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Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：5 Percentile：87.42(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
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.
113 of the 113th elementMorita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sumita, Takayuki*; Wakabayashi, Yasuo*; Yoneda, Akira*; Tanaka, Kengo*; et al.
Journal of the Physical Society of Japan, 81(10), p.103201_1 - 103201_4, 2012/10
Times Cited Count：167 Percentile：97.31(Physics, Multidisciplinary)An isotope of the 113th element, 113, was produced in a nuclear reaction with a 
Zn beam on a 
Bi target. We observed six consecutive 
decays following the implantation of a heavy particle in nearly the same position in the semiconductor detector, in extremely low background condition. The fifth and sixth decays are fully consistent with the sequential decays of 
Db and 
Lr both in decay energies and decay times. This indicates that the present decay chain consisted of 113, 
Rg (Z = 111), 
Mt (Z = 109), 
Bh (Z = 107), Db (Z = 105), and Lr (Z = 103) with firm connections. This result, together with previously reported results from 2004 and 2007, conclusively leads the unambiguous production and identification of the isotope 113, of the 113th element.
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.
Nohara, Tsuyoshi; Umeda, Koji; Sasao, Eiji; Asamori, Koichi; Hanamuro, Takahiro; Moriya, Toshifumi*; Nakatsuka, Noboru
JAEA-Research 2007-087, 102 Pages, 2008/02
JAEA-Research-2007-087.pdf:35.58MB
The Japanese islands are located in the tectonically active Circum-Pacific Mobile Belt. As a result, Japan has a high frequency of earthquakes and eruptions. Special consideration is given to the long-term stability of the geological environment, taking into account volcanism, faulting, uplift, denudation, climatic change and sea-level change in Japan. Development of research/prediction technologies for geotectonic events has been carried out to evaluate the long-term stability of the geological environment in Japan. Until fiscal year 2005, to confirm existence of phenomena that have a influence on geological disposal system (e.g. active fault or Quarternary volcanoes) and to confirm that there was not the trace that the phenomena occurred in the past and to predict/evaluate possibility of the phenomena, development of the research/prediction techniques for geotectonic events (e.g. Research techniques for earthquake source faults, Research techniques for detecting magmas and high-temperature fluids, Three-dimensional landform development simulator) were carried out. This report describes our efforts of these technologies based on its R&D program until fiscal year 2005.
Asano, Yoshihiro; Kishi, Noriyuki*; Moriya, Takahiro*; Miura, Yuta*; Inoue, Katsuaki*
AIP Conference Proceedings 705, p.568 - 571, 2004/04
no abstracts in English
Asano, Yoshihiro; Kishi, Noriyuki*; Moriya, Takahiro*
AIP Conference Proceedings 705, p.564 - 567, 2004/00
no abstracts in English
Hanamuro, Takahiro; Nohara, Tsuyoshi; Umeda, Koji; Moriya, Toshifumi; Nakatsuka, Noboru
no journal, ,
Geoscientific research is performed as a basis of the research and development on the geological disposal technology of high-level radioactive waste in the Tono Geoscience Center, JAEA. In this seminar, we report on the current status of the research on long-term stability of the geological environment among research topics set by the geoscientific research.
Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Kadono, Atsunobu*; Moriya, Koichi*; Nakanishi, Takahiro
no journal, ,
Accelerated release of carbon (C) previously stored in soils is considered one of the most important positive feedbacks from terrestrial ecosystems to the atmosphere in a future warmer world. We used 14C analysis following chemical fractionation to quantify the sizes and turnover times of C pools of Japanese forest soils. The 
C-based approach revealed higher variations of the family of MRTs soil by soil. The size of C pools that cycle slowly on timescales of 100-1000 years strongly correlated with the content of pyrophosphate-extractable Al. In contrast, faster-cycling C pools that turn over within decades showed a negative correlation with mean annual temperature at the sites. Our results suggest that C dynamics in the isolated SOC pools may be regulated by different mechanisms: temperature control on decadal cycling C versus mineralogy control on slower-cycling C, and clearly demonstrate that the forest soils will respond very differently to climate change over the next century.
Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Kadono, Atsunobu*; Moriya, Koichi*; Nakanishi, Takahiro
no journal, ,
Soils are the largest carbon (C) reservoir in terrestrial ecosystems, and may act as both a source and sink of atmospheric CO
in response to climate change. Identifying the sizes and turnover times of soil organic carbon (SOC) pools is a crucial step to predicting the fate of soil C. Here, we used a C-based approach to quantitatively understand how much and how long Japanese forest soils store C in their surface horizons. We collected soil samples from deciduous forests, separated the samples into SOC fractions, and then determined their C ratios to estimate mean residence times (MRTs). The MRTs ranged from years to millennia, which revealed a different distribution of MRTs between the soils. We found that the total amount of C correlated positively with the size of the SOC pools cycling on time scales of 
100 years, but poorly with the size of faster-cycling pools. The results suggest that the soils with higher C stocks do not necessarily have higher potential for CO emission.
respired from a beech forest floorAtarashi-Andoh, Mariko; Koarashi, Jun; Moriya, Koichi; Nakanishi, Takahiro; Ishizuka, Shigehiro*; Hirai, Keizo*
no journal, ,
no abstracts in English
Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Kadono, Atsunobu*; Moriya, Koichi*; Nakanishi, Takahiro
no journal, ,
no abstracts in English
Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Kadono, Atsunobu*; Moriya, Koichi; Nakanishi, Takahiro
no journal, ,
no abstracts in English
