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Journal Articles

Molecular dynamics simulations of physical properties of water and cations in montmorillonite interlayer; Application to diffusion model

Yotsuji, Kenji*; Tachi, Yukio; Kawamura, Katsuyuki*; Arima, Tatsumi*; Sakuma, Hiroshi*

Nendo Kagaku, 58(1), p.8 - 25, 2019/00

Molecular dynamics (MD) simulations were conducted to investigate physical properties of water and cations in montmorillonite interlayer nanopores. The swelling behaviors and hydration states were firstly evaluated as functions of interlayer cations and layer charge. The diffusion coefficients of water and cations in interlayer nanopores were decreased in comparison with those in bulk water and came closer to those in bulk water when basal spacing increased. The viscosity coefficients of interlayer water estimated indicated a significant effect of viscoelectricity at 1- and 2-layer hydration states and higher layer charge of montmorillonite. These trends from MD calculations were confirmed to be consistent with existing measured data and previous MD simulation. In addition, model and parameter related to viscoelectric effect used in the diffusion model was refined based on comparative discussion between MD simulations and measurements. The series of MD calculations could provide atomic level understanding for the developments and improvements of the diffusion model for compacted montmorillonite.

Journal Articles

Applicability of $$K_{d}$$ for modelling dissolved $$^{137}$$Cs concentrations in Fukushima river water; Case study of the upstream Ota River

Sakuma, Kazuyuki; Tsuji, Hideki*; Hayashi, Seiji*; Funaki, Hironori; Malins, A.; Yoshimura, Kazuya; Kurikami, Hiroshi; Kitamura, Akihiro; Iijima, Kazuki; Hosomi, Masaaki*

Journal of Environmental Radioactivity, 184-185, p.53 - 62, 2018/04

 Times Cited Count:5 Percentile:47.7(Environmental Sciences)

A study is presented on the applicability of the distribution coefficient ($$K_{d}$$) absorption/desorption model to simulate dissolved $$^{137}$$Cs concentrations in Fukushima river water. The simulation results were in good agreement with the observations on water and suspended sediment fluxes, and on particulate bound $$^{137}$$Cs concentrations under both ambient and high flow conditions. By contrast the measured concentrations of dissolved $$^{137}$$Cs in the river water were much harder to reproduce with the simulations. By tuning the $$K_{d}$$ values for large particles, it was possible to reproduce the mean dissolved $$^{137}$$Cs concentrations during base flow periods (observation: 0.32 Bq/L, simulation: 0.36 Bq/L). However neither the seasonal variability in the base flow dissolved $$^{137}$$Cs concentrations (0.14-0.53 Bq/L), nor the peaks in concentration that occurred during storms (0.18-0.88 Bq/L, mean: 0.55 Bq/L), could be reproduced with realistic simulation parameters.

Journal Articles

Stability of montmorillonite edge faces studied using first-principles calculations

Sakuma, Hiroshi*; Tachi, Yukio; Yotsuji, Kenji; Suehara, Shigeru*; Arima, Tatsumi*; Fujii, Naoki*; Kawamura, Katsuyuki*; Honda, Akira

Clays and Clay Minerals, 65(4), p.252 - 272, 2017/08

 Times Cited Count:0 Percentile:100(Chemistry, Physical)

Structure and stability of montmorillonite edge faces (110), (010), (100), and (130) of the layer charges y = 0.5 and 0.33 are investigated by the first-principles electronic calculations based on the density functional theory. Stacking and single layer models are tested for understanding the effect of stacking on the stability of montmorillonite edge faces. Most stacking layers stabilize the edge faces by making hydrogen bonds between the layers; therefore, the surface energy of stacking layers is reduced rather than the single layer model. This indicates that the surface energy of edge faces should be estimated depending on the swelling conditions. Lowest surface energies of (010) and (130) edge faces were realized by the presence of Mg ions on the edge faces. These edge faces have a strong adsorption site for cations due to local negative charge of the edges.

