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Journal Articles

Mitigation of cavity voltage jump due to high intensity beam extraction in J-PARC RCS

Tamura, Fumihiko; Sugiyama, Yasuyuki*; Okita, Hidefumi; Yamamoto, Masanobu; Yoshii, Masahito*; Omori, Chihiro*; Seiya, Kiyomi*; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; et al.

Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.774 - 776, 2024/10

The 3GeV RCS of J-PARC accelerates proton beams with a maximum beam intensity of 8e13 ppp, utilizing the features of magnetic alloy (MA) cavities. The beam is extracted in a single turn by kicker magnets, and immediately after the beam is extracted, a short voltage jump occurs in the cavity. This is due to a delay in the voltage control feedback, which takes a certain amount of time to respond to the step-like decrease of beam current upon single-turn extraction. In a wideband (Q=2) MA cavity, this response delay is observed as a voltage jump. This voltage jump can cause damage to the cavity system if the voltage at the time of extraction is high. Therefore, we prepared a logic to suppress the output synchronously with the beam extraction as a function of the LLRF control system. The details of the function and test results are reported.

Journal Articles

Circuit simulation model for the RF system of J-PARC RCS

Okita, Hidefumi; Tamura, Fumihiko; Yamamoto, Masanobu; Miyakoshi, Ryosuke*; Nomura, Masahiro; Shimada, Taihei; Yoshii, Masahito*; Omori, Chihiro*; Seiya, Kiyomi*; Hara, Keigo*; et al.

Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.765 - 769, 2024/10

no abstracts in English

Journal Articles

Post-earthquake rapid resealing of bedrock flow-paths by concretion-forming resin

Yoshida, Hidekazu*; Yamamoto, Koshi*; Asahara, Yoshihiro*; Maruyama, Ippei*; Karukaya, Koichi*; Saito, Akane*; Matsui, Hiroya; Mochizuki, Akihito; Jo, Mayumi*; Katsuta, Nagayoshi*; et al.

Communications Engineering (Internet), 3, p.67_1 - 67_10, 2024/05

A capability to permanently seal fluid flow-paths through bedrock, like boreholes or underground tunnels, is needed to ensure the long-term safety and effectiveness of many underground activities e.g. CO$$_{2}$$ storage, hydrocarbon field abandonment, and nuclear waste disposal. Commonly used cementitious seals may not be sufficiently durable due to chemical and physical degradation. Learning from natural calcite (CaCO$$_{3}$$) concretion formation, a more durable sealing method was developed using a "concretion-forming solvent". The method was tested by sealing flow-paths next to a tunnel in an underground research laboratory at 350 meters depth. The flow-paths initially sealed rapidly, then resealed after disturbance by earthquakes (M5.4). The treated rock recovered its very low natural permeability, demonstrating permanent sealing that is robust.

Journal Articles

Rapid and long-lasting bedrock flow-path sealing by a "concretion-forming resin"; Results from ${it in-situ}$ evaluation tests in an Underground Research Laboratory, Horonobe, Japan

Yoshida, Hidekazu*; Yamamoto, Koshi*; Asahara, Yoshihiro*; Maruyama, Ippei*; Karukaya, Koichi*; Saito, Akane*; Matsui, Hiroya; Mochizuki, Akihito; Katsuta, Nagayoshi*; Metcalfe, R.*

Powering the Energy Transition through Subsurface Collaboration; Proceedings of the 1st Energy Geoscience Conference (Energy Geoscience Conference Series, 1), 20 Pages, 2024/00

A capability to permanently seal fluid flow-paths in bedrock, such as natural faults/fractures, and damaged zones around boreholes/excavations, is needed to ensure the long-term safety and effectiveness of many underground activities. Cementitious materials are commonly used as seals, however these materials unavoidably undergo physical and chemical degradation, therefore potentially decreasing seal durability. In order to solve these problems, a more durable sealing method using concretion-forming resin has been developed by learning from natural calcite (CaCO$$_{3}$$) concretion formation. The sealing capability of resin was tested by ${it in-situ}$ experiments on bedrock flow-paths in an underground research laboratory (URL), Hokkaido, Japan. The results showed a decrease the permeability rapidly down to 1/1,000 of the initial permeability due to calcite precipitation over a period of one year. During the experiment inland earthquakes occurred with foci below the URL (depths 2-7 km and maximum magnitude 5.4). Due to the earthquakes the hydraulic conductivities of the flow-paths sealed initially by concretion-forming resin increased. However, these flow-paths subsequently resealed rapidly, and within a few months recovered the same hydraulic conductivities as before the earthquakes. This new technique for rapidly producing long-lasting seals against fluid flow through rocks will be applicable to many kinds of underground activities.

