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Journal Articles

Upgrade of the 3-MeV linac for testing of accelerator components at J-PARC

Kondo, Yasuhiro; Hirano, Koichiro; Ito, Takashi; Kikuzawa, Nobuhiro; Kitamura, Ryo; Morishita, Takatoshi; Oguri, Hidetomo; Okoshi, Kiyonori; Shinozaki, Shinichi; Shinto, Katsuhiro; et al.

Journal of Physics; Conference Series, 1350, p.012077_1 - 012077_7, 2019/12

 Times Cited Count:0 Percentile:0.07

We have upgraded a 3-MeV linac at J-PARC. The ion source is same as the J-PARC linac's, and the old 30-mA RFQ is replaced by a spare 50-mA RFQ, therefore, the beam energy is 3 MeV and the nominal beam current is 50 mA. The main purpose of this system is to test the spare RFQ, but also used for testing of various components required in order to keep the stable operation of the J-PARC accelerator. The accelerator has been already commissioned, and measurement programs have been started. In this paper, present status of this 3-MeV linac is presented.

Journal Articles

Study on loss-of-cooling and loss-of-coolant accidents in spent fuel pool, 4; Investigation of fuel loading effects in BWR spent fuel rack

Tojo, Masayuki*; Kanazawa, Toru*; Nakashima, Kazuo*; Iwamoto, Tatsuya*; Kobayashi, Kensuke*; Goto, Daisuke*; Nemoto, Yoshiyuki; Kaji, Yoshiyuki

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 13 Pages, 2019/05

In this study, fuel loading effects in BWR spent fuel rack accidents are widely investigated using three-dimensional analysis methods from both nuclear and thermal hydraulics viewpoints, including: (a) Decay heat of spent fuel after discharge, (b) The maximum temperature of spent fuel cladding in the spent fuel rack depending on heat transfer phenomena, and (c) Criticality of the spent fuel rack after collapsing of the fuel due to a severe accidents in the BWR spent fuel pool (SFP).

Journal Articles

Upgrade and Replacement of Plant Dynamics Test Loop (PLANDTL)

Uchiyama, Naoki*; Ozawa, Tatsuya*; Sato, Koji*; Kobayashi, Jun; Onojima, Takamitsu; Tanaka, Masaaki

FAPIG, (194), p.12 - 18, 2018/02

no abstracts in English

Journal Articles

Turbulent transport reduction induced by transition on radial electric field shear and curvature through amplitude and cross-phase in torus plasma

Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku*; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*

Scientific Reports (Internet), 7(1), p.14971_1 - 14971_8, 2017/11

 Times Cited Count:17 Percentile:83.92(Multidisciplinary Sciences)

Journal Articles

Research on vitrification technology to immobilize radioactive sludge generated from Fukushima Daiichi Power Plant; Enhanced glass medium

Amamoto, Ippei; Kobayashi, Hidekazu; Kitamura, Naoto*; Takebe, Hiromichi*; Mitamura, Naoki*; Tsuzuki, Tatsuya*; Fukayama, Daigen*; Nagano, Yuichi*; Jantzen, T.*; Hack, K.*

Journal of Nuclear Science and Technology, 53(10), p.1467 - 1475, 2016/10

 Times Cited Count:1 Percentile:14.27(Nuclear Science & Technology)

The iron phosphate glass (IPG) medium is known to be a high-efficiency glass medium, therefore we try to evaluate its applicability to immobilize sludge bearing radioactive nuclides arising from treatment of contaminated water at the stricken Fukushima Daiichi Nuclear Power Plant. For this study, many physical and chemical properties of target materials are necessary to evaluate the behaviours of IPG medium and its waste forms. Inevitably, it will entail the need for many and varied types of experiments to be carried out under high temperature. It is therefore rational to apply appropriate theoretical analysis first so as to reduce the number of experimental run. For this reason, some necessary thermodynamic values for theoretical analysis were estimated by CALPHAD approach followed by making up the calculated phase diagrams. By comparison with experimental results, they were found to be reliable for evaluating the behaviours of IPG medium and its waste forms.

