• Tunnel and Underground Space
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• v.33 no.6
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• pp.445-471
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• 2023

Long-term safety over millennia is the top priority consideration in the construction of disposal sites. However, ensuring the mechanical stability of deep geological repositories for spent fuel, a.k.a. radwaste, disposal during construction and operation is also crucial for safe operation of the repository. Imposing restrictions or limitations on tunnel support and lining materials such as shotcrete, concrete, grouting, which might compromise the sealing performance of backfill and buffer materials which are essential elements for the long-term safety of disposal sites, presents a highly challenging task for rock engineers and tunnelling experts. In this study, as part of an extensive exploration to aid in the proper selection of disposal sites, the anticipation of constructing a deep geological repository at a depth of 500 meters in an unknown state has been carried out. Through a review of 2D and 3D numerical analyses, the study aimed to explore the range of properties that ensure stability. Preliminary findings identified the potential range of rock properties that secure the stability of central and disposal tunnels, while the stability of the vertical tunnel network was confirmed through 3D analysis, outlining fundamental rock conditions necessary for the construction of disposal sites.

• Tunnel and Underground Space
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• v.19 no.6
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• pp.507-516
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• 2009

In cases of high-level radioactive waste repositories, heat load is apparent by radioactive waste decay. The safety of a waste repository would be influenced by changing circumstances caused by heat transfer through rock. Thus, a ventilation system is necessary to secure the waste repository. The first priority for building an appropriate ventilation system is completing a computer simulation research with thermal rock properties and a heat transfer coefficient. In this study, the heat transfer coefficient in KURT was calculated using the measurement of inner circumstance factors that include dry bulb and wet bulb temperature, rock surface temperature, and barometric pressure. The heater that is 2 m in length and 5 kw in capacity heats the inside of rock in the research module by $90^{\circ}C$. As a result of determining the heat transfer coefficient in the heating section, the changes of heat transfer coefficient were found to be a maximum of 7.9%. The average heat transfer coefficient is approximately 4.533 w/$m^2{\cdot}K$.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.3
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• pp.183-192
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• 2005

Natural ventilation in radioactive waste repositories is considered to be less efficient than mechanically forced ventilation for the repository working environment and hygiene & safety of the public at large, for example, controlling the exposure of airborne radioactive particulate matter. It is, however, considered to play an important role and may be fairly efficient for maintaining environmental conditions of the repository over the duration of its lifetime, for example, moisture content and radon (Rn) gas elimination in repository. This paper describes the feasibility of using natural ventilation which can be generated in the repository itself, depending on the conditions of the natural environment during the periods of repository construction and operation. Evidences from natural cave analogues, actual measurements of natural ventilation pressures in mountain traffic tunnels with vertical shafts, and calculations of airflow rates with given natural ventilation pressures indicate possible benefits from passive ventilation for the prospective Korean radioactive waste repository. Natural ventilation may provide engineers with a cost-efficient method for heat and moisture transfer, and radon (Rn) gas elimination in a radioactive waste repository. The overall thermal performance of the repository may be improved. The dry-out period may be extended, and the seepage flux likely would be decreased.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.212-218
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• 2004

저준위 방사성폐기물 안전성 평가를 위해 대상 부지를 선정하고 경계 조건을 도입하였다. 연안에 처분장이 위치할 경우를 가상하여 처분장 심도 및 단열까지의 거리등에 대한 지하수 유동 민감도를 분석하였다. 또한 처분장 진입 터널이 지하수 유동에 미치는 영향을 평가하였다. 이를 통하여 각 암반별 이동 거리 및 시간을 CONNECTFLOW를 이용해 산정하고, 그 결과들이 방사선적 안전성 종합 평가 코드인 MASCOT의 입력 자료로 활용되도록 하였다.

