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JAEA Reports

Interim activity status report of "the group for investigation of reasonable safety assurance based on graded approach" (from September, 2019 to September, 2020)

Yonomoto, Taisuke; Nakashima, Hiroshi*; Sono, Hiroki; Kishimoto, Katsumi; Izawa, Kazuhiko; Kinase, Masami; Osa, Akihiko; Ogawa, Kazuhiko; Horiguchi, Hironori; Inoi, Hiroyuki; et al.

JAEA-Review 2020-056, 51 Pages, 2021/03

JAEA-Review-2020-056.pdf:3.26MB

A group named as "The group for investigation of reasonable safety assurance based on graded approach", which consists of about 10 staffs from Sector of Nuclear Science Research, Safety and Nuclear Security Administration Department, departments for management of nuclear facility, Sector of Nuclear Safety Research and Emergency Preparedness, aims to realize effective graded approach (GA) about management of facilities and regulatory compliance of JAEA. The group started its activities in September, 2019 and has had discussions through 10 meetings and email communications. In the meetings, basic ideas of GA, status of compliance with new regulatory standards at each facility, new inspection system, etc were discussed, while individual investigation at each facility were shared among the members. This report is compiled with expectation that it will help promote rational and effective safety management based on GA by sharing contents of the activity widely inside and outside JAEA.

Journal Articles

New PbTiO$$_{3}$$-type giant tetragonal compound Bi$$_{2}$$ZnVO$$_{6}$$ and its stability under pressure

Yu, R.*; Hojo, Hajime*; Oka, Kengo*; Watanuki, Tetsu; Machida, Akihiko; Shimizu, Keisuke*; Nakano, Kiho*; Azuma, Masaki*

Chemistry of Materials, 27(6), p.2012 - 2017, 2015/03

 Times Cited Count:21 Percentile:64.2(Chemistry, Physical)

no abstracts in English

Journal Articles

The Possible interplanetary transfer of microbes; Assessing the viability of ${it Deinococcus}$ spp. under the ISS environmental conditions for performing exposure experiments of microbes in the Tanpopo mission

Kawaguchi, Yuko*; Yang, Y.*; Kawashiri, Narutoshi*; Shiraishi, Keisuke*; Takasu, Masako*; Narumi, Issey*; Sato, Katsuya; Hashimoto, Hirofumi*; Nakagawa, Kazumichi*; Tanigawa, Yoshiaki*; et al.

Origins of Life and Evolution of Biospheres, 43(4-5), p.411 - 428, 2013/10

 Times Cited Count:29 Percentile:78.06(Biology)

Journal Articles

Corrosion modeling for carbon steel under oxygen depleted underground environment

Shibata, Toshio*; Watanabe, Masatoshi; Taniguchi, Naoki; Shimizu, Akihiko*

Zairyo To Kankyo, 62(2), p.70 - 77, 2013/02

In the oxygen depleted underground environment, carbon steel reacts with H$$_{2}$$O, producing H$$_{2}$$ gas and forming corrosion film on the steel surface. Corrosion rate is controlled by diffusion of reaction species through corrosion film. Diffusion constants of some species working in the corrosion process were obtained from literatures. However, no data were found on the diffusion constant of H$$_{2}$$O in iron oxides based on an appropriate assumption. Mass transfer model for the corrosion rate was used to simulate the corrosion rate of carbon steel. Liquid phase diffusion model of Fe$$^{2+}$$ or H$$_{2}$$O through pores in the corrosion film and solid phase diffusion model of H$$_{2}$$O through corrosion film itself were examined by Excel simulation. Change in corrosion current density and corrosion loss with time and pH and temperature dependence of corrosion current density were examined. By comparing the results, it is suggested that the solid phase diffusion of H$$_{2}$$O in the corrosion film controls the corrosion rate of carbon steel in oxygen depleted environment.

