| 摘要: | 本研究針對台電公司現行耐用100年之低放射性廢棄物盛裝容器(High Integrity Container, HIC)混凝土配比，探討其抵抗硫酸鹽侵襲之能力，透過國際文獻研析掌握混凝土受硫酸鹽侵襲引致之劣化機制及分析模式，進行關鍵因子與參數之影響效應評估，藉以建立混凝土容器受硫酸鹽侵襲之劣化模擬方法，供混凝土容器評估之參考依據。研究內容包括:(1)研析國內外有關混凝土受硫酸鹽侵襲劣化機制及劣化模式相關文獻；(2)評估混凝土材質容器受硫酸鹽侵蝕之劣化模式(CONCLIFE、SULFATE2、Atkinson力學模式、抗壓強度預估模式)及其重要影響參數(擴散係數、吸水率、孔隙率、抗拉強度)；(3)提出適用於高完整性容器混凝土受硫酸鹽侵襲之劣化分析方法及使用劣化推估模式。
為獲得各模式所需輸入參數，本研究依據ASTM C1585進行吸水率試驗並於養護齡期90天、180天、270天進行測定，與ASTM C1556硫酸鹽擴散濃度剖面試驗根據硫酸鹽溶液於浸泡齡期28天、90天、180天、270天、360天進行測定，量測混凝土吸水深度與硫酸根離子分佈，進而迴歸計算吸水率與擴散係數。SULFATE2模擬中之孔隙率參數則以實測數據進行比對修正，進一步提升參數代表性與模擬精度。
研究成果應用於模擬混凝土高完整性容器受硫酸鹽侵襲產生之劣化，推估其劣化速率，CONCLIFE模式與SULFATE2開裂前緣分析因適用環境與HIC容器處置條件較不一致，故建議使用SULFATE2中之擴散濃度剖面分析並配合文獻進行抗壓強度預測。就抵抗硫酸鹽侵襲能力而言，經過多種方法模擬HIC混凝土皆可符合「低放射性廢棄物最終處置及其設施安全管理規則」針對B、C類低放射性廢棄物耐用300年之要求。
;This study investigates the concrete mix design currently adopted by Taiwan Power Company (TPC) for High Integrity Containers (HIC), which are designed for a service life of 100 years and are used for storing low-level radioactive waste. The objective is to evaluate their resistance to sulfate attack. By reviewing international literature, the degradation mechanisms and analytical models related to sulfate-induced concrete deterioration were examined. The study evaluates the effects of key factors and parameters to establish a simulation methodology for predicting the degradation of concrete containers under sulfate exposure, providing a reference framework for container performance assessment. The scope of this study includes: (1) reviewing domestic and international literature on sulfate attack mechanisms and concrete degradation models; (2) assessing relevant deterioration models for concrete containers (CONCLIFE, SULFATE2, Atkinson mechanical model, and compressive strength prediction models), along with critical parameters such as diffusion coefficient, sorptivity, and porosity; and (3) proposing a deterioration analysis approach and predictive modeling method suitable for HIC concrete under sulfate exposure.
To acquire input parameters for each model, water sorptivity tests were performed in accordance with ASTM C1585 at curing ages of 90, 180, and 270 days. Sulfate ion concentration profiles were obtained based on ASTM C1556, with immersion durations of 28, 90, 180, 270, and 360 days. Measurements of water absorption depth and sulfate ion distribution were used to calculate sorptivity and diffusion coefficients through regression analysis. The porosity parameter used in SULFATE2 simulations was calibrated with experimental data to enhance its representativeness and improve simulation accuracy.
The research results were applied to simulate the degradation behavior of HIC concrete under sulfate exposure and estimate its deterioration rate. Since the crack-front analysis results of the CONCLIFE and SULFATE2 models are not fully consistent with the actual disposal environment and conditions of HICs, it is recommended to adopt sulfate concentration profile analysis from SULFATE2, combined with compressive strength prediction methods from literature. Simulation results from various models indicate that the HIC concrete meets the durability requirement of 300 years for Class B and Class C low-level radioactive waste, as stipulated in the “Regulations on the Final Disposal and Safety Management of Low-Level Radioactive Waste.” |
