低放射性廢棄物處置設施之障壁主要是由混凝土構成，但不同於一般混凝土結構物之用途，其服務年限需長達數百年之久。由於台灣處於四面環海環境，低射性廢棄物處置場之場址可能位於濱海區域，處置場障壁混凝土若長期處於此環境下，預估混凝土的服務年限非常重要。 本研究主要探討混凝土材料受氯離子入侵之劣化情形，並使用氯離子濃度門檻值與擴散係數，用於經驗公式中，來預估氯離子入侵達保護層時的濃度。以可能使用於高完整性容器之HIC 配比與傳統配合設計方法ACI 配比，進行信賴度分析。 針對鋼筋開始腐蝕之時間建立服務年限信賴度分析模式。考慮混凝土水化程度隨時間增長而使擴散係數降低，歷時越長擴散係數趨於穩定，利用較長歷時推估擴散行為之時間因子時，其數據變異性較低，可提高推估服務年限之精確性。低放處置場混凝土推估方面，依氯離子長期擴散係數與規範之保護層厚度，可預估鋼筋腐蝕之時間。在規範保護層厚度下，傳統ACI配比受氯離子入侵於假定服務年限300年時，其服務成效低於HIC配比。 The barriers of facilities which dispose wastes with low radioactivity are mainly composed of concrete, but unlike the normal purpose of concrete, it should be used for more than several hundred years. However, due to Taiwan’s geographic feature- island, the sites of such facilities are mostly placed in marine environment, which will cause immense influences on the degradation and durability of concrete over a long period of time. This research aims on studying the degradation level of concrete while percolated by chloride ions, through using diffusion coefficient and threshold chloride concentration in empirical formulas, along with doing relative tests and analyses with HIC, ACI, to predict the time when reinforcing steel starts to be corroded. Establish the reliable analysis model of the service life for the propagation time of the reinforcement in concrete. The higher time-dependent hydration, the lower diffusion coefficient is. As the time is long, the value of diffusion coefficient is more stable. Predicting the time factor by using longer time can get the smaller variability and the greater accuracy. It needs the diffusion coefficient of chloride ions and the covered thickness of reinforcement to predict the propagation time of reinforcement in concrete. By diffusion of chloride, the service life of ACI assumed as 300 years is less than HIC.
