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Journal Articles

Development of the buckling evaluation method for large scale vessels in fast reactors by the testing of Grade 91 steel and austenitic stainless steel vessels subjected to horizontal and cyclic vertical loading

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Ando, Masanori; Okajima, Satoshi

Proceedings of ASME 2023 Pressure Vessels and Piping Conference (PVP 2023) (Internet), 8 Pages, 2023/07

Buckling evaluation methods capable of evaluating elasto-plastic buckling under axial compression, bending, and shear loads are required for cylindrical vessels of fast reactors to cope with thinning due to increasing diameter and application to the seismic isolation design against huge seismic ground motion. In this study, in order to confirm the applicability of the proposal evaluation method, several buckling tests and FE analyses were carried out using the specimens made of Gr.91 and austenitic stainless steel. The buckling modes and strength data in the load region where the interaction of cyclic axial compression, bending and shear buckling could occur were examined. As a result, it was confirmed that the proposal evaluation method estimated the buckling load in the tests conservatively.

Journal Articles

Structure analysis of asymmetric interface using spin-contrast-variation neutron reflectometry

Kumada, Takayuki; Miura, Daisuke*; Akutsu, Kazuhiro*; Oku, Takayuki; Torikai, Naoya*; Niizeki, Tomotake*

Hamon, 32(4), p.165 - 168, 2022/11

We demonstrated the advantage of spin-contrast-variation neutron reflectometry on the structure analysis of buried interface between resin and porous silica layers. The interface structure was not reproduced by the normal Gaussian model, but by the asymmetric interface model where crosslinked polymer chains neither permeate the pore nor follow the surface roughness of the silica layer.

Journal Articles

Structure analysis of a buried interface between organic and porous inorganic layers using spin-contrast-variation neutron reflectivity

Kumada, Takayuki; Miura, Daisuke*; Akutsu, Kazuhiro*; Oishi, Kazuki*; Morikawa, Toshiaki*; Kawamura, Yukihiko*; Suzuki, Junichi*; Oku, Takayuki; Torikai, Naoya*; Niizeki, Tomotake*

Journal of Applied Crystallography, 55(5), p.1147 - 1153, 2022/10

AA2021-0903.pdf:1.06MB

 Times Cited Count:1 Percentile:31.49(Chemistry, Multidisciplinary)

Spin-contrast-variation neutron reflectivity obtains multiple reflectivity curves from a single sample and a single beam source. We used the strong point of the technique to reveal that, although methylated-perhydropolysilazane-derived silica layer has a higher porosity near the interface with acrylic urethane resin, the resin did not permeate the pore network.

Journal Articles

Development of the buckling evaluation method for large scale vessel in fast reactors by the testing of austenitic stainless steel vessel with severe initial imperfection subjected to horizontal and vertical loading

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Ando, Masanori; Okajima, Satoshi

Proceedings of ASME 2022 Pressure Vessels and Piping Conference (PVP 2022) (Internet), 9 Pages, 2022/07

Buckling evaluation methods capable of evaluating elasto-plastic buckling under axial compression, bending, and shear loads are required for cylindrical vessels of fast reactors to cope with thinning due to increasing diameter and application to the seismic isolation design against huge seismic ground motion. In this study, in order to confirm the applicability of the proposal evaluation method, several buckling tests and FE analyses were carried out using the specimens made of austenitic stainless steel. The buckling modes and strength data in the load region where the interaction of cyclic axial compression, bending and shear buckling could occur were examined. As a result, it was confirmed that the proposal evaluation method estimated the buckling load in the tests conservatively. Moreover, a series of finite element analyzes to confirm the applicability of the evaluation method in 2.25Cr-1Mo steel and up to 650 $$^{circ}$$C were conducted.

Journal Articles

Development of the buckling evaluation method for large scale vessel by the testing of Gr.91 vessel subjected to horizontal and cyclic vertical loading

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Ando, Masanori; Miyazaki, Masashi

Proceedings of ASME 2021 Pressure Vessels and Piping Conference (PVP 2021) (Internet), 9 Pages, 2021/07

Buckling evaluation methods capable of evaluating elasto-plastic buckling under axial compression, bending, and shear loads are required for cylindrical vessels of fast reactors to cope with thinning due to increasing diameter and application to the seismic isolation design against huge seismic ground motion. In this study, in order to confirm the applicability of the proposal evaluation method, several buckling tests and FE analyses were carried out using the specimens made of Modified 9Cr-1Mo steel. The buckling modes and strength data in the load region where the interaction of cyclic axial compression, bending and shear buckling could occur were examined. As a result, it was confirmed that the proposal evaluation method estimated the buckling load in the tests conservatively. Moreover, a series of finite element analyzes using a model with residual stress due to welding revealed that the effect of residual stress on buckling strength is negligible in the evaluation method.

