Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 46

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Evaluation on cementation by silicates in bentonite

Saito, Yuki*; Ishiwata, Tobimaru*; Horiuchi, Misato*; Nishiki, Yuto*; Kikuchi, Ryosuke*; Otake, Tsubasa*; Kawakita, Ryohei; Takayama, Yusuke; Mitsui, Seiichiro; Sato, Tsutomu*

Shigen, Sozai Koenshu (Internet), 11(1), 7 Pages, 2024/03

no abstracts in English

Journal Articles

Effect of collapse behavior on changes in swelling pressure of bentonite during swelling pressure test

Takayama, Yusuke; Sato, Daisuke*; Kikuchi, Hirohito*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 29(2), p.101 - 111, 2022/12

Swelling pressure tests have been conducted to understand the swelling properties of bentonite which is planned to be used as a buffer material in repositories for the geological disposal of radioactive waste. It has been reported that the swelling pressure obtained by swelling pressure test increases monotonically or temporarily decreases after increasing with the passage of the time depending on the initial water content. In this study, swelling pressure tests were conducted under several different initial water content conditions, and the change in wet density distribution inside the specimen during the swelling pressure tests was observed by X-ray CT measurement. It was confirmed that the presence or absence of collapse behavior and its magnitude affect the shape of the change in swelling pressure. When the collapse deformation was large, the amount of temporary decrease in swelling pressure was large. On the other hand, swelling pressure increased monotonically when there was no deformation due to collapse.

Journal Articles

PSTEP: Project for solar-terrestrial environment prediction

Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.

Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12

 Times Cited Count:7 Percentile:46.67(Geosciences, Multidisciplinary)

The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.

Journal Articles

Observation of collapse behavior of bentonite during swelling pressure test using X-ray CT measurement

Takayama, Yusuke; Kikuchi, Hirohito*

Doboku Gakkai Rombunshu, C (Chiken Kogaku) (Internet), 77(3), p.302 - 313, 2021/09

Numerous swelling pressure tests have been conducted to understand the swelling properties of bentonite which is planned to be used as a buffer material in repositories for the geological disposal of radioactive waste. In this study, in order to clarify the cause of the decrease in swelling pressure during the swell-in pressure test period, the change in wet density distribution inside the specimen during the swelling pressure test was observed by X-ray CT measurement. It was supposed that this phenomenon was caused by the collapse inside the specimen. Furthermore, in order to confirm that collapse is generated by water absorption, the swelling deformation test was carried out under various load conditions. As a result, it was confirmed that collapse occurs even under the load conditions that are equal to or slightly smaller than the swelling pressure. These test data are expected to be used for validation of coupled analysis codes for evaluating the mechanical behavior of disposal facilities during re-saturation period.

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:49 Percentile:96.63(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

A Study on applicability of elasto-plastic constitutive model to mechanical behavior of buffer material in salt water conditions

Takayama, Yusuke; Kikuchi, Hirohito*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(1), p.12 - 21, 2020/06

In this study, an applicability of the modified Cam clay model to the buffer material under saltwater conditions was examined. First, consolidated-undrained triaxial test was conducted using NaCl solution and artificial seawater. Based on the consolidated-undrained triaxial compression test results and the existing consolidation test results, the difference in the mechanical behavior of the buffer material under distilled water and saltwater condition was clarified. In particular, there was a difference in the unloading behavior in the consolidation test. Through reproducibility analysis of these experimental data, it was confirmed that the mechanical behavior of the buffer material can be roughly reproduced by setting the swelling index according to the salt concentration.

Journal Articles

Present status of J-PARC linac

Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10

no abstracts in English

JAEA Reports

Annual report of Nuclear Emergency Assistance and Training Center (April 1, 2012 - March 31, 2013)

Sato, Takeshi; Muto, Shigeo; Okuno, Hiroshi; Katagiri, Hiromi; Akiyama, Kiyomitsu; Okamoto, Akiko; Koie, Masahiro; Ikeda, Takeshi; Nemotochi, Toshimasa; Saito, Toru; et al.

JAEA-Review 2013-046, 65 Pages, 2014/02

JAEA-Review-2013-046.pdf:11.18MB

When a nuclear emergency occurs in Japan, the Japan Atomic Energy Agency (JAEA) has the responsibility of providing technical support to the National government, local governments, police, fire stations and nuclear operators etc., because the JAEA has been designated as the Designated Public Institution under the Basic Act on Disaster Control Measures and the Act on Response to Armed Attack Situations, etc.. The Nuclear Emergency Assistance and Training Center (NEAT) of JAEA provides a comprehensive range of technical support activities to an Off-Site Center in case of a nuclear emergency. Specifically, NEAT gives technical advice and information, dispatches specialists as required, and supplies the National Government and local governments with emergency equipments and materials. NEAT provides various exercise and training courses concerning nuclear disaster prevention to those personnel taking an active part in emergency response organizations at normal times. The tasks of NEAT, with its past experiences as a designated public institution including the responses to TEPCO's Fukushima Accident, have been shifted to technical supports to the national government for strengthening its abilities to emergency responses; the NEAT therefore focused on maintenance and operation of its functions, and strengthening its response abilities in cooperation with the national government. This annual report summarized these activities of JAEA/NEAT in the fiscal year 2012.

