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Journal Articles

Study on irradiation hardening mechanism of RPV steel; Experiments for irradiation temperature control

Ha, Yoosung; Shimodaira, Masaki; Tobita, Toru; Hanawa, Satoshi; Yamasaki, Shota*; Uno, Sadanori*

2018-Nendo Ryoshi Kagaku Gijutsu Kenkyu Kaihatsu Kiko Shisetu Kyoyo Jisshi Hokokusho (Internet), 3 Pages, 2019/09

no abstracts in English

Journal Articles

Measurement of neutron-production double-differential cross sections in most-forward direction by proton incidences

Satoh, Daiki; Iwamoto, Yosuke; Ogawa, Tatsuhiko

2017-Nendo Ryoshi Kagaku Gijutsu Kenkyu Kaihatsu Kiko Shisetu Kyoyo Jisshi Hokokusho (Internet), 1 Pages, 2019/08

Many neutrons are produced in forward directions by intermediate-energy proton-induced reactions. While it is known that collective motion in a target nucleus plays important role in this neutron production, validity of theoretical model and nuclear-data library has not been examined well due to a lack of experimental data. Hence, we obtained systematic data of neutron-production double-differential cross section in the most-forward direction. The experiment was performed at TIARA of Takasaki Advanced Radiation Research Institute, QST. 34-MeV proton beams were bombarded upon thin carbon, aluminum, iron, and lead target, and the neutrons produced in the most-forward direction were led to experimental room passing through a collimator. Scintillation detectors were used to the neutron detection. In comparison with the calculation results of PHITS, it was found that the theoretical model INCL always overestimate the cross sections, and the evaluated nuclear-data library JENDL-4.0/HE reproduce the measure spectra better than the INCL does.

Journal Articles

Molecular dynamics simulations of physical properties of water and cations in montmorillonite interlayer; Application to diffusion model

Yotsuji, Kenji*; Tachi, Yukio; Kawamura, Katsuyuki*; Arima, Tatsumi*; Sakuma, Hiroshi*

Nendo Kagaku, 58(1), p.8 - 25, 2019/00

Molecular dynamics (MD) simulations were conducted to investigate physical properties of water and cations in montmorillonite interlayer nanopores. The swelling behaviors and hydration states were firstly evaluated as functions of interlayer cations and layer charge. The diffusion coefficients of water and cations in interlayer nanopores were decreased in comparison with those in bulk water and came closer to those in bulk water when basal spacing increased. The viscosity coefficients of interlayer water estimated indicated a significant effect of viscoelectricity at 1- and 2-layer hydration states and higher layer charge of montmorillonite. These trends from MD calculations were confirmed to be consistent with existing measured data and previous MD simulation. In addition, model and parameter related to viscoelectric effect used in the diffusion model was refined based on comparative discussion between MD simulations and measurements. The series of MD calculations could provide atomic level understanding for the developments and improvements of the diffusion model for compacted montmorillonite.

Journal Articles

Development of margin assessment methodology of decay heat removal function against external hazards

Yamano, Hidemasa

Genshiryoku Shisutemu Kenkyu Kaihatsu Oyobi Eichi O Kesshushita Genshiryoku Kagaku Gijutsu, Jinzai Ikusei Suishin Jigyo Heisei-28-Nendo Seika Hokokukai Shiryoshu (Internet), 4 Pages, 2017/01

This study has carried out R&D of margin assessment methodology of decay heat removal function for sodium-cooled fast reactors against external hazards in the MEXT innovative nuclear system R&D project from 2012 to 2016. In 2014, the development has been completed for hazard evaluation and event sequence evaluation methods against combination hazards of snow and low temperature as well as strong wind and rainfall. In forest fire, a combination hazard evaluation methodology has been developed by taking into account lightning.

