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Journal Articles

Synergistic enhancement of the extraction and separation efficiencies of lanthanoid(III) ions by the formation of charged adducts in an ionic liquid

Okamura, Hiroyuki; Mizuno, Masayoshi*; Hirayama, Naoki*; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*

Industrial & Engineering Chemistry Research, 59(1), p.329 - 340, 2020/01

 Times Cited Count:6 Percentile:64.04(Engineering, Chemical)

The synergistic ionic-liquid extraction and extraction equilibrium of lanthanoid(III) (Ln(III)) ions have been investigated using 2-thenoyltrifluoroacetone (Htta) and trioctylphosphine oxide (TOPO) in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C$$_{4}$$mim][Tf$$_{2}$$N]). The selective synergistic effect for heavier Ln(III) ions was found using a combination of Htta and TOPO in [C$$_{4}$$mim][Tf$$_{2}$$N], leading to enhanced separability among Ln(III) ions. The extracted Ln(III) species and the extraction constants in the Htta-TOPO system were determined by three-dimensional extraction equilibrium analysis. The selective synergism for heavier Ln(III) ions in the Htta-TOPO system was ascribed to the formation of hydrophobic, charged adducts, such as Ln(tta)$$_{2}$$(TOPO)$$_{3}$$$$^{+}$$ and Ln(tta)(TOPO)$$_{3}$$$$^{2+}$$, in [C$$_{4}$$mim][Tf$$_{2}$$N].

Journal Articles

Comparative study on performance of various environmental radiation monitors

Tamakuma, Yuki*; Yamada, Ryohei; Suzuki, Takahito*; Kuroki, Tomohiro*; Saga, Rikiya*; Mizuno, Hiroyuki*; Sasaki, Hiroyuki*; Iwaoka, Kazuki*; Hosoda, Masahiro*; Tokonami, Shinji*

Radiation Protection Dosimetry, 184(3-4), p.307 - 310, 2019/10

 Times Cited Count:1 Percentile:23.13(Environmental Sciences)

After the Fukushima Daiichi Nuclear Power Plant accident, the radiation dose for first responders was not evaluated accurately due to lack of the monitoring data. It has been important to evaluate a radiation dose for workers in emergency response at a nuclear accident. In this study, a new device which can evaluate both of external and internal exposure doses was developed and the performance of various environmental radiation monitors including commercially available monitors were tested and compared from the viewpoint of an environmental monitoring at emergency situation. Background counts of the monitors and the ambient dose equivalent rate were measured in Fukushima Prefecture. The detection limit for beta particles was evaluated by the method of ISO11929. The sensitivity for gamma-rays of the dust monitor using a ZnS(Ag) and a plastic scintillator was high, but that of the external exposure monitor using a silicon photodiode with CsI(Tl) crystal was relatively low. The detection limit ranged 190-280 Bq m$$^{-3}$$ at 100 $$mu$$Sv h$$^{-1}$$, exceeding the detection limit of 100 Bq m$$^{-3}$$ in the minimum requirement by the National Regulation Authority in Japan. Use of the shielding with lead is necessary to achieve the minimum requirement. These results indicate that the dust monitor using a ZnS(Ag) scintillator and a plastic scintillator is suitable for the external exposure monitor and the developed internal exposure monitor is for the internal exposure monitor at emergency situation among the evaluated monitors. In the future study, the counting efficiency, the relative uncertainty and the performance of the detection for alpha particles will be evaluated, and it will be considered which type of a monitor is suitable after taking the portability into account.

