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Journal Articles

Evaluation of Tsunami debris impact on Tokai Reprocessing Plant

Nishino, Saki; Tsuboi, Masatoshi; Okada, Jumpei; Saegusa, Yu; Omori, Kazuki; Yasuo, Kiyoshi; Seshimo, Kazuyoshi; Domura, Kazuyuki; Yamamoto, Masahiko

Nihon Hozen Gakkai Dai-17-Kai Gakujutsu Koenkai Yoshishu, p.541 - 548, 2021/07

no abstracts in English

Journal Articles

Fundamental study on seismic safety margin for seismic isolated structure using the laminated rubber bearings

Fukasawa, Tsuyoshi*; Miyagawa, Takayuki*; Uchita, Masato*; Yamamoto, Tomohiko; Miyazaki, Masashi; Okamura, Shigeki*; Fujita, Satoshi*

Nihon Kikai Gakkai Rombunshu (Internet), 87(898), p.21-00007_1 - 21-00007_17, 2021/06

This paper describes a fundamental study on the seismic safety margin for the isolated structure using laminated rubber bearings. The variation of the seismic response assumed in the isolated structure will occur under the superposition of "Variations in seismic response due to input ground motions" and "Error with design value accompanying manufacture of the isolation devices ". The seismic response analysis which allows to their conditions is important to assess the seismic safety margin for the isolated structure. This paper clarifies that the seismic safety margin of the isolated structure, which consists of rubber bearings, for Sodium-cooled Fast Reactor (SFR) is ensured against the basis ground motions of Japan Electric Association Guide 4601 (JEAG4601) and SFR through the seismic response analysis considering the variation factors of seismic response. In addition, a relationship between the seismic safety margin and the excess probability of linearity limits is discussed using the results of seismic response analysis.

JAEA Reports

Activities of Working Group on Verification of PASCAL; Fiscal years 2016 and 2017

Li, Y.; Hirota, Takatoshi*; Itabashi, Yu*; Yamamoto, Masato*; Kanto, Yasuhiro*; Suzuki, Masahide*; Miyamoto, Yuhei*

JAEA-Review 2020-011, 130 Pages, 2020/09

JAEA-Review-2020-011.pdf:9.31MB

For the improvement of the structural integrity assessment methodology on reactor pressure vessels (RPVs), the probabilistic fracture mechanics (PFM) analysis code PASCAL has been developed and improved in Japan Atomic Energy Agency based on the latest knowledge. The PASCAL code evaluates the failure probabilities and frequencies of Japanese RPVs under transient events such as pressure thermal shock considering neutron irradiation embrittlement. In order to confirm the reliability of the PASCAL as a domestic standard code and to promote the application of PFM on the domestic structural integrity assessments of RPVs, it is important to perform verification activities, and summarize the verification processes and results as a document. On the basis of these backgrounds, we established a working group, composed of experts on this field besides the developers, on the verification of the PASCAL module and the source program of PASCAL was released to the members of working group. This report summarizes the activities of the working group on the verification of PASCAL in FY2016 and FY2017.

Journal Articles

The $$f$$-electron state of the heavy fermion superconductor NpPd$$_5$$Al$$_2$$ and the isostructural family

Metoki, Naoto; Aczel, A. A.*; Aoki, Dai*; Chi, S.*; Fernandez-Baca, J. A.*; Griveau, J.-C.*; Hagiwara, Masato*; Hong, T.*; Haga, Yoshinori; Ikeuchi, Kazuhiko*; et al.

JPS Conference Proceedings (Internet), 30, p.011123_1 - 011123_6, 2020/03

Rare earths (4$$f$$) and actinides (5$$f$$) provide variety of interesting states realized with competing interactions between the increasing number of $$f$$ electrons. Since crystal field splitting of many-body $$f$$ electron system is smaller than the bandwidth, (1) high resolution experiments are needed, (2) essentially no clear spectrum with well defined peaks is expected in itinerant Ce and U compounds, and (3) Np and Pu is strictly regulated. Therefore, systematic research on magnetic excitations by neutron scattering experiments of localized compounds and rare earth iso-structural reference is useful. We describe the $$f$$ electron states of heavy electron compounds NpPd$$_5$$Al$$_2$$ and actinide and rare earth based iso-structural family.

