Mri, A.*; Mazurek, M.*; Ota, Kunio; Siitari-Kauppi, M.*; Eichinger, F.*; Leuenberger, M.*
Minerals (Internet), 11(10), p.1072_1 - 1072_17, 2021/10
Vela, S.*; Mota, F.*; Deumal, M.*; Suizu, Rie*; Shuku, Yoshiaki*; Mizuno, Asato*; Awaga, Kunio*; Shiga, Motoyuki; Novoa, J.*; Ribas-Arino, J.*
Nature Communications (Internet), 5, p.4411_1 - 4411_9, 2014/07
Recent years have witnessed a growing interest in the use of organic radicals as building blocks for bistable materials, i.e. materials that exist in two inter-exchangeable phases under identical thermodynamic conditions. The neutral radical TTTA is a prominent dithiazolyl-based compound because of its spin transition with a hysterisis nature near the room temperature. From ab initio molecular dynamics simulations, it has been evident that this phase transition is driven by the pair exchange dynamics of molecular stacking units accompanied by a significant gain of vibrational entropy.
Hirota, Takatoshi*; Hirano, Takashi*; Onizawa, Kunio
Proceedings of 2013 ASME Pressure Vessels and Piping Conference (PVP 2013) (DVD-ROM), 7 Pages, 2013/07
Master Curve approach is the effective method to evaluate the fracture toughness of the ferritic steels accurately and statistically. The Japan Electric Association Code JEAC 4216-2011 was published based on the related standard ASTM E 1921-08 and the results of the investigation of the applicability of the Master Curve approach to Japanese reactor pressure vessel (RPV) steels. The reference temperature To can be determined according to this code in Japan. In this study, using the existing fracture toughness data of Japanese RPV steels, the method for determination of the alternative reference temperature RT based on Master Curve reference temperature To was statistically examined, so that RT has an equivalent safety margin to the conventional RT. Through the statistical treatment, the alternative reference temperature RT was proposed as the following equation; RT = To + C + 2. This method is applicable to the Japan Electric Association Code JEAC 4206 as an option item.
Amano, Kenji; Niizato, Tadafumi; Ota, Kunio; Lanyon, B.*; Alexander, W. R.*
Proceedings of 14th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2011) (CD-ROM), p.1477 - 1481, 2011/09
The assurance of the long-term stability of the geological environment is for deep geological disposal. In Japan, since uplift/subsidence and climatic and sea-level changes would result in a significant change to hydraulic and hydrochemical conditions at coastal sites, it is of importance to establish comprehensive techniques for characterising the overall evolution of coastal sites over geological time. To this end, modelling techniques focussing on the coastal site evolution have been developed through the collaborative research programme at the Horonobe coastal study area. A palaeohydrogeological conceptual model has been developed based on all available information and eventually key geological properties and processes as well as a methodology for appropriately defining the initial and boundary conditions for long-term groundwater flow simulations have been clarified.
Kunimaru, Takanori; Ota, Kunio; Alexander, W. R.*; Yamamoto, Hajime*
JAEA-Research 2011-010, 52 Pages, 2011/06
Work has been currently ongoing to establish an appropriate quality management system (QMS), which is applicable to all aspects of the site characterisation process, in the Horonobe Underground Research Laboratory project. A quality assurance (QA) audit of hydrochemical datasets for JAEA's deep boreholes HDB-1 to HDB-8 was carried out, along similar lines to that of the previous study for boreholes HDB-9 to HDB-11, by applying both the groundwater QA methodology employed in the recent site assessments in Sweden and a porewater QA regime proposed in this study. The results of the QA audit indicated that data were classified into low QA categories because mainly of a lack of relevant information, such as the records of groundwater sampling, which are necessary for more fully assessing the data quality. As such, a formalised field manual for hydrochemical sampling was developed. In addition, work to further improve the site characterisation QMS progressed.
