A Numerical simulation study of the desaturation and oxygen infusion into the sedimentary rock around the tunnel in the Horonobe Underground Research Laboratory

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

JAEA-Data/Code 2021-002, 26 Pages, 2021/05

JAEA-Data-Code-2021-002.pdf:2.14MB
JAEA-Data-Code-2021-002-appendix(CD-ROM).zip:40.99MB

Investigations employing numerical simulation have been conducted to study the mechanisms of desaturation and oxygen infusion into sedimentary formations. By mimicking the conditions of the Horonobe underground research laboratory, numerical simulations aided geoscientific investigation of the effects of dissolved gas content and rock permeability on the desaturation (Miyakawa et al., 2019) and mechanisms of oxygen intrusion into the host rock (Miyakawa et al., 2021). These simulations calculated multi-phase flow, including flows of groundwater and exsolved gas, and conducted sensitivity analysis changing the dissolved gas content, rock permeability, and humidity at the gallery wall. Only the most important results from these simulations have been reported previously, because of publishers' space limitations. Hence, in order to provide basic data for understanding the mechanisms of desaturation and oxygen infusion into rock, all data for 27 output parameters (e.g., advective fluxes of heat, gas, and water, diffusive fluxes of water, CH, CO, O, and N, saturation degree, water pressure, and mass fraction of each component) over a modeling period of 100 years are presented here.

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.

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

https://doi.org/10.1007/s10751-016-1381-7

Groundwater/porewater hydrochemistry at Horonobe URL; Data freeze II; Preliminary data quality evaluation for boreholes HDB-1 to 8

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

JAEA-Research 2011-010, 52 Pages, 2011/06

JAEA-Research-2011-010.pdf:2.29MB

Work has been currently ongoing to establish an appropriate quality management system (QMS), which is applicable to all aspects of the site characterisation process, in the Horonobe Underground Research Laboratory project. A quality assurance (QA) audit of hydrochemical datasets for JAEA's deep boreholes HDB-1 to HDB-8 was carried out, along similar lines to that of the previous study for boreholes HDB-9 to HDB-11, by applying both the groundwater QA methodology employed in the recent site assessments in Sweden and a porewater QA regime proposed in this study. The results of the QA audit indicated that data were classified into low QA categories because mainly of a lack of relevant information, such as the records of groundwater sampling, which are necessary for more fully assessing the data quality. As such, a formalised field manual for hydrochemical sampling was developed. In addition, work to further improve the site characterisation QMS progressed.

EUV spectra from highly charged tin ions observed in low density plasma in LHD

Suzuki, Chihiro*; Kato, Takako*; Sato, Kuninori*; Tamura, Naoki*; Kato, Daiji*; Sudo, Shigeru*; Yamamoto, Norimasa*; Tanuma, Hajime*; Ohashi, Hayato*; Suda, Shintaro*; et al.

Journal of Physics; Conference Series, 163, p.012019_1 - 012019_4, 2009/06

https://doi.org/10.1088/1742-6596/163/1/012019

We have measured EUV spectra from highly charged tin ions in low density plasmas produced in the Large Helical Device (LHD). The well known dense spectral structure around 13.5 nm is measured when the plasma is rapidly cooled and approaching radioactive collapse, while the sparse spectrum with several unidentified discrete lines from 13.8-14.6 nm is observed if the plasma is cooled more slowly. The dominant charge states in the former case are Sn -Sn. The latter case may be explained by considering the spectral lines from charge states higher than Sn.

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

Study on the prediction accuracy of nuclide generation and depletion with JENDL

Okumura, Keisuke; Oki, Shigeo*; Yamamoto, Munenari*; Matsumoto, Hideki*; Ando, Yoshihira*; Tsujimoto, Kazufumi; Sasahara, Akihiro*; Katakura, Junichi; Matsumura, Tetsuo*; Aoyama, Takafumi*; et al.

