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Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Sunagawa, Hikaru*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Fujihara, Masayoshi; Tampo, Motonobu*; Kawamura, Naritoshi*; et al.
Interactions (Internet), 245(1), p.31_1 - 31_6, 2024/12
Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Natori, Hiroaki*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Tampo, Motonobu*; Kawamura, Naritoshi*; Teshima, Natsuki*; et al.
Journal of Physics; Conference Series, 2462, p.012033_1 - 012033_5, 2023/03
Times Cited Count：0 Percentile：0.21(Physics, Applied)Yamaga, Chikanobu; Tomikawa, Hirofumi; Kobayashi, Naoki; Naoi, Yosuke; Oda, Tetsuzo; Mochiji, Toshiro
JAEA-Review 2015-023, 108 Pages, 2015/10
JAEA-Review-2015-023.pdf:15.22MB
The JAEA held "International Forum on Peaceful Use of Nuclear Energy, Nuclear Non-proliferation and Nuclear Security -Future direction toward promoting non-proliferation and the ideal method of developing human resources using COEs following the New Strategic Energy Plan -" on 3 December 2014. In the Forum, officials and experts from Japan, the United States explained their efforts. Discussion was made in two panels, entitled "Effective and efficient measures to ensure nuclear non-proliferation based on domestic and foreign issues and the direction and role of technology development" and "Roles of nuclear security COEs and future expectations". In Panel Discussion 1, how to implement effective and efficient safeguards was discussed. In Panel Discussion 2, panelists discussed current status of NSSCs and COEs, new role for COEs and regional cooperation. This report includes abstracts of keynote speeches, summaries of two panel discussions and materials of the presentations in the forum.
Futatsukawa, Kenta*; Kobayashi, Tetsuya*; Sato, Fumiaki; Shinozaki, Shinichi; Chishiro, Etsuji; Hirano, Koichiro; Fang, Z.*; Fukui, Yuji*; Hori, Toshihiko; Michizono, Shinichiro*
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1317 - 1320, 2015/09
In the J-PARC linac, an RF deflector installed in 3-MeV Medium Energy Beam Transport (MEBT1) is used to kick the unnecessary beam and the intermediate-pulse like a comb is created. The kicked beam leads to a scraper downstream the RF deflector and lose all kinetic energy. When the beam current increases to 50 mA of the design value, the heat load of a scraper to irradiate the kicked beam increases and its surface is predicted to be damaged. Therefore, we are preparing the tandem scrapers to reduce the damage. The half of the kicked beam leads to a scraper and the residual is to the other. The chopping operation is achieved by rotating the phase of the RF deflector in the periodic cycles by the LLRF system. We will introduce the phase rotation system and the test results.
Naoi, Yosuke; Kobayashi, Naoki; Mochiji, Toshiro; Senzaki, Masao; Seya, Michio
Proceedings of 37th ESARDA Annual Meeting (Internet), p.100 - 110, 2015/08
In April 2010 at the Nuclear Security Summit in Washington, D.C., Japan made a commitment to establish a center of excellence on nuclear nonproliferation and security. This center would support capacity building for strengthening nuclear nonproliferation and security mainly in the Asian region and also would engage in development of technology related measurement and detection of nuclear material including nuclear forensics based on international cooperation. According to this statement, Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN) was established under Japan Atomic Energy Agency (JAEA) in December 2010. Since its establishment four years ago, ISCN has developed its activities, having already conducted 74 training courses for the nuclear nonproliferation and security fields and having trained 2,096 participants from 49 countries (including Japan) and three international organizations. As for technical development on detection and measurement of nuclear material, ISCN has carried out substantial outcome with the international cooperation of U.S. and EU/JRC. It can be said that it is a significant achievement of the Nuclear Security Summit process. This paper will overview the outcome of ISCN's activities over the past four years.
SGo, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Kobayashi, Motoki*; Kisamori, Keiichi*; Takaki, Motonobu*; Miya, Hiroyuki*; Ota, Shinsuke*; Michimasa, Shinichiro*; Shimoura, Susumu*; et al.
JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06
Mitamura, Hiroyuki*; Watanuki, Ryuta*; Kaneko, Koji; Onozaki, Norimichi*; Amo, Yuta*; Kittaka, Shunichiro*; Kobayashi, Riki*; Shimura, Yasuyuki*; Yamamoto, Isao*; Suzuki, Kazuya*; et al.
Physical Review Letters, 113(14), p.147202_1 - 147202_5, 2014/10
Times Cited Count：23 Percentile：75.16(Physics, Multidisciplinary)Kawamura, Hideyuki; Kobayashi, Takuya; Nishikawa, Shiro*; Ishikawa, Yoichi*; Usui, Norihisa*; Kamachi, Masafumi*; Aso, Noriko*; Tanaka, Yusuke*; Awaji, Toshiyuki*
Global Environmental Research (Internet), 18(1), p.81 - 96, 2014/09
A drift simulation of tsunami debris flushed out from the Tohoku district, Japan, into the North Pacific due to the tsunami on March 11, 2011, has been conducted to monitor and forecast the drift path over the North Pacific. Results showed that tsunami debris was first transported eastward by the intense Kuroshio Extension and westerly, spreading in the north and south directions by both an energetic ocean eddy and a storm track over the ocean. Tsunami debris with larger windage was transported over the North Pacific by ocean surface wind rather than ocean current and arrived at the west coast of the North American Continent in the fall of 2011. Tsunami debris located near the North American Continent migrated, associated with the basin-scale seasonal change in the atmospheric pressure pattern. Our forecast run suggested that the tsunami debris belt will be formed from the North American Continent in the east to the Philippines in the west.
Kawamura, Hideyuki; Kobayashi, Takuya; Furuno, Akiko; Usui, Norihisa*; Kamachi, Masafumi*; Nishikawa, Shiro*; Ishikawa, Yoichi*
Proceedings of 19th Pacific Basin Nuclear Conference (PBNC 2014) (USB Flash Drive), 7 Pages, 2014/08
Numerical simulations on oceanic dispersion of the radioactive cesium in the North Pacific from March 2011 to September 2013 were conducted to clarify the concentration of the radioactive cesium released from the Fukushima Daiichi Nuclear Power Plant. We implemented the oceanic dispersion simulations with two independent ocean reanalysis dataset. It was suggested that the 
Cs concentration in the North Pacific was lower than the pre-Fukushima background level about two years after the Fukushima disaster. The intercomparison revealed that meso-scale eddies in the Kuroshio Extension region may have efficiently diluted the radioactive cesium concentration at the sea surface. In addition, it was suggested that the enhanced downward current accompanied by the meso-scale eddies played an important role in transporting the radioactive cesium into the intermediate layer.
Futatsukawa, Kenta*; Anami, Shozo*; Kobayashi, Tetsuya*; Fang, Z.*; Fukui, Yuji*; Michizono, Shinichiro*; Kawamura, Masato*; Sato, Fumiaki; Shinozaki, Shinichi; Chishiro, Etsuji; et al.
Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.769 - 773, 2013/08
no abstracts in English
Fukui, Yuji*; Kawamura, Masato*; Kobayashi, Tetsuya*; Fang, Z.*; Futatsukawa, Kenta*; Sato, Fumiaki; Shinozaki, Shinichi; Suzuki, Hiroyuki; Chishiro, Etsuji; Hori, Toshihiko; et al.
Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.762 - 764, 2013/08
no abstracts in English
Hirano, Koichiro; Ito, Takashi; Chishiro, Etsuji; Kubota, Chikashi*; Nammo, Kesao*; Kobayashi, Tetsuya*; Naito, Fujio*
Proceedings of 8th Annual Meeting of Particle Accelerator Society of Japan (Internet), 3 Pages, 2011/08
Two RF-deflecting cavities as the chopper have been used in the MEBT between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. A fast rise/fall time of the pulse is a fundamental requirement to minimize any beam losses due to insufficient deflection to some beam bunches during the transient time. We have studied the RF chopper cavity to speed up the transient time. This paper describes the design of the new RF chopper by using HFSS code.
Sakaguchi, Shinobu; Tachibana, Ikuya; Koshino, Katsuhiko; Shirozu, Hidetomo; Shirai, Nobutoshi; Imamoto, Nobuo; Tomita, Tsuneo; Tobita, Hiroo; Yamanaka, Atsushi; Kobayashi, Daisuke; et al.
