為確保高放射性廢棄物與人類環境的隔離，採用多重障壁的深地層處置系統是公認最可行的辦法，其主要障壁單元包括廢棄物包件、緩衝材料、回填材料及母岩。處置系統中廢棄物包件可能與地下水接觸而劣化，致使核種外釋到可接觸的環境，此時對核種遷移的遲滯特性成為候選緩衝材料的首要考量因素。 本研究以移流延散方程式之解析解評估推求傳輸參數方法之正確度，分析結果顯示修正後之近似解切線斜率切線斜率為推求延散係數D及遲滯因子Rd較佳的方法。以國產日興土為研究材料，在實驗室設置管柱試驗，試驗過程試體性質分析結果顯示：(1)管柱試驗進行前，試體之飽和及淋洗前置作業至少14天以上。(2)高水力梯度(285)下所得日興土之水力傳導係數最高僅達3.4×10-8 cm/s，具備低滲透性功能。(3)導電度量測系統可作為未來深層處置場近場環境現地監測及實驗室管柱試驗之時間控管的有效工具。 管柱試驗探討入滲液離子類型、入滲液離子濃度及日興土乾密度效應對試體性質及膨潤土中傳輸行為的影響，結果顯示：(1)鈉離子之延散行為較鈣離子大，而鈣離子容易與膨潤土中其他親和力低之離子發生交換反應，造成鈣離子遲滯現象較為顯著。(2)低濃度條件鈣離子傳輸之遲滯現象較顯著。(3)日興土中含有較多數量的可交換鈣離子，入滲液採用鈉離子則離子交換優勢較低，鈉離子傳輸速度很快，不受濃度效應及乾密度效應影響。 To assure the isolation of high level radioactive wastes from human environment, the multiple barrier deep geologic disposal is considered as the most suitable approach. The major barrier unit consists of waste package, buffer material, backfill material and host rock. The waste package in the disposal could deteriorate if in contact with underground water. The nuclides might release and endanger the environment. The capability in retardation and adsorption of the nuclides is one of critical elements when choosing buffer materials. This research is to reckon the accuracy of the parameter in mass transport. The result shows that the slope of an effluent curve is the best method to figure out the dispersion coefficient(D) and the retardation factor(Rd). Zhisin clay was used as test material. A series of column tests were conducted, and the results are (1)before conducting a column test, a 14-day period of saturating and drip washing of the testing material is required; (2)under a high hydraulic gradient (285) the hydraulic conductivity was found to be 3.4×10-8 cm/s, which is judged to be low in permeation; (3)electrical conductivity testing system can be used effectively to monitor the near-field of deep geologic disposal site and to monitor the testing time of column test. The column test was aimed at understanding the effects of the type of ion in solution, the concentration of the ion, and the dry intensity of Zhisin clay on the testing material in the mass transport process. It was found that: (1)the sodium ion’s dispersion coefficient is higher than calcium ion; and the calcium ion is easy to react with other low-affinity ion of the bentonites, which makes the retardation of the calcium ion more noticeable; (2) if the concentration is lower, the transport of calcium ion would be more noticeable; (3)there are more exchangeable calcium ion in Zhisin clay, thus exhibiting lower exchangeable rate for calcium.
