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Journal Articles

Deposition of radiocesium on the river flood plains around Fukushima

Saegusa, Hiromitsu; Oyama, Takuya; Iijima, Kazuki; Onoe, Hironori; Takeuchi, Ryuji; Hagiwara, Hiroki

Journal of Environmental Radioactivity, 164, p.36 - 46, 2016/11

 Times Cited Count:11 Percentile:46.45(Environmental Sciences)

The environments of Fukushima have been contaminated due to the Fukushima Daiichi Nuclear Power Plant accidents caused by the Great East Japan Earthquake on March 11, 2011. Released radio-cesium mainly affects radiation dose in the environment of Fukushima. It is concerned that redistribution of the radiation dose due to water discharge will be occurred due to the transportation of radio-cesium. Especially, deposition of the transferred soil particle with radio-cesium at flood plain with downstream area is possible cause of increasing radiation dose. Therefore, it is important to understand the influence of deposition behavior of radio-cesium on radiation dose. The paper discusses the deposition behaviors of radio-cesium at river based on the data obtained from the river investigations.

JAEA Reports

Project report on the construction phase at the Mizunami Underground Research Laboratory Project

Nohara, Tsuyoshi; Saegusa, Hiromitsu*; Iwatsuki, Teruki; Hama, Katsuhiro; Matsui, Hiroya; Mikake, Shinichiro; Takeuchi, Ryuji; Onoe, Hironori; Sasao, Eiji

JAEA-Research 2015-026, 98 Pages, 2016/03

JAEA-Research-2015-026.pdf:32.97MB

Tono Geoscience Center (TGC) of Japan Atomic Energy Agency (JAEA) is being performed Mizunami Underground Research Laboratory (MIU) Project, which is a broad scientific study of the deep geological environment as a basis of research and development for geological disposal of nuclear wastes, in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock. The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The project goals of the MIU Project from Phase I through to Phase III are: (1) to establish techniques for investigation, analysis and assessment of the deep geological environment, and (2) to develop a range of engineering for deep underground application. This report summarizes the results of geoscientific study on Phase II to 500m depth. During Construction phase, we have evaluated of adequacy of techniques for investigation, analysis and assessment of the deep geological environment on Surface-based Investigation phase, and have established systematic methodology for stepwise investigation and evaluation of the geological environment on Construction phase. Further, with respect to design and construction of underground facilities, it was confirmed the validity of the engineering involved in the construction, maintenance and management of underground facilities.

JAEA Reports

Information collection regarding geoscientific monitoring techniques during closure of underground facility in crystalline rock

Hosoya, Shinichi*; Yamashita, Tadashi*; Iwatsuki, Teruki; Saegusa, Hiromitsu; Onoe, Hironori; Ishibashi, Masayuki

JAEA-Technology 2015-027, 128 Pages, 2016/01

JAEA-Technology-2015-027.pdf:33.66MB

The study for development of drift backfilling technologies is one of the critical issues in the Mizunami Underground Research Laboratory (MIU) project, and its purposes are to develop closure methodology and technology, and long-term monitoring technology, and to evaluate resilience of geological environment. To achieve the purposes, previous information from the case example of underground facility constructed in crystalline rock in Europe has been collected. In particular, the boundary conditions for the closure, geological characteristics, technical specifications, and method of monitoring have been focused. The information on the international project regarding drift closure test and development of monitoring technologies has also been collected. In addition, interviews were conducted to specialists who have experiences involving planning, construction management, monitoring, and safety assessment for the closure. Based on the collected information, concept and point of attention, which are regarding drift closure testing, and planning, execution management and monitoring on the closure of MIU, have been specified.

Journal Articles

Groundwater flow modeling in construction phase of the Mizunami Underground Research Laboratory project

Onoe, Hironori; Saegusa, Hiromitsu; Takeuchi, Ryuji

Doboku Gakkai Rombunshu, C (Chiken Kogaku) (Internet), 72(1), p.13 - 26, 2016/01

AA2015-0210.pdf:4.75MB

The Japan Atomic Energy Agency is conducting the Mizunami Underground Research Laboratory (URL) project in Mizunami, Gifu, in order to establish scientific and technical basis for geological disposal of high-level radioactive waste. This paper comprehensively describes the result of groundwater flow modeling using data of hydraulic responses and hydrochemical changes due to URL construction. Technical know-how and methodology of hydrogeological monitoring and groundwater flow modeling were presented for characterization of hydraulic heterogeneities in fractured crystalline rock. Furthermore, effectivity of data acquisition of hydrochemical changes in groundwater for validation of result of groundwater flow modeling was indicated.