JAEA Reports

Study on the evaluation method to determine the radioactivity concentration in radioactive waste generated from post-irradiation examination facilities, 2

Tsuji, Tomoyuki; Hoshino, Yuzuru; Sakai, Akihiro; Sakamoto, Yoshiaki; Suzuki, Yasuo*; Machida, Hiroshi*

JAEA-Technology 2017-010, 75 Pages, 2017/06

JAEA-Technology-2017-010.pdf:2.31MB

It is necessary for reasonable disposal to be studied on evaluation methods to determine radioactivity concentrations in the radioactive wastes, which is generated from post-irradiation examination (PIE) facilities, for establishment of reasonable confirmation methods concerning radioactive wastes generated from research, industrial, and medical facilities. It has been chosen the PIE facilities of NUCLEAR DEVELOPMENT CORPORATION as a model for this study. As a result, it has been confirmed that the theoretical methods are applied for the important nuclides (H-3, C-14, Co-60, Ni-63, Sr-90, Tc-99, Cs-137, Eu-154, U-234, U-235, U-238, Pu-238, Pu-239, Pu-240, Pu-241, Am-241 and Cm-244).

Journal Articles

Status of development of Lithium Target Facility in IFMIF/EVEDA project

Wakai, Eiichi; Kondo, Hiroo; Kanemura, Takuji; Hirakawa, Yasushi; Furukawa, Tomohiro; Hoashi, Eiji*; Fukada, Satoshi*; Suzuki, Akihiro*; Yagi, Juro*; Tsuji, Yoshiyuki*; et al.

Proceedings of Plasma Conference 2014 (PLASMA 2014) (CD-ROM), 2 Pages, 2014/11

In the IFMIF/EVEDA (International Fusion Materials Irradiation Facility/ Engineering Validation and Engineering Design Activity), the validation tests of the EVEDA lithium test loop with the world's highest flow rate of 3000 L/min was succeeded in generating a 100 mm-wide and 25 mm-thick free-surface lithium flow steadily under the IFMIF operation condition of a high-speed of 15 m/s at 250$$^{circ}$$C in a vacuum of 10 $$^{-3}$$ Pa. Some excellent results of the recent engineering validations including lithium purification, lithium safety, and remote handling technique were obtained, and the engineering design of lithium facility was also evaluated. These results will advance greatly the development of an accelerator-based neutron source to simulate the fusion reactor materials irradiation environment as an important key technology for the development of fusion reactor materials.

Journal Articles

Engineering validation and engineering design of lithium target facility in IFMIF/EVEDA project

Wakai, Eiichi; Kondo, Hiroo; Kanemura, Takuji; Furukawa, Tomohiro; Hirakawa, Yasushi; Watanabe, Kazuyoshi; Ida, Mizuho*; Ito, Yuzuru; Niitsuma, Shigeto; Edao, Yuki; et al.

Fusion Science and Technology, 66(1), p.46 - 56, 2014/07

 Times Cited Count:4 Percentile:58.26(Nuclear Science & Technology)

Journal Articles

Development of lithium target system in engineering validation and engineering design activity of the International Fusion Materials Irradiation Facility (IFMIF/EVEDA)

Wakai, Eiichi; Kondo, Hiroo; Sugimoto, Masayoshi; Fukada, Satoshi*; Yagi, Juro*; Ida, Mizuho; Kanemura, Takuji; Furukawa, Tomohiro; Hirakawa, Yasushi; Watanabe, Kazuyoshi; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(12), p.691 - 705, 2012/12

no abstracts in English

Journal Articles

Spin-orbital short-range order on a honeycomb-based lattice

Nakatsuji, Satoru*; Kuga, Kentaro*; Kimura, Kenta*; Satake, Ryuta*; Katayama, Naoyuki*; Nishibori, Eiji*; Sawa, Hiroshi*; Ishii, Rieko*; Hagiwara, Masayuki*; Bridges, F.*; et al.