Journal Articles

Weakened oxygen adsorbing the Pt-O bond of the Pt catalyst induced by vacancy introduction into carbon support

Okazaki, Hiroyuki*; Idesaki, Akira*; Koshikawa, Hiroshi*; Matsumura, Daiju; Ikeda, Takashi*; Yamamoto, Shunya*; Yamaki, Tetsuya*

Journal of Physical Chemistry C, 127(49), p.23628 - 23633, 2023/12

 Times Cited Count:0 Percentile:0.00(Chemistry, Physical)

Journal Articles

Consideration of high intensity single bunch acceleration in J-PARC RCS

Tamura, Fumihiko; Okita, Hidefumi; Hotchi, Hideaki*; Saha, P. K.; Meigo, Shinichiro; Yoshii, Masahito*; Omori, Chihiro*; Yamamoto, Masanobu; Seiya, Kiyomi*; Sugiyama, Yasuyuki*; et al.

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.64 - 68, 2023/11

The J-PARC 3GeV synchrotron (RCS) provides high intensity proton beams to the Materials and Life Science Experimental Facility (MLF) and the Main Ring (MR). The harmonic number (h) of the RCS is 2 and the RCS normally accelerates two bunches. For some experiments at the MLF, a single bunch is preferred. In this case, one of the rf bucket is filled with protons and the other is empty. Therefore the beam intensity is halved. If the RCS can accelerate with h=1, the intensity per bunch can be doubled, enabling to provide single bunch beams to the MLF with the maximum intensity. This possibly increases the MR beam power by injecting high intensity single bunches eight times. In this presentation, we report mainly on the consideration of h=1 acceleration in the RCS by longitudinal simulations.

Journal Articles

RF systems of J-PARC proton synchrotrons for high-intensity longitudinal beam optimization and handling

Tamura, Fumihiko; Yamamoto, Masanobu; Yoshii, Masahito*; Omori, Chihiro*; Sugiyama, Yasuyuki*; Okita, Hidefumi; Seiya, Kiyomi*; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; et al.

Proceedings of 68th ICFA Advanced Beam Dynamics Workshop on High Intensity and High Brightness Hadron Beams (HB2023) (Internet), p.305 - 311, 2023/10

The application of MA cores to the accelerating rf cavities in high intensity proton synchrotrons was pioneered for the J-PARC synchrotrons. The MA cavities can generate high accelerating voltages. The wideband frequency response of the MA cavity enables the frequency sweep without the tuning loop. The dual harmonic operation is indispensable for the longitudinal bunch shaping to alleviate the space charge effects in the RCS. These advantages of the MA cavity are also disadvantages when looking at them from a different perspective. Since the wake voltage consists of several harmonics, the beam loading compensation must be multiharmonic. The operation of tubes in the final stage amplifier is not trivial when accelerating very high intensity beams; the output current is high and the anode voltage is also multiharmonic. We summarize our effort against these issues in the operation of the RCS and MR for more than 10 years.

Journal Articles

Changes in electronic structure of carbon supports for Pt catalysts induced by vacancy formation due to Ar$$^{+}$$ irradiation

Okazaki, Hiroyuki*; Kakitani, Kenta*; Kimata, Tetsuya*; Idesaki, Akira*; Koshikawa, Hiroshi*; Matsumura, Daiju; Yamamoto, Shunya*; Yamaki, Tetsuya*

Journal of Chemical Physics, 152(12), p.124708_1 - 124708_5, 2020/03

 Times Cited Count:5 Percentile:26.47(Chemistry, Physical)

Journal Articles

Imidazolium cation based anion-conducting electrolyte membranes prepared by radiation induced grafting for direct hydrazine hydrate fuel cells

Yoshimura, Kimio; Koshikawa, Hiroshi; Yamaki, Tetsuya; Shishitani, Hideyuki*; Yamamoto, Kazuya*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari

Journal of the Electrochemical Society, 161(9), p.F889 - F893, 2014/06

 Times Cited Count:22 Percentile:59.11(Electrochemistry)

