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Journal Articles

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

 Times Cited Count:21 Percentile:98.04(Astronomy & Astrophysics)

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Journal Articles

Static tensile deformation behavior of a lean duplex stainless steel studied by in situ neutron diffraction and synchrotron radiation white X-rays

Tsuchida, Noriyuki*; Kawahata, Takuji*; Ishimaru, Eiichiro*; Takahashi, Akihiko*; Suzuki, Hiroshi; Shobu, Takahisa

ISIJ International, 53(7), p.1260 - 1267, 2013/07

 Times Cited Count:19 Percentile:70.68(Metallurgy & Metallurgical Engineering)

To investigate the tensile deformation behavior of a lean duplex stainless steel (S32101) from the viewpoints of plastic deformability among phases or grains, we performed static tensile tests, in situ neutron diffraction, and white X-ray diffraction experiments at room temperature. From the experimental results of synchrotron radiation white X-ray diffraction experiments, the hard phase of S32101 was changed from the ferrite phase to austenite one during tensile deformation. This led to a larger stress partitioning between the phases at the latter stage of deformation. From the experimental results of in situ neutron diffraction, it was found that the stress partitioning of the $$gamma$$ phase in the S32101 was the largest among the present results. Therefore, the larger work hardening rate of S32101 can be explained by the large stress partitioning of the $$gamma$$ phase, that between $$gamma$$ and $$alpha$$ phases and $$gamma$$ volume fraction.

Journal Articles

Uniaxial-pressure control of magnetic phase transitions in a frustrated magnet CuFe$$_{1-x}$$Ga$$_{x}$$O$$_{2}$$ (x =0, 0.018)

Nakajima, Taro*; Mitsuda, Setsuo*; Takahashi, Keiichiro*; Yoshitomi, Keisuke*; Masuda, Kazuya*; Kaneko, Chikafumi*; Homma, Yuki*; Kobayashi, Satoru*; Kitazawa, Hideaki*; Kosaka, Masashi*; et al.

Journal of the Physical Society of Japan, 81(9), p.094710_1 - 094710_8, 2012/09

Journal Articles

Uniaxial-pressure control of magnetic phase transitions in a frustrated magnet CuFe$$_{1-x}$$Ga$$_{x}$$O$$_{2}$$ ($$x$$ = 0, 0.018)

Nakajima, Taro*; Mitsuda, Setsuo*; Takahashi, Keiichiro*; Yoshitomi, Keisuke*; Masuda, Kazuya*; Kaneko, Chikafumi*; Homma, Yuki*; Kobayashi, Satoru*; Kitazawa, Hideaki*; Kosaka, Masashi*; et al.

Journal of the Physical Society of Japan, 81(9), p.094710_1 - 094710_8, 2012/09

 Times Cited Count:12 Percentile:61.35(Physics, Multidisciplinary)

Journal Articles

Demonstration of remote fabrication for FBR MOX fuel at the PFPF

Takahashi, Saburo; Kikuno, Hiroshi; Shiromo, Hideo; Kuba, Meiji; Abe, Tomoyuki; Takeda, Seiichiro

Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10

Japan Atomic Energy Agency (JAEA) has been accumulating various experience and knowledge on development of MOX fuel technologies for more than 40 years since 1966. Plutonium Fuel Production Facility (PFPF) has introduced a fully automated and remote operation in 1988 as a pioneer in the world, based on the operational and technical experience obtained in the existing facilities. The PFPF has fabricated MOX fuel assemblies for a fast reactor "JOYO" and a fast breeder reactor "MONJU" so far. Through MOX fuel fabrication for JOYO and MONJU, many operational experiences such as a hold-up material problem have been gained. Based on the experiences, process equipments have been newly developed and a process technology has been improved. As the results, fully automated and remote fabrication technologies including easy contact maintenance of process equipments for FBR MOX fuel have been demonstrated in the PFPF on a large scale.