JAEA-Technology 2011-006, 24 Pages, 2011/03
JAEA-Technology-2011-006.pdf:3.07MB
In the Niigataken Chuetsu-oki Earthquake on 2007, observed earthquake motion exceeded design base at the Kashiwazaki Kariwa nuclear plant. However, there was no earthquake damage in safety important equipments to stop reactor, to cool reactor, and to contain radioactive materials. One of this reason is said that many safety margin are included in the design and the permissible value. To know more accurate safety margin, shearing force examinations for the base bolts were conducted. In examinations, delegate test-bolts were made; the test bolts were selected from heavier equipment in Tokai Reprocessing Plant. In this report, the shearing strength obtained from the examinations shows more accurate safety margin.
Obara, Satoshi*; Kobayashi, Ryoei*; Yagi, Shuichi*; Toyama, Yuko*; Kutluk, G.*; Osawa, Tetsutaro*; Ogura, Koichi; Shibata, Takemasa; Azuma, Yoshiro*; Nagata, Tetsuo*
Nuclear Instruments and Methods in Physics Research B, 269(3), p.263 - 271, 2011/02
Times Cited Count：0 Percentile：0.01(Instruments & Instrumentation)A crossed photon-atom beam apparatus has been constructed for absolute measurement of total photoionization cross sections of isolated and neutral metallic atoms. Using this apparatus, measurements on Ba and Eu atoms have been made at their 4d giant resonance regions 110-140 eV and 140-180 eV, respectively. The target atom density was determined using the deposition rate on a quartz crystal sensor and the average velocity of the atoms obtained by a time-of-flight method combined with a pulsed electron gun. The number of photons was determined with use of a double ion chamber. The comparison of the measured cross-section values with previous experimental and theoretical results is reasonable, indicating that the crossed photon-atom beam method is fairly promising technique.
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
Times Cited Count：9 Percentile：40.54(Materials Science, Multidisciplinary)no abstracts in English
Fang, Z.*; Michizono, Shinichiro*; Anami, Shozo*; Yamaguchi, Seiya*; Naito, Fujio*; Fukui, Yuji*; Kobayashi, Tetsuya; Suzuki, Hiroyuki; Chishiro, Etsuji; Shinozaki, Shinichi
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.1068 - 1070, 2010/08
The output energy of the J-PARC proton Linac will be upgraded from 181 to 400 MeV in the next two years by adding 972-MHz high-beta acceleration sections. The RF signals are controlled by the FPGA-based digital feedback control systems installed in a compact PCI (cPCI). Recently, the LLRF control software has also been upgraded for the J-PARC Linac, especially for the 972-MHz high-beta systems. Many functions have been added to the LLRF control software, such as (1) gradually increasing the feedback gains in the feedback loop instead of fixed ones, (2) automatic chopped-beam compensation, (3) automatically switching the beam loading compensation in accordance with the different beam operation mode, (4) input RF-frequency tuning carried out by a FPGA to match the RF cavities during the RF start-up, (5) auto-tuning of the RF cavity tuner by detecting the phase curve of the RF cavity during the field decay instead of the phase difference between the cavity input and output signals.
Fang, Z.*; Michizono, Shinichiro*; Anami, Shozo*; Yamaguchi, Seiya*; Naito, Fujio*; Fukui, Yuji*; Kawamura, Masato*; Kubota, Chikashi*; Nammo, Kesao*; Kobayashi, Tetsuya; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.1434 - 1436, 2010/05
The output energy of the J-PARC proton linac will be upgraded from 181 to 400 MeV in the next two years by adding high-b acceleration sections. The upgrade of the FPGA-based digital LLRF controller for the 400 MeV linac will be presented in this paper. This new LLRF controller works for both the 324-MHz low-b and 972-MHz high-b sections. Many functions have been added into the LLRF controller, such as (1) working for different RF systems, (2) gradually increasing the feedback gains in the feedback loop instead of fixed ones, (3) automatic chopped beam compensation, (4) automatically switching the beam loading compensation in accordance with different beam operation mode, (5) input RF-frequency tuning to match the RF cavities during RF start-up, and (6) auto-tuning of the RF cavity tuner by detecting the phase curve of the RF cavity during the field decay instead of the phase difference between the cavity input and output signals.
