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Journal Articles

Environmental effects on layer-dependent dynamics of Dirac fermions in quasicrystalline bilayer graphene

Zhao, Y.*; Suzuki, T.*; Iimori, T.*; Kim, H.-W.*; Ahn, J. R.*; Horio, Masafumi*; Sato, Yusuke*; Fukaya, Yuki; Kanai, T.*; Okazaki, K.*; et al.

Physical Review B, 105(11), p.115304_1 - 115304_8, 2022/03

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Precious metal separations

Narita, Hirokazu*; Kasuya, Ryo*; Suzuki, Tomoya*; Motokawa, Ryuhei; Tanaka, Mikiya*

Encyclopedia of Inorganic and Bioinorganic Chemistry (Internet), 28 Pages, 2020/12

Journal Articles

Proton chelating ligands drive improved chemical separations for rhodium

Narita, Hirokazu*; Nicolson, R. M.*; Motokawa, Ryuhei; Ito, Fumiyuki*; Morisaku, Kazuko*; Goto, Midori*; Tanaka, Mikiya*; Heller, W. T.*; Shiwaku, Hideaki; Yaita, Tsuyoshi; et al.

Inorganic Chemistry, 58(13), p.8720 - 8734, 2019/07

 Times Cited Count:8 Percentile:62.89(Chemistry, Inorganic & Nuclear)

Journal Articles

Speciation of ruthenium(III) chloro complexes in hydrochloric acid solutions and their extraction characteristics with an amide-containing amine compound

Suzuki, Tomoya*; Ogata, Takeshi*; Tanaka, Mikiya*; Kobayashi, Toru; Shiwaku, Hideaki; Yaita, Tsuyoshi; Narita, Hirokazu*

Metals, 8(7), p.558_1 - 558_10, 2018/07


 Times Cited Count:9 Percentile:55.49(Materials Science, Multidisciplinary)

The refining of platinum group metals is based mainly on solvent extraction methods, whereas Ru is selectively recovered by distillation as RuO$$_4$$. Replacement of distillation byextraction is expected to simplify the purification process. To develop an effective extraction system for Ru, we analyzed the Ru species in HCl with UV-Vis and EXAFS spectroscopies, and we examined the properties of Ru extracted with N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide) amine (EHBAA). EXAFS and UV-Vis spectra of Ru in HCl solutions revealed that the predominant Ru species in 0.5-10 M HCl solutions changed from [RuCl$$_4$$(H$$_2$$O)$$_2$$]$$^-$$ to [RuCl$$_6$$]$$^3$$$$^-$$ with the HCl concentration. The extraction percentages of Ru in the EHBAA system increased with increasing HCl concentration, reached 80% at [HCl] = 5 M, and decreased athigher HCl concentrations. EXAFS analysis of the extracted complex indicated that the Ru$$^3$$$$^+$$ had 5 Cl$$^-$$ and 1 H$$_2$$O in its inner coordination sphere. The similarity of the dependence on HCl concentrations of the extraction in the EHBAA system and the distribution profile of [RuCl$$_5$$(H$$_2$$O)]$$^2$$$$^-$$ on [RuCl$$_n$$(H$$_2$$O)$$_6$$$$_-$$$$_n$$]$$^3$$$$^-$$$$^n$$ suggested that the EHBAA extracted the pentachlorido species.

Journal Articles

Comparison of the extractabilities of tetrachloro- and tetrabromopalladate(II) ions with a thiodiglycolamide compound

Narita, Hirokazu*; Maeda, Motoki*; Tokoro, Chiharu*; Suzuki, Tomoya*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi

Analytical Sciences, 33(11), p.1305 - 1309, 2017/11

 Times Cited Count:8 Percentile:38.02(Chemistry, Analytical)

Journal Articles

Selective extraction of Pt(IV) over Fe(III) from HCl with an amide-containing tertiary amine compound

Maeda, Motoki*; Narita, Hirokazu*; Tokoro, Chiharu*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi

Separation and Purification Technology, 177, p.176 - 181, 2017/04

 Times Cited Count:18 Percentile:62.51(Engineering, Chemical)

Journal Articles

Dipole tracer migration and diffusion tests in fractured sedimentary rock at Horonobe URL

Tanaka, Shingo*; Yokota, Hideharu; Ono, Hirokazu; Nakayama, Masashi; Fujita, Tomo; Takiya, Hiroaki*; Watanabe, Naoko*; Kozaki, Tamotsu*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05

Journal Articles

High-resolution Compton cameras based on Si/CdTe double-sided strip detectors

Odaka, Hirokazu*; Ichinohe, Yuto*; Takeda, Shinichiro*; Fukuyama, Taro*; Hagino, Koichi*; Saito, Shinya*; Sato, Tamotsu*; Sato, Goro*; Watanabe, Shin*; Kokubun, Motohide*; et al.