Journal Articles

Experimental identification of electric field excitation mechanisms in a structural transition of tokamak plasmas

Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*; et al.

Scientific Reports (Internet), 6, p.30720_1 - 30720_7, 2016/08

 Times Cited Count:11 Percentile:67.67(Multidisciplinary Sciences)

In this Letter, we report model verifications for a key physics for the L-H transition. Radial electric field excitation, using discharges having a two-step transition. Examining time derivative of Poissons equation, it is found that the sum of the loss cone loss current and neoclassical bulk viscosity current agrees the experimentally observed current in the order of magnitude at the first transition. Following second transition and an ambipolar condition in the L-mode cannot be explained by the models.

Journal Articles

Development of a design support system for geological disposal using a CIM concept

Sugita, Yutaka; Kawaguchi, Tatsuya; Hatanaka, Koichiro; Shimbo, Hiroshi*; Yamamura, Masato*; Kobayashi, Yuichi*; Fujisawa, Yasuo*; Kobayashi, Ichiro*; Yabuki, Nobuyoshi*

Proceedings of 16th International Conference on Computing in Civil and Building Engineering (ICCCBE 2016) (Internet), p.1173 - 1182, 2016/07

This paper presents status of development of the iSRE (integrated system for repository engineering) as a design supporting system that enables rational designing of a geological disposal repository. The complimentary technique of construction information modeling/management (CIM) has been employed for the development of iSRE. CIM uses a shared three dimensional (3D) model of associated data through common data models. The contents of this paper are the goal of the development, design requirements and required functions, the basic structure of iSRE. The main databases of the iSRE could then be designed with an interface to coordinate with external systems and other databases. Some of the databases and the interfaces were trialed and a data model was then built. A scenario of iSRE operation was also created and the applicability of iSRE using a data model was also examined. Thanks to the use of the existing software, the development process could be conducted while solving problems for realistic test cases. The prospect of the development of the iSRE for geological disposal projects was realized and the iSRE was confirmed as being a useful tool for designing a repository.

Journal Articles

Effect of magnetism on lattice dynamics in SrFe$$_2$$As$$_2$$ using high-resolution inelastic X-ray scattering

Murai, Naoki*; Fukuda, Tatsuo; Kobayashi, Tatsuya*; Nakajima, Masamichi*; Uchiyama, Hiroshi*; Ishikawa, Daisuke*; Tsutsui, Satoshi*; Nakamura, Hiroki; Machida, Masahiko; Miyasaka, Shigeki*; et al.

Physical Review B, 93(2), p.020301_1 - 020301_5, 2016/01

 Times Cited Count:7 Percentile:41.71(Materials Science, Multidisciplinary)

Journal Articles

Numerical evaluation of the light transport properties of alternative He-3 neutron detectors using ceramic scintillators

Ozu, Akira; Takase, Misao*; Haruyama, Mitsuo; Kurata, Noritaka*; Kobayashi, Nozomi*; Kureta, Masatoshi; Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru; Suzuki, Hiroyuki; et al.

Nuclear Instruments and Methods in Physics Research A, 798, p.62 - 69, 2015/10

 Times Cited Count:2 Percentile:22.25(Instruments & Instrumentation)

The light transport properties of scintillator light inside alternative He-3 neutron detector modules using scintillator sheets have been investigated by a ray-tracing simulation code. The detector module consists of a light-reflecting tube, a thin rectangular ceramic scintillator sheet laminated on a glass plate, and two photo-multiplier tubes (PMTs) mounted at both ends of the detector tube. The light induced on the surface of the scintillator sheet via nuclear interaction between the scintillator and neutrons are detected by the two PMTs. The light output of various detector modules in which the scintillator sheets are installed with several different arrangements were examined and evaluated in comparison with experimental results. The results derived from the simulation reveal that the light transport property is strongly dependent on the arrangement of the scintillator sheet inside the tube and the shape of the tube.

