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Journal Articles

Validation practices of multi-physics core performance analysis in an advanced reactor design study

Doda, Norihiro; Kato, Shinya; Hamase, Erina; Kuwagaki, Kazuki; Kikuchi, Norihiro; Ohgama, Kazuya; Yoshimura, Kazuo; Yoshikawa, Ryuji; Yokoyama, Kenji; Uwaba, Tomoyuki; et al.

Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.946 - 959, 2023/08

An innovative design system named ARKADIA is being developed to realize the design of advanced nuclear reactors as safe, economical, and sustainable carbon-free energy sources. This paper focuses on ARKADIA-Design for design studies as a part of ARKADIA and introduces representative verification methods for numerical analysis methods of the core design. ARKADIA-Design performs core performance analysis of sodium-cooled fast reactors using a multiphysics approach that combines neutronics, thermal-hydraulics, core mechanics, and fuel pin behavior analysis codes. To confirm the validity of these analysis codes, validation matrices are identified with reference to experimental data and reliable numerical analysis results. The analysis models in these codes and the representative practices for the validation matrices are described.

Journal Articles

Sodium-cooled Fast Reactors

Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.

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

Sm valence determination of Sm-based intermetallics using $$^{149}$$Sm M$"{o}$ssbauer and Sm L$$_{rm III}$$-edge X-ray absorption spectroscopies

Tsutsui, Satoshi; Higashinaka, Ryuji*; Nakamura, Raito*; Fujiwara, Kosuke*; Nakamura, Jin*; Kobayashi, Yoshio*; Ito, Takashi; Yoda, Yoshitaka*; Kato, Kazuo*; Nitta, Kiyofumi*; et al.

Hyperfine Interactions, 242(1), p.32_1 - 32_10, 2021/12

 Times Cited Count:1 Percentile:84.42

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2014

Hama, Katsuhiro; Mikake, Shinichiro; Ishibashi, Masayuki; Sasao, Eiji; Kuwabara, Kazumichi; Ueno, Tetsuro; Onuki, Kenji*; Beppu, Shinji; Onoe, Hironori; Takeuchi, Ryuji; et al.

JAEA-Review 2015-024, 122 Pages, 2015/11

JAEA-Review-2015-024.pdf:80.64MB

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 technical 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 III, as the Phase II was concluded for a moment with the completion of the excavation of horizontal tunnels at GL-500m level in February 2014. This report presents the results of the investigations, construction and collaboration studies in fiscal year 2014.

Journal Articles

Characterization and storage of radioactive zeolite waste

Yamagishi, Isao; Nagaishi, Ryuji; Kato, Chiaki; Morita, Keisuke; Terada, Atsuhiko; Kamiji, Yu; Hino, Ryutaro; Sato, Hiroyuki; Nishihara, Kenji; Tsubata, Yasuhiro; et al.

Journal of Nuclear Science and Technology, 51(7-8), p.1044 - 1053, 2014/07

 Times Cited Count:16 Percentile:76.9(Nuclear Science & Technology)

For safe storage of zeolite wastes generated by treatment of radioactive saline water at the Fukushima Daiichi Nuclear Power Station, properties of the Herschelite adsorbent were studied and its adsorption vessel was evaluated for hydrogen production and corrosion. Hydrogen production depends on its water level and dissolved species because hydrogen is oxidized by radicals in water. It is possible to evaluate hydrogen production rate in Herschelite submerged in seawater or pure water by taking into account of the depth effect of the water. The reference vessel of decay heat 504 W with or without residual pure water was evaluated for the hydrogen concentration by thermal hydraulic analysis using obtained fundamental properties. Maximum hydrogen concentration was below the lower explosive limit (4 %). The steady-state corrosion potential of a stainless steel 316L increased with absorbed dose rate but its increase was repressed by the presence of Herschelite. At 750 Gy/h and $$<$$60$$^{circ}$$C which were values evaluated at the bottom of the vessel of 504 W, the localized corrosion of SUS316L contacted with Herschelite would not immediately occur under 20,000 ppm of Cl$$^{-}$$ concentration.

