• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.1
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• pp.9-15
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• 2006

For the accurate safety assessment of potential radioactive waste disposal site which is located in the crystalline rock it is important to simulate the mass transportation through engineered and natural barrier system precisely, characterized by porous and fractured media respectively. In this work the methods to construct discrete fracture network for the analysis of flow and mass transport through fractured-porous medium are described. The probability density function is adopted in generating fracture properties for the realistic representation of real fractured rock. In order to investigate the intersection between a porous and a fractured medium described by a 2 dimensional rectangular and a cuboid grid respectively, an additional imaginary fracture is adopted at the face of a porous medium intersected by a fracture. In order to construct large scale flow paths an effective method to find interconnected fractures and algorithms of swift detecting connectivities between fractures or porous medium and fractures are proposed. These methods are expected to contribute to the development of numerical program for the simulation of radioactive nuclide transport through fractured-porous medium from radioactive waste disposal site.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.381-384
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• 2005

암반의 단열은 현재까지의 대상암석에 기록된 변형이력의 하나로서, 이는 지하수유동이나 암반의 안정성 해석에 중요한 정보가 된다. 본 연구에서는 대전 유성지역의 암반의 단열 파악을 목적으로, 초음파 텔레뷰어(BHTV) 검층 자료를 선정하여 D/B를 구축하였다. 구축한 D/B를 토대로 시추공의 속성 자료를 3차원 가시화하여 단열분포에 대한 이해를 증진시키고자 하였으며, 3차원 가시화는 GIS의 소프트웨어인 ArcGIS의 AML (ArcMacro Language)을 이용하여 표현하였다. 이러한 연구방법을 통하여 사용자는 암반의 단열 분포를 정확하고, 효과적으로 파악할 수 있을 것이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1929-1933
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• 2009

수자원 수요가 급증함에 따라 단열 암반 대수층의 지하수를 개발해 이용하려는 연구가 많이 이루어지고 있다. 본 연구에서는 단열암반 대수층의 지하수 유동 특성을 알아보기 위해 한국원자력연구원 연구 지역 내에 NX 규격의 직경 78mm를 갖는 500m 심도의 심부시추공 (DB-01)을 굴착하였다. DB-01에 대한 시추공 단열조사 (BHTV) 및 시추코아 분석을 통해서 심부 시추공에 대한 예비 투수성 구조를 도출하였으며, 투수성이 큰 구조로 단열과 연결된 지점으로 판단되는 심도에 대해서 현장 수리시험을 수행하여, 결정질 암반의 투수성 구조에 대한 수리특성을 규명하였다. 그 결과를 분석하여 비교적 투수성이 큰 심도를 결정질 암반의 대수층이라 정의하였다. 수리특성이 비슷한 3가지의 그룹 중 3그룹은 투수계수도 가장 크고 단열빈도도 밀집되어 있는 것으로 나와 심부 200m에서 250m이하의 이 단열구간은 수자원으로 지하수의 활용이 가능하다고 여겨진다.

• The Journal of Engineering Geology
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• v.26 no.3
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• pp.325-330
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• 2016

The second phase of low- and intermediate-level waste (LILW) disposal facility is under planned on the sedimentary rock in unsaturated zone. In this study, we created two meshes which were a matrix continuum mesh and a fracture continuum mesh to carry out 2 dimensional numerical modeling for groundwater flow in the unsaturated zone containing fractures focused on the second phase of LILW disposal facility. Two continuum meshes were developed using MINC in meshmaker module of TOUGH2 code. A fracture continuum mesh was included the k-field distribution of the permeability derived from the Discrete Fractured Network (DFN) modeling. To apply the unsaturated zone for the modeling, the gridding steps to generate mesh were developed. Each step to generate a mesh consisted of definition of materials, setting the initial conditions and creating grids using MINC. The methodology development of meshes in this study will be applied for more precise modeling of groundwater flow and mass transport.

• Proceedings of the KSEG Conference
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• 2005.04a
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• pp.157-164
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• 2005

BIPS와 Televiewer를 이용하여 10개의 지하수 관측공에서 획득된 1,591개 불연속면을 분석하여 지하수 유동과의 관계를 비교${\cdot}$분석하였다. 연구지역 내의 지형은 산계가 잘 발달된 계곡형 지형이며, 수계의 발달은 매우 미약하다. 연구지역 주변에는 북북동-남남서 방향의 양산단층과 동래단층이 발달되어 있으며, 연구지역 내에는 EW방향의 선구조도 발달되어 있다. 지하수공내에서 조사된 불연속면의 주 방향은 위성사진에서 판독된 선구조의 방향과 대부분 일치한다. 지구통계기법을 이용하여 작성된 지하수위 등고선도에서 추정된 지하수 유동방향과 유향${\cdot}$유속기에서 측정된 지하수 유향은 거의 일치하지만, 단열암반에 발달된 불연속면의 방향과 지하수 유동방향은 2가지로 해석되었다. 첫째는 단열암반에 발달된 불연속면의 방향과 지하수 유동방향이 잘 일치하는 경우(BH-01, 03, 04, 12공), 둘째는 불연속면의 방향과 지하수 유동방향이 잘 일치하지 않는 경우(BH-02, 05, 07, 11) 이다. 지하수 유동방향이 불연속면의 방향과 일치하지 않는 경우는 지형의 변화에 더 영향을 받는 것으로 나타났다. 따라서 단열암반 내에서 지하수의 유동은 단열의 방향성에 영향을 받지만, 지형의 특성에도 큰 영향을 받는다.

