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Journal Articles

Water-assisted microphase separation of cationic random copolymers into sub-5 nm lamellar materials and thin films

Imai, Sahori*; Arakawa, Masato*; Nakanishi, Yohei*; Takenaka, Mikihito*; Aoki, Hiroyuki; Ouchi, Makoto*; Terashima, Takaya*

Macromolecules, 55(20), p.9113 - 9125, 2022/10

Journal Articles

Depositional processes of circular abandoned channels around the middle parts of the Kumano River, Southwest Japan

Nakanishi, Toshimichi*; Komatsu, Tetsuya; Ogata, Manabu; Kawamura, Makoto; Yasue, Kenichi*

Gekkan Chikyu "Kiso deta Kara Kangaeru Dai Yonkigaku No Shintenkai-I" Gogai No.71, p.148 - 155, 2022/02

The formation process of terrace topography was investigated by observing and analyzing boring core samples collected in the middle reaches of the Kumano River. It was assumed that the older terrace topography was distributed higher than the current riverbed surface. However, since tributary debris flow deposits may be thickly distributed beneath the old gyre river valley, care must be taken when using the surface of the ground as an index of uplift and erosion.

JAEA Reports

Study on the evaluation method to determine the radioactivity concentration in radioactive waste on Oarai Research and Development Institute (FY2020)

Asakura, Kazuki; Shimomura, Yusuke; Donomae, Yasushi; Abe, Kazuyuki; Kitamura, Ryoichi; Miyakoshi, Hiroyuki; Takamatsu, Misao; Sakamoto, Naoki; Isozaki, Ryosuke; Onishi, Takashi; et al.

JAEA-Review 2021-020, 42 Pages, 2021/10

JAEA-Review-2021-020.pdf:2.95MB

The disposal of radioactive waste from the research facility need to calculate from the radioactivity concentration that based on variously nuclear fuels and materials. In Japan Atomic Energy Agency Oarai Research and Development Institute, the study on considering disposal is being advanced among the facilities which generate radioactive waste as well as the facilities which process radioactive waste. This report summarizes a study result in FY2020 about the evaluation method to determine the radioactivity concentration in radioactive waste on Oarai Research and Development Institute.

Journal Articles

Signatures of the vortical quark-gluon plasma in hadron yields

Taya, Hidetoshi*; Park, A.*; Cho, S.*; Gubler, P.; Hattori, Koichi*; Hong, J.*; Huang, X.-G.*; Lee, S. H.*; Monnai, Akihiko*; Onishi, Akira*; et al.

Physical Review C, 102(2), p.021901_1 - 021901_6, 2020/08

AA2020-0306.pdf:0.47MB

 Times Cited Count:7 Percentile:70.75(Physics, Nuclear)

Journal Articles

Deuterium permeation behavior for damaged tungsten by ion implantation

Oya, Yasuhisa*; Li, X.*; Sato, Misaki*; Yuyama, Kenta*; Oyaizu, Makoto; Hayashi, Takumi; Yamanishi, Toshihiko; Okuno, Kenji*

Journal of Nuclear Science and Technology, 53(3), p.402 - 405, 2016/03

 Times Cited Count:10 Percentile:68.73(Nuclear Science & Technology)

The deuterium (D) permeation behaviors for ion damaged tungsten (W) by 3 keV D$$_{2}$$$$^{+}$$ and 10 keV C$$^{+}$$ were studied. The D permeability was obtained for un-damaged W at various temperatures. For both D$$_{2}$$$$^{+}$$ and C$$^{+}$$ implanted W, the permeability was clearly reduced. But, for the D$$_{2}$$$$^{+}$$ implanted W, the permeability was recovered by heating at 1173 K and it was almost consistent with that for un-damaged W. In the case of C$$^{+}$$ implanted W, the permeability was not recovered even if the sample was heated at 1173 K, indicating that the existence of carbon would prevent the recovery of permeation path in W. In addition, TEM observation showed the voids were grown by heating at 1173 K and not removed, showing the existence of damages would not largely influence on the hydrogen permeation behavior in W in the present study.