Journal Articles

Safe storage of zeolite adsorbents used for treatment of accident-generated water at Fukushima Daiichi Power Station

Yamagishi, Isao; Nagaishi, Ryuji; Terada, Atsuhiko; Kamiji, Yu; Kato, Chiaki; Morita, Keisuke; Nishihara, Kenji; Tsubata, Yasuhiro; Ji, W.*; Fukushima, Hisashi*; et al.

IAEA-CN-211 (Internet), 5 Pages, 2013/01

Since the accident at Fukushima Daiichi Nuclear Power Station, a large amount of radioactive contaminated water has been generated to cool damaged reactor cores. Adsorption of cesium with zeolite-like media was employed for treatment of this contaminated saline water. As spent zeolite media are highly radioactive, their safe storage is a pressing issue. Japan Atomic Energy Agency has extensively conducted R&D on the management of secondary wastes produced by the operation of the treatment system. Subjects on the safe storage of spent zeolites include the analysis of their characteristics and the evaluation of effectiveness of the present safety measures in consideration of decay heat emission and hydrogen generation by water radiolysis as well as durability of vessels exposed to saline. Preliminary results obtained are described in the present paper.

Journal Articles

Lower critical fields and the anisotropy in PrFeAsO$$_{1-y}$$ single crystals

Okazaki, Ryuji*; Konczykowski, M.*; Van der Beek, C. J.*; Kato, Tomonari*; Hashimoto, Kenichiro*; Shimozawa, Masaaki*; Shishido, Hiroaki*; Yamashita, Minoru*; Ishikado, Motoyuki; Kito, Hijiri*; et al.

Physica C, 470(Suppl.1), p.S485 - S486, 2010/12

 Times Cited Count:0 Percentile:0(Physics, Applied)

We report the lower critical fields $$H_{c1}$$ measurements on Fe-based oxipnictide PrFeAsO$$_{1-y}$$ single crystals for $$H$$ $$parallel$$ $$c$$ and $$H$$ $$parallel$$ $$ab$$-planes. To avoid the difficulty of $$H_{c1}$$ determinations due to the flux pinning, we developed a novel method using a miniature hall-sensor array which can evaluate the local magnetic induction ai each sensor position. The hall sensor which is placed on the edge of the crystal clearly resolves the first flux penetration from the Meissner state. The temperature dependence of $$H_{c1}$$ for $$H$$ $$parallel$$ $$c$$ is well scaled by the in-plane penetration depth and is consistent with a full-gap superconducting state. The anistropy of $$H_{c1}$$ at low temperatures is estimated to be $$sim$$ 3, which is much smaller than of $$H_{c2}$$. This indicates the multiband superconductivity, in which the active bands for superconductivity are more two-dimensional.

Journal Articles

Disorder and flux pinning in superconducting pnictide single crystals

Van der Beek, C. J.*; Rizza, G.*; Konczykowski, M.*; Fertey, P.*; Monnet, I.*; Okazaki, Ryuji*; Kato, Tomonari*; Hashimoto, Kenichiro*; Shimozawa, Masaaki*; Shishido, Hiroaki*; et al.

Physica C, 470(Suppl.1), p.S385 - S386, 2010/12

 Times Cited Count:1 Percentile:6.5(Physics, Applied)

Crystalline disorder in the pnictide superconductor PrFeAsO$$_{1-x}$$ is studied using magneto-optical visualisation of flux penetration, transmission electron microscopy, and X-ray diffraction using synchrotron radiation. Critical-state like flux distributions and the magnitude and temperature dependence of the critical current demonstrate bulk vortex pinning by oxygen vacancies at all temperatures.

Journal Articles

Pulse radiolysis study of ion-species effects on the solvated electron in alkylammonium ionic liquids

Kondo, Takafumi*; Asano, Akira*; Yang, J.*; Norizawa, Kimihiro*; Takahashi, Kenji*; Taguchi, Mitsumasa; Nagaishi, Ryuji; Kato, Ryuji*; Yoshida, Yoichi*

Radiation Physics and Chemistry, 78(12), p.1157 - 1160, 2009/12

 Times Cited Count:28 Percentile:85.96(Chemistry, Physical)

