• The Journal of Engineering Geology
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• v.11 no.3
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• pp.245-254
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• 2001

The experimental study on disposal cover through the performance test facility offers reliability in the safety of near surface disposal of low and intermediate level radioactive waste. To ensure the long-term safety of the repository, the impermeability, integrity, resistance to degradation and ease of maintenance might be considered as the basic performance requirement of the disposal cover. considering the difficulties to meet these performance requirement by using single layer, the disposal cover design which is composed of top layer, middle drainage layer and bottom low permeability layer is schemed for the test facility. The water balance of the cover was evaluated by using HELP code. For the long-term monitoring of the soil moisture content and matric potential, TDR probes and tensiometers will be installed in 6 test cells. Each test cell is dimensioned 3$\times$3$\times$3.3m.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2
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• pp.133-141
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• 2020

A geological repository comprises a natural barrier and an engineered barrier system. Its design components consist of canisters, buffers, backfill, and near-field rock. Among the engineered barrier system components, bentonite buffers minimize the groundwater flow from near-field rock and prevent the release of nuclide. Investigation of the hydraulic conductivity of the buffer to groundwater flow is an important factor in the performance evaluation of the stability and integrity of the engineered barrier of the repository. In this study, saturated hydraulic conductivity tests were performed using Gyeongju bentonite at various dry densities and temperatures, and a hydraulic conductivity prediction model was developed through multiple regression analysis using the 120 result sets of hydraulic conductivity. The test results showed that the hydraulic conductivity tends to decrease as the dry density increases. In addition, the hydraulic conductivity increased with increasing temperature. The multiple regression analysis results showed that the coefficient of determination (R²) of the hydraulic conductivity prediction equation was as high as 0.93. The hydraulic conductivity prediction equation presented in this study could be used for the design of engineered barrier systems.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.355-362
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• 2019

This technical note introduces a newly-proposed concept of deep horizontal drillhole disposal of spent nuclear fuel, and considers how it can be applied in the Korean environment. This disposal concept, in which high-level radioactive waste is disposed in deep horizontal drillholes installed with directional drilling technique, is expected to have great advantages over the existing deep mined repository concept in economics and safety. Since this concept is still at the idea level, however, it is necessary for worldwide expert groups to demonstrate its safety and performance. In addition, the development of guidelines by the regulatory body should be supported. The Korean circumstances, which include a narrow territory and a high population density, as well as the amount of spent nuclear fuel, make the NIMBY (Not In My Back Yard) phenomenon very strong and the siting conditions difficult. Under these conditions, if the disposal section of deep horizontal drillhole concept can be located at the continental shelf, with a stable environment, rather than in a coastal land area, it is expected to alleviate the psychological anxiety of the local community and stakeholders. Moreover, even when constructing a centralized deep mined repository in the future, it is necessary to consider locating the repository in the continental shelf.

• Nuclear industry
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• v.37 no.2
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• pp.2-19
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• 2017

정부는 1월 25일 국무조정실, 미래창조과학부, 외교부, 산업통상자원부 등 관계부처 합동으로 향후 5년간(2017~21년)의 원자력 진흥 이용 정책 방향을 제시하는 '제5차 원자력진흥종합계획'을 확정했다. 이번 제5차 원자력진흥종합계획 주요 특징은 국민적 관심사인 원전 안전과 방사성폐기물 관리에 역점을 두고 수립됐으며, 갈수록 중요성이 증대되고 있는 소통을 위한 정책이 비중있게 다뤘다는 점이다. 또한 핵심 주제 도출, 추진 전략 설정 등 수립 과정상 온라인 및 오프라인 공청회를 병행하는 등 다양한 의견 수렴 절차를 거쳤으며, 관계 부처 간 유기적인 역할 분담 및 협력 내용을 충실히 반영하고, 원자력 연구개발 5개년 계획을 수립하여 상하위 계획간의 일관성과 실행력을 높였다. 정부는 제5차 원자력진흥종합계획의 충실한 이행을 통해 고준위폐기물 관리 정책 확립 등 투명한 정책 추진으로 국민 신뢰를 향상하고 신기후체제 출범에 따른 온실가스 감축 목표에 효과적으로 대응하며 원자력의 지속적 이용을 통한 국가 성장 동력 창출 기반을 확보할 수 있을 것으로 기대하고 있다. 원자력진흥종합계획은 원자력 진흥 이용 관련 종합 계획으로 지난 1997년부터 매 5년마다 수립하여 추진하고 있다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.1
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• pp.13-21
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• 2011

To characterize the site specific properties of a study area for high-level radioactive waste disposal research in KAERI, the several geological investigations such as surface geological surveys and borehole drillings were carried out since 1997. Especially, KURT (KAERI Underground Research Tunnel) was constructed to understand the further study of geological environments in 2006. As a result, the first geological model of a study area was constructed by using the results of geological investigation. The objective of this research is to construct a hydrogeological model around KURT area on the basis of the geological model. Hydrogeological data which were obtained from in-situ hydraulic tests in the 9 boreholes were estimated to accomplish the objective. And, the hydrogeological properties of the 4 geological elements in the geological model, which were the subsurface weathering zone, the log angle fracture zone, the fracture zones and the bedrock were suggested. The hydrogeological model suggested in this study will be used as input parameters to carry out the groundwater flow modeling as a next step of the site characterization around KURT area.