Journal Articles

Geochemical factors for secondary mineral formation at naturally-occurring hyperalkaline spring in Oman ophiolite

Anraku, Sohtaro; Matsubara, Isamu*; Morimoto, Kazuya*; Sato, Tsutomu*

Nendo Kagaku, 55(2), p.17 - 30, 2017/00

Anionic radionuclides are important for the long-term safety assessment of Japanese transuranic (TRU) waste disposal facilities. Degradation of cementitious materials used to construct the TRU waste disposal facilities, however, can produce a hyperalkaline leachate and so it is necessary to understand the reaction mechanisms that will control the behavior and fate of anionic radionuclides under these hyperalkaline conditions. An excellent natural analogue site to study relevant reaction mechanisms is provided in Oman where hyperalkaline spring waters (pH $$>$$ 11) from serpentinized peridotites discharge into moderately alkaline rivers. Aragonite was found in all secondary mineral samples, with accessory minerals of calcite, layered double hydroxide (LDH) and brucite. LDH was observed at the high Al concentration springs and brucite at the low Al concentration springs. Calcite was only found close to the springs. Distal calcite formation was inhibited due to high Mg concentrations in the river water. The spatial distribution of minerals therefore implicates the importance of the mixing ratio of spring to river water and the relative chemical compositions of the spring and river waters. Supporting mixing model calculations could successfully reproduce the precipitation of aragonite and LDH. The observed decrease in Ca concentration could be explained by aragonite precipitation. pH exerted a strong control on the precipitation of LDH and so too, therefore, on Al concentration. In the mixing water experiments containing up to 40% river water, LDH and brucite were both oversaturated, but brucite was not always identified by XRD. The possible inhibition of brucite by LDH precipitation was an unexpected result.

Journal Articles

Development of margin assessment methodology of decay heat removal function against external hazards

Yamano, Hidemasa

Genshiryoku Shisutemu Kenkyu Kaihatsu Oyobi Eichi O Kesshushita Genshiryoku Kagaku Gijutsu, Jinzai Ikusei Suishin Jigyo Heisei-27-Nendo Seika Hokokukai Shiryoshu (Internet), 4 Pages, 2016/01

This study is carrying out R&D of margin assessment methodology of decay heat removal function for sodium-cooled fast reactors against external hazards in the MEXT innovative nuclear system R&D project from 2012 to 2016. In 2014, the development has been completed for hazard evaluation and event sequence evaluation methods against external precipitation and volcanic eruption hazards. In forest fire, a hazard evaluation methodology has been developed using fire spread simulations.

Journal Articles

Journal Articles

Cesium sorption and desorption behavior of clay minerals

Yokoyama, Shingo*; Nakata, Kotaro*; Suzuki, Shinichi

Nendo Kagaku, 54(1), p.28 - 35, 2015/08

no abstracts in English

Journal Articles

Development of the realtime data acquisition system for JT-60SA with LabVIEW

Sueoka, Michiharu

Heisei-25-Nendo Kaku Yugo Kagaku Kenkyusho Gijutsu Kenkyukai Hokokusho (CD-ROM), p.251 - 258, 2014/02

no abstracts in English

Journal Articles

Molecular orbital analysis on dissolution of smectite under strong alkaline condition with high Ca concentration

Matsue, Naoto*; Abidin, Z.*; Fujii, Naoki*; Oda, Chie; Honda, Akira

Nendo Kagaku, 52(2), p.62 - 70, 2014/00

Bentonite is expected to be used along with cement as engineered barrier components of TRU waste geological disposal system. There is a concern that the bentonite dissolved or altered owing to the contact with strong alkaline and high Ca concentration water derived from the reaction of the cement and groundwater. The first-principles quantum chemical calculations using the cluster model of montmorillonite, the main component of bentonite, were performed, and it was indicated that octahedral Al has higher solubility than octahedral Mg under strong alkaline condition and unsaturated Si-O-Al bond connecting tetrahedral and octahedral sheets at the edge of 110 and 010 planes cleaves easily. The adsorption of OH$$^{-}$$ on tetrahedral Si atom caused dissolution of adjacent Si and Al atoms in addition to the Si atom. While, the dissociation of Si-OH and Al-OH$$_{2}$$ groups and the difference in exchangeable cation species were shown to be less likely to affect the dissolution behavior of montmorillonite.

