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.

Reconstructing the thermal structure of shallow crust in the Tono region using multi-OSL-thermometry of K-feldspar from deep borehole core

Ogata, Manabu; King, G. E.*; Herman, F.*; Sueoka, Shigeru

Earth and Planetary Science Letters, 591, p.117607_1 - 117607_14, 2022/08

https://doi.org/10.1016/j.epsl.2022.117607

Optically stimulated luminescence (OSL)-thermometry can be used to reconstruct the thermal structure in slowly denuded regions where infrared stimulated luminescence (IRSL) signals of samples obtained from deep boreholes are measured and evaluated with depth. Until now, only one study has explored this approach, using a target mineral of Na-feldspar. In this study, we applied multi-OSL-thermometry to K-feldspar obtained from deep borehole core samples (MIZ-1) drilled at the Tono region, central Japan, which is a well-documented thermally stable crustal environment. The inverted temperature for the IRSL 50 C of the samples at a depth of 1 km (40 C) were consistent with the in-situ temperature. The results suggest that the application of OSL-thermometry to K-feldspar in a borehole is useful to reconstruct the paleothermal condition.

Report on the 17th International Conference on Thermochronology

Nakajima, Toru; Fukuda, Shoma; Ogata, Manabu; Sueoka, Shigeru

Fuisshon, Torakku Nyusureta, (34), p.25 - 26, 2021/12

The 17th International Conference on Thermochronology (Thermo2021) was held on September 12-17, 2021 at the Eldorado Resort in downtown Santa Fe, New Mexico, USA. Due to the social situation and the spread of the COVID-19, the event had been postponed. In this paper, I report on the circumstances surrounding our participation in the conference, the contents and trends of the presentations made at the conference, and the tasks for the 2023 and 2025 conferences.

Ultra-low-temperature thermochronology using optically stimulated luminescence (OSL)

Ogata, Manabu; Sueoka, Shigeru

Radioisotopes, 70(3), p.159 - 172, 2021/03

https://doi.org/10.3769/radioisotopes.70.159

no abstracts in English

Multi-OSL-thermochronometry using deep borehole core for thermal history over 0.1 Myr in Rokko Mountains

Ogata, Manabu; King, G. E.*; Herman, F.*; Yamada, Ryuji*; Omura, Kentaro*; Sueoka, Shigeru

no journal, , 

Optically stimulated luminescence (OSL) thermochronometry is a tool for constraining cooling histories in low-temperature domains (several tens of degree Celsius) during the past 10-100 kyr. This method is currently applied only to rapidly denuded regions (about 5 mm/yr), because luminescence signals in slowly denuded regions saturate before the rocks are exhumated to the surface. However, cooling histories in slowly denuded regions may be constrained if unsaturated samples are obtained from deep boreholes. We applied multi-OSL-thermochronometry to the deep borehole core drilled at the Rokko Mountains, Japan, where slow denudation rates (0.1-1.0 mm/yr) are expected from previous studies. We used the Kabutoyama core collected by National Research Institute for Earth Science and Disaster Resilience. The total length of Kabutoyama core is 1,313 m and we collected the samples at 408, 642, 818 and 1048 m for OSL-thermochronometry. We found that the sample temperatures remained around the present ambient temperature at each depth for the last 0.1 Myr, indicating that the Rokko Mountains is topographically stable, which was consistent with previous findings. Thus, the thermal denudation history of slowly denuded regions may be constrained by multi-OSL-thermochronometry using samples from deep borehole cores. However, the denudation rates in the Rokko Mountains were too low and could not be determined by this method.

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.

Working towards a robust thermochronometer based on the ESR of quartz minerals

King, G.*; Bartz, M.*; Bossin, L.*; Wen, X.*; Tsukamoto, Sumiko*; Herman, F.*; Ogata, Manabu; Sueoka, Shigeru

no journal, , 

Will ESR thermochronometry reveal the timing of Rhne valley incision?

King, G. E.*; Wen, X.*; Bartz, M.*; Anderson, L.*; Bossin, L.*; Tsukamoto, Sumiko*; Li, Y.*; Herman, F.*; Ogata, Manabu; Sueoka, Shigeru

no journal, , 

Feldspar OSL dating of MIS 5e marine terrace deposits; Case study in the Kii Peninsula

Ogata, Manabu; Komatsu, Tetsuya; Nakanishi, Toshimichi*

no journal, , 

Marine terraces are formed by regional uplift and sea level change, being useful for estimating uplift rates on geomorphological time scale (10-10 years). However, the emergent ages, and then the uplift rates, are difficult to determine when the sediments include few organic materials and tephra. Optically stimulated luminescence (OSL) dating method on feldspar is useful to date sediments on 10-10-year timescales. Thus, this method has been applied to date marine terrace deposits in the last several years. In this presentation, we will present the case study for MIS 5e marine terraces in the Kii Peninsula, for which the depositional ages were estimated by using feldspar OSL dating.

Estimation of incision and uplift rate based on feldspar OSL dating of river channel sediments; Case study in the Oi River

Ogata, Manabu; Tsukahara, Yuzuko; Nishiyama, Nariaki; Komatsu, Tetsuya; Uchida, Mao; Kawamura, Makoto; Ishihara, Takanori; Nakanishi, Toshimichi*

no journal, , 

Terrace to terrace (TT) method is mainly used for estimating uplift rate on mountain areas of Japan on 10-year time scale. However, this method cannot be applied to the area with poor distribution of fluvial terraces. In such area, the method based on the emergence ages of the fluvial landform, e.g., an abandoned river valley around a cutoff spur, and the relative elevation between old and present reiver bed is expected instead of TT method. This method calculates the river-incision rate by dividing the relative elevation by the emergence age. The river-incision rate is equal to the uplift rate if the river is at equilibrium (graded stream). We are investigating the fluvial landform in the Oi River basin for verifying this method. In this presentation, we will present the incision and uplift rate estimated by feldspar OSL dating results.