JAEA Reports

Studies on the reconstruction of the concept of rock mass around the tunnel; Japanese fiscal year, 2014 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Aoki, Kenji*; Tochiyama, Osamu*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Yoshida, Hidekazu*; Murakami, Hiroaki; Sasao, Eiji

JAEA-Research 2015-017, 54 Pages, 2015/12

JAEA-Research-2015-017.pdf:17.3MB

This report is concerned with research to reconstruct more realistic near-field (NF) concept for the geological disposal of radioactive waste. This year is the final year of this committee activities. So we have carried out the summary on Re-thinking of NF concept and its technical basis. Cooperation between the study fields and combination of various science and technology and evaluation methods are one of the important technical bases of NF concept. In addition, since the "Great East Japan Earthquake 2011", the safety paradigm has shifted dramatically. In the reconstruction of realistic NF concept, it is necessary to analyze what security matters whether society has become unacceptable for geological disposal. Committee, we also exchange views on such matters and presented the direction of future research and development for geological disposal.

Journal Articles

R&D activities of tritium technologies on Broader Approach in Phase 2-2

Isobe, Kanetsugu; Kawamura, Yoshinori; Iwai, Yasunori; Oyaizu, Makoto; Nakamura, Hirofumi; Suzuki, Takumi; Yamada, Masayuki; Edao, Yuki; Kurata, Rie; Hayashi, Takumi; et al.

Fusion Engineering and Design, 98-99, p.1792 - 1795, 2015/10

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

Activities on Broader Approach (BA) were started in 2007 on the basis of the Agreement between the Government of Japan and the EURATOM. The period of BA activities consist of Phase1 and Phase2 dividing into Phase 2-1 (2010-2011), Phase 2-2 (2012-2013) and Phase 2-3 (2014-2016). Tritium technology was chosen as one of important R&D issues to develop DEMO plant. R&D activities of tritium technology on BA consist of four tasks. Task-1 is to prepare and maintain the tritium handling facility in Rokkasho BA site in Japan. Task 2, 3 and 4 are main R&D activities for tritium and these are focused on: Task-2) Development of tritium accountancy technology, Task-3) Development of basic tritium safety research, Task-4) Tritium durability test. R&D activities of tritium technology in Phase 2-2 were underway successfully and closed in 2013.

Journal Articles

Recent progress on tritium technology research and development for a fusion reactor in Japan Atomic Energy Agency

Hayashi, Takumi; Nakamura, Hirofumi; Kawamura, Yoshinori; Iwai, Yasunori; Isobe, Kanetsugu; Yamada, Masayuki; Suzuki, Takumi; Kurata, Rie; Oyaizu, Makoto; Edao, Yuki; et al.

Fusion Science and Technology, 67(2), p.365 - 370, 2015/03

 Times Cited Count:1 Percentile:9.79(Nuclear Science & Technology)

Journal Articles

Hydrogen isotope behavior on a water-metal boundary with simultaneous transfer from and to the metal surface

Hayashi, Takumi; Isobe, Kanetsugu; Nakamura, Hirofumi; Kobayashi, Kazuhiro; Oya, Yasuhisa*; Okuno, Kenji*; Oyaizu, Makoto; Edao, Yuki; Yamanishi, Toshihiko

Fusion Engineering and Design, 89(7-8), p.1520 - 1523, 2014/10

 Times Cited Count:1 Percentile:8.95(Nuclear Science & Technology)

Tritium confinement is the most important safety issue in the fusion reactor. Tritium behavior on the water metal boundary is very important to design tritium plant with breading blanket system using cooling water. A series of tritium permeation experiment into pressurized water or water vapor jacket with He or Ar have been performed through pure iron piping with/without 7 micro-meter gold plating, which contained about 1 kPa of pure tritium gas at 423 K, with monitoring the chemical forms of tritium. Also, deuterium permeation experiments from heavy water vessel through various metal piping, such as pure iron (Fe), nickel (Ni), stainless steel (SS304), and pure iron with 10 micro-meter gold plating, were performed at 573 K and at 15 MPa. Recently, using the above heavy water system, we have succeeded to detect simultaneous hydrogen isotopes transfer from and to the metal surface by introducing H$$_{2}$$ gas to the metal piping after stabilized deuterium permeation was detected.