Journal Articles

Nonhomologous end-joining repair plays a more important role than homologous recombination repair in defining radiosensitivity after exposure to high-LET radiation

Takahashi, Akihisa*; Kubo, Makoto*; Ma, H.*; Nakagawa, Akiko*; Yoshida, Yukari*; Isono, Mayu*; Kanai, Tatsuaki*; Ono, Tatsuya*; Furusawa, Yoshiya*; Funayama, Tomoo; et al.

Radiation Research, 182(3), p.338 - 344, 2014/09

 Times Cited Count:38 Percentile:87.69(Biology)

To clarify whether high-LET radiation inhibits all repair pathways or specifically one repair pathway, studies were designed to examine the effects of radiation with different LET values on DNA DSB repair and radiosensitivity. Embryonic fibroblasts bearing repair gene KO were exposed to X rays, carbon-, iron-, neon- and argon-ion beams. Cell survival was measured with colony-forming assays. The sensitization enhancement ratio (SER) values were calculated using the 10% survival dose of wild-type cells and repair-deficient cells. Cellular radiosensitivity was listed in descending order: double-KO cells $$>$$ NHEJ-KO cells $$>$$ HR-KO cells $$>$$ wild-type cells. Although HR-KO cells had an almost constant SER value, NHEJ-KO cells showed a high-SER value when compared to HR-KO cells, even with increasing LET values. These results suggest that with carbon-ion therapy, targeting NHEJ repair yields higher radiosensitivity than targeting homologous recombination repair.

Journal Articles

Increase in cell motility by carbon ion irradiation via the Rho signaling pathway and its inhibition by the ROCK inhibitor Y-27632 in lung adenocarcinoma A549 cells

Murata, Kazutoshi*; Noda, Shinei*; Oike, Takahiro*; Takahashi, Akihisa*; Yoshida, Yukari*; Suzuki, Yoshiyuki*; Ono, Tatsuya*; Funayama, Tomoo; Kobayashi, Yasuhiko; Takahashi, Takeo*; et al.

Journal of Radiation Research, 55(4), p.658 - 664, 2014/07

 Times Cited Count:15 Percentile:60.96(Biology)

The effect of carbon ion irradiation on cell motility through the Rho signaling pathway in the human lung adenocarcinoma cell line A549 was studied. At 48 h after irradiation, the cell motility of A549 cells became significantly greater, and the formation of protrusions significantly increased in cells irradiated with carbon ion. The observed increase in cell motility due to carbon ion irradiation was similar to that observed due to X-ray irradiation. Western-blot analysis showed that carbon ion irradiation increased P-MLC2-S19 expression compared with in unirradiated controls, while total MLC2 expression was unchanged. Exposure to a non-toxic concentration of Y-27632, a specific inhibitor of ROCK, reduced the expression of P-MLC2-S19 after C-ion irradiation, resulting in a significant reduction in migration. These data suggest that carbon irradiation increases cell motility in A549 cells via the Rho signaling pathway and that ROCK inhibition reduces that effect.

Journal Articles

Dynamics of edge limit cycle oscillation in the JFT-2M tokamak

Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*; et al.

Nuclear Fusion, 54(7), p.073017_1 - 073017_14, 2014/07

 Times Cited Count:22 Percentile:79.14(Physics, Fluids & Plasmas)

In the JFT-2M tokamak, limit-cycle oscillation among several variables is observed before L-to-H transition. Spatiotemporal dynamics of the LCO is analyzed in detail. Zonal fows are not seen, and modulation in edge-localized poloidal flow and density gradient is observed. Modulation is also seen in Reynolds stress, caused by that in turbulence intensity and turbulence wavenumber. However, flow acceleration is not able to be explained by the modulation in the Reynolds stress. Rapid inward propagation in density gradient and turbulence packet is also observed. Characteristics of the propagation are veried by means of turbulence spreading theory and diffusion theory.

