| 摘要: | 用過核子燃料具有高放射性、長半衰期與高衰變熱的特性，若未妥善處理，將對環境與人類健康造成嚴重危害。深層地質處置被國際公認為最安全且可長期隔離核廢料的最終處置方法，而處置場中的處置罐是承載核廢料的核心結構。隨著處置場啟用，處置罐將受到地表冰川壓力、地震剪力及燃料棒釋放的熱能所產生的熱應力等各種應力影響 。本研究將使用有限元素分析軟體 ABAQUS 建立三維處置罐模型，透過剪位移、圍壓與溫度應力場等多種載重模擬其受力與變形反應，評估多重載重下罐體結構之安全性。
第四章模擬無燃料棒之處置罐於圍壓條件下之力學行為，並與 SKB 文獻試驗結果進行比對，結果顯示模型具有良好準確性。進一步導入燃料棒模型來模擬更接近真實之處置情況，發現燃料棒能提升處置罐整體結構強度。
第五章探討不同位置施加剪位移與複合載重條件下之罐體應力應變行為，結果顯示位移會使罐體應力明顯上升，且施加位移區域越大，罐體越早進入塑性階段。
第六章加入燃料棒衰變熱所產生之溫度場，根據保守方法分析，發現溫度越高，罐體應力亦隨之上升，顯示溫度場變化對罐體應力變化具顯著影響。;Used nuclear fuel possesses characteristics such as high radioactivity, long half-life, and significant decay heat. If not properly managed, it can pose serious risks to both the environment and human health. Deep geological disposal is internationally recognized as the safest and most effective method for the long-term isolation of nuclear waste, with the disposal canister serving as the core structural component containing the waste. Once the disposal site becomes operational, the canister will be subjected to multiple loading conditions, including glacial pressure, seismic shear forces, and thermal stresses induced by the decay heat of the fuel rods. This study utilizes the finite element analysis software ABAQUS to construct a three-dimensional model of the disposal canister, simulating its stress and deformation responses under shear displacement, confining pressure, and thermal loading, in order to assess its structural integrity and potential failure risks under combined loading scenarios.
Chapter 4 investigates the mechanical behavior of the canister without fuel rods under confining pressure, and the simulation results are compared with experimental data from SKB literature. The agreement between the results confirms the model′s accuracy. A fuel rod model is then incorporated to simulate more realistic disposal conditions, revealing that the presence of fuel rods improves the overall structural strength of the canister.
Chapter 5 analyzes the stress–strain response of the canister under shear displacement applied at different locations and under combined loading conditions. The results indicate that shear displacement significantly increases the stress within the canister, and the larger the applied area, the earlier the canister enters the plastic deformation phase.
Chapter 6 introduces the temperature field generated by the decay heat of the fuel rods. Based on a conservative analysis approach, it is observed that higher temperatures result in increased stress levels, demonstrating that thermal effects significantly influence the canister′s stress distribution and must be considered in structural safety assessments. |