Spectrum and kinetic behavior of solvated electrons (e$$_{sol}$$$$^{-}$$) in alkyl ammonium ionic liquids (ILs), ${it i.e.}$ DEMMA-TFSI, DEMMA-BF4, TMPA-TFSI, PP13-TFSI, P13-TFSI and P14-TFSI were investigated by pulse radiolysis method. The e$$_{sol}$$$$^{-}$$ in the ILs have same absorption peak at 1100 nm with a molar absorption coefficient of 1.5-2.3$$times$$10$$^{4}$$ dm$$^{3}$$mol$$^{-1}$$cm$$^{-1}$$. The reaction rate constant of e$$_{sol}$$$$^{-}$$ with Pyrene (Py) was 1.5-3.5$$times$$10$$^{8}$$ dm$$^{3}$$mol$$^{-1}$$s$$^{-1}$$. These values were about one order of magnitude higher than that of diffusion controlled limit, which was calculated from measured viscosity. The dry electron (e$$_{dry}$$$$^{-}$$) reacts with Py, and its rate constant in DEMMA-TFSI was 7.9$$times$$10$$^{11}$$ dm$$^{3}$$mol$$^{-1}$$s$$^{-1}$$, three orders of magnitude higher than that of the e$$_{sol}$$$$^{-}$$ reactions.

Journal Articles

Lower critical fields of superconducting PrFeAsO$$_{1-y}$$ single crystals

Okazaki, Ryuji*; Konczykowski, M.*; Van der Beek, C. J.*; Kato, Tomonari*; Hashimoto, Kenichiro*; Shimozawa, Motoyuki*; Shishido, Hiroaki*; Yamashita, Minoru*; Ishikado, Motoyuki; Kito, Hijiri*; et al.

Physical Review B, 79(6), p.064520_1 - 064520_6, 2009/02

 Times Cited Count:59 Percentile:87.81(Materials Science, Multidisciplinary)

We have studied the lower critical fields H$$_{c1}$$ of superconducting iron oxipnictide PrFeAsO$$_{1-y}$$ single crystals for H parallel and perpendicular to the ab-planes.

Journal Articles

Picosecond pulse radiolysis; Dynamics of solvated electrons in ionic liquid and geminate ion recombination in liquid alkanes

Yang, J.*; Kondo, Takafumi*; Norizawa, Kimihiro*; Nagaishi, Ryuji; Taguchi, Mitsumasa; Takahashi, Kenji*; Kato, Ryuji*; Anishchik, S. V.*; Yoshida, Yoichi*; Tagawa, Seiichi*

Radiation Physics and Chemistry, 77(10-12), p.1233 - 1238, 2008/10

 Times Cited Count:25 Percentile:82.59(Chemistry, Physical)

First observation of picosecond dynamics in ionic liquid of DEMMA-TFSI in radiation chemistry was reported. It is found that the electron produced by ionization is solvated to full solvation in ionic liquid with a rate constant of 3.9$$times$$10$$^{10}$$ s$$^{-1}$$. The yield of solvated electrons in picosecond time region is 1.2$$times$$10$$^{-7}$$ mol J$$^{-1}$$. The dry electron in ionic liquid reacts rapidly with biphenyl and pyrene with a rate constant of 3.8 to 7.9$$times$$10$$^{11}$$ L mol$$^{-1}$$ s$$^{-1}$$. The geminate ion recombination in n-dodecane and n-hexane was also observed by monitoring the transient absorptions at 523 nm.

Journal Articles

Electron photodetachment from iodide in ionic liquids through charge-transfer-to-solvent band excitation

Kato, Ryuji*; Yoshida, Yoichi*; Katsumura, Yosuke; Takahashi, Kenji*

Journal of Physical Chemistry B, 111(18), p.4770 - 4774, 2007/05

 Times Cited Count:53 Percentile:76.58(Chemistry, Physical)

Journal Articles

Luminescence study on preferential solvation of europium (III) in water/non-aqueous solvent mixtres

Kimura, Takaumi; Nagaishi, Ryuji; Kato, Yoshiharu; Yoshida, Zenko

Journal of Alloys and Compounds, 323-324(1-4), p.164 - 168, 2001/07

 Times Cited Count:50 Percentile:87.72(Chemistry, Physical)

no abstracts in English

Journal Articles

Luminescence study on solvation of americium(III), curium(III) and several lanthanide(III) ions in nonaqueous and binary mixed solvents