Journal Articles

A Portable radioactive plume monitor using a silicon photodiode

Tamakuma, Yuki*; Yamada, Ryohei; Iwaoka, Kazuki*; Hosoda, Masahiro*; Kuroki, Tomohiro*; Mizuno, Hiroyuki*; Yamada, Koji*; Furukawa, Masahide*; Tokonami, Shinji*

Perspectives in Science (Internet), 12, p.100414_1 - 100414_4, 2019/09

In this study, a portable radioactive plume monitor using a silicon photodiode was developed for the detection of a radioactive plume (e.g. $$^{131}$$I, $$^{134}$$Cs and $$^{137}$$Cs) in an emergency situation. It was found that the background count rate was proportional to ambient dose equivalent rate and the detection limit for the monitor at 20 $$mu$$Sv h$$^{-1}$$ as an ambient dose equivalent rate was evaluated to be 187 Bq m$$^{-3}$$ using the ISO11929 method. These results suggest that the detection limit for the system can be decreased effectively by lead shielding with optimized thickness.

JAEA Reports

Mizunami Underground Research Laboratory Project, Plan for fiscal year 2012

Kunimaru, Takanori; Mikake, Shinichiro; Nishio, Kazuhisa; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Ishibashi, Masayuki; Kuboshima, Koji; Takeuchi, Ryuji; Mizuno, Takashi; Sato, Toshinori; et al.

JAEA-Review 2012-028, 31 Pages, 2012/08


Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU project is planned in three overlapping phases; Surface-based Investigation Phase (Phase I), Construction Phase (Phase II) and Operation Phase (Phase III). Currently, the project is under the Construction Phase and the Operation Phase. This document introduces the research and development activities planned for 2012 fiscal year based on the MIU Master Plan updated in 2010, construction plan and research collaboration plan, etc.

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2010

Kunimaru, Takanori; Mikake, Shinichiro; Nishio, Kazuhisa; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Ishibashi, Masayuki; Ueno, Takashi; Tokuyasu, Shingo; Daimaru, Shuji; Takeuchi, Ryuji; et al.

JAEA-Review 2012-020, 178 Pages, 2012/06


Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) Project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The MIU Project has been ongoing the Phase II. And Phase III started in 2010 fiscal year. This report shows the results of the investigation, construction and collaboration studies in fiscal year 2010, as a part of the Phase II based on the MIU Master Plan updated in 2002.

Journal Articles

1 MV holding and beam optics in a multi-aperture multi-grid accelerator for ITER NBI

Kashiwagi, Mieko; Taniguchi, Masaki; Kojima, Atsushi; Dairaku, Masayuki; Hanada, Masaya; Hemsworth, R. S.*; Mizuno, Takatoshi*; Takemoto, Jumpei; Tanaka, Masanobu*; Tanaka, Yutaka*; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

At JAEA, a multi-aperture multi-grid accelerator has been developed for the ITER neutral beam system. A target is H$$^{-}$$ ion beam acceleration of 0.5 A (200 A/m$$^{2}$$) at 1 MeV. In real accelerators, it was found that the voltage holding was about a half of that obtained in an ideal small electrode. After applying necessary gap length and radii of edges of grid supports to lower local electric field concentrations, the accelerator succeeded in sustaining 1 MV for 4000 s. As a result, beam parameters were increased to 879 keV, 0.36 A (157 A/m$$^{2}$$) at perveance matched condition from 796 kV, 0.32 A (140 A/m$$^{2}$$) reported in FEC2008. In the beam acceleration, the beamlet deflections due to magnetic field and space charge repulsion caused direct interceptions, that resulted in limitations in the beam energy and current. Compensation of these beamlet deflections has been tested applying aperture offset and field shaping plate, which were examined in a three-dimensional beam analysis.

Journal Articles

Three-dimensional analysis of beamlet deflection in a MeV accelerator for ITER NBI

Kashiwagi, Mieko; Taniguchi, Masaki; Umeda, Naotaka; Mizuno, Takatoshi; Tobari, Hiroyuki; Dairaku, Masayuki; Watanabe, Kazuhiro; Inoue, Takashi