Journal Articles

Measurement of the Md$$^{3+}$$/Md$$^{2+}$$ reduction potential studied with flow electrolytic chromatography

Toyoshima, Atsushi; Li, Z.*; Asai, Masato; Sato, Nozomi; Sato, Tetsuya; Kikuchi, Takahiro; Kaneya, Yusuke; Kitatsuji, Yoshihiro; Tsukada, Kazuaki; Nagame, Yuichiro; et al.

Inorganic Chemistry, 52(21), p.12311 - 12313, 2013/11

 Times Cited Count:7 Percentile:31.13(Chemistry, Inorganic & Nuclear)

The reduction behavior of mendelevium (Md) was studied using a flow electrolytic chromatography apparatus. By applying appropriate potentials on the chromatography column, the more stable Md$$^{3+}$$ is reduced to Md$$^{2+}$$. The reduction potential of the Md$$^{3+}$$ + e$$^{-}$$ $$rightarrow$$ Md$$^{2+}$$ couple was determined to be -0.16$$pm$$0.05 V vs. a normal hydrogen electrode.

Journal Articles

Fundamental welding R&D results for manufacturing vacuum vessel of JT-60SA

Asano, Shiro*; Okuyama, Toshihisa*; Onawa, Toshio*; Yanagi, Yutaka*; Ejiri, Mitsuru*; Kanahara, Toshio*; Ichihashi, Koji*; Kikuchi, Atsushi*; Mizumaki, Shoichi*; Masaki, Kei; et al.

Fusion Engineering and Design, 86(9-11), p.1816 - 1820, 2011/10

 Times Cited Count:12 Percentile:65.69(Nuclear Science & Technology)

The real vacuum vessel (VV) manufacturing of JT-60SA has started since Nov. 2009 at Toshiba. Prior to starting manufacturing, fundamental welding R&Ds had been performed by three stages. In the first stage, primary tests for screening welding method were performed. In the second stage, the trial welding for 1m-long straight and curved double shell samples were conducted. The dependences of welding quality and distortion on the welding conditions, such as arc voltage and current, setting accuracy, welding sequence, the shape of grooves, etc. were measured. In addition, welding condition with low heat input was explored. In the last stage, fabrication sequence was confirmed and established by the trial manufacturing of the 20$$^{circ}$$ upper half mock-up. This poster presents the R&D results obtained in the first and second stages.

Journal Articles

Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

 Times Cited Count:189 Percentile:99.42(Physics, Nuclear)

Transverse momentum distributions and yields for $$pi^{pm}, K^{pm}, p$$, and $$bar{p}$$ in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different $$sqrt{s}$$ collisions. We also present the scaling properties such as $$m_T$$ and $$x_T$$ scaling and discuss the mechanism of the particle production in $$p + p$$ collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 Times Cited Count:9 Percentile:52.33(Physics, Nuclear)

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled $$p+p$$ collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to $$p+p$$ collisions.

JAEA Reports

Annual report of Nuclear Emergency Assistance and Training Center (April 1, 2009 - March 31, 2010)

Kanamori, Masashi; Shirakawa, Yusuke; Yamashita, Toshiyuki; Okuno, Hiroshi; Terunuma, Hiroshi; Ikeda, Takeshi; Sato, Sohei; Terakado, Naoya; Nagakura, Tomohiro; Fukumoto, Masahiro; et al.

JAEA-Review 2010-037, 60 Pages, 2010/09

JAEA-Review-2010-037.pdf:3.11MB

When a nuclear emergency occurs in Japan, the Japan Atomic Energy Agency (JAEA) provides technical support to the National government, local governments, police, fire station and license holder etc. They are designated public organizations conforming to the basic law on emergency preparedness and the basic plan for disaster countermeasures. The Nuclear Emergency Assistance & Training Center (NEAT) of JAEA provides a comprehensive range of technical support activities to an off-site center in case of a nuclear emergency. Specifically, NEAT gives technical advice and information, provides for the dispatch of specialist as required, supplies emergency equipments and materials to the national government and municipal office. NEAT provide various lectures and training course concerning nuclear disaster prevention for those personnel taking an active part in emergency response organizations at normal time. And NEAT researches on nuclear disaster prevention and also cooperate with international organizations. This annual report summarized the activities of JAEA/NEAT in the fiscal year 2009.

Journal Articles

Mock-up test results of monoblock-type CFC divertor armor for JT-60SA

Higashijima, Satoru; Sakurai, Shinji; Suzuki, Satoshi; Yokoyama, Kenji; Kashiwa, Yoshitoshi; Masaki, Kei; Shibama, Yusuke; Takechi, Manabu; Shibanuma, Kiyoshi; Sakasai, Akira; et al.