JAEA Reports

Studies on the reconstruction of the concept of rock mass around the tunnel; Japanese fiscal year, 2013 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Aoki, Kenji*; Tochiyama, Osamu*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Yoshida, Hidekazu*; Ogata, Nobuhisa

JAEA-Research 2014-011, 43 Pages, 2014/09

JAEA-Research-2014-011.pdf:56.68MB

This report is concerned with research to reconstruct more realistic near-field (NF) concept for the geological disposal. In previous year, we examined the realistic concept for near-field, including rock mass around the tunnel, particularly based on the nuclide migration scenario. The time-series change of the field was divided into five stages of 0 to IV through the process of geological disposal (Excavation, Operation and Post-closure). Then at each respective stage, post-closure stage in particular; we examined interaction between environmental factors and exhaustive extraction of those factors affecting the near-field, focusing on each scale-time cross-section. In the reconstruction of realistic near-field concept, it is necessary to analyze security matters are unacceptable by society, regarding geological disposal. We also exchanged views on those matters and presented the future direction of research and development for geological disposal.

JAEA Reports

Research for spectroscopy of fuel debris using superconducting phase transition edge sensor microcalorimeter; Measurement experiment and simulated calculation (Joint research)

Takasaki, Koji; Yasumune, Takashi; Onishi, Takashi; Nakamura, Keisuke; Ishimi, Akihiro; Ito, Chikara; Osaka, Masahiko; Ono, Masashi*; Hatakeyama, Shuichi*; Takahashi, Hiroyuki*; et al.

JAEA-Research 2013-043, 33 Pages, 2014/01

JAEA-Research-2013-043.pdf:13.81MB

In the Fukushima Daiichi Nuclear Power Plant, it is assumed that the core fuels melted partially or wholly, and the normal technique of accounting for a fuel assembly is not applicable. Therefore, it is necessary to develop the transparent and rational technique of accounting in the process of collection and storage of fuel debris. In this research, an application of the superconducting phase Transition Edge Sensor microcalorimeter (TES microcalorimeter) is studied for the accounting of nuclear materials in the fuel debris. It is expected that the detailed information of nuclear materials and fission products in fuel debris is obtained by using a high-resolution characteristic of TES microcalorimeter. In this report, the principle of TES microcalorimeter, the measurement experiment using TES in JAEA, and the simulated calculation using the EGS5 code system are summarized.

JAEA Reports

Studies on the reconstruction of the concept of rock mass around the tunnel; Fiscal year, 2012 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Aoki, Kenji*; Tochiyama, Osamu*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Yoshida, Hidekazu*; Ogata, Nobuhisa

JAEA-Research 2013-015, 21 Pages, 2013/11

JAEA-Research-2013-015.pdf:10.41MB

This report is concerned with research to reconstruct more realistic near-field concept for the geological disposal. In chapter, we examined the realistic concept for near field, including rock around the tunnel, based on the nuclide migration scenario in particular. The time-series change of the field was divided into five stages of 0$$sim$$IV through the process of geological disposal (Excavation, Operation and Post-closure). Then, for each stage respectively, we examined interaction between environmental factors and extraction of those factors changing the "field". The Goal of this year is to set up the state in the realistic "field" exhaustively, by focusing on the scale-time cross-section of each stage, especially post-closure stage, and to present the assignment of the next fiscal year.