Journal Articles

First isolation and analysis of caesium-bearing microparticles from marine samples in the Pacific coastal area near Fukushima Prefecture

Miura, Hikaru*; Ishimaru, Takashi*; Ito, Yukari*; Kuribara, Yuichi; Otosaka, Shigeyoshi*; Sakaguchi, Aya*; Misumi, Kazuhiro*; Tsumune, Daisuke*; Kubo, Atsushi*; Higaki, Shogo*; et al.

Scientific Reports (Internet), 11, p.5664_1 - 5664_11, 2021/03

 Times Cited Count:10 Percentile:68.7(Multidisciplinary Sciences)

For the first time, we isolated and investigated seven CsMPs (radioactive caesium-bearing microparticles) from marine particulate matter and sediment. From the elemental composition, the $$^{134}$$Cs/$$^{137}$$Cs activity ratio, and the $$^{137}$$Cs activity per unit volume results, we inferred that the five CsMPs collected from particulate matter were emitted from Unit 2 of the FDNPP, whereas the two CsMPs collected from marine sediment were possibly emitted from Unit 3. The presence of CsMPs can cause overestimation of the solid-water distribution coefficient of Cs in marine sediments and particulate matter and a high apparent radiocaesium concentration factor for marine biota. CsMPs emitted from Unit 2, which were collected from the estuary of a river that flowed through a highly contaminated area, may have been deposited on land and then transported by the river. By contrast, CsMPs emitted from Unit 3 were possibly transported eastward by the wind and deposited directly onto the ocean surface.

Journal Articles

Development of spin-contrast-variation neutron reflectometry

Kumada, Takayuki; Akutsu, Kazuhiro*; Oishi, Kazuki*; Morikawa, Toshiaki*; Kawamura, Yukihiko*; Sahara, Masae*; Suzuki, Junichi*; Miura, Daisuke*; Torikai, Naoya*

J-PARC 20-02; J-PARC MLF Annual Report 2019, p.38 - 40, 2021/00

Journal Articles

Development of spin-contrast-variation neutron reflectometry for structural analyses of multilayer films

Kumada, Takayuki; Miura, Daisuke*; Akutsu, Kazuhiro*; Suzuki, Junichi*; Torikai, Naoya*

Hamon, 30(4), p.207 - 211, 2020/11

We developed a technique of spin-contrast-variation neutron reflectivity (SCV-NR) for structural analyses of multilayer films. The SCV-NR curves of the polystyrene monolayer film were precisely reproduced using a common set of structural parameters and neutron scattering length density at each proton polarization. This result ensures that SCV-NR curves are not deformed by inhomogeneous PH due to the spin-diffusion mechanism. The number of structural parameters of the lamellar microphase-separated poly(styrene-block-isoprene) thin film is too large to determine with a single unpolarized reflectivity curve only. However, these parameters converged through the global analysis of the SCV-NR curves. In this manner, SCV-NR determines the structure of multilayer films while excluding the incorrect structural model that accidentally accounts for a single unpolarized reflectivity curve only.

Journal Articles

Development of the buckling evaluation method for large scale vessel by the testing of Gr.91 vessel subjected to vertical and horizontal loading

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Ando, Masanori; Miyazaki, Masashi

Proceedings of ASME 2020 Pressure Vessels and Piping Conference (PVP 2020) (Internet), 9 Pages, 2020/08

Buckling evaluation methods capable of evaluating elasto-plastic buckling under axial compression, bending, and shear loads are required for cylindrical vessels of fast reactors to cope with thinning due to increasing diameter and application to the seismic isolation design against huge seismic ground motion. In this study, in order to confirm the applicability of the proposal evaluation method, several buckling tests and FE analyses were carried out using the specimens made of Modified 9Cr-1Mo steel. The buckling modes and strength data in the load region where the interaction of axial compression, bending and shear buckling could occur were examined. As a result, it was confirmed that the proposal evaluation method estimated the buckling load in the tests conservatively. In addition, buckling strength evaluated by elasto-plastic buckling analysis had good accuracy compared to each test result by considering the stress-strain relationship and imperfection of test specimen.

