Tunnel and Underground Space (터널과지하공간)

Korean Society for Rock Mechanics and Rock Engineering (한국암반공학회)
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A Numerical Study on the Step 0 Benchmark Test in Task C of DECOVALEX-2023: Simulation for Thermo-Hydro-Mechanical Coupled Behavior by Using OGS-FLAC

DECOVALEX-2023 Task C 내 Step 0 벤치마크 수치해석 연구: OGS-FLAC을 활용한 열-수리-역학 복합거동 수치해석

  • Kim, Taehyun (Korea Atomic Energy Research Institute (KAERI)) ;
  • Park, Chan-Hee (Korea Institute of Geoscience and Mineral Resources (KIGAM)) ;
  • Lee, Changsoo (Korea Atomic Energy Research Institute (KAERI)) ;
  • Kim, Jin-Seop (Korea Atomic Energy Research Institute (KAERI))
  • Received : 2021.12.10
  • Accepted : 2021.12.20
  • Published : 2021.12.31
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Abstract

The DECOVALEX project is one of the representative international cooperative projects to enhance the understanding of the complex Thermo-Hydro-Mechanical-Chemical(THMC) coupled behavior in the high-level radioactive waste disposal system based on the numerical simulation. DECOVALEX-2023 is the current phase consisting of 7 tasks, and Task C aims to model the THM coupled behavior in the disposal system based on the Full-scale Emplacement (FE) experiment at the Mont-Terri underground rock laboratory. This study performs the numerical simulation based on the OGS-FLAC developed for the current study. In the numerical model, we emplaced the heater with constant power horizontally based on the FE experiment and monitored the pressure development, temperature increase, and mechanical deformation at the specific monitoring points. We monitored the capillary pressure as the primary effect inducing the flow in the buffer system, and thermal stress and pressurization were dominant in the surrounding rocks' area. The results will also be compared and validated with the other participating groups and the experimental data further.

DECOVALEX 프로젝트는 고준위방사성폐기물 처분 시스템에서 발생하는 복잡한 열-수리-역학-화학적(THMC) 복합거동에 대해 수치해석을 통해 보다 더 깊이 이해하기 위해 수행되고 있는 대표적 국제공동 연구이다. 현재 DECOVALEX-2023이 7개 task를 기반으로 진행 중이며, 이 중 Task C는 Mont-Terri 지하연구시설에서 수행된 실규모 정치(FE) 시험을 대상으로 처분시스템 내 THM 복합거동을 모사하는 것을 목표로 하고 있다. 본 연구에서는 자체개발 해석 코드인 OGS-FLAC을 활용하여 수치해석 연구를 수행하였다. 수치모델에서는 FE 시험과 같이 일정 출력의 히터를 수평으로 위치시켰으며, 주어진 계측지점에서 압력 분포, 온도 변화, 역학적 변형을 계측하였다. 완충재 내부로 유입되는 유체 흐름은 완충재의 흡입력으로 인해 발생하였으며, 주변 영역에서는 열 팽창 및 열 압력이 지배적으로 작용함을 확인하였다. 해석 결과는 향후 타 참여 그룹 및 실험 결과와 비교 검증을 수행할 계획이다.

Keywords

Acknowledgement

The authors appreciate and thank the DECOVALEX-2023 Funding Organisations Andra, BASE, BGE, BGR, CAS, CNSC, COVRA, US DOE, ENRESA, ENSI, JAEA, KAERI, NWMO, RWM, SURAO, SSM and Taipower for their financial and technical support of the work described in this paper. The statements made in the paper are, however, solely those of the authors and do not necessarily reflect those of the Funding Organisations. This research was also supported by the Institute for Korea Spent Nuclear Fuel (iKSNF) and National Research Foundation of Korea(NRF) grant funded by the Korea government(Ministry of Science and ICT, MSIT)(2021M2E1A1085193) and the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources (KIGAM, GP2020-010) funded by the Ministry of Science and ICT, Korea.

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