• Nuclear Engineering and Technology
• /
• v.45 no.1
• /
• pp.29-40
• /
• 2013

Two different kinds of nuclear power plants produce a substantial amount of spent fuel annually in Korea. According to the current projection, it is expected that around 60,000 MtU of spent fuel will be produced from 36 PWR and APR reactors and 4 CANDU reactors by the end of 2089. In 2006, KAERI proposed a conceptual design of a geological disposal system (called KRS, Korean Reference disposal System for spent fuel) for PWR and CANDU spent fuel, as a product of a 4-year research project from 2003 to 2006. The major result of the research was that it was feasible to construct a direct disposal system for 20,000 MtU of PWR spent fuels and 16,000 MtU of CANDU spent fuel in the Korean peninsula. Recently, KAERI and MEST launched a project to develop an advanced fuel cycle based on the pyroprocessing of PWR spent fuel to reduce the amount of HLW and reuse the valuable fissile material in PWR spent fuel. Thus, KAERI has developed a geological disposal system for high-level waste from the pyroprocessing of PWR spent fuel since 2007. However, since no decision was made for the CANDU spent fuel, KAERI improved the disposal density of KRS by introducing several improved concepts for the disposal canister. In this paper, the geological disposal systems developed so far are briefly outlined. The amount and characteristics of spent fuel and HLW, 4 kinds of disposal canisters, the characteristics of a buffer with domestic Ca-bentonite, and the results of a thermal design of deposition holes and disposal tunnels are described. The different disposal systems are compared in terms of their disposal density.

• Geophysics and Geophysical Exploration
• /
• v.9 no.3
• /
• pp.231-240
• /
• 2006

A variety of geophysical well loggings have been conducted to investigate the geological characteristics for basaltic volcanic area in Jeju Island. Specially, there is no precedent case study using geophysical well loggings in Jeju Island. And so, the proper understandings for geological features of Jeju Island are the key to interpret geophysical well logs. Presently, seawater intrusion monitoring systems have been constructed for systematic development and conservation of groundwater resources. As the results of geophysical well loggings in this seawater intrusion monitoring boreholes, the responses of well logs for saturated zone have distinctly identified basalt sequences. In particular, neutron logging, gamma-gamma (density) logging, and resistivity logging have well exhibited the characteristics of lava flows and lithologic boundaries. In hyalocastite, porosity is high, and resistivity is low. Eventually, geophysical well logs are useful for securing sustainable development of groundwater in Jeju Island in that it has identified the characteristics of geological responses.

• Tunnel and Underground Space
• /
• v.30 no.2
• /
• pp.136-148
• /
• 2020

Nuclear power plants have been operated in Korea since 1978, thus the high-level radioactive waste (HLW) produced from the plants has been accumulated accordingly. Hence, it is urgent to secure a final repository for HLW disposal, however, siting process should be preceded, which usually takes long time, as it requires broad and precise investigation. The investigation is generally carried out in stages, which consists of multidisciplinary approaches. In this study, the case studies mainly pertaining to rock mechanics were conducted. Rock mechanical aspects required in each stage and their applications were investigated and corresponding R&D researches were presented as well. At the same time, current research status in Korea was presented, followed by a brief future research plan with regard to the site investigation. The future research aims to produce fundamental information for siting process, and the compiled cases in this study will be utilized as references in the research.

• Tunnel and Underground Space
• /
• v.12 no.2
• /
• pp.120-129
• /
• 2002

Natural cavitied were found at shallow depth during construction of a huge bridge in Cambro-Ordovician Limestone Basin in the central part or Korea. The distribution patterns of cavities in this area were investigated carefully with a supplementary field job such as a structural geological survey, a geophysical survey, and a rock mechanical test in laboratory or field. A structural geological mapping produced a detail geological map focusing the route of the Proposed highway. It suggested that there were three faults in this wet and these faults had an influence on the mechanism of natural cavities. Among many kinds of geophysical surveys, an electrical resistivity prospecting was applied first on the specific area that was selected by results from the geological survey. Many evidences far cavities were disclosed from this geophysical data. Therefore, a seismic tomography was tested on the target wet which was focused by results from the electrical resistivity Prospecting and was believed to have several large cavities. A distinct element numerical simulation using the UDEC was followed on the target area after completing all of field surveys. Data from field tests were directly dumped or extrapolated to numerical simulations as input data. It was verified from numerical analysis that several natural cavities underneath the foundation of the bridge should be reinforced Based on the project result, finally, most of fecundations far the bridge were re-examined and the cement grouting reinforcement was constructed on several foundations among them.

• Geomechanics and Engineering
• /
• v.21 no.4
• /
• pp.357-369
• /
• 2020

Different from the conventional planar fracture and simplified Newton model, for power-law slurries with a lower water-cement ratio commonly used in grouting engineering, flow model in geological rough fractures is built based on ten standard profiles from Barton (1977) in this study. The numerical algorithm is validated by experimental results. The flow mechanism, grout superiority, and water plugging of pseudo plastic slurry are revealed. The representations of hydraulic grouting properties for JRCs are obtained. The results show that effective plugging is based on the mechanical mechanisms of the fluctuant structural surface and higher viscosity at the middle of the fissure. The formulas of grouting parameters are always variable with the roughness and shear movement, which play a key role in grouting. The roughness can only be neglected after reaching a threshold. Grouting pressure increases with increasing roughness and has variable responses for different apertures within standard profiles. The whole process can be divided into three stationary zones and three transition zones, and there is a mutation region (10 < JRCs < 14) in smaller geological fractures. The fitting equations of different JRCs are obtained of power-law models satisfying the condition of -2 < coefficient < 0. The effects of small apertures and moderate to larger roughness (JRCs > 10.8) on the permeability of surfaces cannot be underestimated. The determination of grouting parameters depends on the slurry groutability in terms of its weakest link with discontinuous streamlines. For grouting water plugging, the water-cement ratio, grouting pressure and grouting additives should be determined by combining the flow conditions and the apparent widths of the main fracture and rough surface. This study provides a calculation method of grouting parameters for variable cement-based slurries. And the findings can help for better understanding of fluid flow and diffusion in geological fractures.