JAEA Reports

Study on Methodology for Biosphere Assessment Data

Kato, Tomoko; Suzuki, Yuji*; Makino, Hitoshi; Uchida, Masahiro; Naito, Morimasa; Wakasugi, Keiichiro*; Takahashi, Yoshiaki*

JNC TN1400 2005-024, 14 Pages, 2005/08

JNC-TN1400-2005-024.pdf:0.67MB

Biosphere assessment is positioned as part of an important factor in safety assessment to convert nuclide release rates into surface environment to measures of effect for human, such as radiation dose. In general, a lot of data are handled in the biosphere assessment, and they are based on the feature of specific site. Therefore, it is reasonable to screen parameters in order to manage the limited resource and develop the biosphere assessment effectively. JNC and NUMO established

Journal Articles

Evidence for the diffusion of Au atoms into the Te UPD layer formed on a Au(111) substrate

Kawamura, Hiroyuki; Takahashi, Masamitsu; Hojo, Nobuhiko*; Miyake, Masao*; Murase, Kuniaki*; Tamura, Kazuhisa*; Uosaki, Kohei*; Awakura, Yasuhiro*; Mizuki, Junichiro; Matsubara, Eiichiro*

Journal of the Electrochemical Society, 149(2), p.C83 - C88, 2002/02

 Times Cited Count:6 Percentile:22.23(Electrochemistry)

The structure of a Te layer formed on a Au(111) substrate by underpotential deposition (UPD) in an electrolytic solution has been studied using in-situ surface X-ray diffraction technique. The measurements were carried out for a series of samples which were kept at UPD potential for 4 to 59 hours. The results revealed that the Te UPD layer is unstable. The top layer is analyzed to consist of the UPD Te atoms and Au atoms which diffuse from the Au(111) substrate. Also, the Te UPD layer does not have the structure with periodicity reported in previous works, such as ($$sqrt{3}$$$$times$$$$sqrt{3}$$) R30$$^{circ}$$ after ample time elapses. Stripping voltammetry for the Te UPD layer shows that the interaction between Te and Au increases with time, supporting the finding that the top layer is a mixture of Te and Au.

Journal Articles

PLANNING OF WASTE MANAGEMENT PROGRAM FOR LOW LEVEL RADIOACTIVE WASTES GENERATED FROM JNC SITES

Takahashi, Kuniaki; Takeda, Seiichiro; ; ;

Spectrum2000, 0 Pages, 2000/00

None

JAEA Reports

Investigation of the Hydraulic Properties in the Active Fault Survey Tunnel

Takemura, Tomoyuki*; Sakogaichi, Kaoru*; Takahashi, Eiichiro*; Takebe, Akimitsu*; Nakajima, Toshihide*; Yamashita, Mitsugu*; Yamanouchi, Hirofumi*

JNC TJ7420 2005-041, 129 Pages, 1999/03

JNC-TJ7420-2005-041.pdf:65.88MB

The active fault survey tunnel that crossed the Mozumi-Sukenobu fault (a member of the Atotsugawa fault system) is located at the Kamioka mine, northern Gifu prefecture, Central Japan. The comprehensive study of the active fault such as the earthquake mechanism is done by using this tunnel. The purpose of this investigation is to define the hydrological characteristics inside and around the Mozumi - Sukenobu fault crush zones. The investigation is mainly Lugeon test and simple permeability test inside and around the crush zones.

JAEA Reports

Investigation of the Hydraulic Properties around the Active Fault in the Crustal Deformation Zone

Takemura, Tomoyuki*; Shingu, Kazuki*; Takahashi, Eiichiro*; Okada, Yoichi*; Takebe, Akimitsu*; Nakajima, Toshihide*; Inoue, Toshio*

JNC TJ7420 2005-033, 128 Pages, 1998/03

JNC-TJ7420-2005-033.pdf:51.98MB

The active fault survey tunnel that crossed the Mozumi-Sukenobu fault (a member of the Atotsugawa fault system) is located at the Kamioka mine, northern Gifu prefecture, Central Japan. The comprehensive study of the active fault is done by using this tunnel. The purpose of this investigation is to define the hydrological characteristics of the Mozumi-Sukenobu fault crush zones. The permeability of the crush zones is measured by the Lugeon test and the simple injection test.

JAEA Reports

None

*; Shingu, Kazuki*; Takahashi, Eiichiro*; Nakajima, Toshihide*; Yamashita, Mitsugu*; *; *

PNC TJ7187 97-002, 586 Pages, 1997/11

PNC-TJ7187-97-002.pdf:47.21MB

None

JAEA Reports

Additional Groundwater Sampling and Analysis in the Investigation of Deep Groundwater (DH-15 Hole)

Hama, Hiroshi*; Yamada, Tsuyoshi*; Ide, Mitsuyoshi*; Takahashi, Eiichiro*; Yamamoto, Katsuya*; Nakajima, Toshihide*; Watabe, Takeo*

