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Journal Articles

Investigation of the electronic structure of the Mg$$_{99.2}$$Zn$$_{0.2}$$Y$$_{0.6}$$ alloy using X-ray photoelectron spectroscopy

Miyazaki, Hidetoshi*; Akatsuka, Tatsuyoshi*; Kimura, Koji*; Egusa, Daisuke*; Sato, Yohei*; Itakura, Mitsuhiro; Takagi, Yasumasa*; Yasui, Akira*; Ozawa, Kenichi*; Mase, Kazuhiko*; et al.

Materials Transactions, 64(6), p.1194 - 1198, 2023/06

We investigated the electronic structure of the Mg$$_{99.2}$$Zn$$_{0.2}$$Y$$_{0.6}$$ alloy using hard and soft X-ray photoemission spectroscopy and electronic band structure calculations to understand the mechanism of the phase stability of this material. Electronic structure of the Mg$$_{99.2}$$Zn$$_{0.2}$$Y$$_{0.6}$$ alloy showed a semi-metallic electronic structure with a pseudo-gap at the Fermi level. The observed electronic structure of the Mg$$_{99.2}$$Zn$$_{0.2}$$Y$$_{0.6}$$ alloy suggests that the presence of a pseudogap structure is responsible for phase stability.

Journal Articles

Development of safety design philosophy of HTTR-Heat Application Test Facility

Aoki, Takeshi; Shimizu, Atsushi; Noguchi, Hiroki; Kurahayashi, Kaoru; Yasuda, Takanori; Nomoto, Yasunobu; Iigaki, Kazuhiko; Sato, Hiroyuki; Sakaba, Nariaki

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 9 Pages, 2023/05

The safety design philosophy is developed for the HTTR (High Temperature Engineering Test Reactor) heat application test facility connecting high temperature gas-cooled reactor (HTGR) and the hydrogen production plant. The philosophy was proposed to apply proven conventional chemical plant standards to the hydrogen production facility for ensuring public safety against anticipated disasters caused by high pressure and combustible gases. The present study also proposed the safety design philosophy to meet specific safety requirements identified to the nuclear facilities with coupling to the hydrogen production facility such as measures to ensure a capability of normal operation of the nuclear facility against a fire and/or explosion of leaked combustible material, and fluctuation of amount of heat removal occurred in the hydrogen production plant. The safety design philosophy will be utilized to establish its basic and detailed designs of the HTTR-heat application test facility.

Journal Articles

Development plan for coupling technology between high temperature gas-cooled reactor HTTR and hydrogen production facility, 1; Overview of the HTTR heat application test plan to establish high safety coupling technology

Nomoto, Yasunobu; Mizuta, Naoki; Morita, Keisuke; Aoki, Takeshi; Okita, Shoichiro; Ishii, Katsunori; Kurahayashi, Kaoru; Yasuda, Takanori; Tanaka, Masato; Isaka, Kazuyoshi; et al.

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 7 Pages, 2023/05

Journal Articles

Development plan for coupling technology between high temperature gas-cooled reactor HTTR and Hydrogen Production Facility, 2; Development plan for coupling equipment between HTTR and Hydrogen Production Facility

Mizuta, Naoki; Morita, Keisuke; Aoki, Takeshi; Okita, Shoichiro; Ishii, Katsunori; Kurahayashi, Kaoru; Yasuda, Takanori; Tanaka, Masato; Isaka, Kazuyoshi; Noguchi, Hiroki; et al.

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 6 Pages, 2023/05

Journal Articles

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

 Times Cited Count:3 Percentile:80.29(Nuclear Science & Technology)

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Journal Articles

Application of virtual tour for online training safeguards exercises

Sekine, Megumi; Sukegawa, Hidetoshi; Ishikuro, Yasuhiro; Oyama, Koji; Obata, Takashi; Hayashi, Kazuhiko; Inoue, Naoko

Proceedings of INMM & ESARDA Joint Virtual Annual Meeting (Internet), 10 Pages, 2021/08

The Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN) of the Japan Atomic Energy Agency (JAEA) developed the virtual tour of a reference nuclear facility. The developed virtual tour was applied to the Design Information Questionnaire (DIQ) workshop exercise for the online SSAC course held in November 2020 in connection with the IAEA safeguards-related regional training course. Also, it was applied to the Complementary Access (CA) exercise for the online workshop of the Nuclear Security and Safeguards Project under the Forum for Nuclear Cooperation in Asia (FNCA), held in February 2021. The workshop exercises have been implemented for in-person format however due to COVID-19 pandemic, a virtual tour was applied. The virtual tour was found to be a strong tool not only for online training as an alternative for a facility tour, but also considered to be more advantageous even for the in-person training. The developed virtual tour of a reference nuclear facility, going to shut down, can find potentially varied applications. The paper describes how to create a virtual tour of a reference research reactor facility for the DIQ and CA exercises respectively which have different learning objectives. It emphasizes how the features of the reference facility were captured and the challenges encountered to convey to the training participants the importance of providing the required design information while not being physically present at the facility. It also show the advantage of using the same virtual tour to describe the safeguards-related verification activities of a complementary access. Virtual tours can be applied to a variety of training.

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

A Sampling method of oriented small sample from fault cores for SEM observation

Shimada, Koji; Kametaka, Masao*; Nakayama, Kazuhiko; Seshimo, Kazuyoshi; Tanaka, Yoshihiro; Hayashi, Toshio*; Tanaka, Yukumo; Shimogama, Kota*; Okazaki, Kazuhiko*

Chishitsugaku Zasshi, 119(11), p.727 - 731, 2013/11

Staples for a stapler can be used as a frame of a small oriented sample taken from fragile and scarce fault gouge. The fault gouge was slotted for staples of an insert. Staples are a group of about ten or less ones holding right-angled three small surfaces. Pre-oriented staples set the slot would remove then presented for the SEM observation. Only a knife, some glues and simple equipment are needed for the method in the field or laboratories.

Journal Articles

Rehearsal and actual measurement of Fugen spent fuel assemblies by integrated PNAR and SINRD under the JAEA-USDOE collaboration program

Hayashi, Kenta; Nakamura, Takahisa; Takagi, Hisatsugu; Horie, Kaoru; Nakayama, Tamotsu; Hashimoto, Kazuhiko; Hayashi, Shoichi; Nakamura, Shinji; Takenaka, Shigeki; Ishizuka, Nobuo; et al.

Proceedings of INMM 54th Annual Meeting (CD-ROM), 10 Pages, 2013/07

JAEA and USDOE (Los Alamos National Laboratory (LANL)) have been collaborating on spent fuel measurements with a PNAR/SINRD NDA instrument at Fugen, in the course of the NGSI Spent Fuel Nondestructive Assay Project. In this collaboration, LANL's role has been to design and fabricate the detector (integrated PNAR and SINRD system), while JAEA's role has been to undertake the installation of the detector at the appropriate position in the spent fuel pool and to prepare for the actual measurements. In this paper we report the rehearsal of the measurement using a mock-up detector and a dummy fuel assembly in December 2012 and the plan of actual measurements in June 2013 (at the time of submission of this paper).

JAEA Reports

Studies on the design method of multi tunnels in geological disposal facility, 4

Hayashi, Katsuhiko; Kishi, Hirokazu; Kabayashi, Yasushi*; Takebe, Atsuji*; Fujiyama, Tetsuo*; Hiramoto, Masayuki*; Mizutani, Kazuhiko*; Morita, Atsushi*

JAEA-Research 2010-059, 92 Pages, 2011/03

JAEA-Research-2010-059.pdf:3.71MB

In this study, the first investigation is the order of the multi-tunnels excavation. The second is the strain-softening model for multi-tunnels which is based on test data at Horonobe site. As results of first investigation, we showed as 2 dimensional analyses that it was desirable to excavate the tunnel of the remote distance at first and excavate the tunnel between these tunnels next, and it is necessary for the examination that reflected a real plan, such as evacuation machine and actual multi tunnel layout. As the results of second investigation, we also showed the more reliable EDZ by using the strain-softening model that is based on test data at Horonobe site. Furthermore, we standardized the design method (draft) for the practical use by referring the past studies of multi tunnel design method.