• Journal of Soil and Groundwater Environment
• /
• v.19 no.4
• /
• pp.1-11
• /
• 2014

Rural groundwater monitoring network has been managed by Korea Rural Community Corporation (KRC) since 1998. The network consists of two kinds of subnetworks; rural groundwater management network (RGMN) and seawater intrusion monitoring network (SIMN). RGMN has been operated to promote a sound and sustainable development of rural groundwater within the concerned area for groundwater quality and quantity. SIMN has been operated to protect the crops against hazards by the saline water in coastal areas in which the shortage of irrigation water become a main problem for agriculture. Currently, a total of 283 monitoring wells has been installed; 147 wells in 79 municipalities for RGMN and 136 wells in 52 ones for SIMN, respectively. Two subnetworks commonly monitor three hydrophysical properties (groundwater level, temperature, and electric conductivity) every hour. Monitored data are automatically transferred to the management center located in KRC. Data are opened to the public throughout website named to be the Rural Groundwater Net (www.groundwater.or.kr). Annual reports involving well logging and hydrochemical data of RGMN and SIMN have been published and distributed to the rural water management office of each municipalities. In addition, anyone who concerns about RGMN an SIMN can freely download these reports throughout the Rural Groundwater Net as well.

• Journal of the Korean Society of Earth Science Education
• /
• v.15 no.2
• /
• pp.171-191
• /
• 2022

The purpose of this study is to explore inductively learning effects of virtual field trips(VFTs) programs developed by elementary school students under the theme of minerals and rocks, focusing on learning in virtual geological components. Ten students attending 'H' elementary school in the metropolitan area voluntarily participated. In order to develop a virtual field trips programs, pre-actual outdoor geological field trips were conducted and virtual field trips programs were developed. In this process, written data of students observing, all video recording and voice recording materials of the course in which students participated, VR development data, and post-interview data were collected. Data were inductively analyzed focusing on four areas(cognitive, psychological, geography, and technical components) of learning in virtual geological field trips. As a result, there were positive learning effects for students in four areas. This study revealed that the study participants were not just participants in virtual learning, but rather developed classes for virtual field trips programs, which had significant results in terms of authentic inquiry.

• Journal of the Korean GEO-environmental Society
• /
• v.24 no.8
• /
• pp.13-20
• /
• 2023

Tunnelling through the geological anomalies has widely known to have many difficulties such as bottom heave, crack of lining, squeezing and so on. To stabilize the tunnel during the construction or after construction, various reinforcing methods have been introduced and applied such as micropiling at the bottom of tunnel to prevent the bottom heave. In this study, long-term behavior of tunnel in the presence of geological anomalies was predicted using numerical analyses. To this end, material properties for swelling rock model capable of representing the rock swelling behavior was obtained using matching process with measured data to validate the adopted model. After the model validation, simulations were performed to predict the long-term behavior of tunnel in the geological anomalies.

• Geomechanics and Engineering
• /
• v.35 no.6
• /
• pp.647-663
• /
• 2023

The investigation of the disc cutter wear prediction has an important guiding role in TBM equipment selection, project planning, and cost forecasting, especially when tunneling in a long-distance rock formations with high strength and high abrasivity. In this study, a comprehensive database of disc cutter wear data, geological properties, and tunneling parameters is obtained from a 1326 m excavated metro tunnel project in leptynite in Shenzhen, China. The failure forms and wear consumption of disc cutters on site are analyzed with emphasis. The results showed that 81% of disc cutters fail due to uniform wear, and other cutters are replaced owing to abnormal wear, especially flat wear of the cutter rings. In addition, it is found that there is a reasonable direct proportional relationship between the uniform wear rate (WR) and the installation radius (R), and the coefficient depends on geological characteristics and tunneling parameters. Thus, a preliminary prediction formula of the uniform wear rate, based on the installation radius of the cutterhead, was established. The correlation between some important geological properties (K_V and UCS) along with some tunneling parameters (F_n and p) and wear rate was discussed using regression analysis methods, and several prediction models for uniform wear rate were developed. Compared with a single variable, the multivariable model shows better prediction ability, and 89% of WR can be accurately estimated. The prediction model has reliability and provides a practical tool for wear prediction of disc cutter under similar hard rock projects with similar geological conditions.

• Economic and Environmental Geology
• /
• v.57 no.2
• /
• pp.119-128
• /
• 2024

In Australia & Canada, architectural rock and aggregate are one of the mineral resources, and related data and information provided integrated with them. In these countries, the provided data and information, through the information system of local government and national geological survey organizations, are interactive maps, geological and thematic maps, exploration data set, 3 dimension geological models, minning rights status, survey reports and related papers etc. However, in case of Korea, aggregate and architectural rock are not assigned as the kind of mineral resources in accordance to domestic mining law, and related geological data and information are not provided from comprehensive mineral information system established in public geoscience organizations. And the administrative and informative management are conducted separately through the different governmental organizations such as Ministry of construction, Korea forest service, geoscience institute & Korea Mine & Reclamation Corporation. For securing the supply of architectural rock and aggregate resources, and for the convenience of their development & utilization, the unified information system and governance reform for the related industry is needed.