Science, 336(6081), p.559 - 563, 2012/05

 Times Cited Count:96 Percentile:3.94(Multidisciplinary Sciences)

Frustrated magnetic materials can remain disordered to the lowest temperatures. Such is the case for Ba$$_3$$CuSb$$_2$$O$$_9$$, which is magnetically anisotropic at the atomic scale but curiously isotropic on mesoscopic length and time scales. We find that the frustration on the triangular lattice is imprinted in a nanostructured honeycomb lattice of Cu$$^{2+}$$ ions that resists a coherent static Jahn-Teller distortion. The resulting two-dimensional random-bond spin-1/2 system on the honeycomb lattice has a broad spectrum of spin-dimer like excitations and low-energy spin degrees of freedom that retain.

Journal Articles

Present status of Japanese tasks for lithium target facility under IFMIF/EVEDA

Nakamura, Kazuyuki; Furukawa, Tomohiro; Hirakawa, Yasushi; Kanemura, Takuji; Kondo, Hiroo; Ida, Mizuho; Niitsuma, Shigeto; Otaka, Masahiko; Watanabe, Kazuyoshi; Horiike, Hiroshi*; et al.

Fusion Engineering and Design, 86(9-11), p.2491 - 2494, 2011/10

 Times Cited Count:9 Percentile:34.26(Nuclear Science & Technology)

In IFMIF/EVEDA, tasks for lithium target system are shared to 5 validation tasks (LF1-5) and a design task (LF6). The purpose of LF1 task is to construct and operate the EVEDA lithium test loop, and JAEA has a main responsibility to the performance of the Li test loop. LF2 is a task for the diagnostics of the Li test loop and IFMIF design. Basic research for the diagnostics equipment has been completed, and the construction for the Li test loop will be finished before March in 2011. LF4 is a task for the purification systems with nitrogen and hydrogen. Basic research for the purification equipment has been completed, and the construction of the nitrogen system for the Li test loop will be finished before March in 2011. LF5 is a task for the remote handling system with the target assembly. JAEA has an idea to use the laser beam for cutting and welding of the lip part of the flanges. LF6 is a task for the design of the IFMIF based on the validation experiments of LF1-5.

Journal Articles

Target system of IFMIF-EVEDA in Japanese activities

Ida, Mizuho; Fukada, Satoshi*; Furukawa, Tomohiro; Hirakawa, Yasushi; Horiike, Hiroshi*; Kanemura, Takuji*; Kondo, Hiroo; Miyashita, Makoto; Nakamura, Hiroo; Sugiura, Hirokazu*; et al.

Journal of Nuclear Materials, 417(1-3), p.1294 - 1298, 2011/10

 Times Cited Count:3 Percentile:68.93(Materials Science, Multidisciplinary)

Engineering Validation and Engineering Design Activities (EVEDA) of the International Fusion Materials Irradiation Facility (IFMIF) was started. As a Japanese activity for the target system, EVEDA Lithium Test Loop simulating hydraulic and impurity conditions of IFMIF is under design and preparation for fabrication. Feasibility of thermo-mechanical structure of the target assembly and the replaceable back-plate made of F82H (a RAFM) and 316L (a stainless steel) is a key issue. Toward final validation on the EVEDA loop, diagnostics applicable to a high-speed free-surface Li flow and hot traps to control nitrogen and hydrogen in Li are under tests. For remote handling of target assemblies and the replaceable back-plates activated up to 50 dpa/y, lip weld on 316L-316L by laser and dissimilar weld on F82H-316L are under investigation. As engineering design of the IFMIF target system, water experiments and hydraulic/thermo-mechanical analyses of the back-plate are going.

Journal Articles

Microscopic magnetization process in Tb$$_{43}$$Co$$_{57}$$ film by magnetic Compton scattering

Agui, Akane; Matsumoto, Sayaka*; Sakurai, Hiroshi*; Tsuji, Naruki*; Homma, Satoshi*; Sakurai, Yoshiharu*; Ito, Masayoshi*

Applied Physics Express, 4(8), p.083002_1 - 083002_3, 2011/08

 Times Cited Count:13 Percentile:44.46(Physics, Applied)

We have succeeded in measuring microscopic magnetic hysteresis loop of amorphous Tb$$_{43}$$Co$$_{57}$$ film. Spin selective magnetic hysteresis (SSMH) loop was measured by magnetic Compton scattering at synchrotron radiation facility SPring-8 and obtaining orbital selective magnetic hysteresis (OSMH) loop was firstly obtained by combining with result of macroscopic magnetic hysteresis loop.

