針對低放射性廢棄物的最終處置，目前各國多採「多重障壁」的概念，即以多種防護措施，將放射性廢棄物隔絕於人類及物種活動範圍外；其中工程障壁提供放射性廢棄物長期圍阻功能，而混凝土是最終處置場最為常用的工程障壁材料之一，因此其長期服務品質至為重要。國內最終處置場候選場址可能建造於濱海區域且採用淺地層處置，在此不良環境的長期侵襲下，障壁用混凝土的長期耐久性成為保障處置安全的關鍵。因此，持續針對混凝土障壁材料尋求提升其品質的方法，以及混凝土長時間服務於處置場環境下可能造成的劣化現象，必須尋求有效的品質評估方法。 本研究根據最終處置盛裝容器可能採用之混凝土配比，將鋼纖維混凝土做為最終處置場工程障壁材料，進行實驗探討混凝土配比抵抗氯離子入侵之能力。此外，為提升盛裝容器混凝土之品質，採用高溫養護方式，以期改善混凝土內部微結構，並提升其品質與服務性能。透過針對常溫與高溫養護混凝土的特性及耐久性比較，評估混凝土配比高溫養護的效能。另一方面，處置容器混凝土的品質檢驗方法，將透過引進先進技術，擬以非破壞檢測方式進行品質評估，尤其是混凝土中鋼纖維分布之均勻性，以及低滲透、低擴散係數混凝土等需求相關的品質檢測方法，需要針對處置容器混凝土建立資料庫及檢測標準，以提高未來使用者的信心。 ;Safety is the most important consideration in the development of concrete mix for containment of low-level radioactive wastes. This study intends to find methods to improve the durability of the concrete mix by thermal curing in 80°C hot water for 3 or 4 days. To evaluate the effectiveness of the improvement by thermal curing of the concrete mixes, the chloride ion diffusion, mechanical, durability, and non-destructive test results were compared with those cured at room temperature of 23°C. It is expected that heat curing can speed up the pozzolanic reaction and accelerate cement hydration so as to fill the pores in the concrete and produce a denser structure. Continuing the long term study on chloride ion penetration measurements of the potential mixes (C and M) to be used for highly integrated containers (HIC), the long term chloride concentration profile will be determined in accordance with ASTM C1556 method, and the time factor for diffusion will be re-evaluated using updated data. Based on long-term measurements on the concrete mixes, a more reliable estimation on the service life of HIC will be made carefully. Testing on the surface resistivity and porosity of concrete mixes C and M will be conducted to show if there is a good correlation between the two tests. Since the durability of concrete is known to be highly influenced by the porosity and pore size distribution. The surface resistivity measurement will be evaluated for suitability as a method for estimating the durability of barrier concrete.
