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Journal Articles

Method for groundwater monitoring on the disposal of radioactive waste

Murakami, Hiroaki; Iwatsuki, Teruki; Takeuchi, Ryuji; Nishiyama, Nariaki*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(1), p.22 - 33, 2020/06

Geological disposal of radioactive waste requires the large amounts of fundamental technical knowledge throughout the project. Monitoring is carried out to collect site-relevant information for the creation of an environmental database, to assist in the decision-making process, etc. We summarized the current technical level and problems of the groundwater monitoring in the world. Through the research and technology development so far, the technologies have been developed for drilling borehole in the geological environment survey prior to monitoring and the selection of the monitoring site. However, the following technical developments are remaining issues: long-term operation method of monitoring equipment, retrieving method of monitoring equipment after long-term operation, transport method of backfill material for borehole sealing, technical basis for the sealing performance when the borehole-protective casing and strainer tube are left.

JAEA Reports

Study of groundwater sampling casing for monitoring device

Okihara, Mistunobu*; Yahagi, Ryoji*; Iwatsuki, Teruki; Takeuchi, Ryuji; Murakami, Hiroaki

JAEA-Technology 2019-021, 77 Pages, 2020/03

JAEA-Technology-2019-021.pdf:5.33MB

One of the major subjects of the ongoing geoscientific research program, the Mizunami Underground Research Laboratory (MIU) Project in the Tono area, central Japan, is accumulation of knowledge on monitoring techniques of the geological environment. In this report, the conceptual design of the monitoring system for groundwater pressure and water chemistry was carried out. The currently installed and used system in research galleries at various depths was re-designed to make it possible to collect groundwater and observe the water pressure on the ground.

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry data in the Mizunami group and the Toki granite (fiscal year 2018)

Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Aosai, Daisuke*; Kumamoto, Yoshiharu*; Iwatsuki, Teruki

JAEA-Data/Code 2019-019, 74 Pages, 2020/03

JAEA-Data-Code-2019-019.pdf:3.53MB

Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the influence of excavation and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry and microbiology obtained at the MIU in the fiscal year 2018. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method and analytical method) and methodology for quality control are described.

Journal Articles

Temporal change in radiological environments on land after the Fukushima Daiichi Nuclear Power Plant accident

Saito, Kimiaki; Mikami, Satoshi; Ando, Masaki; Matsuda, Norihiro; Kinase, Sakae; Tsuda, Shuichi; Sato, Tetsuro*; Seki, Akiyuki; Sanada, Yukihisa; Wainwright-Murakami, Haruko*; et al.

Journal of Radiation Protection and Research, 44(4), p.128 - 148, 2019/12

JAEA Reports

Proceedings of Information and Opinion Exchange Conference on Geoscientific Study, 2018

Nishio, Kazuhisa*; Murakami, Hiroaki; Iyatomi, Yosuke; Hama, Katsuhiro

JAEA-Review 2018-037, 53 Pages, 2019/03

JAEA-Review-2018-037.pdf:79.22MB

The Tono Geoscience Center (TGC) of Japan Atomic Energy Agency (JAEA) has been conducting geoscientific study in order to establish a scientific and technological basis for the geological disposal of HLW. Technical information of the result on the geoscientific study conducted at TGC is provided at the annual Information and Opinion Exchange Conference on Geoscientific Study of TGC for exchanging opinions among researchers and engineers from universities, research organizations and private companies. This document compiles the research presentations and posters of the conference in Mizunami on November 29, 2018.

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry data in the Mizunami group and the Toki granite (fiscal year 2017)

Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Hayashida, Kazuki*; Aosai, Daisuke*; Kumamoto, Yoshiharu*; Iwatsuki, Teruki

JAEA-Data/Code 2018-021, 76 Pages, 2019/03

JAEA-Data-Code-2018-021.pdf:3.78MB

Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the influence of excavation and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry and microbiology obtained at the MIU in the fiscal year 2017. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method and analytical method) and methodology for quality control are described.

