Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2023)

Niwa, Masakazu; Shimada, Koji; Sueoka, Shigeru; Fujita, Natsuko; Yokoyama, Tatsunori; Ogita, Yasuhiro; Fukuda, Shoma; Nakajima, Toru; Kagami, Saya; Ogata, Manabu; et al.

JAEA-Review 2023-017, 27 Pages, 2023/10

JAEA-Review-2023-017.pdf:0.94MB

This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2023. The objectives and contents in fiscal year 2023 are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. The plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

Position-by-position cooling paths within the Toki granite, central Japan; Constraints and the relation with fracture population in a pluton

Yuguchi, Takashi*; Sueoka, Shigeru; Iwano, Hideki*; Izumino, Yuya*; Ishibashi, Masayuki; Danhara, Toru*; Sasao, Eiji; Hirata, Takafumi*; Nishiyama, Tadao*

Journal of Asian Earth Sciences, 169, p.47 - 66, 2019/01

AA2018-0254.pdf:5.48MB

https://doi.org/10.1016/j.jseaes.2018.07.039

This study presents position-by-position paths within a granitic pluton based on thermochronological data, and describes their constraints and their relationship with fracture frequency, as an example from the Toki granite, central Japan. The cooling paths have position-specific characteristics; a single path does not represent the cooling behavior of the entire pluton. Such position-specific paths enable us to evaluate three-dimensional thermal evolution within the granitic pluton, and thus can clarify the detailed formation history of the entire pluton after the incipient intrusion of the granitic magma into the shallow crust. This study reveals the relationship between position-specific paths and fracture frequency, and thus provides a criterion for evaluating the fracture population in terms of thermal stress.

Zircon growth in a granitic pluton with specific mechanisms, crystallization temperatures and U-Pb ages; Implication to the "spatiotemporal" formation process of the Toki granite, central Japan

Yuguchi, Takashi*; Iwano, Hideki*; Kato, Takenori*; Sakata, Shuhei*; Hattori, Kentaro*; Hirata, Takafumi*; Sueoka, Shigeru; Danhara, Toru*; Ishibashi, Masayuki; Sasao, Eiji; et al.

Journal of Mineralogical and Petrological Sciences, 111(1), p.9 - 34, 2016/02

https://doi.org/10.2465/jmps.151007

Zircon growth collected from a granitic pluton shows four (1st - 4th) events with specific mechanisms, crystallization temperatures and U-Pb ages, revealing the sequential formation process from intrusion through emplacement to crystallization / solidification. The events are recognized by: (1) internal structure of zircon based on the cathodoluminescence observation, (2) crystallization temperatures by the Ti-in-zircon thermometer in the internal structure and (3) U-Pb ages in the internal structure.

Inspection of JMTR secondary cooling system; Secondary cooling system piping and cooling tower

Watahiki, Shunsuke; Asano, Norikazu; Hanawa, Yoshio; Gorai, Shigeru; Nishiyama, Yutaka; Tsuboi, Kazuaki

JAEA-Review 2010-019, 65 Pages, 2010/07

JAEA-Review-2010-019.pdf:7.25MB

JMTR secondary cooling system piping and a cooling tower were inspected from the view point of long term utilization before the renewal work for the secondary cooling system of the JMTR on FY 2008. As the result, it was confirmed that crack, swelling, and exfoliations in inner of piping lining, and decay and dryness of wood in the upper part of the cooling tower. From the result of this inspection some facilities and machinery were repaired or replaced from the view point of preventive maintenance.

Synthesis of pinguisane-type sesquiterpenoids acutifolone A, pinguisenol, and bisacutifolones by a Diels-Alder dimerization reaction

Shiina, Junichi*; Oikawa, Masataka; Nakamura, Kensuke; Obata, Rika*; Nishiyama, Shigeru*

European Journal of Organic Chemistry, 2007(31), p.5190 - 5197, 2007/11

https://doi.org/10.1002/ejoc.200700522

It is important to synthesize bio-active compounds which will affect DNA repair system. The total synthesis of pinguisane-type sesquiterpenoids, acutifolone A and pinguisenol, has been achieved by using the Mukaiyama aldol reaction as the key step. The intermolecular Diels-Alder reaction of these monomeric natural products successfully led to stereoselective dimerization, leading to bisacutifolones A and B. Theoretical calculations revealed that the dimerization reaction proceeded through the most stable transition state.