Journal Articles

Study on the seismic buckling evaluation method for Mod. 9Cr-1Mo steel cylindrical vessel

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Kubo, Koji*; Sato, Kenichiro*; Wakai, Takashi; Shimomura, Kenta

Nihon Kikai Gakkai M&M 2017 Zairyo Rikigaku Kanfarensu Koen Rombunshu (Internet), p.591 - 595, 2017/10

no abstracts in English

Journal Articles

Progress report of Japanese simulation research projects using the high-performance computer system Helios in the International Fusion Energy Research Centre

Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03

The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.

Journal Articles

Operational experience of CW SRF injector and main linac cryomodules at the Compact ERL

Sakai, Hiroshi*; Enami, Kazuhiro*; Furuya, Takaaki*; Kako, Eiji*; Kondo, Yoshinari*; Michizono, Shinichiro*; Miura, Takako*; Qiu, F.*; Sato, Masato*; Shinoe, Kenji*; et al.

Proceedings of 56th ICFA Advanced Beam Dynamics Workshop on Energy Recovery Linacs (ERL 2015) (Internet), p.63 - 66, 2015/12

no abstracts in English

Journal Articles

The Operation status of the superconducting cavity for CERL main linac; Toward the deep understanding inside the superconducting cavity with high current beam

Numata, Naoto*; Asakawa, Tomoyuki*; Sakai, Hiroshi*; Umemori, Kensei*; Furuya, Takaaki*; Shinoe, Kenji*; Enami, Kazuhiro*; Egi, Masato*; Sakanaka, Shogo*; Michizono, Shinichiro*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.566 - 570, 2015/09

no abstracts in English

Journal Articles

Mechanical vibration search of compact ERL main linac superconducting cavities in cryomodule

Sato, Masato*; Enami, Kazuhiro*; Furuya, Takaaki*; Michizono, Shinichiro*; Miura, Takako*; Qiu, F.*; Sakai, Hiroshi*; Shinoe, Kenji*; Umemori, Kensei*; Sawamura, Masaru; et al.

Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.2531 - 2533, 2014/07

For the main linac of ERL, high loaded Q (QL) operation is desirable to reduce the input generator power. In such operation mode, the suppression of the micophonics is important to stabilize RF amplitude and phase. One of reasons which causes microphonics is mechanical vibration, which changes the cavity frequency. The vibrations of the cavities, the cryomodule and the floor were investigated and compared with the microphnics data taken during cERL operation.

Journal Articles

Performance evaluation of ERL main linac tuner

Enami, Kazuhiro*; Furuya, Takaaki*; Sakai, Hiroshi*; Sato, Masato*; Shinoe, Kenji*; Umemori, Kensei*; Michizono, Shinichiro*; Miura, Takako*; Qiu, F.*; Arakawa, Dai*; et al.

Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.2534 - 2536, 2014/07

We evaluated a slidejack tuner adopted as compact ERL Main Linac tuner. The tuner compensates the frequency by extending a cavity. Tuning is driven by two system, piezo and slidejack system. Slide-jack mechanism with long stroke drives coarsely piezo adjust precisely and fast. We tested performance of the tuners on operation.

Journal Articles

Operation status of compact ERL main linac cryomodule

Umemori, Kensei*; Enami, Kazuhiro*; Furuya, Takaaki*; Michizono, Shinichiro*; Miura, Takako*; Qiu, F.*; Sakai, Hiroshi*; Sato, Masato*; Shinoe, Kenji*; Sawamura, Masaru; et al.

Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.2537 - 2539, 2014/07

We developed ERL main linac cryomodule for Compact ERL (cERL) project, which was constructed in KEK. The module includes two 9-cell L-band superconducting cavities. After construction of cERL recirculation loop, beam operation was started. First electron beam successfully passed the main linac cavities. After adjusting beam optics, energy recovery operation was achieved. Main linac cavity was enough stable for ERL beam operation, however, field emission was a problem for long term operation.