Journal Articles

Hydrochemical influence of shotcrete used in underground facilities on groundwater chemistry; Proposal of the evaluation method by geochemical simulation code

Iwatsuki, Teruki; Shibata, Masahito*; Murakami, Hiroaki; Watanabe, Yusuke; Fukuda, Kenji

Doboku Gakkai Rombunshu, G (Kankyo) (Internet), 75(1), p.42 - 54, 2019/03

In order to clarify the influence of shotcrete in the underground facility on the groundwater chemistry, an in-situ closed test was conducted in the mock-up tunnel at the depth of 500 m. Brucite, Ettringite, Ca(OH) $$_{2}$$, Gibbsite, K$$_{2}$$CO$$_{3}$$, Na$$_{2}$$CO$$_{3}$$ $$cdot$$ 10H$$_{2}$$O, SiO$$_{2}$$ (a) and Calcite were identified as the dominant minerals affecting the water chemistry. Furthermore, the shotcrete constructed in the tunnel has a reaction capacity which can produce about 570 m$$^{3}$$ of alkaline groundwater (pH12.4) saturated with Ca(OH)$$_{2}$$. The estimation would improve the accuracy of prediction analysis of the long-term chemical influence of cement materials after the closure of the tunnel.

Journal Articles

U-Pb dating of calcite using LA-ICP-MS; Instrumental setup for non-matrix-matched age dating and determination of analytical areas using elemental imaging

Yokoyama, Tatsunori; Kimura, Junichi*; Mitsuguchi, Takehiro; Danhara, Toru*; Hirata, Takafumi*; Sakata, Shuhei*; Iwano, Hideki*; Maruyama, Seiji*; Chang, Q.*; Miyazaki, Takashi*; et al.

Geochemical Journal, 52(6), p.531 - 540, 2018/12

 Times Cited Count:4 Percentile:44.25(Geochemistry & Geophysics)

Journal Articles

Characteristics and formation process of fractures in crystalline rocks in northern Kyushu

Murakami, Hiroaki; Ashizawa, Masaomi*; Tanaka, Kazuhiro*

Oyo Chishitsu, 59(1), p.2 - 12, 2018/04

This study describes the features of fractures and their fillings along with the long-term behavior of their hydrogeological structures in an underground environment based on the results of a geological investigation conducted at an underground facility in northern Kyushu. Fractures were classified into five groups on the basis of fracture orientation: A, B, C, D, and low-angle groups. The genesis of all fractures is the cooling process of granodiorite pluton. Almost all of the water-conducting fractures are included in the B group. Because a number of fracture fillings in the B group are filled by prehnite and crushed fragments of epidote and quartz, the fractures in this group alternated sealing and re-opening. The fracture characteristics in the B group are follow as: accompanying many alteration halos, long trace length, and cutting off other fractures. These results indicate that fractures in the B group have possibly functioned as pathways for groundwater flow in the long term.

Journal Articles

Evaluation of hydrogeochemical processes provoked by tunnel excavation and closure based on simulated experiment in a mock-up test drift

Hayashida, Kazuki; Kato, Toshihiro*; Kubota, Mitsuru*; Murakami, Hiroaki; Amano, Yuki; Iwatsuki, Teruki

Chikyu Kagaku, 52(1), p.55 - 71, 2018/03

In this study, the simulated experimental drift was constructed in the granite of 500 m depth at Mizunami Underground Research Laboratory, and the hydrochemical process after the drift closure was observed. The groundwater chemistry around the drift changed with the change of the groundwater flow in the fractures when the gallery was constructed. The redox potential increased due to the infiltration of oxygen from the drift into the rock. After closing the drift, the redox potential of the groundwater plunged due to microbial activity, while the groundwater became alkalized conditon due to the influence of cement material such as shotcrete. The amount of cement material consumed for this alkalization was small, and it was considered that its influence would last long in accordance with the amount of cement used.

Journal Articles

Onsite chelate resin solid-phase extraction of rare earth elements in natural water samples; Its implication for studying past redox changes by inorganic geochemistry

Watanabe, Takahiro; Kokubu, Yoko; Murakami, Hiroaki; Iwatsuki, Teruki

Limnology, 19(1), p.21 - 30, 2018/01

 Times Cited Count:5 Percentile:30.22(Limnology)

Rare earth element (REE) patterns in natural water and geological samples provides information on changes in past environmental conditions, such as redox changes and material cycles; however, quantitative analysis of REEs in these samples is complicated because of relative low content and mass interference from barium oxide in the inductively coupled plasma mass spectrometry (ICP-MS) analyses. In this study, we adopted onsite solid-phase extraction and preconcentration methods for REEs using an iminobisacetic acid-ethylenediaminetriacetic acid chelate resin for the analyses. Standard reference materials, natural ground water, and spring water samples were used for the evaluation of these methods. The REE patterns in the natural water samples were in good agreement with those obtained using previous methods. Therefore, it was deduced that onsite solid-phase extraction using chelate resin is a rapid and simple preparation technique for REE analyses.