Journal Articles

Present status of personnel protection system at J-PARC

Kikuzawa, Nobuhiro; Niki, Kazuaki*; Yamamoto, Noboru*; Hayashi, Naoki; Adachi, Masatoshi*; Watanabe, Kazuhiko*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.877 - 880, 2019/07

Interlock system of J-PARC is classified into a personnel protection system (PPS) for human safety and a machine protection system (MPS) for protecting equipment. The PPS of the J-PARC accelerator started from the operation at Linac in 2006 and was completed by the MR operation in 2008. In the next 10 years, some improvements have been made, such as updating video monitoring systems and establishing new interlocks. In addition to describing recent operations including these updatings, this paper reports the current status of inspections and maintenance conducted to maintain and improve reliability.

Journal Articles

Advanced analysis technology for new material and product development

Sasaki, Hirokazu*; Nishikubo, Hideo*; Nishida, Shinsuke*; Yamazaki, Satoshi*; Nakasaki, Ryusuke*; Isomatsu, Takemi*; Minato, Ryuichiro*; Kinugawa, Kohei*; Imamura, Akihiro*; Otomo, Shinya*; et al.

Furukawa Denko Jiho, (138), p.2 - 10, 2019/02

no abstracts in English

Journal Articles

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.

Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01

 Times Cited Count:10 Percentile:72.43(Physics, Multidisciplinary)

Excitation functions of quasielastic scattering cross sections for the $$^{48}$$Ca + $$^{208}$$Pb, $$^{50}$$Ti + $$^{208}$$Pb, and $$^{48}$$Ca + $$^{248}$$Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the $$^{48}$$Ca + $$^{208}$$Pb and $$^{50}$$Ti + $$^{208}$$Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the $$^{48}$$Ca + $$^{248}$$Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.

Journal Articles

Improvement of the IPM for the high-intensity beam profile measurement in the J-PARC RCS

Kato, Shinichi; Harada, Hiroyuki; Hatakeyama, Shuichiro; Kawase, Masato; Yamamoto, Kazami; Kinsho, Michikazu

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1089 - 1093, 2016/11

In the J-PARC RCS, the residual gas ionization profile monitor (IPM) is adopted for the nondestructive detection of the 1D transverse distribution of the circulating proton beam. The IPM mainly consists of the divided electrodes generating the external electric field and the detection unit. For the profile measurement, the residual gas ionized by the beam is transported to the detection unit by the external transverse electric field and amplified by the Multi-Channel Plate (MCP) as the electron. After that, these electrons are detected and the 1D distribution is reconstructed. To improve IPM performance, some updates have been performed continuously such as the optimization of the electric field potential and the introduction of the new MCP which has the gradual gain response to the applied voltage. As a result, the IPM shows intended performance in the beam commissioning with the low current condition. However, the distribution cannot be measured in the high current condition such as over 100 kW because the noise increases and hides the signal. To solve this problem, we investigated the source of this noise and examined measures. To compare the simulation and the noise measurement results, we identified the cause of the noise as the electric field from the beam. Therefore, we developed additional electrode component to shield that field based on the simulation result. This component will be installed in 2016 summer. It is expected that the noise is reduced to be 1/100 compared with present one by the new component and the distribution measurement can be performed in the high current condition.

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

International round robin test on Master Curve reference temperature evaluation utilizing Miniature C(T) specimen

Yamamoto, Masato*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Mabuchi, Yasuhiro*; Valo, M.*; Lambrecht, M.*; Viehrig, H.-W.*; Miura, Naoki*; Soneda, Naoki*

Small Specimen Test Techniques; 6th Volume (ASTM STP 1576), p.53 - 69, 2015/05

In order to ensure the robustness of the Master Curve technique, round-robin tests were performed using 0.16 inch-thick Mini-CT specimens by different investigators to see if consistent $$T$$$$_{0}$$ values can be obtained. All the specimens used were machined and pre-cracked by one fabricator from unique Japanese RPV material. Seven institutes participated in this exercise, and obtained valid $$T$$$$_{0}$$ values according to the ASTM E1921 standard. The scatter of $$T$$$$_{0}$$ values obtained was well within the uncertainty range defined in the standard, indicating the robustness of the Mini-CT specimen test technique. Throughout this activity, we could obtain 182 $$K$$$$_{Jc}$$ for a single material. We investigated the statistics of this large database, and found that there is no remarkable difference not only in the $$T$$$$_{0}$$ values but also in the fracture toughness distribution between the Mini-CT specimen and the standard size 1T-C(T) specimen results.

