• 제목/요약/키워드: Radioactive waste repository

검색결과 322건 처리시간 0.024초

Swelling and hydraulic characteristics of two grade bentonites under varying conditions for low-level radioactive waste repository design

  • Chih-Chung Chung;Guo-Liang Ren;I-Ting Chen;Che-Ju, Cuo;Hao-Chun Chang
    • Nuclear Engineering and Technology
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    • 제56권4호
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    • pp.1385-1397
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    • 2024
  • Bentonite is a recommended material for the multiple barriers in the final disposal of low-level radioactive waste (LLW) to prevent groundwater intrusion and nuclear species migration. However, after drying-wetting cycling during the repository construction stage and ion exchange with the concrete barrier in the long-term repository, the bentonite mechanical behaviors, including swelling capacity and hydraulic conductivity, would be further influenced by the groundwater intrusion, resulting in radioactive leakage. To comprehensively examine the factors on the mechanical characteristics of bentonite, this study presented scenarios involving MX-80 and KV-1 bentonites subjected to drying-wetting cycling and accelerated ion migration. The experiments subsequently measured free swelling, swelling pressure, and hydraulic conductivity of bentonites with intrusions of seawater, high pH, and low pH solutions. The results indicated that the solutions caused a reduction in swelling volume and pressure, and an increase in hydraulic conductivity. Specifically, the swelling capability of bentonite with drying-wetting cycling in the seawater decreased significantly by 60%, while hydraulic conductivity increased by more than three times. Therefore, the study suggested minimizing drying-wetting cycling and preventing seawater intrusion, ensuring a long service life of the multiple barriers in the LLW repository.

고준위 방사성폐기물 처분장 불량 용기 발생 시나리오에 대한 폐쇄후 장기 방사선적 안전성 평가 (Post Closure Long Term Safely of the Initial Container Failure Scenario for a Potential HLW Repository)

  • 황용수;서은진;이연명;강철형
    • 방사성폐기물학회지
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    • 제2권2호
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    • pp.105-112
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    • 2004
  • 고준위 방사성폐기물 처분장에서 적용하고 있는 다중 방벽의 한 부분인 처분 용기는 벤토나이트 완충재의 팽윤과 지압으로부터 폐기물을 역학적으로 안정하게 보호함과 동시에 일정 기간 방사성폐기물의 유출을 억제하는 역할을 한다. 처분용기의 건전성은 엄격한 재질 선정과 품질 보증을 통해 확보된다. 그러나 용기 제작 과정이나 수송 중 예상치 못한 사건으로 인해 불량 용기가 발생할 가능성이 있다. 본 논문에서는 이와 같은 경우 방사성폐기물로 인해 생태계에 미치는 환경 영향을 연간 개인 선량으로 평가하였다. 연구결과 일부 불량 처분 용기가 발생하더라도 현 평가에 사용한 입력 데이터 범위에서는, 국내 고준위 방사성폐기물 처분 개념이 방사선적 안전성을 확보할 수 있는 것으로 판명되었다.

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PROPERTIES OF LOW-PH CEMENT GROUT AS A SEALING MATERIAL FOR THE GEOLOGICAL DISPOSAL OF RADIOACTIVE WASTE

  • Kim, Jin-Seop;Kwon, S.;Choi, Jong-Won;Cho, Gye-Chun
    • Nuclear Engineering and Technology
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    • 제43권5호
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    • pp.459-468
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    • 2011
  • The current solution to the problem of using cementitious material for sealing purposes in a final radioactive waste repository is to develop a low-pH cement grout. In this study, the material properties of a low-pH cement grout based on a recipe used at ONKALO are investigated by considering such factors as pH variation, compressive strength, dynamic modulus, and hydraulic conductivity by using silica fume and micro-cement. From the pH measurements of the hardened cement grout, the required pH (< pH 11) is obtained after 130 days of curing. Although the engineering properties of the low-pH cement grout used in this study are inferior to those of conventional high-pH cement grout, the utilization of silica fume and micro-cement effectively meets the long-term environmental and durability requirements for cement grout in a radioactive waste repository.