Journal Articles

Raman and UV-visible absorption spectroscopy of rare-earth hydride under high pressure

Kume, Tetsuji*; Machida, Akihiko; Aoki, Katsutoshi; Sasaki, Shigeo*; Shimizu, Hiroyasu*

Koatsuryoku No Kagaku To Gijutsu, 21(3), p.184 - 189, 2011/09

Raman and visible absorption spectra of rare earth trihydrides have been measured at high pressures, in order to investigate the structural and electronic phase transitions. The successive phase transitions of hcp-intermediatefcc phase were confirmed by Raman measurements. From the visible absorption experiments, the band gap energy was estimated. The gap closure was found to occur on the transition from the intermediate to the fcc phase.

Journal Articles

Electrical resistance measurement techniques for metal hydrides under high-pressure H$$_2$$ conditions & electrical transport and structural properties of FeH$$_x$$

Matsuoka, Takehiro*; Hirao, Naohisa*; Oishi, Yasuo*; Shimizu, Katsuya*; Machida, Akihiko; Aoki, Katsutoshi

Koatsuryoku No Kagaku To Gijutsu, 21(3), p.190 - 196, 2011/09

We present the newly developed electrical resistance measurement technique for metal hydrides compressed in high-pressure H$$_2$$ and the first successful ${it in-situ}$ simultaneous measurements of electrical resistance and X-ray diffraction of FeH at high pressures and low temperatures. The electrical resistivity $$rho$$ showed a sharp increase with the formation of iron-hydride FeH$$_x$$ ($$xsim1$$) at 3.5 GPa. The $$epsilon$$'-phase of FeH was found to be metallic up to 25.5 GPa. The $$rho$$ vs. $$T$$ curves up to 16.5 GPa approximately follow Fermi-liquid law below 25 K. However, $$T^5$$ was found to be better fitting at 25.5 GPa. This change can be related to the previously reported ferromagnetism collapse at corresponding pressures.

Journal Articles

High-pressure study of ScH$$_{3}$$; Raman, infrared, and visible absorption spectroscopy

Kume, Tetsuji*; Oura, Hiroyuki*; Takeichi, Tomoo*; Omura, Ayako*; Machida, Akihiko; Watanuki, Tetsu; Aoki, Katsutoshi; Sasaki, Shigeo*; Shimizu, Hiroyasu*; Takemura, Kenichi*

Physical Review B, 84(6), p.064132_1 - 064132_7, 2011/08

 Times Cited Count:13 Percentile:53.09(Materials Science, Multidisciplinary)

Raman, IR, and visible absorption spectra of scandium trihydride (ScH$$_{3}$$) have been measured at high pressures up to 50 GPa at room temperature. The structural and electronic phase transitions were investigated. Successive hcp-intermediate-fcc phase transitions took place at 25 and 46 GPa. It was suggested that the intermediate phase of ScH$$_{3}$$ has the same structure as that of YH$$_{3}$$. The energy gap of ScH$$_{3}$$ is 1.7 eV at the ambient condition and is closed around 50 GPa, at which the crystal structure transforms to fcc.

Journal Articles

Structural and valence changes of europium hydride induced by application of high-pressure H$$_{2}$$

Matsuoka, Takahiro*; Fujihisa, Hiroshi*; Hirao, Naohisa*; Oishi, Yasuo*; Mitsui, Takaya; Masuda, Ryo; Seto, Makoto*; Yoda, Yoshitaka*; Shimizu, Katsuya*; Machida, Akihiko; et al.

Physical Review Letters, 107(2), p.025501_1 - 025501_4, 2011/07

 Times Cited Count:24 Percentile:77.07(Physics, Multidisciplinary)

Europium-hydride EuH$$_{x}$$ exposed to high-pressure H$$_{2}$$ conditions has been found to exhibit structural and valence changes, $$Pnma$$ ($$x$$=2, divalent) $$rightarrow$$ $$P$$63/$$mmc$$ ($$x$$=2, 7.2-8.7 GPa) $$rightarrow$$ $$I$$4/$$m$$ ($$x$$$$>$$2, 8.7-9.7 GPa) $$rightarrow$$ $$I$$4/$$mmm$$ ($$x$$$$>$$2, 9.7 GPa-, trivalent). Having trivalent character and distorted cubic fcc structure, the $$I$$4/$$mmm$$ structure is the $$beta$$-phase which has been commonly observed for other rare-earth metal hydrides. Our study clearly demonstrates that EuH$$_{x}$$ is no longer an "irregular" member of the rare earth metal hydrides.

