Spatial distribution of desaturation around the tunnel predicted by three-dimensional two-phase flow modeling of the degassing process of dissolved gases in groundwater

Miyakawa, Kazuya; Yamamoto, Hajime*

JAEA-Research 2022-003, 40 Pages, 2022/05

JAEA-Research-2022-003.pdf:6.08MB

The excavation of large-scale underground facilities, such as geological disposal of high-level radioactive waste, creates an excavation damaged zone (EDZ) with cracks around the tunnel. In the EDZ, oxygen invades the bedrock through unsaturated cracks and affects environmental conditions for nuclide migration. When a tunnel is excavated in a geological formation containing a high concentration of dissolved CH, such as the Neogene marine sediments, degassed CH prevents oxygen intrusion. However, it may be promoted through gas-phase diffusion through desaturation. The purpose of this study is to illustrate the method of estimating the spatial distribution of desaturation associated with the construction and operation of underground facilities in a stratum that contains a large amount of dissolved CH. A sequential excavation analysis that reflected the actual process of 10-year excavation of the Horonobe Underground Research Laboratory (URL) was carried out along with gas-water two-phase flow analysis. The analysis results of the amount of groundwater and gas discharged from the URL were about 100 to 300 m d and 250 to 350 m d, respectively, as of January 2017. These results showed values close to the observations (100 m d and 300 m d, respectively). The analysis results of the saturation distribution were relatively high around the 250 m gallery and relatively low around the 350 m gallery, confirming that they are consistent with the in-situ observations. Although there were still technical issues of analysis regarding the conditions for groundwater drainage from the tunnel wall and the method of handling grout effects, the numerical calculation was generally appropriate. Although the results of the saturation distribution associated with the excavation were insufficient as the quantitative evaluation, they were almost correct from a qualitative point of view.

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

The Effect of dissolved gas on rock desaturation in artificial openings in geological formations

Miyakawa, Kazuya; Aoyagi, Kazuhei; Sasamoto, Hiroshi; Akaki, Toshifumi*; Yamamoto, Hajime*

Proceedings of 5th ISRM Young Scholars' Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future (YSRM 2019 and REIF 2019) (USB Flash Drive), 6 Pages, 2019/12

The construction and operation of geological repositories require excavation and ventilation of galleries, with significant groundwater drainage. Desaturation of rock around galleries is unavoidable and may affect hydraulic properties and redox conditions. This study used numerical modeling to assess the influence of dissolved gas on the degree of saturation of rock surrounding excavated galleries, focusing on siliceous mudstone rock in the 140 m, 250 m, and 350-m-deep galleries of the Horonobe Underground Research Laboratory, Japan. Based on previous electrical survey, the degree of saturation in the 250 m gallery was higher than that in the 140 m and 350 m galleries. In the Horonobe area, deep groundwater contains high concentrations of dissolved methane, and exsolution of this methane from pore water can affect desaturation. Simple numerical modeling, including simulation of multiphase flows, was undertaken for each gallery to confirm the effect of dissolved gas and rock permeability on desaturation. A sensitivity analysis was performed by varying dissolved gas contents and permeability. Results indicate that the dissolved gas content affects both the degree of saturation and its spatial extent, whereas rock permeability affects only the latter. Higher dissolved gas concentrations result in lower degrees of saturation with a greater spatial extent of desaturation, and higher permeability leads to greater extents of desaturation. It is therefore likely that gas content, rather than rock permeability, caused the observed variations in the saturation degree.

Composition analysis of high-stable transparent conductive zinc oxide by X-ray photoelectron spectroscopy and secondary ion mass spectroscopy

Kuchiyama, Takashi*; Hasegawa, Shigehiko*; Yamamoto, Kenji*; Teraoka, Yuden; Asahi, Hajime*

Japanese Journal of Applied Physics, 50(12), p.121101_1 - 121101_4, 2011/12

https://doi.org/10.1143/JJAP.50.121101

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.

