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Goto, Takahiro*; Mitsui, Seiichiro; Takase, Hiroyasu*; Kurosawa, Susumu*; Inagaki, Manabu*; Shibata, Masahiro; Ishiguro, Katsuhiko*
MRS Advances (Internet), 1(63-64), p.4239 - 4245, 2016/00
NUMO and JAEA have conducted a joint research since FY2011, which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage for deep geological disposal of radioactive waste. As a part of this joint research, we have been developing glass dissolution models which consider various processes in EBS, such as precipitation of Fe-silicates associated with iron overpack corrosion, and Si transport through corrosion products in the cracked overpack. The objectives of the modeling work are to evaluate relative importance of relevant processes and to identify further R&D issues towards development of a convincing safety case. Sensitivity analyses suggested that predicted glass dissolution time ranges from 1
10
to 110
years or more due to uncertainties in the current understanding of the key processes, namely precipitation of Fe-silicates and transport characteristics of the altered glass layer.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Kitamura, Akira; Yoshikawa, Hideki; Oda, Chie; Ishidera, Takamitsu; et al.
JAEA-Research 2014-030, 457 Pages, 2015/03
JAEA-Research-2014-030.pdf:199.23MB
JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Hayano, Akira; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.
JAEA-Research 2013-037, 455 Pages, 2013/12
JAEA-Research-2013-037.pdf:42.0MB
Following FY2011, JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, the tree diagram of methodology of groundwater travel time has been extended for crystalline rock, in addition, tree diagram for sedimentary rock newly has been organized. With regard to (2) study on scenario development, the existing approach has been improved in terms of a practical task, and applied and tested for near field focusing on the buffer. In addition, the uncertainty of some important processes and its impact on safety functions are discussed though analysis. With regard to (3) study on setting radionuclide migration parameters, the approaches for parameter setting have been developed for sorption for rocks and solubility, and applied and tested through parameter setting exercises for key radionuclides.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Hayano, Akira; Mitsui, Seiichiro; Taniguchi, Naoki; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.
JAEA-Research 2012-032, 298 Pages, 2012/09
JAEA-Research-2012-032.pdf:33.68MB
JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation phase. The topics and the conducted research are follows; (1) Study on selection of host rock: in terms of hydraulic properties, items for assessing rock property, and assessment methodology of groundwater travel time has been organized with interaction from site investigation. (2) Study on development of scenario: the existing approach has been embodied, in addition, the phenomenological understanding regarding dissolution of and nuclide release from vitrified waste, corrosion of the overpack, long-term performance of the buffer are summarized. (3) Study on setting nuclide migration parameters: the approach for parameter setting has been improved for sorption and diffusion coefficient of buffer/rock, and applied and tested for parameter setting of key radionuclides. (4) Study on ensuring quality of knowledge: framework for ensuring quality of knowledge has been studied and examined aimed at the likely disposal facility condition.
-rays and heavy-ion beam in 
Bolige, A.*; Sakashita, Tetsuya; Kakizaki, Takehiko*; Funayama, Tomoo; Hamada, Nobuyuki*; Wada, Seiichi*; Kobayashi, Yasuhiko; Goto, Ken*
JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 117, 2008/03
We report here how these rhythms are related to each other. First, irradiation temperatures influenced neither survival after exposure to UV, rays, nor C ions, whereas the incubation at high temperatures (25 
C) after irradiation considerably lowered the survival particularly after irradiation, but not after UV irradiation at all. Secondly, although the antioxidants 
carotene and dimethylsulfoxide (DMSO) increased the survival of the alga at the least resistant phase after UV C and UV B irradiation, respectively, to the level of the most resistant alga, none of these were not so effective for or C ion irradiation. Finally, FITC dextran was incorporated into the alga only after C ion irradiation but not irradiation, suggesting that C ion may perforate cell membranes to kill the alga.
7 heteroepitaxial growthAsaoka, Hidehito; Yamazaki, Tatsuya; Shamoto, Shinichi; Arnoldo, A.*; Goto, Seiichi*; Suemitsu, Maki*
Hyomen Kagaku, 28(9), p.500 - 503, 2007/09
Stress evolution during initial stage of Ge nanodot formation on Si(111)-77 has been investigated by using simultaneous measurements of the substrate curvature and the surface morphology. In the beginning of the first bilayer growth of Ge on Si(111)-77, a strong compressive film stress is observed, indicating a formation of a two-dimensional wetting layer. When the layer thickness approaches the critical one for three-dimensional nanodot nucleation, a clear bend in the stress curve is observed, corresponding to a partial relaxation of the lattice planes on the surface of the nanodots. Moreover, a stress transition has been also found to exist in the very early stage of the nanodot formation, which is concurrent with the trench formation around the three-dimensional nanodots.
