미즈나미 지하처분연구시설 결정질암에 대한 부지 특성규명 기술 개발 -지표기반 조사단계- Development of Site Characterization Technologies for Crystalline Rocks at Mizunami Underground Research Laboratory (MIU) - Surface-based Investigation Phase -원문보기
미즈나미 지하처분연구시설 프로젝트는 일본원자력연구개발기구가 결정질암 내의 심부 지하 환경에 관해 종합적으로 연구하는 프로젝트이다. 미즈나미 프로젝트는 3개의 중첩되는 단계로 구성된다: 지표기반 조사단계 (단계 1), 건설단계 (단계 2), 운영단계 (단계 3)의 총 20년. 미즈나미 프로젝트의 1단계에서 3단계까지의 전체 목표는 1) 심부지질환경을 조사, 분석, 평가하기 위한 기술 정립, 2) 심부 지하 활용을 위한 일련의 공학적 기술 개발이다. 전체 목표 1을 달성하기 위하여, 1단계 목표를 굴착 전에 지질환경을 모사하고 굴착거동을 예측하는 모든 지표기반 조사결과로부터 지질환경 모델을 구축하는 것으로 설정하였다. 전체 목표 2를 달성하기 위하여, 2단계 목표는 지하시설을 위한 상세 설계 개념과 건설 계획을 수립하는 것으로 설정하였다. 본 논문은 결정질암내 지하수의 수리지화학적 특성을 조사하고 평가하기 위한 지질통합적 방법을 소개한다.
미즈나미 지하처분연구시설 프로젝트는 일본원자력연구개발기구가 결정질암 내의 심부 지하 환경에 관해 종합적으로 연구하는 프로젝트이다. 미즈나미 프로젝트는 3개의 중첩되는 단계로 구성된다: 지표기반 조사단계 (단계 1), 건설단계 (단계 2), 운영단계 (단계 3)의 총 20년. 미즈나미 프로젝트의 1단계에서 3단계까지의 전체 목표는 1) 심부지질환경을 조사, 분석, 평가하기 위한 기술 정립, 2) 심부 지하 활용을 위한 일련의 공학적 기술 개발이다. 전체 목표 1을 달성하기 위하여, 1단계 목표를 굴착 전에 지질환경을 모사하고 굴착거동을 예측하는 모든 지표기반 조사결과로부터 지질환경 모델을 구축하는 것으로 설정하였다. 전체 목표 2를 달성하기 위하여, 2단계 목표는 지하시설을 위한 상세 설계 개념과 건설 계획을 수립하는 것으로 설정하였다. 본 논문은 결정질암내 지하수의 수리지화학적 특성을 조사하고 평가하기 위한 지질통합적 방법을 소개한다.
The Mizunami Underground Laboratory (MIU) Project is a comprehensive research project investigating the deep underground environment within crystalline rock being conducted by Japan Atomic Energy Agency. The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Const...
The Mizunami Underground Laboratory (MIU) Project is a comprehensive research project investigating the deep underground environment within crystalline rock being conducted by Japan Atomic Energy Agency. The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III), with a total duration of 20 years. The overall 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. For the overall project goals 1), the Phase I goals were set to construct models of the geological environment from all surface-based investigation results that describe the geological environment prior to excavation and predict excavation response. For the overall project goals 2), the Phase I goals were set to formulate detailed design concepts and a construction plan for the underground facilities. This paper introduces geosynthesis procedures for the investigation and assessment of the hydrochemistry of groundwater in crystalline rock.
The Mizunami Underground Laboratory (MIU) Project is a comprehensive research project investigating the deep underground environment within crystalline rock being conducted by Japan Atomic Energy Agency. The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III), with a total duration of 20 years. The overall 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. For the overall project goals 1), the Phase I goals were set to construct models of the geological environment from all surface-based investigation results that describe the geological environment prior to excavation and predict excavation response. For the overall project goals 2), the Phase I goals were set to formulate detailed design concepts and a construction plan for the underground facilities. This paper introduces geosynthesis procedures for the investigation and assessment of the hydrochemistry of groundwater in crystalline rock.