Journal Articles

Development and demonstration of a Pu NDA system using ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator detectors

Nakamura, Hironobu; Ozu, Akira; Kobayashi, Nozomi*; Mukai, Yasunobu; Sakasai, Kaoru; Nakamura, Tatsuya; Soyama, Kazuhiko; Kureta, Masatoshi; Kurita, Tsutomu; Seya, Michio

Proceedings of INMM 55th Annual Meeting (Internet), 9 Pages, 2014/07

To establish an alternative technique of He-3 neutron detector that is used for nuclear material accountancy and safeguards, we have started an R&D project to develop a new type of neutron detector (Pu NDA system) using ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator with support of Japanese government. The design of the alternative system (ASAS: Alternative Sample Assay System) is basically referenced from INVS (INVentory Sample assay system) which is passive neutron assay system of plutonium and has total 18 He-3 tubes (about 42% of counting efficiency), and the small amount of Pu in the MOX powder or Pu nitrate solution in a vial can be measured. In order to establish the technology and performance after the fabrication of the new detector progresses, we are planning to conduct demonstration activity in the early 2015 experimentally. The demonstration activity implements the confirmation of reproducibility about sample positioning, optimization of detector parameters, counting statistical uncertainty, stability (temperature and $$gamma$$-ray change) check and figure of merit (FOM) using check source and actual MOX powder. In addition to that, performance comparison between current INVS and the ASAS are also conducted. In this paper, we present some analytical study results using a Monte-Carlo simulation code (MCNP), entire ASAS design and demonstration plan to prove technology and performance.

Journal Articles

First flight demonstration of glass-type space solar sheet

Shimazaki, Kazunori*; Kobayashi, Yuki*; Takahashi, Masato*; Imaizumi, Mitsuru*; Murashima, Mio*; Takahashi, Yu*; Toyota, Hiroyuki*; Kukita, Akio*; Oshima, Takeshi; Sato, Shinichiro; et al.

Proceedings of 40th IEEE Photovoltaic Specialists Conference (PVSC-40) (CD-ROM), p.2149 - 2154, 2014/06

The electrical performance of a glass-type space solar sheet (G-SSS) was demonstrated in space. G-SSS comprises InGaP/GaAs dual-junction and InGaP/GaAs/InGaAs triplejunction solar cells. It is lightweight solar generation sheet, less than 0.5 mm thick. It is mounted on the "HISAKI" (SPRINT-A) small scientific satellite, which was launched on September 14, 2013. The initial flight data were successfully acquired and this flight demonstration was a world-first experiment for G-SSS using III-V multi-junction thin-film solar cells. The cells demonstrated superior performance and the electrical outputs matched the flight prediction.

Journal Articles

Evaluation of light transport property in alternative He-3 neutron detectors using ceramic scintillators by a ray-tracing simulation

Ozu, Akira; Takase, Misao*; Kurata, Noritaka*; Kobayashi, Nozomi*; Tobita, Hiroshi; Haruyama, Mitsuo; Kureta, Masatoshi; Nakamura, Tatsuya; Suzuki, Hiroyuki; To, Kentaro; et al.

Proceedings of 2014 IEEE Nuclear Science Symposium and Medical Imaging Conference; 21st International Symposium on Room-Temperature Semiconductor X-ray and $$gamma$$-ray detectors (NSS/MIC 2014), 5 Pages, 2014/00

In Japan Atomic Energy Agency, the helium-3 alternative neutron detector using ceramic scintillators for nuclear safeguards is under development with the support of the government. The alternative detector module consists of four components: an aluminum regular square tube, a light reflecting foil put on the inner surface of the square tube, a rectangular scintillator sheet sintered on a glass plate, and two PMTs provided at both ends of the tube. The scintillator sheet is fit on the diagonal inside the square tube. The light transport property of scintillator lights inside the tube influences on the fundamental performance of the alternative detector. Therefore, the properties of the lights emitted on the surface of the scintillator sheet and scintillation lights passing through the glass plate to the PMTs in several arrangements of the scintillator in the tubes were investigated with a ray-tracing simulation. The results are described in comparison with the experimental results.

