深層地質處置場之母岩非均質熱傳效應影響分析

Effects Due to Rock Inhomogeneity for Heat Transfer in Deep Geologic Repositories

本研究考量用過核子燃料之衰變熱，就其在深層地質多孔處置場域引致之熱傳行為進行有限元素計算，並針對母岩非均質熱傳導係數之空間分布效應進行研析。分析結果顯示，在母岩之非均質材料機率分布行為接近常態分布的情況下，以機率分布之平均值進行的均質材料分析，即可得到與隨機分布機制下之非均質材料分析幾近相同之峰值溫度；然而，若考量緊鄰處置孔的局部區域母岩出現機率分布中相應的上(下)限值之極端情況，則處置場之最高溫度即可能受到影響，且其效應隨著局部區域範圍的擴大而加大。本研究方法與成果，因應我國用過核子燃料處置計畫現階段候選場址評選之所需，期能提供具有階段意義的指標性研發參考。

The aim of this research is to perform finite element calculations on the study of the heat transfer behavior caused by decay heat of spent nuclear fuel in the field of multiple deep deposition holes. In particular, the effect of non-homogeneous spatial distribution of thermal conductivity in the rock domain is investigated. The results indicate that, when the probability distribution of the non-homogeneous behavior is close to normal distribution, the analysis of homogeneous materials based on the average value of the probability distribution appears to be similar to that of non-homogeneous materials under randomly distributed conditions. They yield almost the same peak temperature. Nevertheless, for the extreme conditions when the rock domain in the local area immediately adjacent to the disposal hole is modeled by either the upper or the lower limit of the probability distribution, the peak temperature can be different. The effect is more significant as the extension of the local area is enlarged. Associated with the current staged goal of Taiwan’s national disposal plan that addresses the selection of candidate sites, this study is anticipated to support an indicative development reference with prevalent significanc.