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문제 정의
I express our sincere thanks to the anonymous reviewer and researchers who assisted with data collection for this study and took the time to complete the investigation.
The goals of the investigations in this step were to test and update the hydrochemical model and to determine the geological environment prior to the excavation of the underground facilities, based on the data and the analysis results obtained in Steps 0 and 1. Since geochemical data of the groundwater of sedimentary formations around the MIU Construction Site had not been measured up to this point, this step aimed to acquire these data. Therefore, groundwater and rock samples were collected and analyzed for hydrochemical analysis and for updating the model, by conducting borehole investigations for the Mizunami Group with a thickness of a few tens of meters to approximately 200 meters, covering the Toki Granite.
The results described in this paper will be utilized as technical knowledge of disposal technology and effectively used to enhance technical foundation which will support both the implementation and formulation of safety regulations.
Thus, this paper summarizes geosynthesis procedures to investigate and assess the crystalline rock, and development of individual investigation and assessment methods. At the same time, technical findings and know-how which can serve as foundation to implementation of the disposal project were compiled.
제안 방법
At the same time, technical findings and know-how which can serve as foundation to implementation of the disposal project were compiled. Also, this paper clarified the necessity for the Phase II and Phase III investigation by compiling unresolved issues during the Phase I investigation.
clarification of the origin of the Na-Cl type groundwater in the lower sedimentary formation. Comparison of the hydraulic characteristics with the distribution of geochemical characteristics of groundwater would allow the results of the groundwater flow analysis to be tested and the credibility of the conceptual hydrochemical model to be improved. It was considered important to acquire data on the geochemistry of the groundwater in the granite during the investigations in the subsequent steps.
The chemical com positions (Si, Na, K, Mg, Ca, F, Cl, Br, NO3, SO4, I, TC: Total Carbon, TOC: Total Organic Carbon, DIC: Dissolved inorganic Carbon, Alkalinity) of the groundwater were analyzed at suitable intervals as the tracer decreased, to estimate in-situ chemical compositions without drilling fluid contamination. For the last sample obtained from each pumping test, the concentrations of Sr, HS- , NO2- , NH4+, Al, Total Fe, Fe2+ and isotopic composition (2H/1H, tritium, 18O/16O, 13C/12C, 14C) were determined to estimate the origin, residence time and chemical evolution process of the groundwater.
The chemical com positions (Si, Na, K, Mg, Ca, F, Cl, Br, NO3, SO4, I, TC: Total Carbon, TOC: Total Organic Carbon, DIC: Dissolved inorganic Carbon, Alkalinity) of the groundwater were analyzed at suitable intervals as the tracer decreased, to estimate in-situ chemical compositions without drilling fluid contamination. For the last sample obtained from each pumping test, the concentrations of Sr, HS- , NO2- , NH4+, Al, Total Fe, Fe2+ and isotopic composition (2H/1H, tritium, 18O/16O, 13C/12C, 14C) were determined to estimate the origin, residence time and chemical evolution process of the groundwater.
6. In each investigation step, investigations were carried out according to the geosynthesis data flow diagram [5], [6] and following the iterative approach. The geosynthesis data flow diagram illustrates, for the specific aims, the types and combinations of investigations to be carried out, the types of data to be acquired, interpretation of data and synthesis of the information obtained in the different disciplines.
The goals of the investigations in this step were to test and update the hydrochemical model and to determine the geological environment prior to the excavation of the underground facilities, based on the data and the analysis results obtained in Steps 0 and 1. Since geochemical data of the groundwater of sedimentary formations around the MIU Construction Site had not been measured up to this point, this step aimed to acquire these data.