JNC TJ7440 2005-074, 270 Pages, 1995/05

JNC-TJ7440-2005-074.PDF:17.59MB
JNC-TJ7440-2005-074(errata).pdf:0.08MB

In 1997, DH-5 hole was drilled at P.N.C.(present J.N.C.) Toki Branch of Tono Geoscience Centr in Gifu prefecture. The borehole was drilled to a depth of 502.3 meters in Toki granite in order to investigate the deep groundwater. This report describes the investigation of the groundwater conducted at depth from 323.8 to 330.8 meters to make clear geological, hydrogeological and geochemical characteristics of study area. The investigation includes the following items;i) Sampling of the groundwaterii) Measurement of physical chemistry parameters of the groundwater in the borehole iii) Chemicaal analysis of the main composition of the groundwater during the continuous samplingiv) Chemical analysis of the groundwater It has become clear the following points;* The physical chemistry parameters of groundwater was alkalic, low deoxidize and buffer ability. There were few total ions and sulfide ions in the groundwater.* The isotopic analysis showed that the groundwater was regarded as rainwater in origin on the side of the Pacific Ocean and was relatively young with the age of a few decades.* According to the tri-linear diagram, the groundwater was classified into Ca(HCO$$_{3)}$$$$_{2}$$type. Based on hydrochemical facies, the groundwater was classified into Ca$$_{2}$$sup+ Na$$^{+,}$$and HCO$$_{3-}$$Cl$$^{-}$$SO$$_{4}$$$$^{2}$$$$^{-}$$in the cation and anion facies, respectively.* Nitrite oxidizing bacteria, nitrite reducing bacteria and nitrate reducing bacteria were detected in the groundwater by the bacteria analysis.

Oral presentation

Study of complex magnetic structures in frustrated magnets by means of polarized neutrons

Kakurai, Kazuhisa; Wakimoto, Shuichi; Matsuda, Masaaki*; Ishiwata, Shintaro*; Okuyama, Daisuke*; Taguchi, Yasujiro*; Tokura, Yoshiki*; Nishi, Masakazu*; Nakajima, Taro*; Mitsuda, Setsuo*; et al.

no journal, , 

Oral presentation

Preparation of an information basis for development of practical performance assessment models on waste glass corrosion in geological disposal

Mitsui, Seiichiro; Oe, Toshiaki*; Inagaki, Yaohiro*; Okubo, Takahiro*; Kurosawa, Susumu*; Goto, Takahiro*; Inagaki, Manabu*; Ishiguro, Katsuhiko*; Takase, Hiroyasu*; Takahashi, Hirokazu*

no journal, , 

In order to develop robust performance assessment models, we have been preparing an information basis regarding glass properties and glass dissolution/alteration processes under disposal conditions as a part of NUMO-JAEA joint project. Our iterative working process for the preparation of the information basis comprises five steps: (1) integration of current knowledge; (2) development of glass dissolution scenarios based on current knowledge; (3) development of conceptual model; (4) sensitivity analyses to evaluate relative importance of relevant processes and associated uncertainties; and (5) identification of future R&D issues towards further improvement of the information basis. The current status will be presented in this talk.

Oral presentation

Evaluation of safety function affected by long-term evolution of sealing system, 2; Scenario development

Mitsuyama, Kazuaki*; Takeda, Masaki; Sugita, Yutaka; Ono, Hirokazu; Wakasugi, Keiichiro*; Takase, Hiroyasu*; Takahashi, Hirokazu*; Hashimoto, Tomoko*

no journal, , 

no abstracts in English

Oral presentation

Evaluation of safety function affected by long-term evolution of sealing system, 3; Transport modeling

Takahashi, Hirokazu*; Takeda, Masaki; Sugita, Yutaka; Ono, Hirokazu; Wakasugi, Keiichiro*; Takase, Hiroyasu*; Mitsuyama, Kazuaki*; Hashimoto, Tomoko*

no journal, , 

no abstracts in English

Oral presentation

Muonic X-ray analysis for Ryugu samples

Osawa, Takahito; Ninomiya, Kazuhiko*; Nakamura, Tomoki*; Takahashi, Tadayuki*; Terada, Kentaro*; Yurimoto, Hisayoshi*; Noguchi, Takaaki*; Okazaki, Ryuji*; Yabuta, Hikaru*; Naraoka, Hiroshi*; et al.

no journal, , 

I report on the muonic X-ray analysis experiment conducted at J-PARC from 2020 to 2021, in which the analytical method was significantly developed through four preliminary experiments and successfully analyzed samples from the asteroid Ryugyu in July 2021. The experimental process is described from a radiochemical point of view.

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