Nuclear Instruments and Methods in Physics Research A, 695, p.179 - 183, 2012/12

 Times Cited Count:20 Percentile:83.8(Instruments & Instrumentation)

We have developed a new Si/CdTe semiconductor double-sided strip detector (DSD) Compton camera. The camera consists of a 500-$$mu$$m-thick Si-DSD and four layers of 750-$$mu$$m-thick CdTe-DSDs all of which have common electrode configuration segmented into 128 strips on each side with pitches of 250$$mu$$m. In order to realize high angular resolution and to reduce size of the detector system, a stack of DSDs with short stack pitches of 4 mm is utilized to make the camera. Taking advantage of the excellent energy and position resolutions of the semiconductor devices, the camera achieves high angular resolutions of 4.5 degrees at 356 keV and 3.5 degrees at 662 keV. To obtain such high resolutions together with an acceptable detection efficiency, we demonstrate data reduction methods including energy calibration using Compton scattering continuum and depth sensing in the CdTe-DSD. We also discuss imaging capability of the camera and show simultaneous multi-energy imaging.

JAEA Reports

Development of grout materials for a geological disposal system for high-level radioactive waste, 2

Kawaguchi, Masanao; Nakanishi, Tatsuro; Kishi, Hirokazu; Nobuto, Jun*; Yamada, Tsutomu*; Fujita, Tomo; Hatanaka, Koichiro

JAEA-Data/Code 2012-007, 250 Pages, 2012/11


Cementitious materials are commonly used for rock support, lining, and grouting, their pH plume are considered to have an adverse effect on long-term safety of a geological disposal system. In addition, during the emplacement of waste package with buffer material, it is required to limit amount of groundwater inflow to a certain level by grouting. Therefore, it is necessary to develop new grout materials with penetrability for smaller fractures. We have developed new grout materials, which have better penetrability and are environmentally more friendly than exinting cementitious grout materials since FY 2007. This sequel report shows the most appropriate composition and the penetration characteristic of new grout materials to be suitable for the ${it in-situ}$ experiment based on the result of indoor test carried out after FY 2008.

Journal Articles

Applications and imaging techniques of a Si/CdTe Compton $$gamma$$-ray camera

Takeda, Shinichiro*; Ichinohe, Yuto*; Hagino, Koichi*; Odaka, Hirokazu*; Yuasa, Takayuki*; Ishikawa, Shinnosuke*; Fukuyama, Taro*; Saito, Shinya*; Sato, Tamotsu*; Sato, Goro*; et al.

Physics Procedia, 37, p.859 - 866, 2012/10

 Times Cited Count:19 Percentile:98.35

By using new Compton camera consisting of silicon double-sided strip detector (Si-DSD) and CdTe-DSD developed for the ASTRO-H mission, an experiment was conducted to study its feasibility for advanced hotspot monitoring. In addition to hotspot imaging already provided by commercial imaging systems, the identification of the variety of radioisotopes is realized thanks to the good energy resolution given by the semiconductor detectors. Three radioisotopes of $$^{133}$$Ba (356 keV), $$^{22}$$Na (511 keV) and $$^{137}$$Cs (662 keV) were individually imaged by applying event selection in the energy window and the $$gamma$$-ray images was correctly overlapped by an optical picture. The detection efficiency of 1.68$$times$$10$$^{-4}$$ (effective area: 1.7$$times$$10$$^{-4}$$ cm$$^2$$) and angular resolution of 3.8$$^{circ}$$ were obtained by stacking five detector modules for 662 keV $$gamma$$-ray. The higher detection efficiency required in a specific use can be achieved by stacking more detector modules.

Journal Articles

Characteristic evaluation of colloidal silica grout material developed for a high level radioactive waste geological repository

Kishi, Hirokazu; Kawaguchi, Masanao; Naito, Morimasa; Hatanaka, Koichiro; Nobuto, Jun*; Sugiyama, Hirokazu*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 19(1), p.3 - 8, 2012/06

To reduce amount of groundwater inflow into a geological repository, the grouting is expected to play a very important role because the geological environment in Japan is often characterized by many fractures and abundant groundwater. Basically, cementitious materials are used for grouting, however the resulting highly alkaline plume released from the materials could influence the long-term performance of barrier system as a consequence of alteration of both the buffer material and the host rock. To minimize such effects, JAEA has carried out research and development on three types of grout material with low-pH performance that decreases influence in the alteration. This paper focuses on the Colloidal silica grout, and presents its unique characteristics obtained from laboratory tests on pH, viscosity, leaching and so on. The results indicate that the grout has good performances in pH and viscosity. It is concluded that the grout can be greatly used for the repository.