Plasma and Fusion Research (Internet), 5, p.S2097_1 - S2097_4, 2010/12

An accelerator which generates deuterium negative ion beams of 1 MeV, 40 A for 3600 s is required for the ITER neutral beam injector (NBI). To realize such a high power accelerator, numerical studies have been carried out in parallel to acceleration tests in JAEA. After long pulse acceleration tests up to 30 s, it was found that parts of grid were melt around the grid apertures. In order to investigate how the grids melted, a three dimensional beam analysis was carried out in combination with 2D beam analysis code and gas flow code. The analysis clarified that the beamlet was deflected due to their own space charge repulsion and magnetic field at extraction grid, which led to direct interceptions of the beamlets at the grids. The power loads at the grid by these deflected beamlets were found to be more than 20 kW/cm$$^{2}$$. For next long pulse tests, a new extraction grid with aperture offset and field shaping plate has been designed so as to compensate the beamlet deflections.

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry in the Mizunami group and Toki granite area (April, 2004 - March, 2008)

Sai, Masataka; Hagiwara, Hiroki; Matsushima, Hiroyuki*; Noda, Masatoshi*; Noda, Masaru*; Ando, Kenichi*; Tanaka, Tatsuya*; Ueda, Tadashi*; Honda, Yuko*; Mizuno, Takashi

JAEA-Data/Code 2010-010, 75 Pages, 2010/09


This report compiles data set of the groundwater chemistry obtained at Mizunami Underground Research Laboratory (MIU) between the fiscal year 2004 and the fiscal year 2007. These data includes groundwater chemistry of inflow in the shafts and sampled groundwater in the boreholes, which drilled from sub-stages of MIU and from surface (MSB-2, MSB-4, and MIZ-1). Basic information (e.g. sampling location, sampling date, sampling method, analytical method) are also described in terms of quality control and traceability.

Journal Articles

Heat loading of MeV accelerator grids during long pulse beam operation

Umeda, Naotaka; Mizuno, Takatoshi; Taniguchi, Masaki; Kashiwagi, Mieko; Ezato, Koichiro; Tobari, Hiroyuki; Dairaku, Masayuki; Watanabe, Kazuhiro; Sakamoto, Keishi; Inoue, Takashi

Journal of Plasma and Fusion Research SERIES, Vol.9, p.259 - 263, 2010/08

Long pulse acceleration of ITER class H$$^{-}$$ ion beam has carried out at MeV accelerator. Melts of the acceleration grids were found around grid apertures. To accelerate higher power beam, compensation of the beam deflection and design of a new grid which has high cooling performance is required. In this study, 3D thermal transport analysis was carried out and a new acceleration grid was designed. From the analysis, it was found that the grid temperature exceeded the melting point in a few seconds. To overcome this problem, a new acceleration grid was designed whose cooling channel was drilled near upper surface. This countermeasure is effective not only to reduce the temperature rise but to enlarge the aperture size from 14 mm to 16 mm. From the result of heat analysis, temperature rise of the new grid is greatly reduced than that of the previous grid. It is expected that higher power and longer pulse beam would be accelerated at next test campaign.

Journal Articles

Development of the high voltage bushing for the ITER NBI

Tobari, Hiroyuki; Inoue, Takashi; Dairaku, Masayuki; Umeda, Naotaka; Kashiwagi, Mieko; Taniguchi, Masaki; Mizuno, Takatoshi; Watanabe, Kazuhiro; Sakamoto, Keishi

Journal of Plasma and Fusion Research SERIES, Vol.9, p.152 - 156, 2010/08

The high voltage (HV) bushing in ITER NBI acts as a feed through for electric power and cooling water from the -1 MV power supply in pressurized SF$$_{6}$$ gas atmosphere to negative ion source / accelerator inside vacuum. The HV bushing has five-stage structure each of which consists of a large bore ceramic ring with 1.56 m in diameter as the insulator. The ceramic is metalized and brazed with Kovar plate and then metal flanges to form the vacuum boundary as a whole. However, there is no practical example of brazing with such a large ceramic. JAEA has successfully accomplished brazing of the world's largest ceramic with Kovar plate for the first time through sample tests and mechanical analyses. Following the result, manufacturing of a mock-up simulating one-stage of the HV bushing has been completed and its vacuum insulation test is now ongoing. Electric field design inside the HV bushing for -1 MV insulation is also ongoing. In this conference, recent progresses above are reported.