Kimura, Takaumi; Nagaishi, Ryuji; Kato, Yoshiharu; Yoshida, Zenko

Radiochimica Acta, 89(3), p.125 - 130, 2001/05

 Times Cited Count:66 Percentile:96.82(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Reports of ITER physics R&D expert meeting

Hosogane, Nobuyuki; Asakura, Nobuyuki; Sugie, Tatsuo; Yoshino, Ryuji; Fukuda, Takeshi; Kusama, Yoshinori; Tobita, Kenji; Ide, Shunsuke; Shimada, Michiya; Sengoku, Seio; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 75(2), p.156 - 161, 1999/02

no abstracts in English

JAEA Reports

Material strength standard of FBR grade type 316 stainless steel(Draft)

Watashi, Katsumi; Aoto, Kazumi; Aoki, M; Komine, Ryuji; Ito, Takushi; Hasebe, Shinichi; Kato, Shoichi; Koi, Mamoru; Wada, Yusaku

PNC TN9410 93-142, 120 Pages, 1993/06

PNC-TN9410-93-142.pdf:6.08MB

Much progress has been made in improving established creep properties of Type 316 stainless steel and to develop a new structural material named "FBR Grade Type 316 Stainless Steel", 316FR, with superior creep properties. This report includes a draft of Material Strength Standard of 316FR and its interpretation on the basis of the major result of research and development conducted so far. The draft includes identical items described in the "Standards for the Strength of Materials" for Monju, and was carefully prepared to have an identical style for convenience in design evaluation. Creep damage evaluation diagrams, which are depicted in the "Structural Design Guide for Class 1 Components of Prototype Fast Breeder Reactor for Elevated Temperature Service" (ETSDG) for individual materials, are also included in this report.

Oral presentation

Solvated electrons in ionic liquids

Takahashi, Kenji*; Hiejima, Yusuke*; Kato, Ryuji*; Nagaishi, Ryuji; Taguchi, Mitsumasa; Kojima, Takuji; Kondo, Takafumi*; Yang, J.*; Yoshida, Yoichi*

no journal, , 

Solvated electrons were studied using the pulse radiolysis and photo ionization methods. The Vis-NIR spectra and reactivity of the solvated electrons in ionic liquids are discussed.

Oral presentation

A Method of fabrication meso-nozzle for bubbling

Osone, Ryuji; Bucheeri, A.; Kurishita, Hiroaki*; Kato, Masahiro*; Yamasaki, Kazuhiko*; Maekawa, Katsuhiro*; Naoe, Takashi; Futakawa, Masatoshi

no journal, , 

Liquid mercury target system for high power spallation neutron sources is being developed. When high intensity proton beams are injected into the target, pressure waves are generated by the thermal shock in mercury and pitting damage will be imposed on the target vessel. Bubble injection into mercury is effective to mitigate the pressure waves. In this work, we propose a method of fabricating meso-nozzle for bubble injection. The method is based on powder metallurgy by inserting thin glass fibers into a metal powder matrix to create a green compact, followed by sintering at a temperature between the melting points of the powder and the fiber. SUS316L and molybdenum powders were used as the nozzle matrix materials. In order to investigate optimum sintering condition, experiments were performed at different combination of pressing load and sintering temperature. We found that in molybdenum high relative density and straight hole with circlar cross section were obtained.

Oral presentation

Water effects on the solvated electron in ammonium ionic liquids

Kondo, Takafumi*; Yang, J.*; Yoshida, Yoichi*; Nagaishi, Ryuji; Taguchi, Mitsumasa; Takahashi, Kenji*; Kato, Ryuji*

no journal, , 

The effect of the coexistence water on the solvated electrons in ammonium ionic liquids was studied by the electron pulse radiolysis method. The optical absorption band of the solvation electron decreased by coexistence of water, and new absorption band like a hydrated electron were generated in the medium wavelength region between solvated electron and hydrated electron. Furthermore, if quantity of water increase in the hydrophilic ionic liquid, it was found that the spectrum changed into the hydrated electron.

38 (Records 1-20 displayed on this page)