The Key role of vibrational entropy in the phase transitions of dithiazolyl-based bistable magnetic materials

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

http://doi.org/10.1038/ncomms5411

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.

Development of comprehensive techniques for coastal site characterisation; Integrated palaeohydrogeological approach for development of site evolution models

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

https://doi.org/10.1115/ICEM2011-59259

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.

Horonobe Underground Research Laboratory Project; Synthesis of phase I investigation 2001 - 2005, Volume "Geological disposal research"

Fujita, Tomoo; 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

JAEA-Research-2011-001.pdf:5.23MB

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.

Groundwater/porewater hydrochemistry at Horonobe URL: Data Freeze I; Preliminary data quality evaluation for boreholes HDB-9, 10 and 11

Kunimaru, Takanori; Ota, Kunio; Alexander, W. R.*; Yamamoto, Hajime*

JAEA-Research 2010-035, 109 Pages, 2010/11

JAEA-Research-2010-035.pdf:2.53MB

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.

Relationship between fault growth mechanism and permeability variations with depth of siliceous mudstones in northern Hokkaido, Japan

Ishii, Eiichi; Funaki, Hironori; Tokiwa, Tetsuya; Ota, Kunio

Journal of Structural Geology, 32(11), p.1792 - 1805, 2010/11

https://doi.org/10.1016/j.jsg.2009.10.012

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.

Development of comprehensive techniques for coastal site characterisation, 1; Strategic overview

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

https://doi.org/10.1115/ICEM2010-40056

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.

Conference on progress in development of JAEA knowledge management system (Conference report)

Notoya, Shin; Ota, Kunio; Shimizu, Kazuhiko

JAEA-Conf 2009-005, 58 Pages, 2010/02

JAEA-Conf-2009-005.pdf:11.2MB

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.

Development of next-generation technology for integrated site characterization of deep geological repositories

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

http://www.wmsym.org/archives/2009/pdfs/9132.pdf

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.

Development of know-how and systematic techniques for characterisation of coastal geological environment at Horonobe

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.

Grimsel test site phase VI, LTD WP 1; Predictive modelling for LTD monopole experiment

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.