Journal Articles

Increment of the machine protection system in J-PARC rapid cycling synchrotron

Yamamoto, Kazami; Kawase, Masato; Iwama, Yuhei; Fukuta, Shimpei; Kato, Yuko; Ouchi, Nobuo; Meigo, Shinichiro; Oi, Motoki; Kamikubota, Norihiko*

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.771 - 774, 2014/10

The radiation leak accident happened in the hadron experimental hall of J-PARC on May 23, 2013. The accident was caused by a target sublimation due to an unanticipated beam from the 50 GeV main ring (MR). To detect and prevent the radiation leakage in all facilities of J-PARC, we improve the machine protection system (MPS). In the J-PARC 3GeV synchrotron (Rapid Cycling Synchrotron, RCS), a monitoring system of an abnormal state of the extraction beam to the mercury target of material life science experiment facility (MLF) were prepared. The radiation level of the gas in the tunnel were able to always observed by connecting radiation safety system and accelerator control system. The dump temperature was included in the MPS. We also developed new interlock system that can stop the beam immediately when the beam current exceed the limit.

Journal Articles

A Round robin propgram of master curve evaluation using miniature C(T) specimens, 3; Comparison of $$T_{0}$$ under various selections of temperature conditions

Yamamoto, Masato*; Kimura, Akihiko*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Mabuchi, Yasuhiro*; Viehrig, H.-W.*; Miura, Naoki*; Soneda, Naoki*

Proceedings of 2014 ASME Pressure Vessels and Piping Conference (PVP 2014) (DVD-ROM), 7 Pages, 2014/07

The Master Curve (MC) approach for the fracture toughness reference temperature To is expected to be a powerful tool to ensure the reliability of long-term used RPV steels. In order to get sufficient number of data for the MC approach related to the present surveillance program for RPVs, the use of miniature specimens is important. The test technique for the miniature specimens (Mini-CT) of 4 mm thick had been verified the basic applicability of MC approach by means of Mini-CT for the determination of fracture toughness of typical Japanese RPV steels. A round robin (RR) program was organized to assure the robustness of the technique. As the third step of RR program, blinded tests were carried out. Precise material information was not provided to the participants. From the results obtained, the scatter range in $$T_{0}$$ was within the acceptable scatter range specified in the testing standard. The selection of testing temperature seems to give limited effect like that in larger specimens.

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:29 Percentile:82(Physics, Multidisciplinary)

Journal Articles

A Round robin program of master curve evaluation using miniature C(T) specimens, 2; Fracture toughness comparison in specified loading rate condition

Yamamoto, Masato*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Mabuchi, Yasuhiro*; Miura, Naoki*

Proceedings of 2013 ASME Pressure Vessels and Piping Conference (PVP 2013) (DVD-ROM), 8 Pages, 2013/07

Master Curve (MC) approach for the fracture toughness evaluation is expected to be a powerful tool to assess the structural integrity of reactor pressure vessels (RPVs). In order to get sufficient number of reliable data by the MC approach from used specimens of surveillance tests for RPVs, the use of miniature specimens is necessary. For this purpose, a round robin test program on the miniature compact tension specimens (Mini-CT) of 4 mm thick for the MC approach was launched with the participation of academia, industries and a research institute in Japan. The program aims to verify the reliability of experimental data from Mini-CT, and to pick out technical issues to be solved. As the second step of this program, the effect of loading rate (d$$K$$/d$$t$$) was evaluated based on enlarged database. Despite of the difference in d$$K$$/d$$t$$, no specific difference in scatter band of $$T_{rm 0}$$ was found in d$$K$$/d$$t$$ - $$T_{rm 0}$$ relationships. D$$K$$/d$$t$$ seems not to be sensitive on scatter band of To in the present results.

Journal Articles

HBC foil beam study and long-term observation at the 3-GeV RCS in J-PARC

Yoshimoto, Masahiro; Saha, P. K.; Yamazaki, Yoshio; Kawase, Masato; Saeki, Riuji; Hayashi, Naoki; Yamamoto, Kazami; Hotchi, Hideaki; Ishiyama, Tatsuya; Kinsho, Michikazu; et al.

Journal of Physics; Conference Series, 417, p.012073_1 - 012073_6, 2013/03

 Times Cited Count:4 Percentile:79.92

The HBC foil are installed in the J-PARC RCS for the charge-exchange H$$^{-}$$ beam injection. In order to examine the characteristics of the HBC foils, beam studies for the HBC foil were carried out from the viewpoint of foil's life time and the beam survival rate due to foils. According to the compromise between charge-exchange efficiency and foil scattering beam loss, we optimized the foils thickness for user operation. The long-term observation during the user operation as well as the HBC foil endurance test for its life time evaluation was carried out. Even after one year was operation, there was no deterioration of the stripping foil.