• Tunnel and Underground Space
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• v.18 no.3
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• pp.165-174
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• 2008

Thermo-hydro-chemico-mechanical evolution of the radioactive waste repository and surrounding geological media is one of the key issues for the radioactive waste disposal. This article describes not only the basic context for the site selection but also a reasonable strategy for the repository related research based on the results of the French repository project carried out by ANDRA (National radioactive waste management agency). To have some alternatives for the determination of a preferable depth and geological media, it would be recommendable to establish a database system. The curing process of the fractures or microfissures in the EDZ (Excavation Disturbed Zone) during operation time has to be examined considering the evolution of the EDZ and the reversibility of the repository. It is prerequisite to carry out a feasibility study and to validate the design concept and design parameters in a properly constructed underground research laboratory (URL) in Korea.

• Tunnel and Underground Space
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• v.14 no.3
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• pp.175-187
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• 2004

고준위방사성폐기물 처분의 경우 심부 암반에 만들어진 처분장에 영구 처분하는 것이 최선의 방안으로 여겨지고 있다. 하지만 지하 심부의 암반에 대한 물리적, 화학적, 역학적, 열적, 수리적 물성과 이들과 핵종 이동의 관계, 처분환경에서의 공학적 방벽 및 암반의 거동이 처분장 안정성 및 안전성에 미치는 영향 등을 파악해야하는 어려움이 따른다. 특히 고준위폐기물 처분의 경우 장기간의 안전성을 고려해야하기 때문에 자연방벽과 공학적 방벽의 시간에 따른 거동변화도 고려하여야 할 필요가 있다. (중략)

• Nuclear industry
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• v.36 no.5
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• pp.67-75
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• 2016

Cigeo 프로젝트는 프랑스에서 수행되고 있는 고준위 방사성폐기물 지층 처분장 건설 사업으로 단순한 기술적 차원의 문제를 넘어선 거대하고 복잡한 다차원의 국책 프로젝트이다.

• Nuclear industry
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• v.36 no.5
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• pp.51-60
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• 2016

핀란드의 사용후핵연료 관리 전담기관인 Posiva는 지난해 말 세계 최초로 심지층 방식의 사용후핵연료 처분장 건설 인허가를 받았다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.157-164
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• 2007

The prediction of the temperature distribution change of the spent nuclear fuel disposal canister and its surrounding structures (bentonite buffer, granitic rock etc.) due to the spent fuel heat is very important for the design of the 500m deep granitic repository for the spent nuclear fuel disposal canister (about 10,000 years long) deposition. In this study, the temperature distribution change of the composite structure which comprises the canister, the bentonite buffer, the deposition tunnel due to the spent fuel heat is computed using the numerical analysis method. Specially, the temperature distribution change of the composite structure is analysed as the deposition time elapses up to m years. The analysis result shows that the temperature of each part of the repository increases slowly in different way but the latest part temperature increases slowly up to 150 years and thereafter decreases slowly.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2001.11a
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• pp.331-336
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• 2001

한국원자력연구소에서는 고준위 방사성폐기물 처분 시스템의 안전성을 투명하게평가하기 위한 방안의 하나로 처분 안전성 관련 시나리오와 구성 요소들인 FEP, 그리고 각 시나리오 별 안전성 평가 방안들을 종합한 프로그램인 FEAS를 개발하고 있다. 고준위 방사성 폐기물 처분 연구는 관련 전문가 뿐 아니라 일반 국민들도 안전성에 관해 많은 관심을 표명하고 있는 바 현재 국내에서 고려하고 있는 처분 개념은 무엇이며 처분장 안전성 평가를 위해서 고려하고 있는 제 사건들은 무엇이며 이들 시나리오를 구성하는 세부 사건들은 무엇인가에 관한 합의를 도출하고 이와 관련된 기록들을 보존하고 각각 세부 사건들에 관해 현재의 평가 방안과 데이터 수집 현황 그리고 해외 사례 등을 체계적으로 정리하는 일은 중요하다. 현재 개발되고 있는 FEAS는 이와 같은 역할을 수행할 뿐 아니라 이 프로그램과 동시에 개발되고 있는 입력 자료 데이터 시스템, 웹을 기반으로 한 품질 보증 체제 및 안전성 평가 방안 등과 향후 연계되어 모든 국민들이 방사성 폐기물 처분장의 안전성을 쉽게 이해할 수 있는 수단으로 확장될 예정이다.