• The Journal of Engineering Geology
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• v.10 no.1
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• pp.13-25
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• 2000

A three-dimensional discrete fracture network model based on probabilistic characteristics of fracture geometry and transmissivity was designed to calculate the conductivity tensor and to estimate theanisotropy of conductivity. The conductivities, $K_p$, obtained from the numerical simulation of single-holepacker test corresponded well to those from the field tests. From this, it can be concluded that thefracture network model designed in this study can represent hydraulic characteristics of in-situ fractured rock mass. Block-scale conductivities, $K_b$, estimated from the modelling of steady-state flow through the REV-scale block were ranged between the arithmetic mean and harmonic mean of theconductivity estimates from packer tests. The conductivity along north-south direction was 1.4 timesgreater than that along the east-west direction. It was concluded that the anisotropy of conductivitywas insignificant. It was also found that there was a little correlation between $K_b$ and $K_p$. This would be to that the conductivities from the packer test simulation was strongly dependent on thetransmissivity and the number of fractures within the packer test intervals.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.231-238
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• 2005

On the basis of flow resistance theory the conceptual model and related mathematical descriptions is proposed for resistance modeling of groundwater flow in CPM(continuum Porous medium), DFN(discrete fracture network) and fractured-porous medium. The proposed model is developed on the basis of finite volume method assuming steady-state, constant density groundwater flow. The basic approach of the method is to evaluate inter-block flow resistance values for a staggered grid arrangement, i.e. fluxes are stored at cell walls and scalars at cell centers. The balance of forces, i.e. the Darcy law, is utilized for each control volume centered around the point where the velocity component is stored. The transmissivity (or permeability) at the interface is assumed to be the harmonic average of neighboring blocks. Flow resistance theory was utilized to relate the fluxes between the grid blocks with residual pressures. The flow within porous medium is described by three dimensional equations and that within an individual fracture is described by a two dimensional equivalent of the flow equations for a porous medium. Newly proposed models would contribute to develop flow simulation techniques with various matrix characteristics.

• Proceedings of the KGS Conference
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• 2002.11a
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• pp.40-44
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• 2002

우리나라의 경우 이미 1980년대부터 단열암반(fractured rock)의 지하수를 개발ㆍ이용하여 왔다. 서울시의 지하수 이용시설 중 지하 30m 이상의 개발심도를 나타내는 관정이 31.4%(4,677개소), 100m 이상의 개발관정도 7.2%(1,076개소) 존재하는 것으로 보고되었다(서울시, 1996, 12).(중략)

• Tunnel and Underground Space
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• v.12 no.3
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• pp.198-209
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• 2002

To assess deep geological environment for the research and development of hish-level radioactive waste disposal, six boreholes of 3" in diameter were installed in two granitic areas. An areal extent of the rock block scale in the study sites was estimated by the lineament analysis from satellite images and shaded relief maps. The characterization of fracture system developed in rock block scale was carried out based on the acoustic televiewer logging in deep boreholes. In the Yuseong site, the granite rock mass was divided into the upper and lower zones at around -160m based on the probabilistic distribution characteristics of the geometric parameters such as orientation, fracture frequency, spacing and aperture size. Since the groundwater flow is dependent on the fracture system in a fractured rock mass, the correlation of the fracture frequency and cumulative aperture size to the hydraulic conductivity was also discussed.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.8
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• pp.465-471
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• 2015

Adsorption experiments for radionuclides such as $^3H$, $^{90}Sr$ and $^{99}Tc$ were conducted using fractured rock collected in unsaturated zone. The released radionuclide through artificial barrier from the near surface repository can be transported by the flow of rainfall or pore water through fractures in unsaturated zone and reach to groundwater flow. Therefore, it is important to investigate transport behavior (retardation) of radionuclides through fractured rock for the safety assessment and long-term performance of repository. Fractured rock samples were collected and characterized by X-ray microtomography (XMT) analysis, which can be used to develop a more robust unsaturated fracture transport model. When fracture-filling materials are exist, distribution coefficient of $^{90}Sr$ is higher than without fracture-filling materials. In this study, batch sorption distribution coefficient ($K_d$) of radionuclide was determined and used to increase our understanding of radionuclide retardtion through fracture-filling materials.