國內現有核能電廠用過核燃料池的空間設計，並不足以完全貯放營運期間所產生的用過核燃料。台電公司規劃將用過核子燃料置放於混凝土護箱或混凝土模組中，進行約50年左右的用過核子燃料中期貯存計畫。由於中期貯存設施主體是由混凝土材料所構成，且考慮到混凝土材料需長時間承受內部用過核燃料所散發的衰變熱，及台灣地區特殊的環境氣候條件下，對混凝土材料可能受損或劣化有必要加以評估分析。 本文主要針對中期貯存設施外圍所構成之混凝土材料，模擬長期承受內部用過核子燃料持續散發之衰變熱及外在環境因子交互作用下，評估混凝土材料可能的劣化機制，試驗結果顯示(1)250 ℃受熱範圍內，仍可發揮混凝土本身的抗壓強度值，而彈性模數及劈裂強度則隨溫度愈高折損愈多，上述力學性質皆不隨受熱歷時增加而再有顯著劣化現象；(2)混凝土受熱溫度愈高收縮量愈多，但不隨歷時增加而再有明顯收縮；(3)氯離子擴散試驗結果顯示，受熱於250 ℃之混凝土，其抵抗氯離子滲透能力較差；(4)受熱過後之混凝土中性化反應並不明顯，但在常溫環境下，添加卜作嵐材料之混凝土中性化深度較深；(5)混凝土中若添加卜作嵐材料、強塑劑及V型水泥時，能增進混凝土抵抗硫酸鹽侵蝕能力；(6)經微觀分析試驗結果顯示，混凝土受模擬溫度及歷時條件下，水泥漿體之微觀結構及內部水化產物型態並無顯著改變或劣化現象；(7)綜合各試驗結果顯示，添加20 %爐石粉之混凝土，能增進混凝土抵抗高溫作用能力。 The design capacity of the spent fuel pool for the first and second nuclear power plant was not enough to store spent fuel. Taipower company plans to build interim storage facilities in the next few years. The interim storage facility relies much on the concrete structure as a shielding for spent fuel casks. Due to the long term decay heat and severe environments to be encountered, high quality concrete is considered as a major safety contributor to the interim storage facility. To evaluate the degradation effects of concrete applicable to interim storage facilities for long-term safety, several scenarios were considered in this research, including decay heat, salt attack, and carbonation reaction. Experimental results obtained from concrete with varying admixtures indicate that: (1) under elevated temperature, the compressive strength of concrete remains unchanged, and the elastic modulus and splitting strength of concrete decreases slightly; (2) the shrinkage of concrete increases with rising temperature; (3) the chloride diffusivity of concrete specimens negligible change at temperature level below 150 ℃, but increases significantly at 250 ℃; (4) carbonation reaction of heated concrete is insignificant; (5) concrete admixed with pozzolanic materials or superplasticizer exhibits improved resistance to sulfate attack; (6) microstructure observations on the morphology of hydration products indicated no noticeable changes upon heating; (7) concrete made with 20% blast furnace slag was found to perform well in terms of strength and durability aspects.
