Tunnel and Underground Space (터널과지하공간)

Korean Society for Rock Mechanics and Rock Engineering (한국암반공학회)
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Review of In-situ Installation of Buffer and Backfill and Their Water Saturation Management for a Deep Geological Disposal System of Spent Nuclear Fuel

국외 사례를 통한 사용후핵연료 심층처분시스템 완충재 및 뒤채움재의 현장시공 및 포화도 관리 기술 분석

  • Ju-Won Yun (Department of Energy Resources and Geosystems Engineering, Sejong University) ;
  • Won-Jin Cho (Korean Radioactive Waste Society) ;
  • Hyung-Mok Kim (Department of Energy Resources and Geosystems Engineering, Sejong University)
  • 윤주원 (세종대학교 지구자원시스템공학과) ;
  • 조원진 (한국방사성폐기물학회 기술정책연구소) ;
  • 김형목 (세종대학교 지구자원시스템공학과)
  • Received : 2024.04.17
  • Accepted : 2024.04.23
  • Published : 2024.04.30
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Abstract

Buffer and backfill play an essential role in isolating high-level radioactive waste and retard the migration of leaked radionuclides in deep geological disposal system. A bentonite mixture, which exhibits a swelling property, is considered for buffer and backfill materials, and excessive groundwater inflow from surrounding rock mass may affect stability and efficiency of their role as an engineered barrier. Therefore, stringent quality control as well as in-situ installation management and inflow water constrol for buffer and backfill are required to ensure the safety of deep disposal facilities. In this study, we analyzed the design requirements of buffer and backfill by examining various laboratory tests and a field study of the Steel Tunnel Test at the Äspö Hard Rock Laboratory in Sweden. We introduced how to control the quality of buffer and backfill construction in-field, and also presented how to handle excessive groundwater inflow into disposal caverns, validating the groundwater retention capacity of bentonite pellets and the effectiveness of geotexile use.

완충재 및 뒤채움재는 심지층처분시스템 공학적방벽 구성요소로 고준위방사성폐기물을 안전하게 격리하고 폐기물로부터 유출되는 방사성핵종의 누출을 지연시키는 데 필수적인 역할을 한다. 완충재 및 뒤채움재로는 팽윤특성을 보이는 벤토나이트 혼합물의 사용이 고려되고 있으며 주변 암반으로부터 과도한 지하수의 유입은 이러한 공학적방벽의 안정성과 효율성을 저하시킬 수 있다. 따라서, 심층처분장의 안전성 확보를 위해서는 완충재 및 뒤채움재의 엄격한 품질기준 및 현장관리 방안수립과 유입 지하수를 처리할 수 있는 기술이 요구된다. 본 고에서는 다양한 실험실 시험뿐만 아니라 스웨덴 Äspö Hard Rock Laboratory에서 수행된 처분터널 1/2 규모의 Steel Tunnel Test 사례를 심층 분석하여 완충재 및 뒤재움재의 설계 요구사항을 파악하고 현장실험 사례를 통해 파악된 품질관리 요소 및 방안을 소개하였다. 또한, 완충재 및 뒤채움재의 현장시공 안정성과 효율성을 확보하기 위한 처분갱도에서의 유입 지하수 처리방법에 대해 소개하고 벤토나이트 펠렛 채움 내의 지하수 저장능력과 토목섬유(geotextile) 사용 효과에 대한 검증 결과를 소개하였다.

Keywords

Acknowledgement

이 논문은 2024년도 원자력안전위원회의 재원으로 사용후핵연료관리핵심기술개발사업단 및 한국원자력안전재단의 지원(RS-2021-KN066110)과 과학기술정보통신부의 재원으로 한국연구재단의 지원(No. 2022R1A2C1009524)을 받아 수행되었습니다.

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