JAERI-Research 2004-025, 154 Pages, 2005/01

JAERI-Research-2004-025.pdf:19.46MB

This report summarizes the activity (FY2000-2003) of Working Group (WG) on Evaluation of Nuclide Generation and Depletion under Subcommittee on Nuclear Fuel Cycle of Japanese Nuclear Data Committee. In the WG, analyses of Post Irradiation Examinations have been carried out for UO and MOX fuels irradiated in PWRs, BWRs and FBRs, and for actinide samples irradiated in fast reactors, by using ORIGEN or more detailed calculation codes with their libraries based on JENDL-3.2, JENDL-3.3 and other foreign nuclear data files. From these results, current prediction accuracy and problems for evaluation of nuclide generation and depletion are discussed. Furthermore, this report covers other products of our activity; development of the ORIGEN libraries for PWR, BWR and FBR based on JENDL-3.3, study on introduction of neutron spectrum index to ORIGEN calculations, and results of questionnaire survey on desirable accuracy of ORIGEN calculations.

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...

Hydrogeological Modeling and Groundwater Flow Analyses of the Underground Research Laboratory Site Using the Various Conceptual Model

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

JNC TJ7400 2004-003, 610 Pages, 2003/03

JNC-TJ7400-2004-003.pdf:42.03MB

This study involves evaluation of uncertainty in hydrogeological modeling and groundwater flow analysis. Three-dimensional groundwater flow analisys in underground research laboratory site in Tono was carried out using three continuum models and one discontinuum model in the domain of 9km9km area. The acquired knowledge is as follows.The effect of variety of modeling method was evaluated under the condition that same analysis domain and same shape of Tsukiyoshi fault were assingned. The results indicated that the variation of travel pathway and travel length resulted from heterogeneity is sometimes larger than from the difference of models, depending on a place. Besides, since the difference between the models in travel time was larger than a travel pathway and travel length, it turns out that the uncertainty of effective porosity used for alculation of the actual flow velocity is large.Moreover, the existing data flow was reconstituted through a series of modeling and analysis of this work. The results indicated that it is necessary to continue reflecting the results of investigation and evaluation in data flow, since data flow varied with modeling concepts.

Study on Flow and Mass Transport through Fractured Soft Sedimentary Rocks

Shimo, Michito*; Yamamoto, Hajime*; Kumamoto, So*

JNC TJ8400 2003-028, 135 Pages, 2003/02

JNC-TJ8400-2003-028.pdf:3.79MB

The objective of this study is to establish a conceptual model for flow and transport in fractured soft sedimentary rock.In this fiscal year, this study was carried out for two tasks: (1) classification of soft sedimentary rocks by literature survey, (2) laboratory experiments on the flow and mass transport using rock specimens obtained at HDB-4 borehole in Horonobe Deep Underground Research Center. Classification of soft sedimentary rocks is carried out using two databases of rock properties collected by JNC and Geological Survey of Japan. In laboratory experiments, core samples of the Tertiary siliceous mud rock obtained from the HDB-4 borehole, which was excavated in the Horonobe area in this year, were studied. The matrix porosity of intact cores measured by wet and dry weight was ranging from 33% to 41%. The hydraulic conductivities of rock matrix determined by the transient pulse test were in an order of 10-11 m/s. The effective diffusion coefficients obtained from the through diffusion test were 0.8 to 2.5x10-11 m2/s. This suggested that, in these cores, the flow in the rock matrix is not significant comparing with the flow in fractures, and the matrix diffusion from fractures into rock matrix should cause a significant effect to the mass transport phenomenon. Non-sorbing tracer experiment was conducted in fractured cores. As a tracer, potassium iodide solution was injected at a constant rate and the tracer concentration change during injection was observed at the outlet. The obtained breakthrough curve was interpreted and fitted by using a numerical simulator for flow and mass transport called FRAC3DVS (Therrien et al., 1999), and finally, mass transport parameters are obtained. The result indicates that the matrix diffusion plays an important role for mass transport in the fractured soft sedimentary rocks.