Journal Articles

Reconstruction of the 2-dimensitonal beam profile at longitudinal phase space with tomography method in J-PARC RCS and MR

Yoshimoto, Masahiro; Tamura, Fumihiko; Yamamoto, Masanobu; Yoshii, Masahito*; Omori, Chihiro*; Hayashi, Naoki; Kawase, Masato; Watanabe, Kazuhiko*; Yoshikawa, Muneyoshi*

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.737 - 740, 2010/03

The longitudinal phase space tomography, which was evolved to retrieve the two-dimensional beam distribution in the longitudinal phase space with computer tomography algorithms, is very useful diagnostic tool in the accelerator domain. The simple reconstruction tool was developed for the J-PARC RCS and MR with the convolution back projection method for the beam storage mode. On the assumption that the longitudinal profiles should not be disturbed for one period of the synchrotron oscillation, such two-dimensional profiles can be reconstructed easily from one-dimensional bunch beam profiles, which are measured for every turn by the wall current monitor.

JAEA Reports

Studies on the design method of multi tunnels in geological disposal facility, 3

Hayashi, Katsuhiko; Kishi, Hirokazu; Kabayashi, Yasushi*; Takebe, Atsuji*; Fujiyama, Tetsuo*; Hiramoto, Masayuki*; Mizutani, Kazuhiko*; Morita, Atsushi*

JAEA-Research 2009-056, 86 Pages, 2010/02

JAEA-Research-2009-056.pdf:9.96MB

In this study, the effect of constitutive models such as strain softening of rock masses for EDZ, and the stress relief ratio used for multi tunnels analysis were conducted. As the result, it is necessary to confirm mechanical behavior of in situ rock and it is important to choose suitable constitutive models, and it is possible for all tunnels in multi tunnels model to have same stress relief ratio.

JAEA Reports

Studies on the design method of multi tunnels in geological disposal facility, 2

Hayashi, Katsuhiko; Kobayashi, Yasushi; Hiramoto, Masayuki*; Mizutani, Kazuhiko*; Morita, Atsushi*

JAEA-Research 2009-016, 127 Pages, 2009/08

JAEA-Research-2009-016.pdf:5.23MB

"Study on configuration of analytical domain of the multi tunnels model" and "Remainders on an elasto-plastic FEM (Finite Element Method) analysis" in case of the full width of pillar become plastic on simplified model" are studied as "The study on the enhanced reliability of elasto-plastic FEM". In addition, "The effect of rock support and consolidation of the host rock to control the plastic region" was conducted as "The study on the mechanical stability of tunnels". As the results, it was seen that the analytical domain should be assigned 3-5W (W: width of multi tunnels) for a horizontal side from the endmost tunnel and 3-4W for below of the tunnels. It was found reasonable and proper on the elasto-plastic FEM analysis that the analysis domain must be large enough not to have plastic deformation in all analysis of domains under the condition in which the full width of pillar has plastic deformation. It was also found that the ground support suppresses the plasticity domain as the ground support effect. It was acknowledged that the auxiliary construction method by improvement of the ground has the suppression effect of the plasticity domain applying to the multi tunnels.

Journal Articles

Longitudinal phase space tomography at J-PARC RCS

Yoshimoto, Masahiro; Tamura, Fumihiko; Yamamoto, Masanobu; Yoshii, Masahito*; Hayashi, Naoki; Kawase, Masato; Watanabe, Kazuhiko*; Yoshikawa, Hirokazu*

Proceedings of 2009 Particle Accelerator Conference (PAC '09) (DVD-ROM), p.3358 - 3360, 2009/05

The longitudinal phase space tomography, which was evolved to retrieve the two-dimensional beam distribution in the longitudinal phase space with computer tomography algorithms, is very useful diagnostic tool in the accelerator domain. The simple reconstruction tool was developed for the J-PARC RCS with the convolution back projection method for the beam storage mode. On the assumption that the longitudinal profiles should not be disturbed for one period of the synchrotron oscillation, such two-dimensional profiles can be reconstructed easily from one-dimensional bunch beam profiles, which are measured for every turn by the wall current monitor.