Fusion Engineering and Design, 84(2-6), p.949 - 952, 2009/06

 Times Cited Count:9 Percentile:52.46(Nuclear Science & Technology)

An upgrading device of JT-60 tokamak with fully superconducting coils (JT-60SA) is constructed under both the Japanese domestic program and the international program "Broader Approach". The maximum heat flux to JT-60SA divertor is estimated to 15 MW/m$$^{2}$$ for 100 s, and a monoblock-type CFC divertor armor is promising. The JT-60SA armor consists of CFC monoblocks, a cooling CuCrZr screw-tube, and a thin OFHC-Cu buffer layer, and the brazed joints are essential for the armor. Metalization inside CFC monoblock is applied for further improvement, and we confirmed again that the mock-up has heat removal capability in excess of ITER requirement. For optimization of the fabrication method and understanding of the production yield, the mock-ups corresponding to quantity produced in one furnace is also produced, and the half of the mock-ups could remove 15 MW/m$$^{2}$$ as required. This summarizes the recent progress of design and mock-up test results for JT-60SA divertor armor.

Journal Articles

Status of JT-60SA tokamak under the EU-JA broader approach agreement

Matsukawa, Makoto; Kikuchi, Mitsuru; Fujii, Tsuneyuki; Fujita, Takaaki; Hayashi, Takao; Higashijima, Satoru; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Ide, Shunsuke; Ishida, Shinichi; et al.

Fusion Engineering and Design, 83(7-9), p.795 - 803, 2008/12

 Times Cited Count:17 Percentile:71.80(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Overview of national centralized tokamak program; Mission, design and strategy to contribute ITER and DEMO

Ninomiya, Hiromasa; Akiba, Masato; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Inoue, Nobuyuki; et al.

Journal of the Korean Physical Society, 49, p.S428 - S432, 2006/12

To contribute DEMO and ITER, the design to modify the present JT-60U into superconducting coil machine, named National Centralized Tokamak (NCT), is being progressed under nationwide collaborations in Japan. Mission, design and strategy of this NCT program is summarized.

Journal Articles

Overview of the national centralized tokamak programme

Kikuchi, Mitsuru; Tamai, Hiroshi; Matsukawa, Makoto; Fujita, Takaaki; Takase, Yuichi*; Sakurai, Shinji; Kizu, Kaname; Tsuchiya, Katsuhiko; Kurita, Genichi; Morioka, Atsuhiko; et al.

Nuclear Fusion, 46(3), p.S29 - S38, 2006/03

 Times Cited Count:13 Percentile:41.02(Physics, Fluids & Plasmas)

The National Centralized Tokamak (NCT) facility program is a domestic research program for advanced tokamak research to succeed JT-60U incorporating Japanese university accomplishments. The mission of NCT is to establish high beta steady-state operation for DEMO and to contribute to ITER. The machine flexibility and mobility is pursued in aspect ratio and shape controllability, feedback control of resistive wall modes, wide current and pressure profile control capability for the demonstration of the high-b steady state.

Journal Articles

Engineering design and control scenario for steady-state high-beta operation in national centralized tokamak

Tsuchiya, Katsuhiko; Akiba, Masato; Azechi, Hiroshi*; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; et al.

Fusion Engineering and Design, 81(8-14), p.1599 - 1605, 2006/02

 Times Cited Count:1 Percentile:9.80(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Design study of national centralized tokamak facility for the demonstration of steady state high-$$beta$$ plasma operation

Tamai, Hiroshi; Akiba, Masato; Azechi, Hiroshi*; Fujita, Takaaki; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; Hosogane, Nobuyuki; Ichimura, Makoto*; et al.

Nuclear Fusion, 45(12), p.1676 - 1683, 2005/12

 Times Cited Count:15 Percentile:45.00(Physics, Fluids & Plasmas)

Design studies are shown on the National Centralized Tokamak facility. The machine design is carried out to investigate the capability for the flexibility in aspect ratio and shape controllability for the demonstration of the high-beta steady state operation with nation-wide collaboration, in parallel with ITER towards DEMO. Two designs are proposed and assessed with respect to the physics requirements such as confinement, stability, current drive, divertor, and energetic particle confinement. The operation range in the aspect ratio and the plasma shape is widely enhanced in consistent with the sufficient divertor pumping. Evaluations of the plasma performance towards the determination of machine design are presented.

Journal Articles

Advanced fusion technologies developed for JT-60 superconducting Tokamak

Sakasai, Akira; Ishida, Shinichi; Matsukawa, Makoto; Akino, Noboru; Ando, Toshinari*; Arai, Takashi; Ezato, Koichiro; Hamada, Kazuya; Ichige, Hisashi; Isono, Takaaki; et al.

Nuclear Fusion, 44(2), p.329 - 334, 2004/02

 Times Cited Count:7 Percentile:22.64(Physics, Fluids & Plasmas)

no abstracts in English

46 (Records 1-20 displayed on this page)