Journal Articles

Reactive-transport model analyses of bentonite alteration behavior at alkaline condition generated by cement-water interaction in a TRU wastes repository

Oda, Chie; Honda, Akira; Takase, Hiroyasu*; Ozone, Kenji*; Sasaki, Ryoichi*; Yamaguchi, Kohei*; Sato, Tsutomu*

Nendo Kagaku, 51(2), p.34 - 49, 2013/02

Proposed TRU repository designs for geological disposal envisage the use of a bentonite buffer to limit the migration of radionuclides by impeding groundwater flow. Under highly alkaline conditions due to cementitious materials could cause a complex series of coupled changes in the porewater chemistry, mineralogy and, ultimately, the mass transport properties of the bentonite buffer. To elucidate the consequences of these coupled changes, reactive-transport model analyses have been conducted for eight bentonite alteration test cases using different combinations of secondary minerals that could form in the bentonite buffer. It was found that after 100,000 years the amount of dissolved bentonite was at a maximum when metastable secondary minerals precipitated. It was also found that the diffusion and hydraulic coefficients after 100,000 years in all test cases were on the same order of magnitude as the initial values.

Journal Articles

XAFS analysis of Ni diffused in compacted bentonite

Takahashi, Hiroaki; Nemoto, Kazuaki; Tachi, Yukio; Katayama, Misaki*; Inada, Yasuhiro*

2012-Nendo Ritsumeikan Daigaku Sogo Kagaku Gijutsu Kenkyu Kiko Sentan Kenkyu Shisetsu Kyoyo Sokushin Jigyo Seika Hokokusho (Internet), 2 Pages, 2013/00

The diffusion profiles of strongly sorbing nuclides such as Cm, Am, Ni, in a compacted bentonite show two parts with different slopes which cannot be fitted by simple one-dimensional diffusion model considering single species. The reason for this anomalous diffusion behavior is not understood. Some XANES spectral shape of Ni diffused in compacted montmorillonite, which is main content of bentonite, at relatively higher concentrated region exhibit slight broadening of a feature on the high-energy side of the white line. The broadening of a feature doesn't appear in the case of Ni aqueous solution and Ni-montmorillonite. These results indicate that the inner coordination geometry of the Ni(II) ion diffused in compacted montmorillonite at relatively higher concentrated region.

Journal Articles

Removal of radioactive cesium from contaminated soil by using poly-ion complex with clay

Naganawa, Hirochika

Nendo Kagaku, 50(2), p.52 - 57, 2012/01

no abstracts in English

Journal Articles

Report of fellowship recipient for International conference

Kokubu, Yoko

Yoshida Kagaku Gijutsu Zaidan Nempo; Heisei-21-Nendo, p.36 - 37, 2010/12

no abstracts in English

Journal Articles

Ca(II)-Fe(II) and Ca(II)-Mn(II) Exchange Selectivity of Bentonite

Saeki, Kazutoshi*; Nakagawa, Kei*; Wada, Shinichiro*; Shibata, Masahiro; Horoshiro, Yoshinari*; Jinno, Kenji*

Nendo Kagaku, 42(1), p.1 - 5, 2002/08

None

Journal Articles

Large scale simulation and visualization on JAERI Origin3800 system

Idomura, Yasuhiro; Adachi, Masaaki*; Suzuki, Yoshio; Wang, X.*

Saientifikku, Shisutemu Kenkyukai Heisei-14-Nendo Kagaku Gijutsu Keisan Bunkakai Dai-1-Kai Kaigo Shiryo, p.43 - 59, 2002/08

no abstracts in English

Journal Articles

Microstructural Modeling of Compacted Sodium-Bentonite and Application of Unified Molecular Dynamics/Homogenization Analysis for Diffusion Process

Suzuki, Satoru; Fujishima, Atsushi; Ueno, Kenichi; Ichikawa, Yasuaki*; Kawamura, Katsuyuki*; Fujii, Naoki*; Shibata, Masahiro; Sato, Haruo; Kitayama, Kazumi*

Nendo Kagaku, 41(2), p.43 - 57, 2001/12

None

Journal Articles

Beam steering mechanism of the negative ion based NBI for JT-60

Honda, Atsushi; Ito, Takao

Heisei-9-Nendo Kaku Yugo Kagaku Kenkyusho Gijutsu Kenkyukai Hokokusho, p.205 - 208, 1997/00

no abstracts in English

Journal Articles

Monitor TV and infrared camera for negative-ion NBI system

Kazawa, Minoru

Heisei-9-Nendo Kaku Yugo Kagaku Kenkyusho Gijutsu Kenkyukai Hokokusho, p.201 - 204, 1997/00

no abstracts in English

Journal Articles

None

Ishikawa, Hirohisa; ;

Nendo Kagaku, 34(3), p.149 - 156, 1994/00

None

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