核能發電衍生用過核子燃料的最終處置問題，對處置方式而言，採深層地質處置是國際公認較可行的方法。深層處置設施通常是在地下300 m到1,000 m深的完整岩體中，開挖隧道及處置孔；另將用過核子燃料裝入廢棄物罐中，周圍以緩衝材料包覆再埋置於處置孔，藉由工程障壁與母岩所形成之多重障壁，遲滯核種的釋出與遷移。因此，與廢棄物罐直接接觸的緩衝材料，便扮演著極重要的角色，其需具備低滲透性、高回脹性等特性之外，還需要有適當的力學強度，以遲滯核種藉由地下水釋出到生物圈，達到將用過核子燃料永久隔離的目標。 本研究為探討緩衝材料於處置現場之工程性質，透過進行室內試驗，模擬現地處置時可能會引致之情況，主要分為兩種試驗進行。為模擬緩衝材料於處置環境下之力學特性，利用不壓密不排水三軸試驗進行試驗，探討不同統體單位重、不同含水量及不同圍壓下對緩衝材料之強度影響，求取其力學參數；以及模擬長期處置期間緩衝材料受廢棄物罐沉陷與處置場壓力等影響，利用單向度壓密試驗探討相關壓縮參數及推求其滲透性。統整上述試驗結果取得工程性質參數並判別試驗可行性，以提供後續研究參考使用。 ;For the use of radioactive energy, it is important to develop techniques for the disposal of radioactive wastes in the world. The deep geological repository is currently recognized as a feasible disposal concept. The deep repository is host rock at a depth of 300 m to 1,000 m, and the canisters are surrounded by buffers. The deposition holes would be drilled in bed rock and set up with canisters and buffers. These make the canister not easily affected by natural operation, humanity activities and tectonic movement with high stability. As it needs a quite long time for storage, the long-term safety needs to be examined and regulated with design premises. All the design premises must to be fulfill to ensure that the barrier functions works and then reach the long-term safety of deposition. Therefore, engineering properties of buffer material under high confining pressure plays the important role. In order to realize the engineering properties of buffer material, use laboratory tests to simulate the situations of in-situ repository. The experient was divided into two parts for this research. Considering different states of buffer marerial, used different bulk densities, water contents and confining pressures to simulate the mechanical characteristic by unconsolidated-undrained triaxial test. And used one-dimensional consolidation test to simulate the settlement by canister and pressures. This study uses triaxial test and consolidation test to simulate the confining pressure from low to high confining pressure. Using this method to analyze mechanical parameters of buffer material and estimate deformation for long times.