Journal Articles

Long pulse H$$^{-}$$ ion beam acceleration in MeV accelerator

Taniguchi, Masaki; Mizuno, Takatoshi; Umeda, Naotaka; Kashiwagi, Mieko; Watanabe, Kazuhiro; Tobari, Hiroyuki; Kojima, Atsushi; Tanaka, Yutaka; Dairaku, Masayuki; Hanada, Masaya; et al.

Review of Scientific Instruments, 81(2), p.02B101_1 - 02B101_3, 2010/02

 Times Cited Count:7 Percentile:37.33(Instruments & Instrumentation)

A Multi-Aperture Multi-Grid (MAMuG) accelerator called "MeV accelerator" has been developed for neutral beam injection (NBI) system of ITER. The MeV accelerator succeeded in accelerating 796 keV, 320 mA H$$^{-}$$ ion beam until 2007. However, pulse length was limited to 0.2 s due to un-cooled grids. In the present work, long pulse H$$^{-}$$ ion beam acceleration was performed by the MeV accelerator equipped with water-cooled new grids. The H$$^{-}$$ ion current was increased step by step at certain energy with seeding Cs up to the optimum perveance. At present, pulse length was extended to 5 s for 750 keV, 221 mA (perveance match) and maximum power of 1.01 MJ was achieved (650 keV, 163 mA, 10s). At higher energy and current, pulse length was limited by breakdowns between the grids. This was due to high heat load on A3G and GRG grid by deflection of H$$^{-}$$ ion beam.

Journal Articles

Analysis of secondary particle behavior in multiaperture, multigrid accelerator for the ITER neutral beam injector

Mizuno, Takatoshi; Taniguchi, Masaki; Kashiwagi, Mieko; Umeda, Naotaka; Tobari, Hiroyuki; Watanabe, Kazuhiro; Dairaku, Masayuki; Sakamoto, Keishi; Inoue, Takashi

Review of Scientific Instruments, 81(2), p.02B103_1 - 02B103_3, 2010/02

 Times Cited Count:3 Percentile:19.73(Instruments & Instrumentation)

For a neutral beam injector (NBI) of ITER, the negative ion accelerator capable of 1 MeV, 40 A negative ion beam acceleration for up to 3,600 s is required. Suppression of heat load onto acceleration grids is a key issue for the long pulse acceleration of negative ion beams. A major source of the heat load will be from incident of secondary particles, which are neutrals, positive ions and electrons, on the grids. The complicated behavior of secondary particles in the MeV accelerator of JAEA is analyzed using the Electrostatic Accelerator Mote Carlo Code (EAMCC) developed by CEA. Water-cooled new grids were equipped with the MeV accelerator for the long pulse H$$^{-}$$ ion beam acceleration and second acceleration grid (A2G) was removed for simplification. Analytical results for 600 keV H$$^{-}$$ beam acceleration show that the heat load of third acceleration grid (A3G) is inevitably high because of lack of upstream grid, i.e., A2G.

Journal Articles

Analyses of high power negative ion accelerators for ITER neutral beam injector

Kashiwagi, Mieko; Taniguchi, Masaki; Dairaku, Masayuki; Grisham, L.*; Hanada, Masaya; Mizuno, Takatoshi; Tobari, Hiroyuki; Umeda, Naotaka; Watanabe, Kazuhiro; Sakamoto, Keishi; et al.