Journal Articles

Determination of dissolved natural thorium and uranium in Horonobe and Mizunami Underground Research Laboratory groundwater and its thermodynamic analysis

Sasaki, Takayuki*; Kokami, Takayuki*; Kobayashi, Taishi*; Kirishima, Akira*; Murakami, Hiroaki; Amano, Yuki; Mizuno, Takashi; Iwatsuki, Teruki; Sasamoto, Hiroshi; Miyakawa, Kazuya

Journal of Nuclear Science and Technology, 54(3), p.373 - 381, 2017/03

Trace amounts of natural thorium and uranium in deep groundwater were investigated at two underground research laboratories situated at Horonobe and Mizunami, Japan. The groundwater was sampled from underground boreholes, and the colloid contribution was checked by in situ two size-fractionated ultrafiltration systems. A decrease in the concentration after in situ filtration suggested the presence of natural colloids and suspended matter that were carriers of a portion of the elements. The result of the Th and U concentrations in groundwater after 10 kDa filtration was analyzed thermodynamically using existing hydrogeological and geochemical data such as the mineral components in the groundwater at a given pH, ionic strength, concentration of co-existing ions, redox potential, and solid phase assumed. A crystalline solid phase made the solubility very low compared with that of the amorphous phase, and the solubility agreed well with the concentrations measured.

JAEA Reports

Studies on the reconstruction of the concept of rock mass around the tunnel; Japanese fiscal year, 2014 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Aoki, Kenji*; Tochiyama, Osamu*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Yoshida, Hidekazu*; Murakami, Hiroaki; Sasao, Eiji

JAEA-Research 2015-017, 54 Pages, 2015/12

JAEA-Research-2015-017.pdf:17.3MB

This report is concerned with research to reconstruct more realistic near-field (NF) concept for the geological disposal of radioactive waste. This year is the final year of this committee activities. So we have carried out the summary on Re-thinking of NF concept and its technical basis. Cooperation between the study fields and combination of various science and technology and evaluation methods are one of the important technical bases of NF concept. In addition, since the "Great East Japan Earthquake 2011", the safety paradigm has shifted dramatically. In the reconstruction of realistic NF concept, it is necessary to analyze what security matters whether society has become unacceptable for geological disposal. Committee, we also exchange views on such matters and presented the direction of future research and development for geological disposal.

Journal Articles

Geochemical features and the flow system for saline mineral spring at the Tsuwano Town, Shimane Prefecture

Murakami, Hiroaki; Tanaka, Kazuhiro*

Chikasui Gakkai-Shi, 57(4), p.415 - 433, 2015/11

This study examined the geochemical properties and the distribution of mineral spring water, river water and bubbling gas in the Tsuwano Town, Shimane Prefecture, Western Japan. In Tsuwano, high Na-Cl concentration groundwater is discharged with bubbling gas mainly composed of CO$$_{2}$$. The geochemical properties of mineral spring water, gas, hydrogen-oxygen isotopes and rare gas isotopes suggest that mineral spring water at Tsuwano possibly contains deep-seated fluid. In addition, the largest flux of the deep-seated fluid is found along active fault, suggesting that active fault acts as a path way for fluid upwelling. Furthermore, In Tsuwano, deep-seated fluid discharges along the Lake Ohara-West Yauneyama fault system and surface fracture.

JAEA Reports

Mizunami Underground Research Laboratory Project annual report for fiscal year 2013

Hama, Katsuhiro; Mikake, Shinichiro; Nishio, Kazuhisa; Kawamoto, Koji; Yamada, Nobuto; Ishibashi, Masayuki; Murakami, Hiroaki; Matsuoka, Toshiyuki; Sasao, Eiji; Sanada, Hiroyuki; et al.

JAEA-Review 2014-038, 137 Pages, 2014/12

JAEA-Review-2014-038.pdf:162.61MB

Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) Project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The MIU Project has been ongoing the Phase II and the Phase III in fiscal year 2013. This report presents the results of the investigations, construction and collaboration studies in fiscal year 2013, as a part of the Phase II and Phase III based on the MIU Master Plan updated in 2010.

