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Tokuyasu, Kayoko; Yasue, Kenichi; Komatsu, Tetsuya; Tamura, Itoko; Horiuchi, Yasuharu
QST-M-2; QST Takasaki Annual Report 2015, P. 189, 2017/03
Understanding the stage of mountain building is crucial to the stability assessment of geological environments in geological disposal system. In this context, we have carried out the research and development of provenance analysis techniques to elucidate the mountain-building stage. Here we present the results focusing on the R&D using the Electron Spin Resonance (ESR) signals from quartz in sediments and their basement rocks.
Tokuyasu, Kayoko; Furuta, Sadaaki*; Kokubu, Yoko; Umeda, Koji
Nihon Hoshasen Anzen Kanri Gakkai-Shi, 15(1), p.80 - 87, 2016/07
An optically stimulated luminescence reader (Riso TL/OSL DA-20) was installed in Toki Research Institute of Isotope Geology and Geochronology (Toki-shi, Gifu Prefecture), Japan Atomic Energy Agency (JAEA) for dating the geological sample. An accumulated dose of the sample is obtained using the reader. Sealed beta source of strontium-90 is required to be mounted on the reader because repeated artificial irradiation is necessary for the accumulated dose estimation. However, there are not many introduction examples for the reader domestically, and the information as to radiation control of the reader is limited. We therefore report here the process of source loading on the reader and radiation control associated with the use of the source.
Umeda, Koji; Yasue, Kenichi; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Fujita, Natsuko; Shimizu, Mayuko; Matsubara, Akihiro; Tamura, Hajimu; Yokoyama, Tatsunori; et al.
JAEA-Review 2015-019, 42 Pages, 2015/09
JAEA-Review-2015-019.pdf:4.64MB
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 JAEA, in fiscal year 2015. The objectives and contents in fiscal year 2015 are described in detail based on the outline of 7 years plan (fiscal years 2015-2021). Background of this research is clarified with the necessity and the significance for site investigation and safety assessment, and the past progress in this report. In addition, 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.
Umeda, Koji; Yasue, Kenichi; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Fujita, Natsuko; Shimizu, Mayuko; Shimada, Akiomi; Matsubara, Akihiro; Tamura, Hajimu; et al.
JAEA-Review 2015-012, 43 Pages, 2015/08
JAEA-Review-2015-012.pdf:1.24MB
The concept of geological disposal of high-level radioactive waste (HLW) in Japan is based on a multibarrier system which combines a stable geological environment with an engineered barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in tectonically active zone. This report is to outline 7 years plan (fiscal years 2015-2021) of research and development (R&D) for geosphere stability for long-term isolation of the HLW in JAEA. Background of this research is clarified with the necessity and the significance, and the past progress in this report. The objectives, outline, contents and schedule during the next 7 years are described in detail. In addition, 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.
Thiel, C.*; Tsukamoto, Sumiko*; Tokuyasu, Kayoko; Buylaert, J.-P.*; Murray, A. S.*; Tanaka, Kazuhiro*; Shirai, Masaaki*
Quaternary Geochronology, 29, p.16 - 29, 2015/08
Times Cited Count：11 Percentile：33.8(Geography, Physical)The applicability of both quartz and feldspar luminescence dating was tested on twenty-five samples from a marine succession now forming a cliff at Oga Peninsula, Honshu Island, Japan. The quartz shows thermal instability and linear modulated optically stimulated luminescence (LM-OSL) analysis revealed the dominance of a slow component. When compared with independent age control provided by two marker tephra, the quartz OSL ages grossly underestimated the depositional age. In contrast, potassium (K)-rich feldspar is a suitable dosimeter when measured using post-IR infrared stimulated luminescence (IRSL) at 225
C, but it was found that the fading corrected ages calculated using dose rates based on sieved grain-size still underestimate. SEM analyses on the feldspar extracts revealed that the grains are amorphous with small crystalline inclusions; using standard internal dose rate parameters, this would result in a too large dose rate. Three different dose rate scenarios were considered for calculation: (1) sieved grain size (90-180
m) and 12.5
0.5% K. (2) smaller grain size (4020m) and measured K concentration (60.5%), and (3) smaller grain size consistent with the observed crystal dimensions (4020m) and 12.50.5% K. The final dose rate scenario produces fading corrected ages that agree well with independent age control.
Tokuyasu, Kayoko; Tanaka, Kazuhiro*
Dai Yonki Kenkyu, 54(1), p.1 - 9, 2015/02
Optically stimulated luminescence (OSL) signal resetting of quartz grains from modern fluvial sediments (flood and river-bed sediments; four samples in total) were investigated to discuss the applicability of OSL dating for fluvial terrace sediments in Japan. Single aliquot regenerative dose (SAR) protocol was employed to estimate the residual doses of the samples. Residual doses from all samples range from 1.20.3 to 5.93.5 Gy, and the doses can be converted to the OSL age of 6-0.6 ka. We concluded that the OSL dating has the potential to remark the marine isotope stage (MIS) of fluvial terraces at around 100 ka.
