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Journal Articles

Activity enhancement of platinum oxygen-reduction electrocatalysts using ion-beam induced defects

Kimata, Tetsuya*; Kakitani, Kenta*; Yamamoto, Shunya*; Shimoyama, Iwao; Matsumura, Daiju; Iwase, Akihiro*; Mao, W.*; Kobayashi, Tomohiro*; Yamaki, Tetsuya*; Terai, Takayuki*

Physical Review Materials (Internet), 6(3), p.035801_1 - 035801_7, 2022/03

 Times Cited Count:3 Percentile:74.68(Materials Science, Multidisciplinary)

JAEA Reports

Experience and technology consolidation related to dismantling sodium equipment; Technology to reduce sodium remaining in 100m$$^{3}$$ grade large tanks

Hayakawa, Masato; Shimoyama, Kazuhito; Miyakoshi, Hiroyuki; Suzuki, Shigeaki*

JAEA-Technology 2021-027, 33 Pages, 2022/01


At the Oarai Research and Development Institute of the Japan Atomic Energy Agency, experimental studies in various sodium environments are being conducted in connection with the research and development of sodium-cooled fast reactors such as the experimental fast reactor Joyo and the prototype fast reactor Monju. The dismantling of sodium test facilities and equipment that have achieved their purpose has been carried out sequentially, and a wealth of experience and technology has been accumulated. On the other hand, a large amount of metallic sodium used for research and testing is being reused for new testing facilities, and the large sodium tanks that contained the metallic sodium are being dismantled. In order to dismantle these tanks safely and efficiently, it is important to reduce the residual sodium inside the tanks (especially at the bottom) as much as possible before dismantling. Therefore, we have been working on the reduction of residual sodium at the bottom of several large sodium tanks of 100 m$$^{3}$$ class. This report describes the technologies and experiences related to the reduction of residual sodium that have been carried out so far.

Journal Articles

Behavior estimation focusing on the existing form of hydrogen in sodium in sodium-cooled fast reactors

Hatakeyama, Nozomi*; Miura, Ryuji*; Miyamoto, Naoto*; Miyamoto, Akira*; Ara, Kuniaki; Shimoyama, Kazuhito; Kato, Atsushi; Yamamoto, Tomohiko

Journal of Computer Chemistry, Japan, 21(2), p.61 - 62, 2022/00

no abstracts in English

Journal Articles

Coherent eddies transporting passive scalars through the plant canopy revealed by Large-Eddy simulations using the lattice Boltzmann method

Watanabe, Tsutomu*; Takagi, Marie*; Shimoyama, Ko*; Kawashima, Masayuki*; Onodera, Naoyuki; Inagaki, Atsushi*

Boundary-Layer Meteorology, 181(1), p.39 - 71, 2021/10

 Times Cited Count:4 Percentile:50.17(Meteorology & Atmospheric Sciences)

A double-distribution-function lattice Boltzmann model for large-eddy simulations of a passive scalar field is described within and above a plant canopy. For a top-down scalar, for which the plant canopy serves as a distributed sink, the flux of the scalar near the canopy top are predominantly determined by sweep motions originating far above the canopy. By contrast, scalar ejection events are induced by coherent eddies generated near the canopy top. In this paper, the generation of such eddies is triggered by the downward approach of massive sweep motions to existing wide regions of weak ejective motions from inside to above the canopy.

Journal Articles

Sewage sludge ash contaminated with radiocesium; Solidification with alkaline-reacted metakaolinite (geopolymer) and Portland cement

Kozai, Naofumi; Sato, Junya; Osugi, Takeshi; Shimoyama, Iwao; Sekine, Yurina; Sakamoto, Fuminori; Onuki, Toshihiko

Journal of Hazardous Materials, 416, p.125965_1 - 125965_9, 2021/08

 Times Cited Count:14 Percentile:85.08(Engineering, Environmental)

Journal Articles

Carbonated nanohydroxyapatite from bone waste and its potential as a super adsorbent for removal of toxic ions

Sekine, Yurina; Nankawa, Takuya; Yamada, Teppei*; Matsumura, Daiju; Nemoto, Yoshihiro*; Takeguchi, Masaki*; Sugita, Tsuyoshi; Shimoyama, Iwao; Kozai, Naofumi; Morooka, Satoshi

Journal of Environmental Chemical Engineering, 9(2), p.105114_1 - 105114_12, 2021/04

 Times Cited Count:7 Percentile:51.17(Engineering, Environmental)

Remediating toxic ion contamination is crucial for protecting human health and the environment. This study aimed to provide a powerful strategy for effectively utilizing bone waste from the food production and preparation industries for removal of toxic ions. Here, we show that immersing pig bone in NaHCO$$_{3}$$ solution produced a carbonated nanohydroxyapatites (C-NHAP). The C-NHAP exhibited high adsorptivity for Sr$$^{2+}$$, Cd$$^{2+}$$, Pb$$^{2+}$$, and Cu$$^{2+}$$. The strontium adsorptivity was about 250 and 4,500 times higher than that of normal bone and synthetic HAP, respectively. The C-NHAP is an eco-friendly, high-performance material that is simple to prepare and should be useful for tackling problems of food waste disposal and environmental pollution.

