高低放射性廢棄物最終處置採多重障壁設施，在混凝土工程障壁與緩衝材料界面處，因混凝土工程障壁為高鹼環境，且處置場不可避免會受到地下水入侵，其中孔隙溶液的改變可能造成緩衝材料性質的變化。處置場設計年限極長，其近場環境演化情節遠較一般土木工程或大地工程複雜。國內目前面臨放射性廢棄物最終處置工作，亟需及早獲取本土化的工程障壁參數，做為最終處置場設計之參考。本研究將持續前一年度之研究，以台東樟原村日興土與美國懷俄明州膨潤土，採用壓製方式製作膨潤土緩衝材料，調配飽和鈣離子水進行水力傳導度試驗，並以電滲加速試驗來了解混凝土溶出失鈣效應對緩衝材料性質的改變，同時，由於處置場封閉後勢必會遭受地下水入侵之影響，故亦須對混凝土工程障壁長期受失鈣溶出所產生之劣化情形加以評估，以了解混凝土與緩衝材料等兩種工程障壁互制作用分別對其預期障壁功能產生之影響。最後依據試驗結果歸納其功能特性，一方面了解緩衝材料於近場環境下的長期穩定性，另一方面掌握本土膨潤土材料之物理性質，以及混凝土材料介面所受影響等，做為未來工程障壁細部設計之參考。Both concrete and clay-based materials serve as engineered barriers for isolation of high-level radioactive wastes in a repository. The safety of a deep geological repository depends upon the stability of engineered barriers. Being the major components in the barrier system, concrete and buffer material are expected to create an impermeable zone around the high level waste canisters, and the interactions between the two barriers need to be evaluated to insure disposal safety. In this research, a migration technique was applied to accelerate the migration of calcium ions from the pore solution of concrete so as to investigate the alteration of compacted bentonite in contact with the concrete. A direct voltage is used for a composite specimen with cylindrical section in which an electrical potential gradient will be applied. This composite consists of compacted bentonite, including locally available Zhisin clay (日興土) and Black Hills bentonite from Wyoming. After a target cumulative electric charge, the specimen will be removed for analysis. The physical characteristics of both bentonite buffer and concrete barrier will be carefully examined so as to assure that the long-term contact of these 2 barriers does not cause severe degradation. The analysis includes SEM, TGA, swelling potential, permeability for the bentonite material; and SEM, TGA for concrete barrier. 研究期間：10008 ~ 10107