Tokuyasu, Kayoko
no journal, ,
Various source rocks are distributed in Japan, where is located at mobile belt. Thus, quartz grains in sediments are derived from a wide variety of source rocks, it is likely that the characteristics of OSL signal in the quartz grains depend on the source rocks. In general, detectable fast component in a quartz grained sample is essential for accurate OSL dating. However, even though the fast component was detected in quartz grains from some fluvial sediments in Japan, the OSL ages were underestimated due to unstable OSL signal at room temperature. To understand this issue and to determine selection condition of applicable sample for OSL dating, I report here on the thermoluminescence color image (TLCI) and impurity concentration of sediment samples which are likely related to the characteristics of OSL signals and the geological settings.
Yasue, Kenichi; Komatsu, Tetsuya; Tokuyasu, Kayoko; Tamura, Itoko; Horiuchi, Yasuharu
no journal, ,
no abstracts in English
Yasue, Kenichi; Sugai, Toshihiko*; Tokuyasu, Kayoko; Komatsu, Tetsuya; Horiuchi, Yasuharu; Shimizu, Hitoshi*; Morita, Yasuhiko*
no journal, ,
no abstracts in English
Tokuyasu, Kayoko; Yasue, Kenichi; Komatsu, Tetsuya; Tamura, Itoko; Horiuchi, Yasuharu
no journal, ,
We have carried out the research and development of provenance analysis techniques to elucidate the mountain-building stage using quartz ESR signals in sediments. The R&D was conducted using the Tokai Formation including Toki Sand and Gravel Formation distributed over the Tono area. In the northern part of the area, bedrocks consist of sedimentary rocks, Nohi Rhyolite and Sanyo Granite, whereas consist of Ryoke Granites in the southern part. Samples of sediments were taken from the quarry located between the Tsukechi River and Atera fault. Basement rock samples were also taken in and around the quarry. Outcrop observation indicates that the provenance of sediments changed between the lower and upper parts. Quartz grains for ESR measurements were extracted from all samples. As a result, granitic rocks of Sanyo belt were not exposed to the drainage basin during the deposition of the lower part between 3.9 and 2.0 Ma, then the granitic rocks were exposed during the deposition of upper part after about 2.0 Ma. We conclude that it is possible to estimate the sediment provenance using ESR properties.
Tokuyasu, Kayoko; Tamura, Itoko; Komatsu, Tetsuya; Yasue, Kenichi
no journal, ,
The uplift rate during the past hundred thousand years is estimated from the elevation and emergence ages of terrace surfaces which are used as geomorphologic standard. OSL dating is effective method to determine the emergence ages. Here we report a case study of quartz OSL dating of fluvial terrace sediments, and its adequacy is considered in the correlation with intercalated marker tephra. All samples were collected from fluvial terrace sediments along Kiso River and Tsukechi River which is a tributary of the Kiso. The investigated fluvial terrace sediments are composed of laminated sand layer and pumice layer which is likely to be reworked. The pumice was identified as On-Pm1 tephra by mineral composition, refractive indices of volcanic glass and phenocryst minerals, and the major element composition of volcanic glass. This indicated that the fluvial terrace sediments were deposited after 100ka. The extracted quartz grains from terrace sediments were measured by conventional SAR protocol. The obtained OSL ages are about 40-50 ka, being underestimated because the OSL decay curves from all samples were dominant by medium component which is unsuitable for OSL dating. We thus attempt to determine the equivalent dose using the isolated fast component OSL signal which is suitable for OSL dating.
Tokuyasu, Kayoko; Yasue, Kenichi; Komatsu, Tetsuya; Tamura, Itoko; Horiuchi, Yasuharu
no journal, ,
We have carried out the research and development of provenance analysis techniques to elucidate the mountain-building stage using quartz ESR signals in sediments. The R&D was conducted using the Tokai Formation including Toki Sand and Gravel Formation distributed over the Tono area. In the northern part of the area, bedrocks consist of sedimentary rocks, Nohi Rhyolite and Sanyo Granite, whereas consist of Ryoke Granites in the southern part. Samples of sediments were taken from the quarry located between the Tsukechi River and Atera fault. Basement rock samples were also taken in and around the quarry. Outcrop observation indicates that the provenance of sediments changed between the lower and upper parts. Quartz grains for ESR measurements were extracted from all samples. As a result, granitic rocks of Sanyo belt were not exposed to the drainage basin during the deposition of the lower part between 3.9 and 2.0 Ma, then the granitic rocks were exposed during the deposition of upper part after about 2.0 Ma. We conclude that it is possible to estimate the sediment provenance using ESR properties.
Yasue, Kenichi; Tokuyasu, Kayoko; Komatsu, Tetsuya; Horiuchi, Yasuharu; Shimizu, Mayuko; Niwa, Masakazu
no journal, ,
no abstracts in English
Miyakawa, Kazuya; Miyara, Nobukatsu; Tokuyasu, Kayoko; Shimizu, Mayuko
no journal, ,
no abstracts in English
Nishimura, Shusaku; Yasue, Kenichi; Tokuyasu, Kayoko; Tozawa, Terumasa; Horiuchi, Yasuharu; Komatsu, Tetsuya
no journal, ,
no abstracts in English
Kawai, Fumika*; Ganzawa, Yoshihiro*; Tokuyasu, Kayoko*; Yasue, Kenichi
no journal, ,
no abstracts in English