Journal Articles

Influence on groundwater flow conditions by groundwater pressure change induced by earthquakes; Case study of Tono Area

Takeuchi, Ryuji; Tsuyuguchi, Koji*; Onoe, Hironori; Saegusa, Hiromitsu*; Beppu, Shinji

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 22(2), p.37 - 52, 2015/12

Assessment of the geological environment for the long term safety of geological disposal systems for high-level radioactive waste requires consideration for any phenomenon resulting in cumulative change to the geological environment at the regional scale. Groundwater pressure changes induced by earthquakes, for example, are one of the phenomena to be considered. Groundwater pressure changes induced by earthquakes have been observed during long-term monitoring carried out by Japan Atomic Energy Agency in the Tono Area, Gifu. In this paper, the observations of groundwater pressure change induced by earthquakes are summarized. In addition, an impact on groundwater flow conditions induced by earthquakes is discussed. In order to evaluate the long-term stability of groundwater flow condition, it is important to focus not only the change of groundwater pressure by earthquakes but also the change of the hydraulic gradient and hydraulic permeability.

Journal Articles

Task 7 groundwater flow and transport modelling of fracture system at regional, block, and single-fracture scale flow and transport, Olkiluoto

Sawada, Atsushi; Saegusa, Hiromitsu; Takeuchi, Shinji*; Sakamoto, Kazuhiko*; Dershowitz, W. S.*

SKB P-13-46, 82 Pages, 2015/12

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2014

Hama, Katsuhiro; Mikake, Shinichiro; Ishibashi, Masayuki; Sasao, Eiji; Kuwabara, Kazumichi; Ueno, Tetsuro; Onuki, Kenji*; Beppu, Shinji; Onoe, Hironori; Takeuchi, Ryuji; et al.

JAEA-Review 2015-024, 122 Pages, 2015/11

JAEA-Review-2015-024.pdf:80.64MB

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 technical 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 III, as the Phase II was concluded for a moment with the completion of the excavation of horizontal tunnels at GL-500m level in February 2014. This report presents the results of the investigations, construction and collaboration studies in fiscal year 2014.

JAEA Reports

Mizunami Underground Research Laboratory Project, Plan for fiscal year 2015

Hama, Katsuhiro; Takeuchi, Ryuji; Saegusa, Hiromitsu; Iwatsuki, Teruki; Sasao, Eiji; Mikake, Shinichiro; Ikeda, Koki; Sato, Toshinori; Osawa, Hideaki; Koide, Kaoru

JAEA-Review 2015-021, 27 Pages, 2015/10

JAEA-Review-2015-021.pdf:4.35MB

The Mizunami Underground Research Laboratory (MIU) project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of geological disposal technologies through investigations of the deep geological environment in the crystalline host rock (granite rock) at Mizunami City in Gifu Prefecture, central Japan. This report summarizes the research and development activities planned for fiscal year 2015 based on the MIU Master Plan updated in 2015 and so on. On the occasion of the reform of the entire JAEA organization in 2014, JAEA identified the critical issues on the geoscientific research program: "Development of modelling technologies for mass transport", "Development of drift backfilling technologies" and "Development of technologies for reducing groundwater inflow", based on the latest results of the synthesizing R&D. Investigations on those critical issues will be performed at the MIU in fiscal year 2015.

JAEA Reports

Study for development of the methodology for multi-scale hydrogeological modeling taking into account hydraulic heterogeneity caused by fracture network

Saegusa, Hiromitsu; Onoe, Hironori; Ishibashi, Masayuki; Tanaka, Tatsuya*; Abumi, Kensho*; Hashimoto, Shuji*; Bruines, P.*

JAEA-Research 2015-011, 59 Pages, 2015/10

JAEA-Research-2015-011.pdf:49.44MB

It is important to evaluate groundwater flow characteristics on several spatial scales for assessment of long-term safety on geological disposal of high-level radioactive wastes. An estimation of hydraulic heterogeneity caused by fracture network is significant for evaluation of the groundwater flow characteristics in the region of tens of meters square. Heterogeneity of equivalent hydraulic properties is needed to estimate for evaluation of the groundwater flow characteristics in the region of several km square. In order to develop the methodology for multi-scale hydrogeological modeling taking into account the hydraulic heterogeneity, spatial distribution of fractures and their hydraulic properties have been modeled using discrete fracture network (DFN) model. Then, hydrogeological continuum model taking into account the hydraulic heterogeneity has been estimated based on the DFN model. Through this study, the methodology for multi-scale hydrogeological modeling according to type of investigation data has been proposed.

