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2019 Vol.35, Issue 11

Research Article

Evaluation of Water Suction for the Compacted Bentonite Buffer Considering Temperature Variation

온도 변화를 고려한 압축 벤토나이트 완충재의 수분흡입력 평가

Seok Yoon1*
,
Gyu-Hyun Go2
,
Jae-Owan Lee3
,
Geon-Young Kim3
윤 석1*
,
고 규현2
,
이 재완3
,
김 건영3
1Member, Senior Researcher, Radioactive Waste Disposal Research Division, KAERI
2Assistant Prof., Dept. of Civil Engrg., Kumoh National Institute of Technology
3Principal Researcher, Radioactive Waste Disposal Research Division, KAERI
1정회원, 한국원자력연구원 방사성폐기물처분연구부 선임연구원
2비회원, 금오공과대학교 토목공학과 조교수
3비회원, 한국원자력연구원 방사성폐기물처분연구부 책임연구원
* Corresponding Author
30 November 2019. pp. 7-14
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Abstract

압축 벤토나이트는 고준위폐기물을 처분하기 위한 공학적방벽 시스템에서 중요한 구성요소 중 하나인 완충재의 후보물질로 가장 적합한 것으로 고려되고 있다. 완충재는 처분공 내 사용후핵연료가 담긴 처분용기와 근계 암반 사이에 채워지는 방벽재로서 지하수 유입으로부터 처분용기를 보호하고, 방사성 핵종 유출을 저지한다. 처분 초기에는 처분용기로부터 발생하는 고온의 열량으로 인해 완충재의 포화도는 감소하지만, 그 후 주변 암반으로부터 유입되는 지하수로 인해 완충재의 포화도는 증가한다. 이렇듯 완충재는 처분 운영 조건에 따라 불포화에서 포화 상태로 도달하게 되기에 완충재의 불포화-포화 거동 특성은 공학적방벽의 전체 안전성을 좌우할 수 있는 중요한 입력자료이다. 따라서 본 연구에서는 국내 압축 벤토나이트 완충재에 대한 수분보유특성을 규명하고자 하였다. 처분 초기 온도 증가에 따라 완충재의 포화도가 감소하는 상황을 고려하여 상온에서부터 125도까지 압축 벤토나이트의 온도 증가에 따른 체적 함수비와 수분흡입력을 측정하였다. 또한 이를 상온에서 동일한 함수비에서의 수분보유능과 비교하였으며 상온에서의 수분흡입력은 1∼15% 정도 크게 측정되었다.

The compacted bentonite buffer is one of the major components of an engineered barrier system (EBS) for the disposal of high-level radioactive waste (HLW), and it is considered the best candidate for the buffer material. The buffer is located between disposal canisters and near-field rock mass, and it interrupts the release of radionuclide from disposal canisters and protect them from the penetration of groundwater. At initial disposal condition, degree of saturation of the compacted bentonite buffer decreases because of high thermal quantities released from the disposal canisters. However, the degree of saturation of the compacted bentonite buffer gradually increases caused by inflow of groundwater. The saturated and unsaturated behavior of the buffer is a very important input data since it can determine the safety performance of EBS. Therefore, this paper investigated water retention capacity (WRC) for the Korean compacted bentonite buffer. The WRC of the compacted bentonite buffer was derived by measuring volumetric water content and water suction when temperature variation was between 24°C∼125°C considering decrease of degree of saturation with respect to temperature increase. The WRC was also derived with the same volumetric water content under the room temperature condition, and it showed 1∼15% larger water suction than high temperature condition.

Keywords
Compacted bentonite buffer
Temperature variation
Water retention capacity
Water suction

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Information
  • Publisher :The Korean Geotechnical Society
  • Publisher(Ko) :한국지반공학회
  • Journal Title :Journal of the Korean Geotechnical Society
  • Journal Title(Ko) :한국지반공학회 논문집
  • Volume : 35
  • No :11
  • Pages :7-14
  • Received Date : 2019-05-24
  • Revised Date : 2019-09-24
  • Accepted Date : 2019-10-28
  • DOI :https://doi.org/10.7843/kgs.2019.35.11.7
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