Journal Articles

Well-ordered arranging of Ag nanoparticles in SiO$$_{2}$$/Si by ion implantation

Takahiro, Katsumi*; Ninakuchi, Yuki*; Kawaguchi, Kazuhiro; Isshiki, Toshiyuki*; Nishio, Koji*; Sasase, Masato*; Yamamoto, Shunya; Nishiyama, Fumitaka*

Applied Surface Science, 258(19), p.7322 - 7326, 2012/07

 Times Cited Count:2 Percentile:11.18(Chemistry, Physical)

A nanometer-sized metallic particle embedded in a transparent dielectric exhibits a nonlinear susceptibility, and going to be applied to nonlinear optical devices. In the present study, well-ordered arrangements of Ag nanoparticles have been found for Ag-implanted SiO$$_{2}$$. Thermally grown SiO$$_{2}$$ on Si were implanted with 350 keV-Ag ions to fluences of 0.37-1.2 $$times$$ 10$$^{17}$$ ions/cm$$^{2}$$. Cross-sectional transmission electron microscopy and scanning transmission electron microscopy reveal the presence of a two-dimensional array of Ag nanoparticles of 25-40 nm in diameter located at a depth of $$sim$$130 nm, together with the self-organization of tiny Ag nanoparticles aligned along the SiO$$_{2}$$/Si interface. X-ray photoelectron spectroscopy and X-ray diffraction confirm the stability of these Ag nanoparticles embedded in the SiO$$_{2}$$/Si is found to be stable against oxidation and sulfidation when stored in ambient conditions for more than one and a half year.

Journal Articles

A Round robin program of master curve evaluation using miniature C(T) specimens; First round robin test on uniform specimens of reactor pressure vessel materials

Yamamoto, Masato*; Kimura, Akihiko*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Chiba, Atsushi*; Hirano, Takashi*; Sugihara, Takuji*; Sugiyama, Masanari*; Miura, Naoki*; et al.

Proceedings of 2012 ASME Pressure Vessels and Piping Conference (PVP 2012) (DVD-ROM), 7 Pages, 2012/07

Master curve (MC) approach for the fracture toughness evaluation is expected to be a powerful tool to assess the structural integrity of reactor pressure vessels (RPVs). In order to get sufficient number of reliable data for the MC approach from broken halves of surveillance test specimens for RPVs, the use of miniature specimens is necessary. For this purpose, a round robin test program on the miniature compact tension specimens (Mini-CT) of 4 mm thick for the MC approach of a Japanese RPV steel has been launched with the participation of academia, industries and a research institute in Japan. The program aims to verify the reliability of experimental data from Mini-CT, and to pick out further investigation items to be solved. As the first step of this program, four institutes carried out MC testing and evaluation using common test procedure and specimens. Valid reference temperature T$$_{0}$$ was successfully obtained in each institute. However, the T$$_{0}$$ values showed large differences with maximum of 34$$^{circ}$$C. It was indicated on the reason of difference that there is a strong correlation between the T$$_{0}$$ values and loading rate, which was selected by each institute per test standard.

Journal Articles

Application of sputter etching treatment to the formation of semiconducting silicide film on Si substrate

Yamaguchi, Kenji; Esaka, Fumitaka; Sasase, Masato*; Yamamoto, Hiroyuki; Hojo, Kiichi

Transactions of the Materials Research Society of Japan, 37(2), p.245 - 250, 2012/06

"Semiconducting silicides", such as $$beta$$-FeSi$$_2$$, BaSi$$_2$$, Mg$$_2$$Si, etc. are composed of elements which are non or less toxic and are naturally abundant, so that they are considered to be ecologically friendly. These materials are being investigated for applications in optoelectronics, photovoltaics, photonics, thermoelectrics, and so on. In order to fabricate silicide films on crystalline Si substrate, sputter-etching (SE) of the substrate with low energy ion beams has been successfully applied. When the conditions are met, a highly-oriented $$beta$$-FeSi$$_2$$ (100) film can be grown on Si (100) substrate by means of ion beam sputter deposition method. According to cross-sectional transmission electron microscopy (TEM) observation, the interface of the SE-treated substrate and the film deposited at 973 K is smooth, although some defects are produced as a result of this treatment. On the other hand, a combination of X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) revealed that relatively homogeneous $$beta$$-FeSi$$_2$$ surface is formed at this temperature. In order to further improve the film properties with smaller amount of defects, SE-treatment is performed with the ions whose incident energy is below 1 keV. X-ray diffraction (XRD) analysis confirmed that highly-oriented $$beta$$-FeSi$$_2$$ (100) film can be also obtained with SE-treatment by 0.8 keV Ne$$^+$$ ions, as in the case of 3.0 keV Ne$$^+$$.

172 (Records 1-20 displayed on this page)