Furuya, Osamu*; Fujita, Satoshi*; Muta, Hitoshi*; Otori, Yasuki*; Itoi, Tatsuya*; Okamura, Shigeki*; Minagawa, Keisuke*; Nakamura, Izumi*; Fujimoto, Shigeru*; Otani, Akihito*; et al.
Proceedings of ASME 2021 Pressure Vessels and Piping Conference (PVP 2021) (Internet), 6 Pages, 2021/07
Since the Fukushima accident, with the higher safety requirements of nuclear facilities in Japan, suppliers, manufacturers and academic societies have been actively considering the reconstruction of the safety of nuclear facilities from various perspectives. The Nuclear Regulation Authority has formulated new regulatory standards and is in operation. The new regulatory standards are based on defense in depth, and have significantly raised the levels of natural hazards and have requested to strengthen the countermeasures from the perspective of preventing the simultaneous loss of safety functions due to common factors. Facilities for dealing with specific serious accidents are required to have robustness to ensure functions against earthquakes that exceed the design standards to a certain extent. In addition, since the probabilistic risk assessment (PRA) and the safety margin evaluation are performed to include the range beyond the design assumption in the safety improvement evaluation, it is very important to extent the special knowledge in the strength of important equipment for seismic safety. This paper summarizes the research and examination results of specialized knowledge on the concept of maintaining the functions of important seismic facilities and the damage index to be considered by severe earthquakes. In the other paper, the study on reliability of seismic capacity analysis for important equipment in nuclear facilities will be reported.
Muramatsu, Haruka*; Hayashi, Tasuku*; Yuasa, Naoki*; Konno, Ryohei*; Yamaguchi, Atsushi*; Mitsuda, Kazuhisa*; Yamasaki, Noriko*; Maehata, Keisuke*; Kikunaga, Hidetoshi*; Takimoto, Misaki; et al.
Journal of Low Temperature Physics, 200(5-6), p.452 - 460, 2020/09
Ueda, Hiroshi*; Onoda, Shigeki*; Yamaguchi, Yasuhiro*; Kimura, Tsuyoshi*; Yoshizawa, Daichi*; Morioka, Toshiaki*; Hagiwara, Masayuki*; Hagihara, Masato*; Soda, Minoru*; Masuda, Takatsugu*; et al.
Physical Review B, 101(14), p.140408_1 - 140408_6, 2020/04
Yamaguchi, Atsushi*; Muramatsu, Haruka*; Hayashi, Tasuku*; Yuasa, Naoki*; Nakamura, Keisuke; Takimoto, Misaki; Haba, Hiromitsu*; Konashi, Kenji*; Watanabe, Makoto*; Kikunaga, Hidetoshi*; et al.
Physical Review Letters, 123(22), p.222501_1 - 222501_6, 2019/11
Nakamura, Keisuke; Morishita, Yuki; Takasaki, Koji; Maehata, Keisuke*; Sugimoto, Tetsuya*; Kiguchi, Yu*; Iyomoto, Naoko*; Mitsuda, Kazuhisa*
Journal of Low Temperature Physics, 193(3-4), p.314 - 320, 2018/11
Kobata, Masaaki; Fujimori, Shinichi; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Kobayashi, Keisuke*; Yamagami, Hiroshi; Nakamura, Ai*; Hedo, Masato*; Nakama, Takao*; et al.
Journal of the Physical Society of Japan, 85(9), p.094703_1 - 094703_6, 2016/09
Sukegawa, Atsuhiko; Iida, Hiromasa*; Itoga, Toshio*; Okumura, Keisuke; Kai, Tetsuya; Konno, Chikara; Nakashima, Hiroshi; Nakamura, Takashi*; Ban, Shuichi*; Yashima, Hiroshi*; et al.
Hoshasen Shahei Handobukku; Kisohen, p.299 - 356, 2015/03
no abstracts in English
Takasaki, Koji; Yasumune, Takashi; Onishi, Takashi; Nakamura, Keisuke; Ishimi, Akihiro; Ito, Chikara; Osaka, Masahiko; Ono, Masashi*; Hatakeyama, Shuichi*; Takahashi, Hiroyuki*; et al.
JAEA-Research 2013-043, 33 Pages, 2014/01
In the Fukushima Daiichi Nuclear Power Plant, it is assumed that the core fuels melted partially or wholly, and the normal technique of accounting for a fuel assembly is not applicable. Therefore, it is necessary to develop the transparent and rational technique of accounting in the process of collection and storage of fuel debris. In this research, an application of the superconducting phase Transition Edge Sensor microcalorimeter (TES microcalorimeter) is studied for the accounting of nuclear materials in the fuel debris. It is expected that the detailed information of nuclear materials and fission products in fuel debris is obtained by using a high-resolution characteristic of TES microcalorimeter. In this report, the principle of TES microcalorimeter, the measurement experiment using TES in JAEA, and the simulated calculation using the EGS5 code system are summarized.