27th report of ITPA topical group meeting

Osakabe, Masaki*; Shinohara, Koji; Toi, Kazuo*; Todo, Yasushi*; Hamamatsu, Kiyotaka; Murakami, Sadayoshi*; Yamamoto, Satoshi*; Idomura, Yasuhiro; Sakamoto, Yoshiteru; Tanaka, Kenji*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 85(12), p.839 - 842, 2009/12

http://ci.nii.ac.jp/naid/40016957892

no abstracts in English

Status of JT-60SA tokamak under the EU-JA broader approach agreement

Matsukawa, Makoto; Kikuchi, Mitsuru; Fujii, Tsuneyuki; Fujita, Takaaki; Hayashi, Takao; Higashijima, Satoru; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Ide, Shunsuke; Ishida, Shinichi; et al.

Fusion Engineering and Design, 83(7-9), p.795 - 803, 2008/12

https://doi.org/10.1016/j.fusengdes.2008.06.047

no abstracts in English

The H-Invitational Database (H-InvDB); A Comprehensive annotation resource for human genes and transcripts

Yamasaki, Chisato*; Murakami, Katsuhiko*; Fujii, Yasuyuki*; Sato, Yoshiharu*; Harada, Erimi*; Takeda, Junichi*; Taniya, Takayuki*; Sakate, Ryuichi*; Kikugawa, Shingo*; Shimada, Makoto*; et al.

Nucleic Acids Research, 36(Database), p.D793 - D799, 2008/01

https://doi.org/10.1093/nar/gkm999

Here we report the new features and improvements in our latest release of the H-Invitational Database, a comprehensive annotation resource for human genes and transcripts. H-InvDB, originally developed as an integrated database of the human transcriptome based on extensive annotation of large sets of fulllength cDNA (FLcDNA) clones, now provides annotation for 120 558 human mRNAs extracted from the International Nucleotide Sequence Databases (INSD), in addition to 54 978 human FLcDNAs, in the latest release H-InvDB. We mapped those human transcripts onto the human genome sequences (NCBI build 36.1) and determined 34 699 human gene clusters, which could define 34 057 protein-coding and 642 non-protein-coding loci; 858 transcribed loci overlapped with predicted pseudogenes.

Long-term simulation of ambient groundwater chemistry at Horonobe underground research laboratory, Japan; Application of coupled hydro-geochemical model

Yamamoto, Hajime*; Kunimaru, Takanori; Kurikami, Hiroshi; Shimo, Michito*; Xu, T.*

Proceedings of 2nd International Conference on Coupled T-H-M-C Processes in Geo-systems; Fundamentals, Modeling, Experiments and Applications (GeoProc 2006), p.382 - 387, 2006/05

no abstracts in English

Hydrogeological Modeling and Groundwater Flow Analysis of the Underground Research Laboratory Site Using the Various Conceptual Model (Phase 2)

Ijiri, Yuji*; Ono, Makoto*; Sugihara, Yutaka*; Shimo, Michito*; Yamamoto, Hajime*; Fumimura, Kenichi*

JNC TJ7400 2004-015, 732 Pages, 2003/10

JNC-TJ7400-2004-015.pdf:34.55MB

In order to establish the most effective procedures for groundwater flow characterization in order to reduce the uncertainty this study, the identidication of essential uncertainty factors for the groundwater flow characterization has been attempted using various conceptual model. In this study, an integrated data flow on the groundwater flow simuration was developed for previously applied various conceptural models. The data flow consists of five steps in order: (1) field investigation, (2) raw / conditioned data, (3) interpretation / data set, (4) conceptualization / modeling / simulation, and (5) results / applications. These are uncertainties in each work and assumption in every step, and the uncertainties have an influence on the modeling methods and simulation resuls. Following the data flow, the uncertain factors affecting the groundwater flow simulation were extracted based on the simulation resuls. Investigation data, methods of investigation and modeling, and analysis technique were examined to solve the problems due to the uncertainties. Acquired information is summarized in the following. As for each work process in the data flow, the uncertainty factors that are considered to affect the results of simulations are extracted by two kinds of comparison methods as follows: (1) comparison of data flow among analysis cases for each conceptual model, and (2) comparison of data flow among conceptual models for each case. The uncertainty factors include hydrogeological mechanism of fault and effective porosity, and the likes. The development of each data flow for four modeling methods was additionally used to clarify the data interpretation technique, the modeling procedure, and the uncertainty factor in each data flow along with the data flow from investigation through evaluation. Extensive through information without bias is, therefore, reflected in groundwater flow analysis by defining the data flow. Establishment of data flow...