Review of Scientific Instruments, 81(2), p.02B113_1 - 02B113_5, 2010/02

 Times Cited Count:5 Percentile:29.08(Instruments & Instrumentation)

In JAEA, a multi aperture and multi grid accelerator has been tested for ITER NBI. In recent experiments, it was shown that the acceleration gaps (1st/2nd/3rd/4th/5th gap) have to be expanded from 104/94/87/78/72 in the original to all 100 mm to sustain 200 kV in each stage stably, and 1 MV in total. On the contrary, increases of beam divergence, stripping loss of negative ions and beamlet deflections due to space charge repulsion among beamlets could appear as issues due to the longer gaps. Beam divergence and stripping loss of ions have been examined in a 2D beam optics study utilizing BEAMORBT code and 3D gas flow code, respectively. Beamlet deflections have been examined in a 3D multi beamlet analysis utilizing OPERA-3d code. As results of these simulations, it was clarified that the gap length could be expanded up to 120 mm. This results were applied to design of the accelerator with the long gap of 120 mm.

JAEA Reports

Behavior of secondary-particles in a MeV-class electrostatic accelerator

Mizuno, Takatoshi; Inoue, Takashi; Taniguchi, Masaki; Kashiwagi, Mieko; Umeda, Naotaka; Tobari, Hiroyuki; Dairaku, Masayuki; Watanabe, Kazuhiro

JAEA-Research 2008-120, 19 Pages, 2009/03


In an accelerator for a N-NBI, there are several processes of secondary-particle production such as the collision of H$$^-$$ ions with H$$_2$$ gas, extraction of H$$_{2}^{+}$$ ions from beam plasma, and secondary-electron emission. The secondary particles cause heat load to the NBI components. It is necessary to analyze behavior of them in the accelerator. In this report, the secondary-particle behavior in MAMuG type MeV accelerator at JAEA has been analyzed by EAMCC. In the result, it is clarified that about 40% of H$$^-$$ ions extracted from the ion source were lost by the stripping process in the MeV accelerator. More than 90% of the heat load to the intermediate grids was caused by collision of the electrons. A comparison of results obtained from experiments and present analyses showed different tendency in the currents flowing into the 2nd and the 3rd intermediate grids. This is supposed due to H$$_{2}^{+}$$ ions extracted from beam plasma as a possible cause of the difference.

Journal Articles

Numerical analysis of the hydrogen atom density in a negative ion source

Takato, Naoyuki; Hanatani, Junji*; Mizuno, Takatoshi*; Hatayama, Akiyoshi*; Tobari, Hiroyuki; Hanada, Masaya; Inoue, Takashi; Taniguchi, Masaki; Dairaku, Masayuki; Kashiwagi, Mieko; et al.

AIP Conference Proceedings 925, p.38 - 45, 2007/09

The production and transport processes of the H$$^0$$ atom are numerically simulated to obtain the H$$^0$$ atom density. The three dimensional transport code using the Monte Carlo method has been applied to H$$^0$$ atoms in the large "JAEA 10 ampere negative ion source" under the Cs-seeded condition. In this study, the production rate of H$$^0$$ atoms through the dissociation process of H$$_2$$ molecules is estimated from single probe characteristics of the Langmuir probe measurement. In addition, the energy relaxation process of H$$^0$$ atoms is also considered. The results show that the existence of high-energy electrons and the energy relaxation process of H$$^0$$ atoms affect the H$$^0$$ atom density.

Journal Articles

Improvement of beam uniformity by magnetic filter optimization in a Cs-seeded large negative-ion source

Hanada, Masaya; Seki, Takayoshi*; Takado, Naoyuki*; Inoue, Takashi; Tobari, Hiroyuki; Mizuno, Takatoshi*; Hatayama, Akiyoshi*; Dairaku, Masayuki; Kashiwagi, Mieko; Sakamoto, Keishi; et al.

Review of Scientific Instruments, 77(3), p.03A515_1 - 03A515_3, 2006/03

 Times Cited Count:24 Percentile:73.73(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Construction of the J-PARC L3BT control system

Shen, G.; Watanabe, Kazuhiko*; Kato, Yuko; Sakaki, Hironao; Sako, Hiroyuki; Ito, Yuichi; Yoshikawa, Hiroshi; Hanawa, Katsushi*; Mizuno, Seiji*

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.364 - 366, 2006/00

The control system of J-PARC project is under construction. After almost finishing the hardware installation of the L3BT section, an online device commissioning was performed for magnet power supply, stepping motor and vacuum system. Many components for device control have already been developed separately, but not integrated together yet. It is the first experience to combine all the components, including core software for a front-end IO controller, an EPICS run-time database, and a remote graphic user interface. This paper describes the detail of the recent construction status of the L3BT control system, including component development, system integration, and device commissioning.