Fujita, Tomo; Taniguchi, Naoki; Matsui, Hiroya; Tanai, Kenji; Maekawa, Keisuke; Sawada, Atsushi; Makino, Hitoshi; Sasamoto, Hiroshi; Yoshikawa, Hideki; Shibata, Masahiro; et al.
JAEA-Research 2011-001, 193 Pages, 2011/03
This report summarizes the progress of research and development on geological disposal during the surface-based investigation phase (2001-2005) in the Horonobe Underground Research Laboratory project, of which aims are to apply the design methods of geological disposal and mass transport analysis to actual geological conditions obtained from the surface-based investigations in the Horonobe Underground Research Laboratory project as an example of actual geological environment.
Ota, Kunio; Abe, Hironobu; Kunimaru, Takanori
JAEA-Research 2010-068, 370 Pages, 2011/03
The Horonobe Underground Research Laboratory (URL) Project is a comprehensive research and development project aimed at studying the host sedimentary formations at Horonobe in Hokkaido, northern Japan. In phase I, following the selection of the URL area and site in Horonobe, stepwise surface-based investigations were carried out from March 2001 to March 2005. The relevant surface-based investigation techniques were developed and the design and safe construction plans for the URL finalised. Integration of the results ensures that the phase I goals were successfully achieved and identifies key issues that need to be addressed in phases II and III. More importantly, efforts have been made to summarise as many lessons learnt from the phase I investigations as possible to form a "knowledge base" that will reinforce the technical basis for both implementation and the formulation of safety regulations. The present report summarises the results of the phase I geoscientific research.
Kunimaru, Takanori; Ota, Kunio; Alexander, W. R.*; Yamamoto, Hajime*
JAEA-Research 2010-035, 109 Pages, 2010/11
A quality management system (QMS) will save on effort by reducing errors and the requirement to re-sample and re-analysis and eventually lead to ensuring the reliability of the investigation results. In the Horonobe Underground Research Laboratory project, work has been ongoing to develop an appropriate QMS which is applicable to surface-based investigations. A quality assurance (QA) audit of hydrochemical datasets for boreholes HDB-9 - 11 has been carried out by applying both the groundwater QA methodology employed in the recent site assessments in Sweden and the porewater QA regime newly proposed for assigning the QA categories. This QA audit exercise indicates that the HDB-9 - 11 hydrochemical data are classified into lower categories because mainly of contamination of waters by drilling fluids, poor time-series data coverage and oxidation of core materials and also clarifies areas where additional information/work would be required to the ongoing programme.
Notoya, Shin; Sasao, Eiji; Ota, Kunio; Shimizu, Kazuhiko
JAEA-Conf 2010-004, 119 Pages, 2010/11
In March 2010, a prototype of "next generation" knowledge management system (KMS) and a status report (CoolRep H22) synthesizing the R&D results were made publicly available at the conclusion of R&D for the first Midterm Plan (October 2005 to March 2010). This could further reinforce the technical knowledge base and thus enable the geological disposal project and associated safety regulations to be continuously supported. The conference on "Development of JAEA Knowledge Management System, 2010" was held on 16th June 2010 in Tokyo, with main aims of introducing KMS and CoolRep H22 to broader stakeholders, promoting their understanding and having input from them for further improvement of KMS. This report compiles presentation materials and comments to KMS and CoolRep H22 from participants.
Ishii, Eiichi; Funaki, Hironori; Tokiwa, Tetsuya; Ota, Kunio
Journal of Structural Geology, 32(11), p.1792 - 1805, 2010/11
In order to assess influences of a remote mean stress on a principal mode of failure near fault tips due to fault slip in a lithologically homogeneous, fractured rock mass, the growth mechanisms of strike-slip faults on outcrop-scale in the siliceous mudstones of northern Hokkaido, Japan, have been studied. A multifaceted approach combining geological characterizations of fractures, rock mechanical characterizations, and theoretical analyses have been done, which suggested (1) the principal mode of failure depend on not only the rock strengths, but also the remote mean stresses, (2) during and/or after uplift and erosion the faults grew mainly by linking with adjacent faults via many splay cracks which are formed by tensile failure above roughly 400 m depth, while, below the depth, the faults predominantly grew by shear failure. Such growth mechanisms are consistent with the fact that highly permeable sections are restricted to depths of less than 400 m.