Ishihara, Kohei*; Takagi, Keisuke*; Minato, Haruna*; Kawarabayashi, Jun*; Tomita, Hideki*; Maeda, Shigetaka; Naka, Tatsuhiro*; Morishima, Kunihiro*; Nakano, Toshiyuki*; Nakamura, Mitsuhiro*; et al.
Radiation Measurements, 55, p.79 - 82, 2013/08
In order to measure the neutron under a condition of high intensity of -ray background, we made new nuclear emulsion based on non-sensitized OPERA emulsion which had small AgBr grain size (AgBr grain size of 60, 90 and 160 nm). The sensitivity of this new emulsion, which was a correlation between stopping power and grain density, was estimated experimentally by irradiating neutrons with several energies. We also simulated the response to -ray induced electrons and compared with some experimental results by using Co source. The results showed that there might be a threshold energy deposited in one AgBr grain under which it was impossible to develop. We estimated efficiency to the -ray and the neutron with this obtained response of the new emulsion.
Nagao, Keisuke*; Okazaki, Ryuji*; Nakamura, Tomoki*; Miura, Yayoi*; Osawa, Takahito; Bajo, Kenichi*; Matsuda, Shintaro*; Ebihara, Mitsuru*; Ireland, T.*; Kitajima, Fumio*; et al.
Science, 333(6046), p.1128 - 1131, 2011/08
A steroid surface materials record regolith processes and a history of cosmic-ray irradiation. Noble gas isotopes in three rocky grains from Itokawa have been determined. High concentrations of solar He, Ne, and Ar, as high as those in lunar soils, are released at variable temperatures from each sample. The isotopic compositions are essentially identical to those of solar wind but distinguishable in He relative abundance. These noble gas characteristics can be explained by repeated implantation and preferential loss of solar He by removal of weathered He-rich rim on the grain surface through friction among regolith grains on Itokawa. Residence time of regolith materials on Itokawa is alculated to be shorter than 10 Myr, suggesting that regolith materials of small asteroids would escape easily to space.
Nakamura, Keisuke; Maeda, Makoto*; Yasumune, Takashi*; Maehata, Keisuke*; Ishibashi, Kenji*; Tanaka, Keiichi*; Umeno, Takahiro*; Takasaki, Koji; Momose, Takumaro
Radiation Protection Dosimetry, 146(1-3), p.88 - 91, 2011/07
A Transition Edge Sensor (TES) microcalorimeter has been developed for use as an energy dispersive X-ray spectrometer. A TES microcalorimeter is a thermal detector used to measure the energy of an incident photon with increase in temperature. In this work, a TES microcalorimeter with a 5m Au absorber was developed for use in measuring LX rays emitted from transuranium elements. Furthermore, as a cooling system a dilution refrigerator utilizing a Gifford-McMahon refrigerator was used, which needs no liquid helium. The performance of the TES microcalorimeter was evaluated by measuring the LX rays emitted by an Am source. This system proved effective in the measurement of the LX rays because the full width at half maximum of the LX ray was about 80 eV.
Matsuda, Iwao*; Nakamura, Fumitaka*; Kubo, Keisuke*; Hirahara, Toru*; Yamazaki, Shiro*; Choi, W. H.*; Yeom, H. W.*; Narita, Hisashi*; Fukaya, Yuki; Hashimoto, Mie*; et al.
Physical Review B, 82(16), p.165330_1 - 165330_6, 2010/10
no abstracts in English
Kakinouchi, Keisuke*; Nakamura, Tsutomu*; Tamada, Taro; Adachi, Hiroaki*; Sugiyama, Shigeru*; Maruyama, Mihoko*; Takahashi, Yoshinori*; Takano, Kazufumi*; Murakami, Satoshi*; Inoue, Tsuyoshi*; et al.
Journal of Applied Crystallography, 43(4), p.937 - 939, 2010/08
A method for growing large protein crystals is described. In this method, a cut pipette tip is used to hang large-scale droplets (maximum volume 200 l) consisting of protein and precipitating agents. A crystal grows at the vapor-liquid interface; thereafter the grown crystal can be retrieved by droplet-droplet contact both for repeated macroseeding and for mounting crystals in a capillary. Crystallization experiments with peroxiredoxin of K1(thioredoxin peroxidase, ApTPx) and hen egg white lysozyme demonstrated that this large-scale hanging-drop method could produce a large-volume crystal very effectively. A neutron diffraction experiment confirmed that an ApTPx crystal (6.2 mm) obtained by this method diffracted to beyond 3.5 resolution.