Journal Articles

Predictions of transmissivity of fault zones from strength-stress conditions of rocks

Ishii, Eiichi; Matsuoka, Toshiyuki; Saegusa, Hiromitsu; Takeuchi, Ryuji

Nihon Oyo Chishitsu Gakkai Heisei-27-Nendo Kenkyu Happyokai Koen Rombunshu, p.135 - 136, 2015/09

no abstracts in English

JAEA Reports

Study of hydrogeology in the Mizunami Underground Research Laboratory Project; Hydrogeological modeling at site scale in Phase II

Onoe, Hironori; Kosaka, Hiroshi*; Takeuchi, Ryuji; Saegusa, Hiromitsu

JAEA-Research 2015-008, 146 Pages, 2015/08

JAEA-Research-2015-008.pdf:76.46MB

Mizunami Underground Research Laboratory (MIU) Project is being carried out by Japan Atomic Energy Agency (JAEA) in the Cretaceous Toki granite in the Tono area, central Japan. The MIU Project has three overlapping phases: Surface-based Investigation (Phase I), Construction (Phase II) and Operation (Phase III). In this study, calibration of hydrogeological model and groundwater flow simulation using the data obtained by the Phase I and Phase II were carried out in order to develop the methodology for construction and update of hydrogeological model on Site Scale. As a result, hydrogeological model on Site Scale, which is able to simulate comprehensively the obtained data regarding groundwater pressure distribution before excavation of the MIU facilities, hydraulic responses and inflow volume during excavation of the MIU facilities, was constructed.

JAEA Reports

Synthesized research report in the second mid-term research phase; Mizunami Underground Research Laboratory Project, Horonobe Underground Research Laboratory Project and Geo-stability Project

Hama, Katsuhiro; Mizuno, Takashi; Sasao, Eiji; Iwatsuki, Teruki; Saegusa, Hiromitsu; Sato, Toshinori; Fujita, Tomo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Yokota, Hideharu; et al.

JAEA-Research 2015-007, 269 Pages, 2015/08

JAEA-Research-2015-007.pdf:68.65MB
JAEA-Research-2015-007(errata).pdf:0.07MB

We have synthesised the research results from Mizunami/Horonobe URLs and geo-stability projects in the second mid-term research phase. It could be used as technical bases for NUMO/Regulator in each decision point from sitting to beginning of disposal (Principal Investigation to Detailed Investigation Phase). High quality construction techniques and field investigation methods have been developed and implemented and these will be directly applicable to the National Disposal Program (along with general assessments of hazardous natural events and processes). It will be crucial to acquire technical knowledge on decisions of partial backfilling and final closure by actual field experiments in Mizunami/Horonobe URLs as main themes for the next phases.

Journal Articles

Groundwater flow modeling focused on the Fukushima Daiichi Nuclear Power Plant site

Saegusa, Hiromitsu; Onoe, Hironori; Kohashi, Akio; Watanabe, Masahisa

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company is facing contaminated water issues. The amount of contaminated water is continuously increasing due to groundwater leakage into the underground part of reactor and turbine buildings. Therefore, it is important to understand the groundwater flow conditions at the site and to predict the impact of countermeasures taken for isolating groundwater from the source of the contamination, i.e. the reactor buildings. Installations, such as of land-side and sea-side impermeable walls have been planned as countermeasures. In this study, groundwater flow modeling has been performed to estimate the response of groundwater flow conditions to the countermeasures. From the modeling, groundwater conditions and changes in response to implementation of the countermeasures could be reasonably estimated. The results indicate that the countermeasures will decrease the volume of inflow into underground part of the buildings. This means that the countermeasures will be effective in reducing the discharge volume of contaminated groundwater to ocean.

Journal Articles

Current status of R&D activities and future plan of Mizunami Underground Research Laboratory

Osawa, Hideaki; Koide, Kaoru; Sasao, Eiji; Iwatsuki, Teruki; Saegusa, Hiromitsu; Hama, Katsuhiro; Sato, Toshinori

Proceedings of 2015 International High-Level Radioactive Waste Management Conference (IHLRWM 2015) (CD-ROM), p.371 - 378, 2015/04

The Mizunami Underground Research Laboratory (MIU) project, launched as a generic underground research laboratory for crystalline rock in 1996, has proceeded in three overlapping phases, "Phase I: Surface-based investigation", "Phase II: Construction" and "Phase III: Operation". Currently, Phase II construction of research drifts in the MIU has been completed to the -500 m level. Phase III research activities have been conducted underground since 2010. The scientific and technical knowledge and know-how acquired in Phases I and II have been released via a web-based report "CoolRep H26". JAEA will continue to promote R&D activities in Phase III at the MIU to build technical confidence.

