中 文 摘 要
本論文的主要目的是藉由實驗及模式的建立，探討硒銫在粉碎花崗岩與石英砂中的平流延散行為，並且由三重複實驗數據的分析結果顯示，模擬出具有放射性的硒銫核種的平流延散模式。本研究包含了平流延散管柱實驗、硒銫破出曲線的模擬和批次實驗。其中所有的液相皆為合成地下水及合成海水。
在平流延散管柱實驗中，主要是要觀察硒銫在花崗岩與石英砂中的平流延散行為。結果顯示，花崗岩對於硒銫有著遲滯的能力；而四價硒的平流延散行為不受到離子強度的影響，因此花崗岩對於四價硒在合成地下水與合成海水環境下的遲滯因數都在4左右。銫的傳輸行為則會受到離子強度的影響，因此在合成地下水環境下，花崗岩對於銫的遲滯因數都在4左右，相對的，在合成海水環境下，遲滯因數降到只有1左右。而石英砂對於硒銫都沒有遲滯的能力，因此無論在合成地下水或是合成海水環境下，石英砂對硒銫的遲滯因數都在1左右。在硒銫破出曲線模擬部分，藉由運用LEHGC模式以Kd模式模擬，將花崗岩與石英砂對於硒銫的遲滯能力加以數據化。模擬結果顯示，花崗岩對於四價硒在合成地下水與合成海水中的收附比例為0.80與0.81；在合成地下水中，花崗岩對於銫的收附比例為0.80，而在合成海水環境下，收附比率為0。而石英砂對硒銫的收附比率，不管在合成地下水或是合成海水環境下都是0。
在批次實驗中，包含硒銫平衡批次實驗及四價硒的系列萃取實驗，主要是觀察在花崗岩與石英砂達到收附平衡時候，其Kd值與流延散管柱實驗所求取的Kd值的差異。結果顯示，利用批次實驗法所求得的花崗岩對於硒銫的Kd值都明顯大於平流延散行為所求取的Kd值，表示硒銫在花崗岩中管柱中沒有達到收附平衡。而石英砂對硒銫沒有收附能力，因此批次實驗與管柱實驗結果的Kd值差異不大。此外，利用化學系列萃取實驗，驗證花崗岩中的晶相鐵氧化物主導對於四價硒的收附反應。

Abstract
An adequate performance assessment of underground repositories of radiowaste depends on good understanding of the transport behavior of radionuclides with concerned solid. In this study, the transport behavior of selenium and cesium on granite and quartz was investigated by column experiments and LEHGC model simulations. The results suggest that the averaged retardation factor, (Rf) of granite to adsorb selenium under both groundwater and seawater is about four, indicating the sorption of selenium is insensitive to ionic strength. However, the abundant cations in seawater weaken the Cs adsorption and the Rf of granite to adsorb Cs decreases from four of groundwater to one of seawater. The limited sorption ability of quartz to adsorb selenium and cesium leads to an Rf value of one for both radionuclides no matter under groundwater or seawater. The batch experiments were also conducted to study the adsorption ability of granite and quartz to adsorb selenium and cesium. The results show that the Kd values from batch experiments are higher than those from column experiments, suggesting that the sorption of selenium and cesium under granite column does not reach equilibrium. In contrast, the Kd from batch experiments consist with that from column experiments, revealing the limited sorption ability of quartz to adsorb selenium and cesium. Moreover, chemical sequential extraction was also conducted to study the sorption mechanism of granite to selenium. The results suggest the crystalline Fe oxides are the most important minerals for granite to adsorb selenium.

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