Journal Articles

The JAEA grouting test at the Grimsel test site; Numerical simulation of the grout injection process of silica sol in fractured rock mass

Koyama, Tomofumi*; Onishi, Yuzo*; Bruines, P.*; Tanaka, Tatsuya*; Hasui, Akinori*; Katayama, Tatsuo*; Kishi, Hirokazu; Kuzuha, Yuji

Proceedings of 2012 ISRM International Symposium; Rock Engineering and Technology for Sustainable Underground Construction (EUROCK 2012) (USB Flash Drive), 10 Pages, 2012/05

Grouting, which involves injection of grout material, is commonly used to decrease the hydraulic conductivity of the fractured rock masses and control the groundwater inflow. However, the mechanism of grout injection process has not been clarified sufficiently yet due to complicated chemical and physical processes of grout. In this study, to simulate the grout injection process, the three-dimensional numerical model based on equivalent continuum approach was developed.

Journal Articles

The JAEA grouting test at the Grimsel test site; Site characterization of a fractured rockmass and preparation of DFN model and its equivalent continuous porous media model

Bruines, P.*; Tanaka, Tatsuya*; Koyama, Tomofumi*; Kishi, Hirokazu; Nakanishi, Tatsuro; Onishi, Yuzo*

Proceedings of 2012 ISRM International Symposium; Rock Engineering and Technology for Sustainable Underground Construction (EUROCK 2012) (USB Flash Drive), 15 Pages, 2012/05

To better understand the grouting process and the effect of grouting on the performance of a nuclear waste repository, the Japanese Atomic Energy Agency (JAEA) has initiated a grouting test carried out in the fractured granite of the Grimsel Test Site (GTS) located in the Swiss Alps. This paper describes the characterization of the rock mass, how the data obtained has been used to make a discrete fracture network (DFN) model and how an up-scaled equivalent continuous porous media (ECPM) model for the purpose of numerical simulation of the grout injection process is generated. The generated DFN model and the up-scaled ECPM model was able to reproduce the measured fracture characteristics (e.g. orientation, density) as well as the hydraulic behavior observed in the field (e.g. transmissivity distribution, anisotropy, heterogeneity) and has proven to be suitable for modeling grouting behavior.

Journal Articles

Tolerance of anhydrobiotic eggs of the tardigrade ${it Ramazzottius varieornatus}$ to extreme environments

Horikawa, Daiki*; Yamaguchi, Ayami*; Sakashita, Tetsuya; Tanaka, Daisuke*; Hamada, Nobuyuki*; Yukuhiro, Fumiko*; Kuwahara, Hirokazu*; Kunieda, Takekazu*; Watanabe, Masahiko*; Nakahara, Yuichi*; et al.

Astrobiology, 12(4), p.283 - 289, 2012/04

 Times Cited Count:23 Percentile:70.77(Astronomy & Astrophysics)

We examined the hatchability of hydrated and anhydrobiotic eggs of the tardigrade ${it Ramazzottius varieornatus}$ to hatch after ionizing irradiation (helium ions), extremely low and high temperatures, and high vacuum. Anhydrobiotic eggs (50% lethal dose; 1690 Gy) were substantially more radioresistant than hydrated ones (50% lethal dose; 509 Gy). Anhydrobiotic eggs also have a broader temperature resistance compared with hydrated ones. Over 70% of the anhydrobiotic eggs treated at high and low temperatures, but all of the hydrated eggs failed to hatch. After exposure to high vacuum conditions, the hatchability of the anhydrobiotic eggs was comparable to that of untreated control eggs.

Journal Articles

Development of grouting technologies for geological disposal of high level waste in Japan, 3; Numerical simulation for grout injection using equivalent continuum model

Koyama, Tomofumi*; Katayama, Tatsuo*; Hasui, Akinori*; Tanaka, Tatsuya*; Kishi, Hirokazu; Onishi, Yuzo*

Dai-41-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.83 - 88, 2012/01

In this study, to simulate the grout injection process, the 3-D numerical model based on equivalent continuum approach was developed. The viscosity measurements for silica sol was performed to measure the time-dependent viscosity. The developed numerical model was applied to the planned in-situ grout injection tests at Grimsel test site (GTS), Switzerland. The rock type is fractured granite and the equivalent porous media was created from the DFN (Discrete Fracture Network) based on the frature data obtained from the observation boreholes. The preliminary simulation was carried out to determine the suitable grout injection pressure and investigate the arrival distance of grout from injection boreholes.

