由於用過核燃料所產生之長期衰變熱會對我們的環境造成影響，各國未來對於用過核燃料的處理方式傾向以深層地質處置(deep geological disposal)法作為最終處置設施，本研究即在此概念下進行分析。 本研究採用有限元素法，進行熱-水-力學之效應分析，首先針對用過核燃料產生之衰變熱進行處置場熱傳分析，觀察溫度場隨時間變化之情形。 熱應力分析方面採用依序耦合熱應力分析(Sequentially coupled thermal-stress analysis)，使用有效應力理論，以區分孔隙水與母岩實際受力狀態。根據分析結果得知，孔隙水壓主要受溫度、材料之熱膨脹係數與滲透係數等性質影響較大。在有效應力分析方面，結果顯示母岩之部份區域將承受張力作用，忽略母岩抗拉強度則表示此處產生破壞，易造成不良影響；處置場之位移主要為垂直位移，而垂直位移之方向與處置場深度平行。此外，若考慮母岩為彈塑性材料時，處置2000年後，處置區中心處將開始產生塑性區。 The concept of the deep geological disposal for storage of nuclear high-level fuel waste, currently proposed by Atomic Energy of Canada Ltd. (AECL) involves the deep burial of the wastes at 1000m depth. Due to the longevity of the radioactivity, deep geological disposal system is required to provide protection to human health and environment from the hazards of contaminant release which could last for ten of thousands of years. Based upon the concept of deep geological disposal, this research is performed to assess the influence of decay heat on the performance of the host rock around a nuclear fuel waste repository. The finite element code ABAQUS was used for the preliminary analysis of the coupling thermal and hydro-mechanical behavior. The calculations indicate that the decay heat generated by the wastes perturb the groundwater and stress in the host rock. As a result, the heat-induced pore pressure increases around the repository. This results in significant changes of effective stresses. The largest displacement of the rock is observed in the middle of the repository. At 5333 years after deposition, the most extensive volumes of yielded zones are produced around the repository.
