clearly higher than those of other layers (soil deposits, 10.3$$pm$$3.5 on average). These results show that the Na/Ti ratio is a useful indicator of marine incursions in our case. Our rapid and simple method using the Na/Ti ratio can be easily applied to the Tohoku, and it may contribute to the detection of unrecorded muddy tsunami deposits.

Journal Articles

Outlines of JAEA'S instructor training program and future prospects

Hidaka, Akihide; Nakamura, Kazuyuki; Watanabe, Yoko; Yabuuchi, Yukiko; Arai, Nobuyoshi; Sawada, Makoto; Yamashita, Kiyonobu; Sawai, Tomotsugu; Murakami, Hiroyuki

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 9 Pages, 2015/05

Journal Articles

Assembly study for JT-60SA tokamak

Shibanuma, Kiyoshi; Arai, Takashi; Hasegawa, Koichi; Hoshi, Ryo; Kamiya, Koji; Kawashima, Hisato; Kubo, Hirotaka; Masaki, Kei; Saeki, Hisashi; Sakurai, Shinji; et al.

Fusion Engineering and Design, 88(6-8), p.705 - 710, 2013/10

 Times Cited Count:10 Percentile:61.94(Nuclear Science & Technology)

Journal Articles

Microstructural evolution and void swelling in extra high purity Ni-base superalloy under multi-ion irradiation

Kim, G.; Shiba, Kiyoyuki; Sawai, Tomotsugu; Ioka, Ikuo; Kiuchi, Kiyoshi; Nakayama, Jumpei*

Proceedings of 2nd International Workshop on Structural Materials for Innovative Nuclear Systems (SMINS-2), p.273 - 279, 2012/12

Journal Articles

Irradiation behavior of precipitation hardened Ni-base super-alloys with EHP grade under multi-ion irradiation

Kim, G.; Shiba, Kiyoyuki; Sawai, Tomotsugu; Ioka, Ikuo; Kiuchi, Kiyoshi

Materials Research Society Symposium Proceedings, Vol.1298, p.61 - 66, 2011/04

The irradiation behaviour in two different precipitation hardening types of Ni-base alloys with the ultra high purity grade (EHP), namely, the $$gamma$$' type and G phase type was investigated by multi-ion beam techniques simulated to the irradiation conditions in fuel cladding tubes used in sodium cooled FBRs. Single ion-beam irradiation tests were conducted up to 90 dpa (by Fe$$^{3+}$$ or Ni$$^{3+}$$) at 673 K. Triple ion-beam irradiation tests were conducted up to 90 dpa (by Ni$$^{3+}$$, 90 appmHe and 1350 appmH) at 823 K. The irradiation behaviour was examined by nano-indentation tests to irradiation hardening, and the microscopic observation by TEM to the distribution of dislocations, cavities and voids. The behaviour was compared with those of PNC316. The dominating irradiation defects in EHP($$gamma$$') alloy at 673 K by single ion-beam are Frank loops, perfect unfaulted loops and line dislocations. Whereas, those of EHP(WSi) alloy are the irradiation-induced G phase precipitates along ${111}$ planes. Those dominating defect structures at 823 K by triple ion-beam are classified as followings, bimodal distributions in EHP($$gamma$$'), bubbles in EHP(WSi) and voids in PNC316. The ratio of void swelling is estimated as nearly 0.01% in EHP(WSi), 0.2% in EHP($$gamma$$'), 3.4% in PNC316. From those results, the excellent irradiation properties of EHP(WSi) alloy is clarified as the inhibition effects of secondary irradiation defects.