• Journal of the Korean Geotechnical Society
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• v.33 no.10
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• pp.25-31
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• 2017

The buffer is one of the major components of an engineered barrier system (EBS) for the disposal of high-level radioactive waste (HLW). As the buffer is located between a disposal canister and host rock, it is indispensable to assure the disposal safety of high-level radioactive waste. It can restrain the release of radionuclide and protect the canister from the inflow of groundwater. Since high quantity of heat from a disposal canister is released to the surrounding buffer, thermal properties of the buffer are very important parameters for the analysis of the entire disposal safety. Especially, temperature criteria of the compacted bentonite buffer can affect the design of HLW repository facility. Therefore, this paper investigated thermal properties for the Kyungju compacted bentonite buffer which is the only bentonite produced in South Korea. Hot wire method and dual probe method were used to measure thermal conductivity and specific heat capacity of the compacted bentonite buffer according to the temperature variation. Thermal conductivity and specific heat capacity were decreased dramatically when temperature variation was between $22^{\circ}C{\sim}110^{\circ}C$ as degree of saturation decreased according to the temperature variation. However, there was little variation under the high temperature condition at $110^{\circ}C{\sim}150^{\circ}C$.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.191-208
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• 2024

In this study, a hydro-mechanical-damage coupled analysis model was developed to evaluate the structural safety of radioactive waste disposal structures. The Mazars damage model, widely used to model the fracture behavior of brittle materials such as rocks or concrete, was coupled with conventional hydro-mechanical analysis and the developed model was verified via theoretical solutions from literature. To derive the numerical input values for damage-coupled analysis, uniaxial compressive strength and Brazilian tensile strength tests were performed on concrete samples made using the mix ratio of the disposal concrete silo cured under dry and saturated conditions. The input factors derived from the laboratory-scale experiments were applied to a two-dimensional finite element model of the concrete silos at the Wolseong Nuclear Environmental Management Center in Gyeongju and numerical analysis was conducted to analyze the effects of damage consideration, analysis technique, and waste loading conditions. The hydro-mechanical-damage coupled model developed in this study will be applied to the long-term behavior and stability analysis of deep geological repositories for high-level radioactive waste disposal.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.4
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• pp.341-348
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• 2005

Bentonite has been considered as a candidate buffer material in the underground repository for the disposal of high-level radioactive waste because of its low permeability, high sorption capacity, self sealing characteristics, and durability in nature. In this study, the potential for separation of bentonite particles caused by the groundwater erosion was studied experimentally for a Korean Ca-bentonite under the relevant repository conditions. Results showed that bentonite particles can be generated at the bentonite/granite interface and mobilized by the water flow although the intrusion of bentonite into fracture by swelling pressure was observed to be small. Different processes of mobilization of theses colloids from the compacted bentonite block have been identified in this study. The concentration of particles eluted in water was increased as the flow rate increased. Thus the result reveals that the erosion of the bentonite surface due to the groundwater flow together with intrusion processes is the main mechanism that can mobilize bentonite colloids in the fracture of the granite.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.06a
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• pp.253-253
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• 2009

전세계적 고유가 및 $CO_2$ 배출로 인한 지구 온난화 문제 동 앞으로의 에너지 개발은 지속가능하며, 환경친화적이어야 한다. 따라서 가장 값싼 에너지원의 하나이며, 또한 환경문제에서도 유리한 원자력 에너지에 대한 세계적인 관심이 지난 약 30년 정도의 침체기간을 거친후 미국, 중국, 인도, 유럽, 아시아 등을 중심으로 다시 부활하고 있다. 그러나 미래 원자력에너지의 활발한 이용 및 지속 가능성을 위해서는 고준위 방사성 폐기물의 처리문제가 반드시 해결되어야 하며, 그 중에서도 사용후핵연료의 관리문제는 원자력 발전소의 계속 운전을 위해 시급히 해결되어야 한다. 한국원자력연구원도 2008년 12월 결정된 정부의 "미래 원자력시스템 개발 Action Plan" 을 통해 이러한 사용후핵연료의 관리문제를 해결하기 위한 연구 과제를 10여년 동안 수행해오고 있으며, 그 중 하나가 파이로(Pyroprocess) 공정개발이다. 1997년부터 관련연구가 착수되어, 2001년부터는 약 6년간에 걸쳐 파이로의 전처리 공정 및 전해환원 공정에 대한 실험실 규모 실증시설인 ACPF(Advanced spent fuel Conditioning Process Facility)를 개발한 바 있다. 또한 향후 파이로 기술의 상용화를 위해 2016년 까지 약 10톤/년 규모의 공학규모 파이로 실증시설(ESPF)을 건설하고 이를 기초로 2025년까지 100톤/년 규모의 파이로 상용시설 (KAPF) 을 건설하여 여기서 나온 우라늄 및 TRU 물질을 이용해 2030년까지 개발 예정인 소듐냉각 고속로에 필요한 핵연료를 제작, 공급하는 계획을 가지고 있다. 이 논문에서는 파이로 시설개발의 가장 중요한 인자중 하나인 시설의 안전성 확보를 위해 외국 및 국내에서의 연구개발 현황을 알아보고 안전성 분석 및 평가방법에 대한 기본 인자들을 도출해 보았다. 또한 파이로 시설의 인허가를 위한 사용후핵연료 처리시설 규제관련 국, 내외의 연구현황도 알아보았다.

• Tunnel and Underground Space
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• v.10 no.4
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• pp.553-558
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• 2000

Since 1977, KAERI has conducted the fundamental R&D on the permanent disposal of potential HLW repository in Korea. The first ten year project is divided into three short-term phase studies. The first phase study which shall be finished in March of 2000, has the prime target to develop the disposal concept of HLW. Throughout this study the preliminary and generic disposal repository system has been introduced. The potential repository is proposed to be emplaced into crystalline rocks which is the most common rock types in Korea. The proposed depth of the repository is between 300 to 700 meter. The numerical code, MASCOT-K was developed to asserts the long term safety of the proposed repository concept. Based on this conceptual design preliminary safely assessment was performed. Results show that for the given disposal system the potential radioactive release it well below the regulatory limit.