Journal Articles

Development of an alternative plutonium canister assay system (APCA) using He-3 alternative neutron detector

Ozu, Akira; Kureta, Masatoshi; Haruyama, Mitsuo; Takase, Misao; Kurata, Noritaka; Kobayashi, Nozomi; Soyama, Kazuhiko; Nakamura, Tatsuya; Sakasai, Kaoru; To, Kentaro; et al.

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-34-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2013/10

no abstracts in English

Journal Articles

Applicability of iron phosphate glass medium for loading NaCl originated from seawater used for cooling the stricken power reactors

Kobayashi, Hidekazu; Amamoto, Ippei; Yokozawa, Takuma; Yamashita, Teruo; Nagai, Takayuki; Kitamura, Naoto*; Takebe, Hiromichi*; Mitamura, Naoki*; Tsuzuki, Tatsuya*

Proceedings of 15th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2013) (CD-ROM), 6 Pages, 2013/09

no abstracts in English

Journal Articles

Behaviour of IPG waste forms bearing BaSO$$_{4}$$ as the dominant sludge constituent generated from the treatment of water used for cooling the stricken power reactors

Amamoto, Ippei; Kobayashi, Hidekazu; Yokozawa, Takuma; Yamashita, Teruo; Nagai, Takayuki; Kitamura, Naoto*; Takebe, Hiromichi*; Mitamura, Naoki*; Tsuzuki, Tatsuya*

Proceedings of 15th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2013) (CD-ROM), 8 Pages, 2013/09

The great amount of water used for cooling the stricken power reactors at Fukushima Dai-ichi has resulted in accumulation of "remaining water". As the remaining water is subsequently contaminated by FPs, etc., it is necessary to decontaminate it in order to reduce the volume of liquid radioactive waste and to reuse it again for cooling the reactors. Various techniques are being applied to remove FP, etc. and to make stable waste forms. One of the methods using the iron phosphate glass as a medium is being developed to stabilize the strontium-bearing sludge whose main component is BaSO$$_{4}$$. From the results hitherto, the iron phosphate glass is regarded as a potential medium for the target sludge.

Journal Articles

Spatiotemporal structures of edge limit-cycle oscillation before L-to-H transition in the JFT-2M tokamak

Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*; et al.

Physical Review Letters, 111(3), p.035002_1 - 035002_5, 2013/07

 Times Cited Count:83 Percentile:94.89(Physics, Multidisciplinary)

In this Letter, we report analyses of spatiotemporal dynamics of turbulence and structure in the limit cycle oscillation that precedes L-to-H transition. Zonal flows are not observed during LCO, and the oscillation is the periodic generations/decays of barrier with edge localized mean flow. Oscillatory Reynolds stress is found too small to accelerate the LCO flow. Changes of the density gradient and turbulence amplitude are found to propagate into the core in a ballistic manner, suggesting a cause of fast change of core transport after H-mode transition.

Journal Articles

Design of an Alternative Plutonium Canister Assay system (APCA) using ceramic scintillator neutron detectors for the safeguards NDA

Kureta, Masatoshi; Ozu, Akira; Haruyama, Mitsuo; Takase, Misao; Kurata, Noritaka; Kobayashi, Nozomi; Soyama, Kazuhiko; Nakamura, Tatsuya; Nakamura, Hironobu; Seya, Michio

Proceedings of INMM 54th Annual Meeting (CD-ROM), 8 Pages, 2013/07

Against the background of the serious shortage of He-3 gas, the ceramic scintillator neutron detectors have been developed for a safeguards-specific alternative to He-3 for neutron detection with support of Japan government (MEXT). In this paper, the evaluation of optical guide property on ceramic scintillator detectors and design of the demonstrator named Alternative Plutonium Canister Assay system (APCA).

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