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:13.24(Metallurgy & Metallurgical Engineering)

no abstracts in English

Journal Articles

Structural design of ferritic steel tiles for ripple reduction of toroidal magnetic field in JT-60U

Shibama, Yusuke; Arai, Takashi; Miyo, Yasuhiko; Sawai, Tomotsugu; Sakurai, Shinji; Masaki, Kei; Suzuki, Yutaka; Jitsukawa, Shiro; Miya, Naoyuki

Fusion Engineering and Design, 82(15-24), p.2462 - 2470, 2007/10

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The structural design of the tile as a ripple reduction for toroidal magnetic field in JT-60U was outlined. 8Cr-2W-0.2V ferritic steel plates were fabricated and mechanical and vacuum properties were evaluated to assess the design conditions. Tensile properties were uniform in yield and tensile strength at ambient temperature and sufficient strength as the structural integrity at operational temperature of 423 K and 573 K. Vacuum property was measured with the baking at 473 K and similar to the conventional stainless steel but not satisfy the JT-60 standard of the in-situ material of the vacuum vessel. The ferritic steel was judged as an installable because of that the JT-60 baking temperature is 573 K higher than this test temperature of 473 K, and of that residual out-gassing was hydrogen which was the fuel of the operational plasma.

Journal Articles

Creep behavior of reduced activation ferritic/martensitic steels irradiated at 573 and 773K up to 5dpa

Ando, Masami; Li, M.*; Tanigawa, Hiroyasu; Grossbeck, M. L.*; Kim, S.-W.; Sawai, Tomotsugu; Shiba, Kiyoyuki; Kono, Yutaka*; Koyama, Akira*

Journal of Nuclear Materials, 367-370(1), p.122 - 126, 2007/08

 Times Cited Count:15 Percentile:70.74(Materials Science, Multidisciplinary)

Irradiation creep behavior of the F82H and several JLF-1 steels have been measured up to 5 dpa, using helium-pressurized creep tubes irradiated in HFIR. These tubes were pressurized with helium to hoop stress levels of 0 to 400 MPa for irradiation temperature. The results of F82H and JLF-1 with 200 MPa hoop stress showed small creep strains ($$<$$ 0.15%) after irradiation. Irradiation creep rate in these steels is linearly dependent on the applied stress less than 200 MPa. However, at higher hoop stress level, the creep rate of them is nonlinear. The creep compliance coefficient for F82H and JLF-1 at 300 $$^{circ}$$C is very small values. These data contribute to a part of materials database for ITER Test blanket design work.

Journal Articles

Fabrication of 8Cr-2W ferritic steel tile for reduction in toroidal magnetic field ripple on JT-60U

Kudo, Yusuke; Sawai, Tomotsugu; Sakurai, Shinji; Masaki, Kei; Suzuki, Yutaka; Sasajima, Tadayuki; Hayashi, Takao; Takahashi, Ryukichi*; Honda, Masao; Jitsukawa, Shiro; et al.

Journal of the Korean Physical Society, 49(96), p.S297 - S301, 2006/12

Installation of ferritic steel tiles was proposed in JT-60U to reduce the toroidal magnetic field ripple and to improve the fast ion loss, which degrades heating efficiency and increases heat load on plasma facing component under large volume plasma operations. We selected a 8Cr-2W-0.2V ferritic steel with the cost-effectiveness, in which concentration limits of activation elements in F82H were relaxed because of the less number of neutron generations from deuterium operations on JT-60U. The fabricated ferritic steel has clear tempered martensitic microstructure, and sufficient magnetic and mechanical properties. The saturated magnetization was estimated to 1.7 Tesla at 573 K, lower than expected, but effectiveness in JT-60U was confirmed by numerical analyses. To research the effect of material conditions, such as microstructure and heat treatment, on saturated magnetization of the ferritic steel based on 8-9Cr is important for the future fusion reactors which will be planned to install the ferritic steel as the in-vessel components.