Graft-type anion-conducting electrolyte membranes (AEMs) with imidazolium cations on graft polymers were synthesized through radiation-induced graft polymerization of ${it N}$-vinylimidazole (NVIm) on poly(ethylene-co-tetrafluoroethylene) (ETFE) films, followed by ${it N}$-propylation and ion-exchange reactions. The ${it N}$-propylation proceeded quantitatively, whereas the ion-exchange reactions in 1 M KOH at 60$$^{circ}$$C were accompanied by partial $$beta$$-elimination of the imidazolium cations(AEM2), which exhibited an ion-exchange capacity (IEC) of 0.85 mmol g$$^{-1}$$ and ionic conductivity of 10 mS cm$$^{-1}$$. AEM2 showed alkaline stability at 60$$^{circ}$$C but it gradually degraded at 80$$^{circ}$$C for ca. 150 h. The copolymer-type AEM (AEM3) with an IEC of 1.20 mmol g$$^{-1}$$ was prepared through the copolymerization of NVIm with styrene on ETFE films, followed by the same ${it N}$-propylation and ion-exchange reactions. AEM3 was shown higher alkaline durability in 1 M KOH at 80$$^{circ}$$C. As a result, it exhibited higher conductivity ($$>$$10 mS cm$$^{-1}$$) for 250 h. Therefore, alkylimidazolium cations in copolymer grafts are a promising anion conducting group for alkaline-durable AEMs. A maximum power density of 75 mW cm$$^{-2}$$ is obtained for AEM3 in a direct hydrazine hydrate fuel cell.

Journal Articles

Sorption of Eu(III) on granite; EPMA, LA-ICP-MS, batch and modeling studies

Fukushi, Keisuke*; Hasegawa, Yusuke*; Maeda, Koshi*; Aoi, Yusuke*; Tamura, Akihiro*; Arai, Shoji*; Yamamoto, Yuhei*; Aosai, Daisuke*; Mizuno, Takashi

Environmental Science & Technology, 47(22), p.12811 - 12818, 2013/11

 Times Cited Count:31 Percentile:62.18(Engineering, Environmental)

Eu(III) sorption on granite was examined by the combined microscopic and macroscopic approaches. Polished thin sections of the granite were reacted with solutions containing 10 $$mu$$M of Eu(III) and analyzed using EPMA and LA-ICP-MS. The Eu enrichment up to 6 wt.% was observed on most of the biotite grains. The Eu-enriched parts commonly lose K, which is the interlayer cation of biotite, indicating that the sorption mode is cation exchange in the interlayer. Batch Eu(III) sorption experiments on granite and biotite powders were conducted. The macroscopic sorption behavior of biotite was consistent with that of granite. The obtained sorption edges can be reproduced reasonably by the modeling considering single-site cation exchange reactions. Granite is complex mineral assemblages. However, the combined microscopic and macroscopic approaches revealed that elementary reactions by single phase can be representative for the bulk sorption reaction in complex mineral assemblages.

Journal Articles

Counter-anion effect on the properties of anion-conducting polymer electrolyte membranes prepared by radiation-induced graft polymerization

Koshikawa, Hiroshi; Yoshimura, Kimio; Sinnananchi, W.; Yamaki, Tetsuya; Asano, Masaharu; Yamamoto, Kazuya*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari

Macromolecular Chemistry and Physics, 214(15), p.1756 - 1762, 2013/08

 Times Cited Count:17 Percentile:46.16(Polymer Science)

Graft-type anion-conducting polymer electrolyte membranes were prepared by the radiation-induced graft polymerization of chloromethylstyrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and subsequent quaternization with trimethylamine to evaluate the counter anion effects on fuel cell properties. The hydroxide form was maintained in -saturated water to prevent the bicarbonate formation. The hydroxide form showed conductivity and water uptake four and two times higher than the chloride and bicarbonate forms. The hydroxide form is thermally and chemically less stable, resulting in the tendency to absorb water and to convert to the bicarbonate form.

Journal Articles

Assessment of olfactory nerve by SPECT-MRI image with nasal thallium-201 administration in patients with olfactory impairments in comparison to healthy volunteers

Shiga, Hideaki*; Taki, Junichi*; Washiyama, Koshin*; Yamamoto, Jumpei*; Kinase, Sakae; Okuda, Koichi*; Kinuya, Seigo*; Watanabe, Naoto*; Tonami, Hisao*; Koshida, Kichiro*; et al.