Journal Articles

Reflection high-energy positron diffraction study of surface super-structures

Kawasuso, Atsuo; Fukaya, Yuki*; Hayashi, Kazuhiko; Hashimoto, Mie; Ichimiya, Ayahiko

Physica Status Solidi (C), 4(10), p.3924 - 3927, 2007/09

Well-focused and highly parallel positron beam is totally reflected at the first surface layer when grazing incidence at a small enough angles. Therefore, the reflection high-energy positron diffraction (RHEPD) is suited to determine the surface structures without any disturbance from the bulk. Using the electro-magnetic lenses we developed a positron beam which has more coherence than before. We found that the RHEPD pattern from the Si-7$$times$$7 surface is considerably different from that of electron diffraction. The difference is reasonably explained as a strong thermal diffuse scattering of positrons. As a further application, we studied the phase transition of Si-Ag ultra-thin film. We found that the surface-sensitive diffraction spots exhibit significant temperature dependences. Based on the dynamical diffraction theory, the temperature dependences are reproduced considering the order-disorder phase transition. This will terminate the long debates in the surface science community. Furthermore, we recently found that the positron-surface interaction is different from the electron-surface interaction, especially in the elastic processes. We present the above recent advances of surface studies using RHEPD.

Journal Articles

Reflection high-energy positron diffraction study of surface super-structures

Kawasuso, Atsuo; Fukaya, Yuki; Hayashi, Kazuhiko*; Hashimoto, Mie; Ichimiya, Ayahiko

Physica Status Solidi (C), 4(10), p.3924 - 3927, 2007/09

 Times Cited Count:0 Percentile:0.07

In this study, we performed the positron energy loss spectroscopy measurements from several surfaces using energy-filtered reflection high-energy positron diffraction. For Si(111)-7$$times$$7 surface, we observed at least five distinct loss peaks. The interval of energy loss peaks is approximately 10 eV, which corresponds to the surface plasmon loss energy of silicon. The positron energy loss spectra are well-approximated by the Poisson distribution. The average excitation number of surface plasmon is 2.6 under the total reflection condition. This number is similar to what expected for electrons at zero glancing angle. Thus, positrons lose their energy due to surface plasmon excitation much more sufficiently than electrons. We found that the specular spot is broadened in the total reflection region especially at the tail part due to plasmon excitation.

Journal Articles

Introduction to plasma fusion energy

Takamura, Shuichi*; Kado, Shinichiro*; Fujii, Takashi*; Fujiyama, Hiroshi*; Takabe, Hideaki*; Adachi, Kazuo*; Morimiya, Osamu*; Fujimori, Naoji*; Watanabe, Takayuki*; Hayashi, Yasuaki*; et al.

Kara Zukai, Purazuma Enerugi No Subete, P. 164, 2007/03

no abstracts in English

Journal Articles

Reflection high-energy positron diffraction pattern from a Si(111)-(7$$times$$7) surface

Hayashi, Kazuhiko; Kawasuso, Atsuo; Ichimiya, Ayahiko

Surface Science, 600(19), p.4426 - 4429, 2006/10

 Times Cited Count:5 Percentile:27.25(Chemistry, Physical)

no abstracts in English

Journal Articles

Adsorption of oxygen on Si(001) surfaces studied by reflection high-energy positron diffraction

Hayashi, Kazuhiko; Kawasuso, Atsuo; Ichimiya, Ayahiko

e-Journal of Surface Science and Nanotechnology (Internet), 4, p.510 - 513, 2006/05

no abstracts in English

Journal Articles

Observation of Si(111)-$$sqrt{3}$$$$times$$$$sqrt{3}$$-Ag surface at room temperature by reflection high-energy positron diffraction

Fukaya, Yuki; Kawasuso, Atsuo; Hayashi, Kazuhiko; Ichimiya, Ayahiko

Applied Surface Science, 244(1-4), p.166 - 169, 2005/05

 Times Cited Count:5 Percentile:26.2(Chemistry, Physical)

no abstracts in English

50 (Records 1-20 displayed on this page)