JAEA Reports

Construction of the sodium test loop in advanced technology experiment sodium facility (AtheNa)

Imamura, Hiroaki; Suzuki, Masashi*; Shimoyama, Kazuhito; Miyakoshi, Hiroyuki

JAEA-Technology 2019-005, 163 Pages, 2019/06


For the R&D of safety enhance in future fast reactor development, the constructed the large sodium test loop (mother loop) in advanced technology experiment sodium facility (AtheNa) was completed. The sodium test loop possesses the largest capacity of about 240 tons of the world's largest sodium and can supply impurity-controlled high temperature sodium to large structural and technology demonstration test sections. It is greatly expected as R&D such as future international cooperation. For the purpose of future R&D tests, this report compiled the design specifications, fabrication and performance confirmation results of sodium test loop.

Journal Articles

Nanoscale spatial analysis of clay minerals containing cesium by synchrotron radiation photoemission electron microscopy

Yoshigoe, Akitaka; Shiwaku, Hideaki; Kobayashi, Toru; Shimoyama, Iwao; Matsumura, Daiju; Tsuji, Takuya; Nishihata, Yasuo; Kogure, Toshihiro*; Okochi, Takuo*; Yasui, Akira*; et al.

Applied Physics Letters, 112(2), p.021603_1 - 021603_5, 2018/01

 Times Cited Count:7 Percentile:38.54(Physics, Applied)

A synchrotron radiation photoemission electron microscope (SR-PEEM) was applied to demonstrate pinpoint analysis of micrometer-sized weathered biotite clay particles with artificially adsorbed cesium (Cs) atoms. Despite the insulating properties of the clay, we observed the spatial distributions of constituent elements (Si, Al, Cs, Mg, Fe) without charging issues. We found that Cs atoms were likely to be adsorbed evenly over the entire particle. Spatially-resolved X-ray absorption spectra (XAS) of the Cs M$$_{4,5}$$-edge region showed Cs to be present in a monocation state (Cs$$^{+}$$). Further pinpoint XAS measurements were also performed at the Fe L$$_{2,3}$$-edge to determine the chemical valence of the Fe atoms. Our results demonstrate the utility of SR-PEEM as a tool for spatially-resolved chemical analyses of various environmental substances, which is not limited by the poor conductivity of samples.

Journal Articles

Microstructure analysis using X-ray absorption on heat-affected zone of reactor pressure vessel steel

Iwata, Keiko; Takamizawa, Hisashi; Ha, Yoosung; Okamoto, Yoshihiro; Shimoyama, Iwao; Honda, Mitsunori; Hanawa, Satoshi; Nishiyama, Yutaka

Photon Factory Activity Report 2017, 2 Pages, 2018/00

no abstracts in English

Journal Articles

Proposed cesium-free mineralization method for soil decontamination; Demonstration of cesium removal from weathered biotite

Honda, Mitsunori; Shimoyama, Iwao; Kogure, Toshihiro*; Baba, Yuji; Suzuki, Shinichi; Yaita, Tsuyoshi

ACS Omega (Internet), 2(12), p.8678 - 8681, 2017/12

 Times Cited Count:6 Percentile:25.46(Chemistry, Multidisciplinary)

Journal Articles

Development of cesium-free mineralization for decontamination and reuse of radioactive contaminated soil in Fukushima

Shimoyama, Iwao; Honda, Mitsunori; Kogure, Toshihiro*; Baba, Yuji; Hirao, Norie*; Okamoto, Yoshihiro; Yaita, Tsuyoshi; Suzuki, Shinichi

Photon Factory News, 35(1), p.17 - 22, 2017/05

We introduce Cs-free mineralization (CFM) for Cs removal and reuse of radioactive-contaminated soil in Fukushima and report recent work conducted in the BL27A beamline in Photon Factory. In this work, we investigated compositional and structural changes of Cs-sorbed weathered biotite (WB) before and after heating treatment with addition of NaCl-CaCl$$_{2}$$ salts under low-pressure condition, to study Cs desorption mechanism from clay minerals. X-ray fluorescence spectroscopy clarified that almost all Cs and K were removed with the salts at 700 $$^{circ}$$C. On the other hand, Ca increased with heating temperature. X-ray diffraction and transmission electron microscopy analysis clarified that phase transitions from WB to some Ca-rich silicate minerals, e.g., augite, were caused by the heating treatment with the salt. Based on these results, CFM is proposed for Cs removal utilizing the mechanism in which large monovalent cations are discharged with accompanying the phase transition. We also discuss the role of Cl in this reaction showing chemical bonding change of Cl observed using X-ray absorption spectroscopy in the early stage of the chemical reaction.