The investigations at the MIU Construction Site during Phase I followed the sequence of: preliminary characterization of the geological environment on wider area using techniques providing 2D information; identification of open issues requiring more detailed information; borehole investigations addressing the investigation items. Investigations were scheduled so that interactions among drilling or testing of borehole could be avoided.
The objectives of the deep borehole investigations include determining the geochemical characteristics of the groundwater in the granite to a depth of approximately 1,000 meters prior to excavation of the underground facilities in order to incorporate the results in the initial conditions for the analyses of the influence of the excavation on the groundwater regime around the facility in Phase II and subsequent phases. A further objective is to determine geochemical characteristics of the groundwater encountered in the underground facilities as input for planning the investigations in Phase II.
Since geochemical data of the groundwater of sedimentary formations around the MIU Construction Site had not been measured up to this point, this step aimed to acquire these data. Therefore, groundwater and rock samples were collected and analyzed for hydrochemical analysis and for updating the model, by conducting borehole investigations for the Mizunami Group with a thickness of a few tens of meters to approximately 200 meters, covering the Toki Granite.
With regard to the overall project goals 1), “To establish techniques for investigation, analysis and assessment of the deep geological environment”, a step-wise investigation was conducted by iterating investigation, interpretation, and assessment, thereby understanding of geologic environment was progressively and effectively improved with progress of investigation.
대상 데이터
1). The underground facilities will be constructed mainly in the Toki Granite basement (Fig. 2). Topographically, the Tono area, where the MIU is located, is hilly land bounded by the Mino-Hida Moun-tains to the north-west and Mikawa Mountains to the south-east.
이론/모형
For the local-scale area, data on groundwater chemistry, pH and redox conditions had been obtained mainly from borehole investigations carried out as part of the regional hydrogeological study. Using these data, the spatial distribution of the hydrochemical characteristics of the groundwater between the boreholes and in the site-scale area were estimated using the kriging method. It was indicated that, on the south side of the site-scale area, the groundwater in the granite was NaCl type, the concentration of chloride ions increases with depth, the pH of the groundwater was mildly alkaline (Fig.
성능/효과
Using these data, the spatial distribution of the hydrochemical characteristics of the groundwater between the boreholes and in the site-scale area were estimated using the kriging method. It was indicated that, on the south side of the site-scale area, the groundwater in the granite was NaCl type, the concentration of chloride ions increases with depth, the pH of the groundwater was mildly alkaline (Fig.7) and the redox conditions were estimated to be weakly to strongly reducing. Mass balance analysis and multivariate analysis indicate that the chemistry of the groundwater in the site-scale area could be explained by the mixing of several groundwaters with different salinities.
The results of the above investigations indicated that the groundwater in the sedimentary rocks in the site-scale area is Na-Ca-HCO3 type, rich in silicon and sulphate ions in the shallower part and Na-Cl type in the deeper part of the Mizunami Group and the upper part of the Toki Granite (Table 1, Fig. 9). It was also found that the salinity of the groundwater generally increases with increasing depth.
후속연구
The objectives of the deep borehole investigations include determining the geochemical characteristics of the groundwater in the granite to a depth of approximately 1,000 meters prior to excavation of the underground facilities in order to incorporate the results in the initial conditions for the analyses of the influence of the excavation on the groundwater regime around the facility in Phase II and subsequent phases. A further objective is to determine geochemical characteristics of the groundwater encountered in the underground facilities as input for planning the investigations in Phase II. To this end, groundwater and rock samples were collected and analyzed and the hydrochemical model based on the investigation results from Step 2 and preceding steps was updated.
Various spatial, temporal and financial limitations are likely to be encountered when characterizing the geological environment at specific sites. To allow effective investigations under these conditions, the relationship between the types and volume of information obtained during the investigations, the level of understanding and the results of the investigations should be evaluated at each stage. The results should then be reflected in the planning of specific investigation programs in the subsequent stages on the one hand and in the decisions made when proceeding to the next stage on the other hand.
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