Spatial distribution of zircon U-Pb ages in the Toki granite, Central Japan; Relationship of intrusion, emplacement and the subsequent cooling processes

Yuguchi, Takashi; Iwano, Hideki*; Hattori, Kentaro*; Sakata, Shuhei*; Sueoka, Shigeru; Danhara, Toru*; Hirata, Takafumi*; Ishibashi, Masayuki; Kunimaru, Takanori; Nishiyama, Tadao*

no journal, , 

no abstracts in English

Spatial distribution of the apatite fission-track ages in the Toki granite, central Japan; Exhumation rate of the Cretaceous pluton emplaced in the East Asian continental margin

Yuguchi, Takashi*; Sueoka, Shigeru; Iwano, Hideki*; Danhara, Toru*; Ishibashi, Masayuki; Sasao, Eiji; Nishiyama, Tadao*

no journal, , 

The spatial distribution of AFT age in the granitic body is a favorable key to reveal a cooling behavior of the whole pluton. The cooling behavior is attributable to the regional exhumation of the Toki granite related to the regional denudation of the Tono district. Combination of the AERs and AFT inverse model applying to the granite is a powerful procedure for evaluating the cooling and exhumation history of the granitic pluton and thus denudation history of the tectonic region that surrounded the rock body.

Estimation of emergence age using feldspar OSL dating; Case studies in the Noto Peninsula and the Oi River

Ogata, Manabu; Tsukahara, Yuzuko; Kawamura, Makoto; Kanno, Mizuho; Nishiyama, Nariaki*; Sueoka, Shigeru; Komatsu, Tetsuya; Nakanishi, Toshimichi*; Yasue, Kenichi*

no journal, , 

Optically stimulated luminescence (OSL) dating method on feldspar is useful to date sediments on geomorphological time scale. In this presentation, we present the case studies for marine terraces in the Noto Peninsula and abandoned river valleys along the Oi River, for which the emergence ages were estimated by using feldspar OSL dating. This study was carried out as a part of the establishment of advanced technology for estimation of uplift rates using emergence ages of emergent landforms project.

Stress tensor inversion method for minor faults in areas of unclear active fault topography; Example in area of around source of the 1984 Western Nagano Earthquake

Nishiyama, Nariaki; Nakajima, Toru; Goto, Akira*; Hakoiwa, Hiroaki; Sueoka, Shigeru; Shimada, Koji; Niwa, Masakazu

no journal, , 

For some earthquakes of magnitude 6 to 7, the surface earthquake fault is unclear, and it is necessary to establish an evaluation method to understand the active faults that cause such earthquakes. In this study, in the source area of the 1984 western Nagano Prefecture earthquake, where no distinct surface earthquake faults appeared, we estimated the stress field that may have affected the activity of small faults by stress tensor inversion method using striation data of small faults collected by surface exploration, and extracted areas with many small faults consistent with the regional stress field. As a result of the surface survey, we collected data on 321 small faults. Considering the location and number of these small fault data, the study area was divided into 13 areas. As a result of stress tensor inversion method in each area, stress with a maximum compressive stress axis in the NW-SE direction, which is harmonic to the regional stress field in this area, was detected in the area near the upper end of the hidden fault. In these regions, there are relatively many small faults that were displaced by the activity of the hidden fault, and their distribution area is expected to correspond to the damage zone of the hidden fault or a deformation zone that extends over a wider area. Therefore, even when no clear fault displacement topography is recognized, we expect to be able to estimate its distribution and extent of influence by surface exploration. This study was funded by the Ministry of Economy, Trade and Industry (METI), Japan as part of its R&D supporting program titled "Establishment of Advanced Technology for Evaluating the Long-term Geosphere Stability on Geological Disposal Project of Radioactive Waste (JPJ007597) (Fiscal Years 2020-2022)".