Journal Articles

Unique Fermi surface and emergence of charge density wave in EuGa$$_4$$ and EuAl$$_4$$

Nakamura, Ai*; Hiranaka, Yuichi*; Hedo, Masato*; Nakama, Takao*; Miura, Yasunao*; Tsutsumi, Hiroki*; Mori, Akinobu*; Ishida, Kazuhiro*; Mitamura, Katsuya*; Hirose, Yusuke*; et al.

JPS Conference Proceedings (Internet), 3, p.011012_1 - 011012_6, 2014/06

Journal Articles

Magnetic and Fermi surface properties of EuGa$$_4$$

Nakamura, Ai*; Hiranaka, Yuichi*; Hedo, Masato*; Nakama, Takao*; Miura, Yasunao*; Tsutsumi, Hiroki*; Mori, Akinobu*; Ishida, Kazuhiro*; Mitamura, Katsuya*; Hirose, Yusuke*; et al.

Journal of the Physical Society of Japan, 82(10), p.104703_1 - 104703_10, 2013/10

 Times Cited Count:32 Percentile:80.72(Physics, Multidisciplinary)

Journal Articles

Studies on the behavior of tritium in components and structure materials of tritium confinement and detritiation systems of ITER

Kobayashi, Kazuhiro; Isobe, Kanetsugu; Iwai, Yasunori; Hayashi, Takumi; Shu, Wataru; Nakamura, Hirofumi; Kawamura, Yoshinori; Yamada, Masayuki; Suzuki, Takumi; Miura, Hidenori*; et al.

Nuclear Fusion, 47(12), p.1645 - 1651, 2007/12

 Times Cited Count:3 Percentile:11.4(Physics, Fluids & Plasmas)

The confinement and removal of tritium are the key subjects for safety of ITER. The ITER buildings are confinement barriers of tritium. In a hot cell building, tritium is often released, as vapor and is in contact with the inner walls. Also those of an ITER tritium plant building will be exposed to tritium in an accident. However, the data are scarce, especially on the penetration of tritium into the concrete of the wall materials. The tritium released in the buildings is removed by the Atmosphere Detritiation Systems (ADS), where the tritium is oxidized by catalysts and is removed as water. Special gas of SF$$_{6}$$ is used in ITER, and is expected to be released in an accident such as fire. Although the SF$$_{6}$$ gas has the potential as a catalyst poison, the performance of ADS with the existence of SF$$_{6}$$ has not been confirmed yet. Tritiated water is produced in the regeneration process of ADS, and is subsequently processed by the ITER Water Detritiation System (WDS). One of the key components of WDS is an electrolysis cell. The electrolysis cell is made of organic compounds, and there is no data on the durability of the cell exposed to tritium. To overcome these issues in a global tritium confinement, a series of experimental studies have been carried out as an ITER R&D task: (1) tritium behavior in concrete; (2) effect of SF$$_{6}$$ on performance of ADS; and (3) tritium durability of electrolysis cell of ITER-WDS.

Journal Articles

Oxidation performance test of detritiation system under existence of SF$$_{6}$$

Kobayashi, Kazuhiro; Miura, Hidenori*; Hayashi, Takumi; Hoshi, Shuichi; Yamanishi, Toshihiko

Fusion Science and Technology, 52(3), p.711 - 715, 2007/10

 Times Cited Count:3 Percentile:25.53(Nuclear Science & Technology)

The tritium released in the building is removed by Atmosphere Detritiation System (ADS), where the tritium is oxidized by catalysts and is removed as water. Special gas of SF$$_{6}$$ is used as an electric insulation gas in ITER, and is expected to be released in an accident such as fire. Although SF$$_{6}$$ has the potential as a catalyst poison, the performance of ADS with the existence of SF$$_{6}$$ has not been confirmed yet. Therefore, to study the effect of SF$$_{6}$$, the performance tests of ADS was carried out with air containing $$sim$$1% of hydrogen, $$sim$$1% of methane and $$sim$$1% of SF$$_{6}$$. The SF$$_{6}$$ gas was notably decomposed in the case of the catalyst temperature higher than 673 K. In addition, a part of the water produced by the 473 K catalyst was reduced to hydrogen due to the reaction with the decomposed gas in SF$$_{6}$$. Consequently, the detritiation factor of ADS was decreased to less than 50 from $$>$$ 1000 of its initial value.

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