-irradiation and heavy-ion beam in Aoen, B.*; Sakashita, Tetsuya; Kakizaki, Takehiko; Funayama, Tomoo; Hamada, Nobuyuki*; Wada, Seiichi*; Kobayashi, Yasuhiko; Goto, Ken*
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 120, 2007/02
no abstracts in English
Moritani, Kosuke; Okada, Michio*; Sato, Seiichi*; Goto, Seishiro*; Kasai, Toshio*; Yoshigoe, Akitaka; Teraoka, Yuden
Journal of Vacuum Science and Technology A, 22(4), p.1625 - 1630, 2004/08
Times Cited Count：25 Percentile：65.31(Materials Science, Coatings & Films)We studied the oxidation of Cu{111} surface with a hyperthermal O
molecular beam (HOMB) using X-ray photoemission spectroscopy (XPS) in conjunction with a synchrotron radiation (SR) source. The efficiency of oxidation with 0.6-eV-HOMB is higher thab that with 2.3-eV-HOMB under 
0.5ML. Ont the other hand, further oxidation occurs rather inefficiency under 
0.5ML. In this region, efficiency of oxidation with 2.3-eV-HOMB is higher than 0.6-eV-HOMB. We found that such slow oxidation process of Cu can be interpreted in terms of a collision-induced-adsorption mechanism. These results suggest that we can control the oxidation process of Cu by using HOMB.
Tamai, Hiroshi; Matsukawa, Makoto; Kurita, Genichi; Hayashi, Nobuhiko; Urata, Kazuhiro*; Miura, Yushi; Kizu, Kaname; Tsuchiya, Katsuhiko; Morioka, Atsuhiko; Kudo, Yusuke; et al.
Plasma Science and Technology, 6(1), p.2141 - 2150, 2004/02
Times Cited Count：2 Percentile：6.33(Physics, Fluids & Plasmas)The dominant issue for the the modification program of JT-60 (JT-60SC) is to demonstrate the steady state reactor relevant plasma operation. Physics design on plasma parameters, operation scenarios, and the plasma control method are investigated for the achievement of high-. Engineering design and the R&D on the superconducting magnet coils, radiation shield, and vacuum vessel are performed. Recent progress in such physics and technology developments is presented.
Ishida, Shinichi; Abe, Katsunori*; Ando, Akira*; Cho, T.*; Fujii, Tsuneyuki; Fujita, Takaaki; Goto, Seiichi*; Hanada, Kazuaki*; Hatayama, Akiyoshi*; Hino, Tomoaki*; et al.
Nuclear Fusion, 43(7), p.606 - 613, 2003/07
Times Cited Count：33 Percentile：68.09(Physics, Fluids & Plasmas)no abstracts in English
Ishida, Shinichi; Abe, Katsunori*; Ando, Akira*; Chujo, T.*; Fujii, Tsuneyuki; Fujita, Takaaki; Goto, Seiichi*; Hanada, Kazuaki*; Hatayama, Akiyoshi*; Hino, Tomoaki*; et al.
Nuclear Fusion, 43(7), p.606 - 613, 2003/07
no abstracts in English
2Nakano, Takuya*; Hasegawa, Satoshi*; Togashi, Hideaki*; Kato, Atsushi*; Goto, Seiichi*; Teraoka, Yuden; Yoshigoe, Akitaka; Suemitsu, Maki*
no journal, ,
no abstracts in English
Asaoka, Hidehito; Yamada, Yoichi; Yamazaki, Tatsuya; Girard, A.*; Yamamoto, Hiroyuki; Shamoto, Shinichi; Arnoldo, A.*; Goto, Seiichi*; Suemitsu, Maki*
no journal, ,
We reports the recent progress about structural formation on semiconductor surface: real-time stress analysis of Ge nanodot growth on Si(111)-77 surfaces, and preparation of the single-domained Si(110)-162 surface.
2 surface by Si 2p photoemission spectroscopyYamamoto, Yoshihisa*; Togashi, Hideaki*; Kato, Atsushi*; Hasegawa, Satoshi*; Goto, Seiichi*; Nakano, Takuya*; Suemitsu, Maki*; Narita, Yuzuru*; Yoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
Initial oxidation process of Si(110)-162 clean surface has been investigated with synchrotron radiation photoemission spectroscopy. We found that the intensity of the alpha peak, one of the surface core level shifts in the Si 2p photoemission spectra, decreased in the just early stage of oxidation. And it was possible to relate this component with the rapid initial oxidation, which was unique to Si(110) surface. According to recent studies, this component was attributed to the 1st and the 2nd Si layer. We also found that there were significant amount of Si
component just after introducing the oxygen gas, which was contrast to the oxidation of Si(001) surface.