Journal Articles

Mix design of low pH cement shotcrete in high level radioactive waste repositories

Noguchi, Akira; Kishi, Hirokazu; Hatanaka, Koichiro; Naito, Morimasa

Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 6 Pages, 2011/10

A standardized method for choosing a mix design of low pH shotcrete is proposed for their intended use in the construction of a High Level Radioactive Waste (HLW) repository in order to be applied to the various geological environment of the location of the HLW repositories. There are two improvement in this method. One is estimating binder composition to satisfy low pH. The other is estimating water bender ratio to satisfy the strength of sprayed concrete. The method uses a sequential development process with consideration given to a number of physicochemical requirements, incorporates current shotcrete technology. The method is demonstrated in its entirety through a series of experiments and tests using a low pH cement binder comprised of a mixture of ordinary Portland cement, fly ash (FA) and silica fume (SF), referred to here as high-volume FA SF cement (HFSC). Moreover, the method is referred from the demonstration of HFSC shotcrete in Horonobe underground research laboratory.

Journal Articles

Radiation from the SDTL of J-PARC

Naito, Fujio*; Nammo, Kesao*; Tanaka, Hirokazu*; Asano, Hiroyuki; Ito, Takashi

Proceedings of 25th International Linear Accelerator Conference (LINAC 2010) (CD-ROM), p.569 - 571, 2010/09

X-ray radiation from the SDTL of J-PARC linac has been observed with the beam loss monitor by the cavity. The results show that the X-ray intensity depends not only on the RF power level of the tank but also on the RF structure of the tank. In the paper we will show the results of the investigation for the origin of the X-ray radiation from the tank.

Journal Articles

Application of parallel factor analysis for time-resolved laser fluorescence spectroscopy; Implication for metal speciation study

Saito, Takumi*; Sao, Hirokazu*; Ishida, Keisuke*; Aoyagi, Noboru; Kimura, Takaumi; Nagasaki, Shinya*; Tanaka, Satoru*

Environmental Science & Technology, 44(13), p.5055 - 5060, 2010/07

 Times Cited Count:30 Percentile:61.76(Engineering, Environmental)

Journal Articles

Trouble report for J-PARC DTL and SDTL

Ito, Takashi; Asano, Hiroyuki; Tanaka, Hirokazu*; Kubota, Chikashi*; Nammo, Kesao*; Naito, Fujio*

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.690 - 692, 2010/03

The J-PARC DTL and SDTL have been operated since 2006. These linacs accelerate an H$$^{-}$$ ion beam stably now. But we have ever suffered from some troubles. These are the vacuum, the cooling water and the RF trouble mainly. In this paper, these troubles that happened to the DTL and SDTL are reported.

JAEA Reports

Assessment on long-term safety for geological disposal of high level radioactive waste; Application of probabilistic safety assessment methodology to uncertainties in hypothetical geological disposal system (Contract research)

Takeda, Seiji; Yamaguchi, Tetsuji; Nagasawa, Hirokazu; Watanabe, Masatoshi; Sekioka, Yasushi; Kanzaki, Yutaka; Sasaki, Toshihisa; Ochiai, Toru; Munakata, Masahiro; Tanaka, Tadao; et al.

JAEA-Research 2009-034, 239 Pages, 2009/11


In safety assessment for geological disposal of high level radioactive waste, it is of consequence to estimate the uncertainties due to the long-term frame associated with long-lived radionuclides and the expanded geological environment. The uncertainties result from heterogeneity intrinsic to engineered and natural barrier materials, insufficient understanding of phenomena occurring in the disposal system, erroneous method of measurement, and incomplete construction. It is possible to quantify or to reduce the uncertainties according to scientific and technological progress. We applied a deterministic and a Monte Carlo-based probabilistic method simulation techniques to the uncertainty analysis for performance of hypothetical geological disposal system for high level radioactive waste. This study provides the method to evaluate the effects of the uncertainties with respect to scenarios, models and parameters in engineering barrier system on radiological consequence. The results also help us to specify prioritized models and parameters to be further studied for long-term safety assessment.

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