JAEA Reports

Verification on reliability of diaphragm seal

Ide, Hiroshi; Sakuta, Yoshiyuki; Hanawa, Yoshio; Tsuji, Tomoyuki; Tsuboi, Kazuaki; Nagao, Yoshiharu; Miyazawa, Masataka

JAEA-Technology 2009-019, 28 Pages, 2009/06

JAEA-Technology-2009-019.pdf:41.1MB

The main body of the JMTR is composed of reactor pressure vessel, core and reactor pool. At the bottom of the reactor pool, the Diaphragm-seal (2.6m outer diameter, 2m inner diameter, thickness 1.5mm) of the JMTR made of stainless steel is installed to prevent the water leak of the reactor pool and to absorb the expansion of the reactor pressure vessel due to pressure and temperature changes. Prior to the refurbishment of the JMTR, the inspection device which is a deposition-collection apparatus with underwater-camera was developed, and the visual inspection was carried out to confirm the soundness of the diaphragm-seal. As a result, harmful flaws and/or corrosions were not inspected in the visual inspection, and the soundness of the diaphragm seal was confirmed. In future, the long-term integrity of the diaphragm-seal will could be achieved by conducting the periodic inspection.

Journal Articles

Settlement of materials and life science experimental facility at J-PARC

Harada, Masahide; Meigo, Shinichiro; Ito, Manabu; Dantsuji, Eiji; Takagiwa, Katsunori; Takada, Hiroshi; Maekawa, Fujio; Futakawa, Masatoshi; Nakamura, Mitsutaka; Miyake, Yasuhiro*; et al.

Nuclear Instruments and Methods in Physics Research A, 600(1), p.87 - 90, 2009/02

 Times Cited Count:3 Percentile:69.57(Instruments & Instrumentation)

In MLF of J-PARC, since weights of a building and shields are considerably heavy as 130,000 tons and 80,000 tons, respectively, large settlement of the MLF building is expected. The 3NBT line with 300 m in length is similar. To achieve a precise alignment under the large settlement, we conducted periodical survey measurements at the MLF building and 3NBT. At the completion of construction of the MLF building in December 2005, the settlement was about 40 mm. By extrapolating this result with weights to be added in the future for neutron beam line shields, we predicted that the MLF building settled in about 68mm at the completion of all neutron instrument construction. We decided that the muon target should be installed 5 mm higher than the neutron target with expecting future uneven settlement of the MLF building. The validation in the end of 2007 indicated that the measured level difference came up to the expected value.

Journal Articles

Atomic stereophotograph of intercalation compound Fe$$_{1/3}$$NbS$$_{2}$$

Guo, F. Z.*; Matsushita, Tomohiro*; Kobayashi, Keisuke*; Matsui, Fumihiko*; Kato, Yukako*; Daimon, Hiroshi*; Koyano, Mikio*; Yamamura, Yasuhisa*; Tsuji, Toshihide*; Saito, Yuji

Journal of Applied Physics, 99(2), p.024907_1 - 024907_3, 2006/01

 Times Cited Count:7 Percentile:69.56(Physics, Applied)

Stereoatomscope was used to study the atomic arrangements of intercalation compound Fe$$_{1/3}$$NbS$$_{2}$$. The three-dimensional atomic arrangements around different kinds of atoms (Nb and Fe) are visualized by taking the photoelectron angular distribution (PEAD) patterns at clockwise and counterclockwise circularly polarized lights. Atomic distances between the emitters and the scatterers are obtained from the PEAD patterns by measuring the rotation angles of the forward focusing peaks. The applications of stereoatomscope to intercalation compound show the possibility to build an ultimate microscope for scientist.