Aoen, B.*; Sakashita, Tetsuya; Kakizaki, Takehiko; Funayama, Tomoo; Hamada, Nobuyuki*; Wada, Seiichi*; Kobayashi, Yasuhiko; Goto, Ken*
no journal, ,
no abstracts in English
Goto, Takahiro*; Matsubara, Ryuta*; Hamamoto, Takafumi*; Fujisaki, Kiyoshi*; Mitsui, Seiichiro; Taniguchi, Naoki
no journal, ,
To improve long-term glass corrosion model, immersion tests with specimens of carbon steel and simulated waste glass were conducted at 50C and 80C under nitrogen gas atmosphere for 131 days. Control tests with a specimen of carbon steel or glass under the same conditions were also conducted. After the tests, the element concentration in the solution was analyzed to determine glass corrosion rates. We also analyzed the surface of specimens with XRD and TEM/ED (electron diffraction)/EDX to identify secondary phases. Glass corrosion rates for the tests with specimens of carbon steel and glass were two times larger than those for the control tests with glass specimen. With XRD and TEM/ED/EDX, we determined iron silicates on the surface of both carbon steel and glass. These observations are consistent with the results of geochemical calculation and published studies. The results indicate that glass corrosion could be enhanced by the precipitation of iron silicates.
2 surfaceYamamoto, Yoshihisa*; Togashi, Hideaki*; Kato, Atsushi*; Hasegawa, Satoshi*; Goto, Seiichi*; Nakano, Takuya*; Suemitsu, Maki*; Narita, Yuzuru*; Yoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
We have investigated the initial oxidation process on an Si(110)-162 surface by real time synchrotron radiation photoemission spectroscopy (SR-XPS). As a result, a rapid initial oxidation regime was found to exist on this surface, which is not present on other crystal orientations. Analyses of the O1s spectra suggest insertion of oxygen atoms at the Si-Si bonds as the predominant process during initial oxidation. The rapid initial oxidation is accompanied by decrease of the Si2p subpeak that is related to Si(110)-162 reconstruction, indicating the preferential oxidation at the pentagon pair.
2 surfaceTogashi, Hideaki*; Yamamoto, Yoshihisa*; Goto, Seiichi*; Takahashi, Yuya*; Nakano, Takuya*; Kato, Atsushi*; Hasegawa, Satoshi*; Konno, Atsushi*; Suemitsu, Maki*; Asaoka, Hidehito; et al.
no journal, ,
no abstracts in English
2 surface and surface reconstructionTogashi, Hideaki*; Yamamoto, Yoshihisa*; Goto, Seiichi*; Takahashi, Yuya*; Nakano, Takuya*; Konno, Atsushi*; Suemitsu, Maki*; Asaoka, Hidehito; Yoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
Initial oxidaion processes at Si(110)-162 clean surface with O mokecules have been observed by real-time SR-XPS and STM methods. SR-XPS experiments were performed at BL23SU in SPring-8 and STM experiments were performed in JAEA Tokai research center. From comparison of oxygen uptake curves of Si(110)-162 with Si(001)-21, following conclusions were obtained. Rapid initial oxidation occured at the Si(110) surface and layer-by-layer oxidation was also took place. In-situ observation with STM revealed that the rapid initial oxidation was due to oxygen adsorption at pentagon-pair Si atoms on the topmost surface, at least 4 kinds of oxygen-adsorbed states, and the DD site was a condensed oxidation state.
2 surface observed by SR-PESYamamoto, Yoshihisa*; Togashi, Hideaki*; Kato, Atsushi*; Hasegawa, Satoshi*; Nakano, Takuya*; Goto, Seiichi*; Teraoka, Yuden; Yoshigoe, Akitaka; Suemitsu, Maki*
no journal, ,
In this study, we have investigated adsorption of oxygen molecules on Si(110)-162 clean surface at room temperature by synchrotron radiation photoemission spectros (SR-PES). The SR-PES experiments were conducted at the surface chemistry end-station of BL23SU in the SPring-8. The photon energy was 334 eV. Samples were B-doped p-type Si(110) wafers, and were flash-annealed in an UHV ambient prior to the exposure to oxygen gas at room temperature at the gas pressure of 6.710
Pa. By observing a structural change after a mild annealing, we have confirmed presence of a metastable state of oxidation on this RT-oxidized Si(110) surface.