Journal Articles

Lifetime measurements for the first 2$$^{+}$$ states in $$^{162,164}$$Gd populated by the $$beta$$ decay of $$^{162,164}$$Eu

Nagae, Daisuke*; Ishii, Tetsuro; Takahashi, Ryuta*; Asai, Masato; Makii, Hiroyuki; Osa, Akihiko; Sato, Tetsuya; Ichikawa, Shinichi; Shimizu, Yoshifumi*; Shoji, Takuya*

AIP Conference Proceedings 1224, p.156 - 160, 2010/04

 Times Cited Count:2 Percentile:65.93

JAEA Reports

Investigation of the long term corrosion resistance of the overpack FY2006 (Contract research)

Tachikawa, Hirokazu*; Kawakubo, Fumie*; Shimizu, Akihiko*; Shibata, Toshio*; Azumi, Kazuhisa*; Inoue, Hiroyuki*; Sugimoto, Katsuhisa*; Tsuru, Toru*; Fujimoto, Shinji*

JAEA-Research 2007-086, 74 Pages, 2008/02

JAEA-Research-2007-086.pdf:5.96MB

The corrosion life time of the overpack has been investigated on the basis of experimental data and past research, assuming the ranging geological environment of Japan. However, some subject for the realization of the overpack design, such as the behavior of the overpack under high pH conditions, the behavior of the overpack with change of near-field environmental condition and the corrosion behavior of the welds have still been left. To take into account these conditions, expert committee composed of metal corrosion science experts were established in the Nuclear Safety Research Association and past research outcomes and the theory of safety assessment for long term corrosion resistance were investigated from the view points of metal corrosion science.

Journal Articles

High-pressure study of YH$$_{3}$$ by Raman and visible absorption spectroscopy

Kume, Tetsuji*; Oura, Hiroyuki*; Sasaki, Shigeo*; Shimizu, Hiroyasu*; Omura, Ayako*; Machida, Akihiko; Watanuki, Tetsu; Aoki, Katsutoshi; Takemura, Kenichi*

Physical Review B, 76(2), p.024107_1 - 024107_5, 2007/07

 Times Cited Count:35 Percentile:79.4(Materials Science, Multidisciplinary)

Raman and visible absorption spectra of YH$$_{3}$$ were measured at high pressures, in order to clarify the structural and electronic phase transitions. The Raman results revealed the presence of an intermediate phase at 9-24 GPa between the low-pressure hexagonal and high-pressure fcc phases. The Y-framework structure and the positions of interstitial H atoms are changed on the transition to the intermediate phase. The results of the absorption measurements demonstrate that the optical band gap begins to close in response to the phase transition.

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.

JAEA Reports

Investigation of the long term corrosion resistance of the overpack (Contract research)

Tachikawa, Hirokazu*; Kawakubo, Fumie*; Shimizu, Akihiko*; Shibata, Toshio*; Sugimoto, Katsuhisa*; Seo, Masahiro*; Tsuru, Toru*; Fujimoto, Shinji*; Inoue, Hiroyuki*

JAEA-Research 2006-058, 80 Pages, 2006/10

JAEA-Research-2006-058.pdf:10.86MB

The Japan Nuclear Cycle Development Institute submitted "Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan" to the Japanese government. This report contains investigations of the corrosion life time of the overpack on the basis of experimental data and past research, assuming the ranging geological environment of Japan. However some subjects, such as the behavior of the overpack under high pH conditions and the behavior of the engineering barrier with change of near-field environmental condition with time for promoting reliability have still been left. To take into account these conditions, expert committee composed of metal corrosion science experts were established in the Nuclear Safety Research Association and past research outcomes and the theory of safety assessment were investigated from the view points of long term stability and corrosion resistance of engineering barrier.