PLOS ONE (Internet), 8(2), p.e57671_1 - e57671_8, 2013/02

 Times Cited Count:20 Percentile:70.40(Multidisciplinary Sciences)

Journal Articles

Alkaline durable anion exchange membranes based on graft-type fluoropolymer films for hydrazine hydrate fuel cell

Yoshimura, Kimio; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Yamamoto, Kazuya*; Shishitani, Hideyuki*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*

ECS Transactions, 50(2), p.2075 - 2081, 2012/10

no abstracts in English

Journal Articles

Detailed analyses of key phenomena in core disruptive accidents of sodium-cooled fast reactors by the COMPASS code

Morita, Koji*; Zhang, S.*; Koshizuka, Seiichi*; Tobita, Yoshiharu; Yamano, Hidemasa; Shirakawa, Noriyuki*; Inoue, Fusao*; Yugo, Hiroaki*; Naito, Masanori*; Okada, Hidetoshi*; et al.

Nuclear Engineering and Design, 241(12), p.4672 - 4681, 2011/12

 Times Cited Count:19 Percentile:78.96(Nuclear Science & Technology)

A five-year research project has been initiated in 2005 to develop a code based on the MPS (Moving Particle Semi-implicit) method for detailed analysis of key phenomena in core disruptive accidents (CDAs) of sodium-cooled fast reactors (SFRs). The code is named COMPASS (Computer Code with Moving Particle Semi-implicit for Reactor Safety Analysis). The key phenomena include (1) fuel pin failure and disruption, (2) molten pool boiling, (3) melt freezing and blockage formation, (4) duct wall failure, (5) low-energy disruptive core motion, (6) debris-bed coolability, (7) metal-fuel pin failure. Validation study of COMPASS is progressing for these key phenomena. In this paper, recent COMPASS results of detailed analyses for the several key phenomena are summarized. The present results demonstrate COMPASS will be useful to understand and clarify the key phenomena of CDAs in SFRs in details.

Journal Articles

Preparation of anion-exchange membranes for fuel cell applications by $$gamma$$-ray pre-irradiation grafting

Koshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Maekawa, Yasunari; Yamaguchi, Susumu*; Yamamoto, Kazuya*; Asazawa, Koichiro*; Yamada, Koji*; Tanaka, Hirohisa*

Proceedings of 12th International Conference on Radiation Curing in Asia (RadTech Asia 2011) (Internet), p.240 - 241, 2011/06

The anion-exchange membranes (AEM) for fuel cells were prepared by the radiation-induced graft polymerization of chloromethylstyrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and subsequent quaternization of the grafts with trimethylamine. When the AEM were treated in 1M-KOH and washed with N$$_{2}$$-saturated water, the membranes with chloride form can be converted quantitatively to hydroxide form. However, the hydroxide form was easily converted to the bicarbonate form by the treatment in non-bubbled (CO$$_{2}$$ dissolved) water. When we introduced the crosslinkers in polymer grafts, which is proved to be very effective in the proton conducting PEM having a poly(styrenesulfonic acid) grafts, the grafted AEM with both chloride and hydroxide forms showed only slight decrease of water uptake. It should be noted that AEM with hydroxide form showed very high tendency to absorb water.

Journal Articles

COMPASS code development; Validation of multi-physics analysis using particle method for core disruptive accidents in sodium-cooled fast reactors

Koshizuka, Seiichi*; Morita, Koji*; Arima, Tatsumi*; Tobita, Yoshiharu; Yamano, Hidemasa; Ito, Takahiro*; Naito, Masanori*; Shirakawa, Noriyuki*; Okada, Hidetoshi*; Uehara, Yasushi*; et al.

Proceedings of 8th International Topical Meeting on Nuclear Thermal-Hydraulics, Operation and Safety (NUTHOS-8) (CD-ROM), 11 Pages, 2010/10

In this paper, FY2009 results of the COMPASS code development are reported. Validation calculations for melt freezing and blockage formation, eutectic reaction of metal fuel, duct wall failure (thermal-hydraulic analysis), fuel pin failure and disruption and duct wall failure (structural analysis) are shown. Phase diagram calculations, classical and first-principles molecular dynamics were used to investigate physical properties of eutectic reactions: metallic fuel/steel and control rod material/steel. Basic studies for the particle method and SIMMER code calculations supported the COMPASS code development. COMPASS is expected to clarify the basis of experimentally-obtained correlations used in SIMMER. Combination of SIMMER and COMPASS will be useful for safety assessment of CDAs as well as optimization of the core design.