Journal Articles

Groundwater recovery experiment in Mizunami Underground Research Laboratory; Numerical simulation of H-M coupled behavior of rock and backfill materials to evaluate the influence on the surrounding rock

Takayama, Yusuke; Sato, Toshinori; Onoe, Hironori; Iwatsuki, Teruki; Saegusa, Hiromitsu; Onuki, Kenji

Dai-43-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.313 - 318, 2015/01

In the Mizunami Underground Research Laboratory, groundwater recovery experiment is being conducted to construct the method to understand the transition of geological environment due to groundwater recovery at the -500m access and research gallery-north. As a part of this experiment, backfill test is planned using drilling pits filled with artificial materials (clay and concrete) to evaluate the influence on the surrounding rock mass due to the interaction of rock and artificial materials. In this study, numerical simulation of the backfill test has been carried out to predict the qualitative hydro-mechanical behavior.

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

Mizunami Underground Research Laboratory Project, Plan for fiscal year 2014

Hama, Katsuhiro; Mikake, Shinichiro; Nishio, Kazuhisa; Sasao, Eiji; Saegusa, Hiromitsu; Iwatsuki, Teruki; Ikeda, Koki; Sato, Toshinori; Osawa, Hideaki; Koide, Kaoru

JAEA-Review 2014-035, 34 Pages, 2014/10

JAEA-Review-2014-035.pdf:44.83MB

The Mizunami Underground Research Laboratory (MIU) project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host crystalline rock at Mizunami City in Gifu, central Japan. The project proceeds in three overlapping phases, "Phase I: Surface-based investigation Phase", "Phase II: Construction Phase" and "Phase III: Operation Phase". The MIU Project has been ongoing the Phase III, as the Phase II was concluded for a moment with the completion of the excavation of horizontal tunnels at GL-500m level in February 2014. The present report summarizes the research and development activities planned for fiscal year 2014 based on the MIU Master Plan updated in 2010.

Journal Articles

Groundwater recovery experiment using an underground gallery in fractured crystalline rock

Onoe, Hironori; Iwatsuki, Teruki; Saegusa, Hiromitsu; Onuki, Kenji; Takeuchi, Ryuji; Sanada, Hiroyuki; Ishibashi, Masayuki; Sato, Toshinori

Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 10 Pages, 2014/10

The selection of a geological disposal site for high-level radioactive waste (HLW) will be done taking into consideration performance of the geological environment. Geological environments would likely be influenced for several decades by changes due to the construction and operation of a large underground facility such as a HLW repository. Therefore, the post-closure recovery of the geological environment after backfilling of a facility is an important aspect for the safety assessment of geological disposal of HLW. With a focus on the hydraulic pressure and hydrochemical recovery processes around underground galleries in fractured crystalline rock, the groundwater recovery experiment will be conducted at the Mizunami Underground Research Laboratory to evaluate the natural groundwater and hydrochemical recovery of the rock mass. This paper provides an outline of the groundwater recovery experiment plan and progress of the supporting field investigations.

Journal Articles

Development and application of the GeoDFN and HydroDFN at the Mizunami Underground Research Laboratory

Bruines, P.*; Tanaka, Tatsuya*; Abumi, Kensho*; Hashimoto, Shuji*; Saegusa, Hiromitsu; Onoe, Hironori; Ishibashi, Masayuki

Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 10 Pages, 2014/10

Journal Articles

Discrete fracture network modeling based on in-situ data at underground gallery, 2

Nakajima, Makoto*; Seno, Shoji*; Onoe, Hironori; Ishibashi, Masayuki; Saegusa, Hiromitsu; Sawada, Atsushi

Dai-42-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.107 - 112, 2014/01

Japan Atomic Energy Agency is proceeding with the Mizunami Underground Research Laboratory Project in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock for geological disposal of high level radioactive wastes. We have carried out discrete fracture network modeling, groundwater flow and particle tracking simulation in order to understand the important factors for the solute transport characterizations. In this paper, a method for estimating hydraulic parameter of discrete fracture network model based on in-situ data at underground gallery are described.

243 (Records 1-20 displayed on this page)