Journal Articles

Development of a 500-kV photoemission DC gun at JAEA

Nishimori, Nobuyuki; Nagai, Ryoji; Matsuba, Shunya; Hajima, Ryoichi; Yamamoto, Masahiro*; Miyajima, Tsukasa*; Honda, Yosuke*; Iijima, Hokuto*; Kuriki, Masao*; Kuwahara, Makoto*; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.255 - 259, 2013/08

no abstracts in English

Journal Articles

Effects of tritiated water on passivation behavior of SUS304 stainless steel

Oyaizu, Makoto; Isobe, Kanetsugu; Yamanishi, Toshihiko

ECS Transactions, 50(50), p.63 - 69, 2013/00

 Times Cited Count:3 Percentile:81.01

The effects of tritiated water on the passivation behavior of SUS304 stainless steel were electrochemically studied by anodic polarization measurements and diachronic measurements of open circuit potential with changing tritium concentration and dissolved oxygen concentration as parameters in the electrolyte of 1N sulfuric acid solution, where the passivation inhibitory effects by tritiated water could be clearly observed. As a result, it was found that the passivation would be proceed with two steps. The effects of tritiated water could be observed in both of two steps; delay in the first step and deceleration in the second step. From these results, it was suggested that the passivation inhibitory effect might be promoted by further oxidation and sequential dissolution of Cr$$^{3+}$$ by radiolysis products.

Journal Articles

Development status of low activation ternary Au-In-Cd alloy decoupler for a MW class spallation neutron source; 1st production of Au-In-Cd alloy

Oi, Motoki; Teshigawara, Makoto; Wakui, Takashi; Nishi, Tsuyoshi; Harada, Masahide; Maekawa, Fujio; Futakawa, Masatoshi

Journal of Nuclear Materials, 431(1-3), p.218 - 223, 2012/12

 Times Cited Count:6 Percentile:43.65(Materials Science, Multidisciplinary)

The Japan Spallation Neutron Source (JSNS) at the Japan Proton Accelerator Research Complex (J-PARC) is developed as a 1 MW spallation neutron source. The Ag-In-Cd (AIC) alloy was adopted as a decoupler material for two decoupled moderators. A high decoupling energy at 1 eV was for the first time achieved in MW class spallation neutron source due to the adoption of the AIC alloy. Although the AIC decoupler is superior in the neutronic performance, it has a demerit in high residual radioactivity due to production of Ag-110m and Ag-108m. To overcome this demerit, Au-In-Cd alloy was proposed. We studied to make ternary Au-In-Cd alloy and successfully done it at the maximum temperature of 1123 K with diffusion of the cadmium into the gold. Uniformity of the alloy was confirmed with EDX analysis. Thermal conductivity of Au-In-Cd alloy was 87.7 W/m/K. These results show enough performance as a decoupler.

Journal Articles

Overview of R&D activities on tritium processing and handling technology in JAEA

Yamanishi, Toshihiko; Nakamura, Hirofumi; Kawamura, Yoshinori; Iwai, Yasunori; Isobe, Kanetsugu; Oyaizu, Makoto; Yamada, Masayuki; Suzuki, Takumi; Hayashi, Takumi

Fusion Engineering and Design, 87(5-6), p.890 - 895, 2012/08

 Times Cited Count:1 Percentile:10.14(Nuclear Science & Technology)

In JAEA, the tritium processing and handling technologies have been studied at TPL. The main basic R&D activities in this field are: the tritium processing technology for the blanket recovery system; the tritium behavior in a confinement; and detritiation and decontamination. The R&D for tritium processing and handling technologies to a demonstration reactor (DEMO) are also planned to be carried out in the Broader Approach (BA) program in Japan by JAEA with Japanese universities. The ceramic electrolysis cell has been studied as a tritium processing method for the blanket system. The permeation behavior of tritium through pure iron into the gas containing water vapor has been studied. As for the behavior of high concentration tritium water, it was observed that the formation of the oxidized layer was prevented by the presence of tritium in water. Tritium durability tests were also carried out for the electrolysis cell of the chemical exchange column.