Ota, Kunio; Amano, Kenji; Niizato, Tadafumi; Alexander, W. R.*; Yamanaka, Yoshiaki*
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.123 - 132, 2010/10
The assurance of the long-term stability of the geological environment is for deep geological disposal. In Japan, since uplift/subsidence and climatic and sea-level changes would result in a significant change to hydraulic and hydrochemical conditions at coastal sites, it is of importance to establish comprehensive techniques for characterising the overall evolution of coastal sites over geological time. To this end, palaeohydrogeological study is ongoing in the coastal area around Horonobe in northern Hokkaido. A "Geosynthesis Data Flow Diagram" defining a methodology for characterising the palaeohydrogeological evolution of the site has been formulated and, based on the geosynthesis methodology, a basic strategy has been established for stepwise investigations from initial survey of existing information to the final borehole programme at any coastal site. This technique has now been tested and optimised with the progress of the investigations.
Kunimaru, Takanori; Ota, Kunio; Amano, Kenji; Alexander, W. R.*
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.159 - 168, 2010/10
Niizato, Tadafumi; Amano, Kenji; Ota, Kunio; Kunimaru, Takanori; Lanyon, B.*; Alexander, W. R.*
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.97 - 106, 2010/10
A critical issue for building confidence in the long-term safety of geological disposal is to demonstrate the stability of the geosphere, taking into account its likely future evolution. This study aims to establish comprehensive techniques for characterising the overall evolution of coastal sites through studying the palaeohydrogeological evolution in the coastal system around the Horonobe area, Hokkaido, northern Japan. Information on natural events and processes related to the palaeohydrogelogical evolution of the area have been integrated into the conceptual models that indicates the temporal and spatial sequences of the events and processes, such as climatic and sea-level changes, palaeogeography, and geomorphological and geological evolution in the area. The methodology will be applied to other analogous coastal areas on Japan to produce comprehensive techniques to support understanding the geosphere evolution of potential coastal sites for the repositories.
Notoya, Shin; Ota, Kunio; Shimizu, Kazuhiko
JAEA-Conf 2009-005, 58 Pages, 2010/02
Geological Isolation Research and Development Directorate has now been developing a "next generation" knowledge management system (KMS) that would continuously support the disposal project and associated safety regulations. Work has been also ongoing on synthesizing the results of R&D for the first midterm plan in the style of "next generation" scientific reporting "CoolRep" which is strongly linked with KMS. In March 2010, a prototype of KMS and a status report (CoolRep H22) will be made publicly available. It is thus of much significance to promote stakeholder's understanding of KMS and CoolRep and have input from them at this timing in order to efficaciously proceed with the future work. To this end, the conference on "Progress in Development of JAEA Knowledge Management System" was held on 1st July 2009 in Tokyo. This report compiles presentation materials and comments/input to KMS and CoolRep from the stakeholders.
Alexander, W. R.*; Frieg, B.*; Ota, Kunio
Nagra NTB 00-07, 105 Pages, 2009/11
Nagra and JAEA worked together for nearly a decade on a Radionuclide Retardation Project (RRP) at Nagra's Grimsel Test Site in Switzerland with the main aim of enhancing the understanding of radionuclide transport/retardation in fractured rock. This report summarises the results of the final phase (1996-1998) of excavation project that is an integral part of RRP. It focuses on in situ characterisation of the shear zone structure and the behaviour of radionuclides that are relevant to repository post-closure safety, but are so strongly retarded by interaction with the shear zone rock that they are not expected to migrate through the dipole flow-field in experimentally reasonable time scales. The subsequent excavation of the experimental shear zone is detailed and the results of the laboratory analysis of the three-dimensional geological structure and of the distribution of injected radionuclides within the flow-field are presented.