Journal Articles

Ion beam modification of Pt electrocatalyst nanoparticles for polymer electrolyte membrane fuel cells

Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Koshikawa, Hiroshi

Materials Research Society Symposium Proceedings, Vol.1217, p.151 - 157, 2010/07

This study concerns our attempt to improve catalytic properties of nanoparticles of Pt and Pt-group metals by modification with ion beams. We expected that a completely high electronic excitation induced by high-energy ion beams could achieve new atomic arrangement and electronic states at the nanoparticle surface. Pt nanoparticles were prepared on a glassy carbon plate by a sputtering method and then irradiated with proton beams at energies of 0.38 and 10 MeV at room temperature. Cyclic voltammetry in a 0.5 M sulfonic acid aqueous solution suggested that the lower-energy beam irradiation enhanced the active surface area of the Pt nanoparticles, calculated from the coulombic charge for hydrogen adsorption. Thus, the nanoparticles will be modified by the proton-beam excitation so that they have higher surface reactivity. The mechanism determining this irradiation effect is still unclear at present, but we may discuss it in relation to a change in the interfacial crystal structure induced by the irradiation.

Journal Articles

Detailed analyses of specific phenomena in core disruptive accidents of sodium-cooled fast reactors by the COMPASS code

Morita, Koji*; Zhang, S.*; Arima, Tatsumi*; Koshizuka, Seiichi*; Tobita, Yoshiharu; Yamano, Hidemasa; Ito, Takahiro*; Shirakawa, Noriyuki*; Inoue, Fusao*; Yugo, Hiroaki*; et al.

Proceedings of 18th International Conference on Nuclear Engineering (ICONE-18) (CD-ROM), 9 Pages, 2010/05

A five-year research project has been initiated in 2005 to develop a code based on the MPS (Moving Particle Semi-implicit) method for detailed analysis of specific phenomena in core disruptive accidents (CDAs) of sodium-cooled fast reactors (SFRs). The code is named COMPASS (Computer Code with Moving Particle Semi-implicit for Reactor Safety Analysis). The specific phenomena include (1) fuel pin failure and disruption, (2) molten pool boiling, (3) melt freezing and blockage formation, (4) duct wall failure, (5) low-energy disruptive core motion, (6) debris-bed coolability, and (7) metal-fuel pin failure. Validation study of COMPASS is progressing for these key phenomena. In this paper, recent COMPASS results of detailed analyses for the several specific phenomena are summarized.

Journal Articles

Validation for multi-physics simulation of core disruptive accidents in sodium-cooled fast reactors by COMPASS code

Koshizuka, Seiichi*; Morita, Koji*; Arima, Tatsumi*; Zhang, S.*; Tobita, Yoshiharu; Yamano, Hidemasa; Ito, Takahiro*; Naito, Masanori*; Shirakawa, Noriyuki*; Okada, Hidetoshi*; et al.

Proceedings of 13th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-13) (CD-ROM), 11 Pages, 2009/09

Dispersion and freezing of molten core material was calculated by the COMPASS code to compare with the experimental data of GEYSER. Molten core material flowed up with freezing on the pipe inner surface. As a molten pool behavior, CABRI-TPA2 experiment was analyzed, where a sphere of solid steel was surrounded by solid fuel. Power was injected to cause melting and boiling of the steel sphere. SCARABEE-BE+3 test was analyzed by COMPASS as a validation of failure of duct walls.

Journal Articles

Next generation safety analysis methods for SFRs, 3; Thermal hydraulics models of COMPASS code and experimental analyses

Yamamoto, Yuichi*; Hirano, Etsujo*; Oue, Masaya*; Shimizu, Sensuke*; Shirakawa, Noriyuki*; Koshizuka, Seiichi*; Morita, Koji*; Yamano, Hidemasa; Tobita, Yoshiharu

Proceedings of 17th International Conference on Nuclear Engineering (ICONE-17) (CD-ROM), 10 Pages, 2009/06

The COMPASS code is designed to analyze multi-physics problems involving thermal hydraulics, structure and phase change, in a unified framework of MPS method. In FY2006 and 2007, development of the basic functions of COMPASS was completed and fundamental verification calculations were carried out. In FY2007, the integrated verification program using available experimental data for key phenomena in CDAs was also started. In this paper, we show the basic verification calculations for the phase change model of COMPASS and the results of experimental analyses, together with the outline of the formulation of MPS method and the conceptual design of the COMPASS code.

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