Results of environmental impact investigations as part of environmental monitoring investigation in backfilling of shafts and tunnels of Mizunami Underground Research Laboratory (2022)

Takeuchi, Ryuji; Nishio, Kazuhisa*; Kokubu, Yoko

JAEA-Data/Code 2023-013, 74 Pages, 2024/01

JAEA-Data-Code-2023-013.pdf:4.2MB

The Tono Geoscience Center of Japan Atomic Energy Agency (JAEA) has been conducting the environmental monitoring investigation to confirm the environmental impacts associated with the backfilling of shafts and tunnels at the Mizunami Underground Research Laboratory (MIU). This report summarizes the results of the environmental impact investigations conducted as part of the environmental monitoring investigation around the MIU Site in FY2022, which include groundwater level measurement in wells, river flow rate measurement, water analysis of Hazama river, noise and vibration surveys, and soil survey.

Results of environmental impact investigations as part of environmental monitoring investigation in backfilling of shafts and tunnels of Mizunami Underground Research Laboratory (2020-2021)

Takeuchi, Ryuji; Nishio, Kazuhisa*; Hanamuro, Takahiro; Kokubu, Yoko

JAEA-Data/Code 2022-010, 110 Pages, 2023/03

JAEA-Data-Code-2022-010.pdf:6.2MB

The Tono Geoscience Center of Japan Atomic Energy Agency (JAEA) has been conducting the environmental monitoring investigation to confirm the environmental impacts associated with the backfilling of shafts and tunnels at the Mizunami Underground Research Laboratory (MIU). This report summarizes the results of environmental impact investigations conducted as part of the environmental monitoring investigation around the MIU Site from FY2020 to FY2021, which include groundwater level measurement in wells, river flow rate measurement, water analysis of Hazama river, noise and vibration surveys, and soil survey.

Demonstration of the groundwater observation network system in backfilled underground facility

Murakami, Hiroaki; Takeuchi, Ryuji; Iwatsuki, Teruki

JAEA-Technology 2022-022, 34 Pages, 2022/10

JAEA-Technology-2022-022.pdf:3.47MB

Japan Atomic Energy Agency (JAEA) has been conducting the hydro-pressure and hydrochemical monitoring for more than two decades to understand the hydrochemical disturbance due to the excavation of tunnels at Mizunami Underground Research Laboratory (MIU). To understand the environmental influence due to the backfilling of research tunnels that started in 2019, environmental monitoring of groundwater has been performed and recovery status of groundwater is being confirmed. In order to observe the deep-groundwater environment from the ground, the groundwater pressure monitoring and sampling, which have been performed in the research tunnel, are to be performed from the ground. However, backfilling of a large-scale underground facilities such as MIU is globally unprecedented, thus it was necessary to develop a new observation system. Accordingly, we developed a new observation network to observe the environment around the research tunnels of the MIU. This system enables monitoring of groundwater pressure and water sampling of the backfilled tunnel from the ground while utilizing the existing-monitoring system installed in the tunnels. Accordingly, we demonstrated its technology through the environmental monitoring of groundwater. The results of the environmental monitoring and the existing groundwater data of MIU indicate that this system is able to monitor the groundwater environment in the backfilled tunnels.

Monitoring of groundwater inflow into research galleries in the Mizunami Underground Research Laboratory Project (MIU Project); Fiscal year 2019

Onoe, Hironori; Takeuchi, Ryuji

JAEA-Data/Code 2020-015, 22 Pages, 2020/11

JAEA-Data-Code-2020-015.pdf:2.3MB
JAEA-Data-Code-2020-015-appendix(DVD-ROM).zip:2.42MB

Japan Atomic Energy Agency (JAEA) has been conducting 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 high-level radioactive waste, targeting in crystalline rock. The main goals of the MIU Project from Phase I to Phase III are: to establish techniques for investigation, analysis and assessment of the deep geological environment, and to develop a base of engineering for deep underground application. The groundwater inflow monitoring into shafts and research galleries, has been conducted to achieve the Phase II goals. Furthermore, these monitoring were ceased at the end of FY2019 due to the completion of the MIU project. This report describes the results of the groundwater inflow monitoring from April 2019 to March 2020.

Monitoring of groundwater inflow into research galleries in the Mizunami Underground Research Laboratory Project (MIU Project); From fiscal year 2016 to 2018

Onoe, Hironori; Takeuchi, Ryuji

JAEA-Data/Code 2019-009, 22 Pages, 2019/10

JAEA-Data-Code-2019-009.pdf:2.57MB
JAEA-Data-Code-2019-009-appendix(CD-ROM).zip:2.34MB

Tono Geoscience Center of Japan Atomic Energy Agency (JAEA) 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). As for The MIU Project (Phase II) was carried out from 2004 fiscal year, and has been started the Phase III in 2010 fiscal year. The groundwater inflow monitoring into shafts and research galleries, has been maintained to achieve the Phase II goals, begins in 2004 fiscal year and follows now. This document presents the results of the groundwater inflow monitoring from fiscal year 2016 to 2018.