JAEA Reports

Study on geology on the Mizunami Underground Research Laboratory Project; Geology and geological structure at the -500m stage

Kawamoto, Koji; Kuboshima, Koji*; Murakami, Hiroaki; Ishibashi, Masayuki; Sasao, Eiji

JAEA-Research 2014-021, 30 Pages, 2014/11

JAEA-Research-2014-021.pdf:6.79MB

The MIU (Mizunami Underground Research Laboratory) Project has three overlapping phases, Surface-based investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). Currently, the project is under Phase II and Phase III. One of Phase II goals is set up to develop and revise models of the geological environment using the investigation results obtained during excavation, and to determine and assess changes in the geological environment in response to excavation. This report aims at compiling results of study on geology and geological structure at the -500m Stage in the MIU construction site, investigated in the Phase II and provides the fundamental information on the geology and geological structure for future study and modeling of geological environment.

JAEA Reports

Mizunami Underground Research Laboratory Project; Compilation of results of geological investigation at the -500m stage

Kawamoto, Koji; Murakami, Hiroaki; Ishibashi, Masayuki; Sasao, Eiji; Watanabe, Kazuhiko; Mikake, Shinichiro; Ikeda, Koki

JAEA-Data/Code 2014-014, 27 Pages, 2014/08

JAEA-Data-Code-2014-014.pdf:24.28MB
JAEA-Data-Code-2014-014-appendix(CD-ROM).zip:92.23MB

This document presents the data of geological investigations at the -500m stage of the MIU from the 2011 fiscal year to the 2013 fiscal year. At the -500m stage of the MIU, although the Cretaceous Toki granite is distributed, pegmatite, aplite and lampropyre dike are distributed partially.

Journal Articles

The Origin of muddy sand sediments associated with mud volcanism in the Horonobe area of northern Hokkaido, Japan

Miyakawa, Kazuya; Tokiwa, Tetsuya; Murakami, Hiroaki

Geochemistry, Geophysics, Geosystems (Internet), 14(12), p.4980 - 4988, 2013/12

 Times Cited Count:3 Percentile:84.02(Geochemistry & Geophysics)

The origin of mud from the mud-volcano-like sediments in the Horonobe area of northern Hokkaido, Japan was characterized by analyzing the mineral and chemical compositions of the mud. Mineral and chemical compositions of the mud are similar to those of the Hakobuchi Formation located at approximately 1500-2500 m depth. The results suggest that the mud originates from the Hakobuchi Formation, and also that the mud ascended from a depth of 1500-2500 m to ground surface. This result could be an exemplification of the occurrence of mud volcanism in oil and gas field and tectonic compressional region. This is useful information that should be taken into consideration in the planning and construction of underground facilities for geological disposal of HLW.

JAEA Reports

Collection of URL measurement data in 2011 fiscal year at the Horonobe Underground Research Laboratory Project

Inagaki, Daisuke; Tokiwa, Tetsuya; Murakami, Hiroaki

JAEA-Data/Code 2012-029, 132 Pages, 2013/02

JAEA-Data-Code-2012-029.pdf:8.0MB
JAEA-Data-Code-2012-029-appendix(DVD-ROM)-1.zip:5339.82MB
JAEA-Data-Code-2012-029-appendix(DVD-ROM)-2.zip:4415.05MB
JAEA-Data-Code-2012-029-appendix(DVD-ROM)-3.zip:127.72MB

In the Horonobe Underground Research Laboratory (URL) Project, construction of the Ventilation Shaft, the East Shaft and the drifts has been conducted as a phase 2 research. In the research, observation of the lithofacies and fracture, and ${it in-situ}$ tests, simple elastic wave exploration, schmidt hammer test, equotip test, point load test are conducted in each face, and measuring instruments such as extensometer, rock-bolt axial force meter, shotcrete stress meter and tunnel lining concrete stress meter are installed in particular face. In addition, for the purpose of the validation of the results of predictive analysis, conducted in phase 1, about the amount of spring water during construction of underground facilities, data on the changes of amount of spring water and water quality is obtained. This report summarizes the measurements data acquired at the Ventilation Shaft, the East shaft and the 250 m Gallery.

Journal Articles

Chemical forms of uranium, thorium and trace elements in sedimentary rocks distributed in Horonobe area, Hokkaido

Kosemura, Takashi*; Honda, Teruyuki*; Mizuno, Takashi; Murakami, Hiroaki; Nomura, Masao*

Fisshion, Torakku Nyusureta, (26), p.16 - 20, 2013/00

We Analyze existence form of REE in the rock from HDB-6 borehole at the Horonobe Town, Hokkaido. As a result, U and Th is mainly sulfate at fault. REE is mainly silicate at fault.

109 (Records 1-20 displayed on this page)