Journal Articles

Hydrogen isotope permeation from cooling water through various metal piping

Hayashi, Takumi; Nakamura, Hirofumi; Isobe, Kanetsugu; Kobayashi, Kazuhiro; Oyaizu, Makoto; Yamanishi, Toshihiko; Oya, Yasuhisa*; Okuno, Kenji*

Fusion Engineering and Design, 87(7-8), p.1333 - 1337, 2012/08

 Times Cited Count:8 Percentile:52.71(Nuclear Science & Technology)

In order to investigate the behavior of hydrogen isotope on the water-metal boundary, deuterium permeation experiments from heavy water vessel through various metal piping, such as pure iron (Fe), nickel (Ni), stainless steel (SS304), and pure iron with 10 $$mu$$m gold plating, were performed at 573 K and at 15 MPa. During the experiment, surfaces of metal piping except gold plating one were oxidized at the heavy water boundary and then deuterium would generate by the oxidation reactions. This deuterium could be detected by mass spectrometer, which monitored the inside gases of the piping under vacuum. The result showed clearly that the deuterium permeated through Fe, Ni, and SS304 piping was detected as deuterium gas (D$$_{2}$$) under vacuum, though that through gold plating one could not be detected effectively. The D$$_{2}$$ permeation rate through Fe, Ni, and SS304 piping reached some stabilized value. This paper summarizes the above experimental results and discusses the mechanism of deuterium behavior on the water metal boundary.

Journal Articles

Development of a photoemission DC Gun at JAEA

Nishimori, Nobuyuki; Nagai, Ryoji; Matsuba, Shunya; Hajima, Ryoichi; Yamamoto, Masahiro*; Honda, Yosuke*; Miyajima, Tsukasa*; Iijima, Hokuto*; Kuriki, Masao*; Kuwahara, Makoto*; et al.

Proceedings of 34th International Free Electron Laser Conference (FEL 2012) (Internet), p.161 - 164, 2012/08

JAEA Reports

Interdisciplinary approach to improve and systematize the investigation and evaluation techniques on geological environment in relation to radioactive waste repository; Japanese fiscal year, 2010 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Watanabe, Kunio*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Shimada, Jun*; Aoki, Kenji*; Tochiyama, Osamu*; Yoshida, Hidekazu*; Ogata, Nobuhisa; et al.

JAEA-Research 2011-033, 126 Pages, 2012/02

JAEA-Research-2011-033.pdf:31.33MB

The next advancements for the research of radioactive waste repository was started to improve and systematize the investigation and evaluation techniques on geological environment in consideration of intra-field of science and technology. Intra-field means the various fields among each study area of (a) geological environment, (b) design and engineering, (c) safety evaluation for radioactive waste repository, here. The following items were studied and discussed this year. (1) To Reconstruct Near Field (NF) Concept in consideration of coupled phenomena on geological environment. (2) To develop systematic investigation techniques on the geological environment in consideration of intra-field among each study area above mentioned (a), (b) and (c). Regarding (1), examination of NF concept focused on the realistic crystalline rock was carried out. Also through the overall discussion in the committee, comments from the all commissioners in relation to the intra-field of their study area were made to reflect on reconstruction of NF concept. Regarding (2), the research and development in consideration of NF and intra-field among each study area were conducted.

Journal Articles

Effects of tritiated water on corrosion behavior of SUS304

Oyaizu, Makoto; Isobe, Kanetsugu; Hayashi, Takumi; Yamanishi, Toshihiko

Fusion Science and Technology, 60(4), p.1515 - 1518, 2011/11

 Times Cited Count:3 Percentile:26.09(Nuclear Science & Technology)

The effects of tritiated water on the corrosion behavior of SUS304 stainless steel was studied using Tafel extrapolation method, one of electrochemical techniques with changing tritium concentration, dissolved oxygen concentration and pH in electrolyte as parameters. It was indicated that there would be two or more effects of tritium that enhance the corrosion of SUS304 stainless steel under several experimental conditions. One is passivation inhibitory effect, which could be observed only in highly corrosive circumstance of 1N H$$_{2}$$SO$$_{4}$$ electrolyte. The other effects of tritium on corrosion behavior could be observed not only in 1N H$$_{2}$$SO$$_{4}$$ but also in corrosive circumstance of 1N Na$$_{2}$$SO$$_{4}$$ electrolyte, which would be affected by dissolved oxygen concentration as well as tritium concentration.

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