Journal Articles

Influence of configuration at dopant sites on catalytic activity of phosphorus-doped graphite

Shimoyama, Iwao; Hakoda, Teruyuki; Shimada, Akihiko; Baba, Yuji

Carbon, 81, p.260 - 271, 2015/01

 Times Cited Count:23 Percentile:61.2(Chemistry, Physical)

The relationship between catalytic activity and local structure at dopant sites of phosphorus-doped graphite prepared by ion implantation was studied by electrochemical measurements and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The P K-edge NEXAFS spectra of samples doped at room temperature and high temperature showed different polarization dependences, with graphite-like clear polarization dependence observed for the sample prepared by high-temperature doping. NEXAFS spectra were analyzed by density functional theory calculations to reveal the chemical-bonding states of P sites. In electrochemical measurements with an acid solution, samples with relatively small polarization dependence of NEXAFS exhibited marked catalytic activity in oxygen reduction reactions while those with larger polarization dependence showed lower catalytic activity. This indicates the influence of the configuration at dopant sites on catalytic activity and suggests that the introduction of curved structures is one way to design carbon catalysts with high catalytic activity.

Journal Articles

Colossal thermomagnetic response in the exotic superconductor URu$$_2$$Si$$_2$$

Yamashita, Takuya*; Shimoyama, Yusuke*; Haga, Yoshinori; Matsuda, Tatsuma*; Yamamoto, Etsuji; Onuki, Yoshichika; Sumiyoshi, Hiroaki*; Fujimoto, Satoshi*; Levchenko, A.*; Shibauchi, Takasada*; et al.

Nature Physics, 11(1), p.17 - 20, 2015/01

 Times Cited Count:47 Percentile:89.34(Physics, Multidisciplinary)

Journal Articles

Electron-spin relaxation times of irradiated fructose measured with pulsed ESR

Kikuchi, Masahiro; Kameya, Hiromi*; Shimoyama, Yuhei; Ukai, Mitsuko*; Kobayashi, Yasuhiko

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 85, 2014/03

Journal Articles

In situ stress measurement by CCBO in Mizunami Underground Researh Laboratory

Sato, Toshinori; Tanno, Takeo; Sanada, Hiroyuki; Yokoyama, Tatsuya*; Shimoyama, Masahiro*

Heisei-25 Nendo (2013 Nen) Shigen, Sozai Gakkai Shuki Taikai Koenshu, p.257 - 258, 2013/09

Japan Atomic Energy Agency is operating underground research laboratory projects in order to establish a firm scientific basis for safe geological disposal of HLW. One of these is the Mizunami Underground Research Laboratory (MIU) project focused on crystalline rock. In situ stress measurement by Compact Conical-ended Borehole Overcoring (CCBO) are conducted to understand in situ stress state at 300 m depth.

Journal Articles

In-situ stress measurement in the Mizunami Underground Research Laboratory; A New test of strain sensitivity method applying to CCBO

Tanno, Takeo; Sato, Toshinori; Sanada, Hiroyuki; Hikima, Ryoichi*; Yokoyama, Tatsuya*; Shimoyama, Masahiro*

Heisei-25 Nendo (2013 Nen) Shigen, Sozai Gakkai Shuki Taikai Koenshu, p.255 - 256, 2013/09

${it In-situ}$ rock stresses were measured by Compact Conical-ended Borehole Overcoring (CCBO) technique in the 300m depth gallery at the Mizunami Underground Research Laboratory and the measurement results were evaluated using a conventional method and a new test of strain sensitivity method. To compare the ${it in-situ}$ rock stress evaluated by both methods, the new test of strain sensitivity method resulted in more accurate evaluation than the conventional method, because of its improved stress deviations.

Journal Articles

Rapid ESR measurement of irradiated fresh papaya

Kikuchi, Masahiro; Shimoyama, Yuhei; Ukai, Mitsuko*; Kobayashi, Yasuhiko

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 78, 2013/01

no abstracts in English

Journal Articles

Electron-spin relaxation phenomena in irradiated saccharides detected by pulsed electron paramagnetic resonance spectroscopy

Kikuchi, Masahiro; Kameya, Hiromi*; Shimoyama, Yuhei; Ukai, Mitsuko*; Kobayashi, Yasuhiko

Radiation Physics and Chemistry, 81(10), p.1639 - 1645, 2012/10

 Times Cited Count:1 Percentile:10.57(Chemistry, Physical)

no abstracts in English

Journal Articles

Analysis of radicals induced in irradiated foods

Kishida, Keigo*; Kaimori, Yoshihiko*; Kawamura, Shoei*; Sakamoto, Yuki*; Nakamura, Hideo*; Kikuchi, Masahiro; Shimoyama, Yuhei; Kobayashi, Yasuhiko; Ukai, Mitsuko*

Shokuhin Shosha, 47(1), p.1 - 5, 2012/09

no abstracts in English

Journal Articles

Analysis of relaxation times of radicals in irradiated black pepper using pulse-ESR and CW-ESR

Kameya, Hiromi*; Kikuchi, Masahiro; Todoriki, Setsuko*; Furuta, Masakazu*; Kobayashi, Yasuhiko; Hara, Hideyuki*; Shimoyama, Yuhei; Ukai, Mitsuko*

Shokuhin Shosha, 47(1), p.6 - 10, 2012/09

no abstracts in English

119 (Records 1-20 displayed on this page)