Journal Articles

Why is the Fusion Reactor called "The sun on the earth" ?

Tsuji, Hiroshi

Chodendo Web 21 (Internet), (2004年8月), p.18 - 19, 2004/08

The expression "The fusion reacctor is the sun on the earth," is often used to introduce research and development of fusion reactors. This document was prepared so as to explain the reason why it is so called to the students at the 3rd grade of junior high schools and at high schools. This document was made according to a request by the publication office of the technical internet journal "Superconductivity Web 21" which is published by the International Superconductivity Technology Center.

JAEA Reports

The Present situation and future utilization of testing reactors in the world

Ito, Haruhiko; Ide, Hiroshi; Yamaura, Takayuki; Tsuji, Tomoyuki

JAERI-Review 2004-001, 39 Pages, 2004/02

JAERI-Review-2004-001.pdf:2.02MB

no abstracts in English

Journal Articles

Acoustic emission and disturbances in central solenoid model coil for international thermonuclear experimental reactor

Arai, K.*; Ninomiya, Akira*; Ishigooka, Takeshi*; Takano, Katsutoshi*; Nakajima, Hideo; Michael, P.*; Vieira, R.*; Martovetsky, N.*; Sborchia, C.*; Alekseev, A.*; et al.

Cryogenics, 44(1), p.15 - 27, 2004/01

 Times Cited Count:3 Percentile:83.36(Thermodynamics)

no abstracts in English

Journal Articles

Development of a Nb$$_{3}$$Al conductor to be applied to a fusion reactor and its application to a large superconducting coil

Koizumi, Norikiyo; Okuno, Kiyoshi; Nakajima, Hideo; Ando, Toshinari*; Tsuji, Hiroshi

Teion Kogaku, 38(8), p.391 - 398, 2003/08

no abstracts in English

Journal Articles

Program of in-pile IASCC testing under the simulated actual plant condition; Thermohydraulic design study of saturated temperature capsule for IASCC irradiation test

Ide, Hiroshi; Matsui, Yoshinori; Nagao, Yoshiharu; Komori, Yoshihiro; Itabashi, Yukio; Tsuji, Hirokazu; Tsukada, Takashi; Nagata, Nobuaki*; Dozaki, Koji*; Takiguchi, Hideki*

Proceedings of 11th International Conference on Nuclear Engineering (ICONE-11) (CD-ROM), 7 Pages, 2003/04

The advanced water chemistry controlled irradiation research device has been developed in JAERI to perform irradiation tests for research on IASCC. The irradiation device consists of the SATCAP (Saturated Temperature Capsule) inserted into the JMTR core and the water control unit installed out-of-core. Regarding the SATCAP, thermohydraulic design of the SATCAP was performed aiming at controlling the specimen temperature with high accuracy and increasing water flow velocity on the specimen surface to improve the controllability of water chemistry. As a result of irradiation test using the new type SATCAP, each specimen temperature and water chemistry were able to be controlled as designed.

JAEA Reports

Nb$$_3$$Al insert experiment log book; 3rd Experiment of CS model coil

Sugimoto, Makoto; Koizumi, Norikiyo; Isono, Takaaki; Matsui, Kunihiro; Nunoya, Yoshihiko; Tsutsumi, Fumiaki*; Oshikiri, Masayuki*; Wakabayashi, Hiroshi*; Okuno, Kiyoshi; Tsuji, Hiroshi

JAERI-Tech 2002-080, 100 Pages, 2002/11

JAERI-Tech-2002-080.pdf:7.89MB

The cool down of CS model coil and Nb$$_3$$Al insert was started on March 4, 2002. It took almost one month and immediately started coil charge since April 3, 2002. The charge test of Nb$$_3$$Al insert and CS model coil was completed on May 2, 2002. All of the experiments including the warm up was also completed on May 30, 2002.In this campaign, total shot numbers were 102 and the size of the data file in the DAS (Data Acquisition System) was about 5.2 GB. This report is a database that consists of the log list and the log sheets of every shot.

241 (Records 1-20 displayed on this page)