Excavation of shafts and research galleries at the Mizunami Underground Research Laboratory (construction work of MIU part VII); Construction progress report, fiscal year 2016-2017

Geoscience Facility Construction Section, Tono Geoscience Center

JAEA-Review 2018-026, 92 Pages, 2019/02

JAEA-Review-2018-026.pdf:11.89MB

This progress report presents an outline compilation of construction activities, primary tasks performed, construction progress and safety patrol report, in Fiscal Year 2016-2017. The outline of construction activities is a summary based on the scope of work planned in Fiscal Year 2016-2017: the main activities are based on the Tono Geoscience Center weekly reports; and the construction progress is based on the planned and actual schedules. Regarding the actual performance of the construction work of MIU part VII (March 16, 2016 -March 15, 2018) performance carried out from April 1, 2016 until March 15, 2018 is described in this report and the performance started from March 16, 2018 is supposed to be described in progress report of construction work of MIU part VIII.

Development of groundwater management technology report

Iyatomi, Yosuke; Mikake, Shinichiro; Matsui, Hiroya

JAEA-Review 2018-004, 42 Pages, 2018/03

JAEA-Review-2018-004.pdf:4.71MB

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) at Mizunami City in Gifu Prefecture, central Japan. The three remaining important issues have been carrying out on the MIU project. This report focuses on "Development of groundwater management technology" for "Development of countermeasure technologies for reducing groundwater inflow", which is one of those important issues. The concentrations of naturally occurring fluorine and boron dissolved in groundwater pumped from shafts and horizontal tunnels at MIU, are reduced to the levels below the environmental standards at a water treatment facility. The development of groundwater management technologies including such groundwater treatment is one key issue for large-scale underground facility construction. With this background, literature survey related to investigations on the latest treatment technologies for removing fluorine and boron from waste water were conducted and applicability of the technologies to MIU were reviewed. Additionally, the countermeasures against rocks, soils and groundwater containing naturally occurring heavy metals were summarized. The literature survey results indicated that the adsorbent was able to remove fluorine and boron, and the coprecipitation was able to remove fluorine to the levels below their respective environmental standards. However, the ground water at MIU contains suspended solids and cement due to excavation, its removal rates of fluorine and boron are different from the ones of general waste water. From this point, it concluded that the present groundwater treatment method performed at MIU: coagulation treatment for removal of fluorine and control of pH primary, and adsorbent treatment for removed boron is appropriated.

Evaluation of combined pre- and post-excavation grouting for reducing water inflow under high water pressure condition

Mikake, Shinichiro; Ikeda, Koki; Matsui, Hiroya; Tsuji, Masakuni*; Nishigaki, Makoto*

Doboku Gakkai Rombunshu, C (Chiken Kogaku) (Internet), 74(1), p.76 - 91, 2018/03

https://doi.org/10.2208/jscejge.74.76

Pre-grouting of shafts and galleries had been conducted during the construction of MIU in the aspect of reducing water inflow. After excavating GL.-500m gallery, a post-grouting was performed on section of the pre-excavation grouting area under high water pressure condition (max: 4MPa). The post-grouting experiment was performed outside of the pre-grouting zone with designs, applying colloidal silica grouting material and complex dynamic grouting. It was estimated that the inflow after post-grouting was reduced by 1/100 of the case that pre- and post-grouting were not performed. These results indicate that the applied combined pre- and post-grouting methodology is effective in reducing water inflow and it can be applicable under high water pressure condition. Then, this paper states the theoretical evaluation of relationship between reduction of hydraulic conductivity and the grouting zone is very convenient and useful for grouting design and estimate of water inflow.

Excavation of shafts and research galleries at the Mizunami Underground Research Laboratory (construction work of MIU part VI); Construction progress report, fiscal year 2014-2015

Geoscience Facility Construction Section, Tono Geoscience Center

JAEA-Review 2016-027, 190 Pages, 2017/02

JAEA-Review-2016-027.pdf:41.77MB

This progress report presents an outline compilation of construction activities, primary tasks performed, construction progress and safety patrol report, in Fiscal Year 2014-2015. The outline of construction activities is a summary based on the scope of work planned in Fiscal Year 2014-2015: the main activities are based on the Tono Geoscience Center weekly reports; and the construction progress is based on the planned and actual schedules. Regarding the actual performance of the construction work of MIU part VI (March 16, 2014 -March 15, 2016) performance carried out from April 1, 2014 until March 15, 2016 is described in this report and the performance started from March 16, 2016 is supposed to be described in progress report of construction work of MIU part VII.

Excavation of shafts and research galleries at the Mizunami Underground Research Laboratory (construction work of MIU part V); Construction progress report, fiscal year 2012-2013

Geoscience Facility Construction Section, Tono Geoscience Center

JAEA-Review 2016-002, 116 Pages, 2016/06

JAEA-Review-2016-002.pdf:62.4MB

This progress report presents an outline compilation of construction activities, primary tasks performed, construction progress and safety patrol report, in Fiscal Year 2012-2013. The outline of construction activities is a summary based on the scope of work planned in 2012-2013: the main activities are based on the Tono Geoscience Center weekly reports; and the construction progress is based on the planned and actual schedules. The safety patrol report is based on defects recording by the safety manager of the Geoscience Facility Construction Section.