Osawa, Hideaki; Umeki, Hiroyuki; Ota, Kunio; Hama, Katsuhiro; Sawada, Atsushi; Takeuchi, Shinji; Semba, Takeshi; Takase, Hiroyasu*; McKinley, I. G.*
Proceedings of International Waste Management Symposium 2009 (WM '09) (CD-ROM), 11 Pages, 2009/03
The focus of this paper is development of advanced technology from the field of Knowledge engineering, termed the Information Synthesis and Interpretation System (ISIS), which incorporates past experience and know-how currently being obtained in complex URL projects within Expert System (ES) modules in 2009.
Osawa, Hideaki; Ota, Kunio; Hama, Katsuhiro; Sawada, Atsushi; Takeuchi, Shinji; Amano, Kenji; Saegusa, Hiromitsu; Matsuoka, Toshiyuki; Miyamoto, Tetsuo; Toyoda, Gakuji; et al.
JAEA-Research 2008-085, 742 Pages, 2008/11
This report shows the results the project for the establishment of comprehensive site characterization technology, entrusted from Natural Resources and Energy Agency, Ministry of Economy, Trade and Industry Natural Resources and Energy Agency in 2007.
Yamanaka, Yoshiaki; Matsuoka, Toshiyuki; Asamori, Koichi; Ota, Kunio
Shadan Hojin Butsuri Tansa Gakkai Dai-119-Kai (Heisei-20-Nendo Shuki) Gakujutsu Koenkai Koen Rombunshu, p.73 - 75, 2008/10
Characterisation of the coastal geological environment has now been running since July 2007 at Horonobe, northern Hokkaido, with the main aims of establishing a comprehensive coastal site characterisation technology and enhancing its reliability. Work carried out to date involves a survey and interpretation of the existing information, identification of key investigation issues and planning of ground exploration. Development of technical know-how and decision process for the work, in particular the geophysical surveys, has been initiated to provide "knowledge" to support a site characterisation project.
Izawa, Yasukazu*; Nishihara, Katsunobu*; Tanuma, Hajime*; Sasaki, Akira; Murakami, Masakatsu*; Sunahara, Atsushi*; Nishimura, Hiroaki*; Fujioka, Shinsuke*; Aota, Tatsuya*; Shimada, Yoshinori*; et al.
Journal of Physics; Conference Series, 112, p.042047_1 - 042047_4, 2008/00
In the development of a high power EUV source used in the EUV lithography system, we have been constructed EUV database of laser-produced tin plasma by the theoretical and experimental studies. On the basis of our understanding, the optimum conditions of lasers and plasmas were clarified, and we proposed the guidelines of laser plasma to obtain clean, efficient and high power EUV source for the practical EUV lithography system. In parallel to such studies, novel targets and high power laser system to generate the optimized EUV source plasma have been developed.
Mri, A.*; Soler, P.*; Ota, Kunio; Havlov, V.*
Nagra NAB 07-42, 31 Pages, 2007/12
The Long-Term Diffusion (LTD) project, an integral part of Phase IV at the Grimsel Test Site, Switzerland, is an international cooperative project (HYRL, Finland; JAEA and AIST, Japan; NRI/RAWRA, Czech Republic; Nagra, Switzerland) and consists of a series of experiments which aims to obtain quantitative information on matrix diffusion under in situ conditions. The LTD is divided into four work packages, WP1-4. The in situ monopole diffusion experiment (WP1) is preceded by predictive modelling exercise to support the design of the in situ experiment and to increase confidence in the modelling of long-term and large-scale diffusion process by comparing the predictions with the experimental results. This report presents a short overview of the conceptual models and codes applied and the predicted tracer profiles in the rock matrix as well as the expected tracer concentration in the injection solution.