JAEA Reports

Feasibility Study on Commercialization of Fast Breeder Reactor Cycle Systems Interim Report of Phase II; Technical Study Report for Reactor Plant Systems

Konomura, Mamoru; Ogawa, Takashi; Okano, Yasushi; Yamaguchi, Hiroyuki; Murakami, Tsutomu; Takaki, Naoyuki; Nishiguchi, Youhei; Sugino, Kazuteru; Naganuma, Masayuki; Hishida, Masahiko; et al.

JNC TN9400 2004-035, 2071 Pages, 2004/06


The attractive concepts for Sodium-, lead-bismuth-, helium- and water-cooled FBRs have been created through using typical plant features and employing advanced technologies. Efforts on evaluating technological prospects of feasibility have been paid for these concepts. Also, it was comfirmed if these concepts satisfy design requierments of capability and performance presumed in the feasibilty study on commertialization of Fast Breeder Reactor Systems. As results, it was concluded that the selection of sodium-cooled reactor was most rational for practical use of FBR technologies in 2015.

JAEA Reports

Design study on core characteristics of sodium cooled fast reactors; Mixed oxide fuel cores

Yamadate, Megumi; Yamaguchi, Hiroyuki; Naganuma, Masayuki; Mizuno, Tomoyasu; Takaki, Naoyuki

JNC TN9400 2002-065, 131 Pages, 2002/12


Phase-II of the Feasibility Study on Commercialized Fast Reactor Cycle System in Japan (F/S) has been started since April 2001 and the design studies of various FR and recycle concepts are being conducted. In this report the JFY2001 studies of sodium cooled FR with mixed oxide fuel are summarized. The main results are as following. (1) Large scale reactors (1,500 MWe) (a) As for the large scale homogeneous ABLE type fuel core, we aimed to improve the effective average burn-up (that includes contribution of blankets) in order to reduce the fuel cycle cost. The specifications of Phase-I core and fuel were modified, which results in reducing the numbers of radial blanket sub-assemblies. As a result, the effective average burn-up was improved from 63 GWd/t to 77GWd/t. (b) As for the inner-duct sub-assembly core, the thickness of inner-duct was decided according to the evaluation of inner-duct expansion. As a result, the core reveals greater burn-up swing by about 0.6% $$Delta$$k/kk' than that of the ABLE type fuel core. (c) As for the heterogeneous core, the inner-blanket shuffling concept was studied in order to improve the effective average burn-up and the thermal hydraulic characteristics, As a result, though the breeding ratio decreases in some extent, the possible improvement is obtained in the effective average burn-up (from 56 GWd/t to 80 GWd/t) and core thermal hydraulic design. (2) Medium scale reactors (500 MWe) (a) As for the medium scale core, with the aim of an attractive core concept the high internal conversion ration core was studied. As a result, the obtained typical core concept reveals around 1.05 of breeding ratio with core diameter 10% greater than conventional one and without radial blanket. The core achieves over 100 GWd/t of the effective average burn-up with the potential capability of long operation cycle.

Oral presentation

Dependence of the beam uniformity on the magnetic filter strength in a large Cs-seeded negative ion source for ITER

Seki, Takayoshi; Hanada, Masaya; Tobari, Hiroyuki; Inoue, Takashi; Takado, Naoyuki*; Mizuno, Takatoshi*; Hatayama, Akiyoshi*; Kashiwagi, Mieko; Taniguchi, Masaki; Watanabe, Kazuhiro; et al.

no journal, , 

no abstracts in English

28 (Records 1-20 displayed on this page)