Maehata, Keisuke*; Nakamura, Keisuke*; Yasumune, Takashi*; Ishibashi, Kenji*; Takasaki, Koji; Tanaka, Keiichi*; Odawara, Akikazu*; Nagata, Atsushi*
Journal of Nuclear Science and Technology, 47(3), p.308 - 313, 2010/03
A phase transition edge sensor (TES) microcalorimeter was developed for the energy dispersive measurement of LX-ray photons emitted from transuranium elements. The phase transition temperature of the TES was designed to be 200 mK by using bilayer structure of Au of 120 nm thick and Ti of 50 nm thick. The Au layer of 5.0 m thick was deposited on the Au/Ti bilayer for absorption efficiency of 50% and counting rate of 100 counts per second in the detection of LX-ray photons with the energy from 10 to 20 keV. The TES microcalorimeter was operated for the detection of LX-ray photons emitted from Am, Pu and Pu sources. The decay time constant of 180 s of detection signal pulses allowed the TES microcalorimeter operating with the counting rate higher than 100 counts per second. The energy resolution was obtained to be 50 eV of FWHM value for a peak corresponding to Np L X-ray of 17.75 keV.
Iwatsuki, Teruki; Sato, Haruo; Tanai, Kenji; Inagaki, Manabu; Sawada, Atsushi; Niinuma, Hiroaki; Ishii, Eiichi; Maekawa, Keisuke; Tomura, Goji; Sanada, Hiroyuki; et al.
JAEA-Research 2009-002, 156 Pages, 2009/05
The research and development plan for geological investigation, engineering technology and safety assessment during the drilling of a shaft down to intermediate depth are summarized according to the Midterm Plan till 2009 Fiscal year of JAEA. This report describes subject, current status and programme in the "Phase 2: Construction phase" (investigations during construction of the underground facilities). Furthermore regarding R&D plan in next Midterm Plan of JAEA, preliminary ideas are summarized.
Nara, Takayuki; Agematsu, Takashi; Ishibori, Ikuo; Kurashima, Satoshi; Yoshida, Kenichi; Fukuda, Mitsuhiro; Okumura, Susumu; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Nakamura, Yoshiteru; et al.
JAEA-Review 2005-001, TIARA Annual Report 2004, P. 370, 2006/01
no abstracts in English
Nara, Takayuki; Agematsu, Takashi; Ishibori, Ikuo; Kurashima, Satoshi; Yoshida, Kenichi; Fukuda, Mitsuhiro; Okumura, Susumu; Miyawaki, Nobumasa; Nakamura, Yoshiteru; Akaiwa, Katsuhiro*; et al.
Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.209 - 211, 2004/08
no abstracts in English
Kinsho, Michikazu; Saito, Yoshio*; Kabeya, Zenzaburo*; Tajiri, Keisuke*; Nakamura, Tomaru*; Abe, Kazuhiko*; Nagayama, Taketoshi*; Nishizawa, Daiji*; Ogiwara, Norio
Vacuum, 73(2), p.187 - 193, 2004/03
Alimina ceramics vacuum duct has been developing at JAERI for the 3GeV-RCS of the J-PARC project. There are two type of the alumina ceramics vacuum ducts, one is a 1.5m-long duct with a circular cross section for use in the quadrupole magnet, the other is a 3.5m-long being bending 15 degree with an elliptical cross section for use in the dipole magnet.These ducts could be manufactured by brazed jointing several duct segments of 0.5-0.8 m long. Since some electrically conductive boundary is necessary to form on the ceramics duct in order to reduce the duct impedance, the alumina ceramics ducts have copper stripes on the outside surface of the ducts. This is called for rf shielding system. The copper stripes as rf shielding is produced by an electroforming method. In order to reduce emitting secondary electrons when primary protons or electrons impinge onto the surface, TiN film is coated inside surface of the alumina ceramics duct.
Nakamura, Yoshiteru; Nara, Takayuki; Agematsu, Takashi; Ishibori, Ikuo; Tamura, Hiroyuki; Kurashima, Satoshi; Yokota, Wataru; Okumura, Susumu; Fukuda, Mitsuhiro; Akaiwa, Katsuhiro*; et al.
Proceedings of 13th Symposium on Accelerator Science and Technology, p.193 - 195, 2001/00
The AVF cyclotron system at JAERI Takasaki has been smoothly operated without serious troubles since the first beam extraction in March, 1991. A yearly operation time is about 3200 hours on an average for recent eight years. In last two years, we performed some improvements and developments as followings: stabilization of the cyclotron beam by addition on an exclusive cooling system, designing and investigation of the flat-top system using fifth-harmonic RF, reconstruction of the rotary shutter for radiation shielding and reinforcement of the magnetic channel and its power supply. Furthermore, the renewal of main circulation pump for cooling system, replacement of shunt resistor in the power supplies and re-alignment of the several magnets along the trunk beam transport line were also carried out.
Katagiri, Masaki; Kishimoto, Maki; Ukibe, M.*; Nakamura, Tatsuya*; Kurakado, M.*; Maehata, Keisuke*; *; Nakazawa, Masaharu*
Japanese Journal of Applied Physics, 37(SUPPL.37-2), p.13 - 18, 1998/00
no abstracts in English