고준위폐기물처분장에서 완충재는 오랜 기간 동안 방사성핵종의 붕괴열과 여러가지 화학조건의 지하수에 노출되며, 이러한 열수조건은 완충재물질의 차수 및 핵종저지 방벽성능에 심각한 영향을 줄 수 있다. 본 연구에서는 국산 스멕타이트를 대상으로 열수실험을 수행하고, 열수반응에 의한 스멕타이트 점토의 팽창도, 층전하, 양이온교환능의 변화를 조사하였다. 열수실험 결과, 온도와 용액 중 칼륨농도를 증가시켰을 때, 스멕타이트의 팽창도는 감소하였고, 층전하는 더 큰 음전하를 가졌으며, 양이온교환능도 감소하였다.
고준위폐기물처분장에서 완충재는 오랜 기간 동안 방사성핵종의 붕괴열과 여러가지 화학조건의 지하수에 노출되며, 이러한 열수조건은 완충재물질의 차수 및 핵종저지 방벽성능에 심각한 영향을 줄 수 있다. 본 연구에서는 국산 스멕타이트를 대상으로 열수실험을 수행하고, 열수반응에 의한 스멕타이트 점토의 팽창도, 층전하, 양이온교환능의 변화를 조사하였다. 열수실험 결과, 온도와 용액 중 칼륨농도를 증가시켰을 때, 스멕타이트의 팽창도는 감소하였고, 층전하는 더 큰 음전하를 가졌으며, 양이온교환능도 감소하였다.
In a HLW repository, the buffer is exposed to an elevated temperature due to a radioactive decay and geochemical conditions for a long time and such a hydrothermal condition may cause a significant loss of its barrier function. This study carried out hydrothermal tests with a domestic smectite clay ...
In a HLW repository, the buffer is exposed to an elevated temperature due to a radioactive decay and geochemical conditions for a long time and such a hydrothermal condition may cause a significant loss of its barrier function. This study carried out hydrothermal tests with a domestic smectite clay to investigate the changes in the expandibility, layer charge, and cation exchange capacity of the smectite. When the temperature and potassium concentration in solution was increased for the hydrothermal treatments, the expandibility decreased, the layer charge negatively increased, and the CEC also decreased.
In a HLW repository, the buffer is exposed to an elevated temperature due to a radioactive decay and geochemical conditions for a long time and such a hydrothermal condition may cause a significant loss of its barrier function. This study carried out hydrothermal tests with a domestic smectite clay to investigate the changes in the expandibility, layer charge, and cation exchange capacity of the smectite. When the temperature and potassium concentration in solution was increased for the hydrothermal treatments, the expandibility decreased, the layer charge negatively increased, and the CEC also decreased.
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제안 방법
In this study, hydrothermal tests were carried out with a domestic smectite clay. The mineralogical alteration of the smectite was identified by examining its X-ray diffraction patterns, and the effect of a hydrothermal reaction on expandibility, layer charge, and cation exchange capacity was investigated.
The cooled suspension was centrifuged at 10,000 rpm for 10 minutes, and then the filtered solids were freeze-dried. The mineralogical investigations for the solid samples were conducted by means of X-ray diffraction (XRD) analysis, Electron Probe Micro Analysis (EPMA), and Cation exchange capacity (CEC) measurement.
The layer charge was evaluated from a structural formula calculated based on 22 anion equivalents and four tetrahedral cations [20]. The structural formulae were determined from the chemical composition data of EPMA [21], where the samples for the EPMA analysis were prepared by compacting the powdered smectite into a pallet specimen. CEC was measured according to Sumner and Miller's [22] procedure using 0.
대상 데이터
In this study, hydrothermal tests were carried out with a domestic smectite clay. The mineralogical alteration of the smectite was identified by examining its X-ray diffraction patterns, and the effect of a hydrothermal reaction on expandibility, layer charge, and cation exchange capacity was investigated.
The solid sample used for the hydrothermal tests is natural smectite fractioned into the <2 μm size from bentonite [17] which was taken from Kyeongju, Korea.
이론/모형
Moreover, because the reacted samples were resaturated with calcium ions to remove exchangeable potassium ions prior to the XRD measurement, the interstratificational features support the occurrence of potassium ions which had been changed into a nonexchangeable form by being fixed within the newly formed illite-like layers during the hydrothermal experiments. The percentage of the smectite layer in the randomly interstratified I-S was reduced to a minimum of 56.8 % under the experimental condition of this study, when it was determined using the saddle/001 peak intensity ratio method [18]. It follows from this that the starting smectite transforms into randomly interstratified I-S under the given hydrothermal conditions.
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