Journal Articles

Effect of heat treatments on mechanical properties and microstructures of 8Cr-2W(F82H) steel doped with boron or boron and nitrogen

Wakai, Eiichi; Sato, Michitaka*; Okubo, Nariaki; Sawai, Tomotsugu; Shiba, Kiyoyuki; Jitsukawa, Shiro

Nihon Kinzoku Gakkai-Shi, 69(6), p.460 - 464, 2005/06

 Times Cited Count:1 Percentile:16.46(Metallurgy & Metallurgical Engineering)

no abstracts in English

Journal Articles

Extra radiation hardening and microstructural evolution in F82H by high-dose dual ion irradiation

Ando, Masami; Wakai, Eiichi; Sawai, Tomotsugu; Matsukawa, Shingo; Naito, Akira*; Jitsukawa, Shiro; Oka, Keiichiro*; Tanaka, Teruyuki*; Onuki, Somei*

JAERI-Review 2004-025, TIARA Annual Report 2003, p.159 - 161, 2004/11

The objectives of this study are to evaluate radiation hardening on ion-irradiated F82H up to 100 dpa and to examine the extra component of radiation hardening due to implanted helium atoms (up to $$sim$$3000 appmHe) in F82H under ratio of 0, 10, 100 appmHe/dpa.The ion-beam irradiation experiment was carried out at the TIARA facility of JAERI. Specimens were irradiated at 633 K by 10.5 MeV Fe ions with/without 1.05 MeV He ions. Micro-indentation tests were performed at loads to penetrate about 0.40 mm in the irradiated specimens using an UMIS-2000. The results are summarized as follows:1) As a result of the single irradiated F82H, the micro-hardness tended to increase about 30 dpa. 2) The extra radiation hardening was obviously caused by co-implanted helium atoms more than 1000 appm in F82H irradiated at 633 K. 3) In the dual-beam (100 appmHe/dpa) irradiated microstructure, nano-voids and fine defects were observed. It is suggested that the formation of nano-voids causes the extra radiation hardening by helium co-implantation.

Journal Articles

Synergistic effect of displacement damage and helium atoms on radiation hardening of F82H at TIARA facility

Ando, Masami; Wakai, Eiichi; Sawai, Tomotsugu; Tanigawa, Hiroyasu; Furuya, Kazuyuki; Jitsukawa, Shiro; Takeuchi, Hiroshi; Oka, Keiichiro*; Onuki, Somei*; Koyama, Akira*

Journal of Nuclear Materials, 329-333(2), p.1137 - 1141, 2004/08

 Times Cited Count:48 Percentile:94.01(Materials Science, Multidisciplinary)

One of the most crucial issues on R&D of reduced activation ferritic/martensitic steels is the effect of helium on the degradation of fracture toughness. The synergistic effects of displacement damage and helium on F82H steel can be partially simulated by martensitic steels doped with $$^{10}$$B or $$^{58}$$Ni in a mixed spectrum fission reactor. However, the control of helium production rate is difficult and the chemical effects of B or Ni doping on mechanical property are not small. Therefore, multi-ion irradiation method is the most convenient and accurate method to simulate various irradiation conditions. Moreover, the effects of helium on irradiation hardening behavior can be examined by combining ion-irradiation with ultra micro-indentation technique. The purpose of this study is to examine the extra component of radiation hardening due to implanted helium in F82H. The extra component of irradiation hardening due to helium was hardly detected in the dual-beam irradiation. Therefore, the effect on irradiation hardening below 630K of helium ($$<$$500 appm) was very small.

Journal Articles

Effects of heat treatment process for blanket fabrication on mechanical properties of F82H

Hirose, Takanori; Shiba, Kiyoyuki; Sawai, Tomotsugu; Jitsukawa, Shiro; Akiba, Masato

Journal of Nuclear Materials, 329-333(Part1), p.324 - 327, 2004/08

 Times Cited Count:55 Percentile:95.03(Materials Science, Multidisciplinary)

Reduced activation ferritic/martensitic steel, RAFs is the leading candidates for the structural materials of breeding blankets. HIP is examined as a near-net-shape fabrication process for this structure. The HIP requires heating above the normalizing temperature and the final microstructural features depends on the HIP processing conditions. Conventional HIP process caused a prior-austenite grain (PAG) coarsening of RAFs and subsequent increase of ductile brittle transition temperature. Japanese RAFs F82H and its modified steels were investigated by metallurgical method after isochronal heat treatment up to 1473K simulating HIP equivalent thermal hysteresis. Although Conventional F82H IEA heat showed significant grain growth after conventional solid HIP conditions (1313K $$times$$ 2hr.), F82H with 0.1wt.% tantalum kept fine grain after the same heat treatment. On the other hands, conventional RAF/Ms with coarse grain were recovered by the post HIP normalizing at temperature below TaC dissolution temperature. This process can refine the PAG size of F82H more than ASTM grain size number 7.