Nakayama, Masashi; Kobayashi, Yasushi; Noguchi, Akira; Miura, Norihiko*; Noda, Masaru*; Iriya, Keishiro*; Hitomi, Takashi*
JAEA-Research 2009-036, 49 Pages, 2009/11
JAEA-Research-2009-036.pdf:20.34MB
In Horonobe Underground Research Laboratory (Horonobe URL) Project, construction practicality test with HFSC (Highly Fly-ash contained Silica-fume Cement) is planned in a part of the gallery. It is necessary to validate that HFSC has performance under the actual construction, before HFSC is placed in the gallery. The main tasks in 2008 are follows; (1) suggestion of mix design for liner concrete of shaft in Horonobe URL, (2) investigation of long term pH changes in order to use for modeling, and (3) an experiment for interaction between HFSC and ground water around Horonobe URL. (1) 4 types of mix proportion are designed for ordinary concrete and high strength concrete which contains polypropylene fiber or not. As early age strength, 5N/mm
is required because of concrete formwork. HFSC424 with low water binder ratio can fulfill this requirement in combination with super plasticizer. (2) pH and components of solid and liquid phase which were made in 2003, and stored in water were analyzed. And cement paste of shotcrete which are made in 2006 were also analyzed. In this pH of shotcrete is lower than other in situ concrete since accelerating agent may act as decreasing factor of pH. (3) An experiment which investigates dissolution of HFSC cement hydrates to ground water around Horonobe URL. According to the experiment, dissolving depth of HFSC is 4 times small comparing to Ordinary Portland Cement hydrates after 30th water exchange.
Nakayama, Masashi; Kobayashi, Yasushi; Matsuda, Takeshi*; Noda, Masaru*; Iriya, Keishiro*; Takeda, Nobufumi*
JAEA-Research 2009-035, 70 Pages, 2009/11
JAEA-Research-2009-035.pdf:11.27MB
In Horonobe Underground Research Center construction of underground facility began in 2005 and construction practicality test with HFSC (Highly Fly-ash contained Silica-fume Cement) is planned in a part of the gallery. Before HFSC will be placed in the gallery it is necessary to validate that HFSC has performance under the actual construction. The research results in 2007 were as follows. As corrosion behavior in HFSC, reinforced concrete specimen with HFSC 226 have been exposed to off-shore condition at in saline water and splashed zone and analyzed corrosion rate and chloride intrusion, and they were summarized. Service life time of HFSC reinforced concrete was assessed more than 50 years until cracking due to corrosion is generated. pH and components of solid and liquid phase which were made in 2002, and stored in water were analyzed. And cement paste of shotcrete which are made in 2006 were also analyzed. In this pH of shotcrete is lower than other in situ concrete since accelerating agent may act as decreasing factor of pH. The results obtained from this ten year's study were summarized on shotcerete, in situ concrete and grouting. Based on the summery, method of quality control, such as testing method, frequency, and standards so on, were investigated.
Hasegawa, Kazuo; Asano, Hiroyuki; Chishiro, Etsuji; Hori, Toshihiko; Ito, Takashi; Kobayashi, Tetsuya; Kondo, Yasuhiro; Namekawa, Yuya; Oguri, Hidetomo; Okoshi, Kiyonori; et al.
Proceedings of 24th International Linear Accelerator Conference (LINAC 2008) (CD-ROM), p.55 - 57, 2009/00
The beam commissioning of the J-PARC linac started in November 2006 and 181 MeV acceleration was successfully achieved in January 2007. The linac has delivered beams to the 3 GeV Rapid Cycling Synchrotron for its commissioning, and then, the subsequent Main Ring Synchrotron and the neutron target commissioning. The linac uses a Cs-free LaB
-driven ion source and 20 units of 324 MHz klystrons. As of June 2008, the operation times are about 3,000 and 6,000 hours for the ion source and the RF source, respectively. The operating experience of the linac is described.