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:44.28(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:10.64(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Overview of design and R&D of test blankets in Japan

Enoeda, Mikio; Akiba, Masato; Tanaka, Satoru*; Shimizu, Akihiko*; Hasegawa, Akira*; Konishi, Satoshi*; Kimura, Akihiko*; Koyama, Akira*; Sagara, Akio*; Muroga, Takeo*

Fusion Engineering and Design, 81(1-7), p.415 - 424, 2006/02

 Times Cited Count:60 Percentile:97.02(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:48.09(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

Plan and strategy for ITER blanket testing in Japan

Enoeda, Mikio; Akiba, Masato; Tanaka, Satoru*; Shimizu, Akihiko*; Hasegawa, Akira*; Konishi, Satoshi*; Kimura, Akihiko*; Koyama, Akira*; Sagara, Akio*; Muroga, Takeo*

Fusion Science and Technology, 47(4), p.1023 - 1030, 2005/05

 Times Cited Count:4 Percentile:32.08(Nuclear Science & Technology)

The Fusion Council of Japan has established the long-term research and development program of the blanket in 1999. In the program, the solid breeder blanket was selected as the primary candidate blanket of the fusion power demonstration plant in Japan. In the program, Japan Atomic Energy Research Institute (JAERI) has been nominated as a leading institute of the development of solid breeder blankets, in collaboration with universities, for the near term power demonstration plant, while, universities including National Institute for Fusion Science (NIFS) are assigned mainly to develop advanced blankets for longer term power plant development. In the long term research and development program, ITER blanket module testing is identified as the most important milestone, by which integrity of candidate blanket concepts and structures are evaluated. In Japan, universities, NIFS and JAERI cover a variety of types of blanket development. This paper presents a plan and strategy for ITER blanket module testing in Japan.

JAEA Reports

Investigation of the Long Term Stability and Corrosion Resistance of Engineering Barriers

Aoyama, Eri*; Tachikawa, Hirokazu*; Shimizu, Akihiko*

JNC TJ8400 2004-034, 442 Pages, 2005/03

JNC-TJ8400-2004-034.pdf:18.48MB

The Japan Nuclear Cycle Development Institute submitted 'Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan' to the Japanese government. This report contains investigations of the long term behavior of alteration of bentonite, and of the corrosion life time of overpack on the basis of experimental data and past research, assuming the ranging geological environment of Japan. However some subjects, such as the behavior of the bentonite and overpack under high pH conditions and the behavior of the engineering barrier with change of near-field environmental condition with time for promoting reliability have still been left.To take into account these conditions, expert committees composed of clay science and metal corrosion science experts were established in the Nuclear Safety Research Association and past research outcomes and the theory of safety assessment were investigated from the view points of long term stability and corrosion resistance of engineering buffer materials.

JAEA Reports

Investigations of and Technical Reviews on the Reliability of Prediction for Migration Behavior of Radionuclides (H.16)

Sano, Eri*; Tachikawa, Hirokazu*; Shimizu, Akihiko*

JNC TJ8420 2004-004, 342 Pages, 2005/02

JNC-TJ8420-2004-004.pdf:15.39MB

The research plan of the radionuclides migration drawn up by Japan Nuclear Fuel Cycle Development Institute and its' research outcome were reviewed comprehensively by an expert committee established in Nuclear Safety Research Association. Also, experimental investigations for the migration behavior of actinide elements and fission products in engineering barrier and natural barrier media, and for solution chemistry of them were carried out and discussed by the committee, in order to enhance the reliability of prediction for migration behavior of radionuclides. The subjects investigated by the expert committee are as follows; (1)Diffusion and electromigration behavior of Plutonium in bentnite under reducing condition (2)Numerical analysis of distribution coefficients of nuclides in compacted bentonite using surface complexization model (3)Radioactive disequilibrium of decay series nuclides in natural water and various materials (4)Research on complexation reactions of f - elements

33 (Records 1-20 displayed on this page)