Journal Articles

Mechanical properties and microstructure of F82H steel doped with boron or boron and nitrogen as a function of heat treatment

Wakai, Eiichi; Sato, Michitaka*; Sawai, Tomotsugu; Shiba, Kiyoyuki; Jitsukawa, Shiro

Materials Transactions, 45(2), p.407 - 410, 2004/01

 Times Cited Count:4 Percentile:32.98(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Tensile and impact properties of F82H steel applied to HIP-bond fusion blanket structures

Furuya, Kazuyuki; Wakai, Eiichi; Ando, Masami; Sawai, Tomotsugu; Iwabuchi, Akira*; Nakamura, Kazuyuki; Takeuchi, Hiroshi

Fusion Engineering and Design, 69(1-4), p.385 - 389, 2003/09

 Times Cited Count:21 Percentile:78.9(Nuclear Science & Technology)

In a fusion reactor, a blanket made of a low activation material like F82H is fabricated by solid Hot Isostatic pressing (HIP) joining method. In a previous study, blanket, grain coarsenings were found in a mock-up around HIP-joined region. To verify an effect of the coarsenings on a strength of the HIP-joined region, tensile test and hardness measurement were done. As the results, the tensile strength increased by about 50 MPa, and the elongation decreased by about 4 % in comparison with that of a standard alloy. Though the hardness was almost constant both in the coarsening and a non-coarsening regions, both of these hardness increased by about 5 %. Therefore, it could be judged that change of the tensile property is due to increase of the hardness. On the other hand, tensile and impact tests of a base metal without coarsening resulted in DBTT increase by about 40 K, although the tensile property was nearly equal to that of the joined-region with coarsening. It can be understood that this is the effect of the heat treatments in the fabrication process of the mock-up.

Journal Articles

Microstructure and hardness of HIP-bonded regions in F82H blanket structures

Furuya, Kazuyuki; Wakai, Eiichi; Ando, Masami; Sawai, Tomotsugu; Nakamura, Kazuyuki; Takeuchi, Hiroshi; Iwabuchi, Akira*

Journal of Nuclear Materials, 307-311(Part1), p.289 - 292, 2002/12

 Times Cited Count:7 Percentile:44.54(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Evaluation of hardening behavior of ion irradiated reduced activation ferritic/martensitic steels by an ultra-micro-indentation technique

Ando, Masami; Tanigawa, Hiroyasu; Jitsukawa, Shiro; Sawai, Tomotsugu; Kato, Yudai*; Koyama, Akira*; Nakamura, Kazuyuki; Takeuchi, Hiroshi

Journal of Nuclear Materials, 307-311(Part1), p.260 - 265, 2002/12

 Times Cited Count:38 Percentile:89.88(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Swelling of cold-worked austenitic stainless steels irradiated in HFIR under spectrally tailored conditions

Wakai, Eiichi; Hashimoto, Naoyuki*; Robertson, J. P.*; Sawai, Tomotsugu; Hishinuma, Akimichi

Journal of Nuclear Materials, 307-311(Part.1), p.352 - 356, 2002/12

 Times Cited Count:11 Percentile:58.55(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Effects of triple ion beams in ferritic/martensitic steel on swelling behavior

Wakai, Eiichi; Sawai, Tomotsugu; Furuya, Kazuyuki; Naito, Akira; Aruga, Takeo; Kikuchi, Kenji; Yamashita, Shinichiro*; Onuki, Somei*; Yamamoto, Shunya; Naramoto, Hiroshi; et al.

Journal of Nuclear Materials, 307-311(Part.1), p.278 - 282, 2002/12

 Times Cited Count:49 Percentile:93.87(Materials Science, Multidisciplinary)

no abstracts in English

41 (Records 1-20 displayed on this page)