摘要
基於實驗觀察與分析以建構合適的反應性傳輸模式，使能有效地模擬放射性核種的宿命與傳輸行為，乃評估放射性廢料地下處置場安全性的必要工具。本研究的目的在於經由一系統的分析來建立適合的評估模式，用以探討銫於粉碎花崗岩組成之多孔隙介質中的宿命與傳輸。所採用的液相包括合成地下水與合成海水。為建立此一模式，本研究對固相進行比表面積測量（N2-BET）、x-光粉末繞射、偏光顯微/放射照相、固相消化分析，並加上批次實驗與多階段（mutli-stage）平流-延散管柱實驗，希望能將銫主要的宿命與傳輸機制決定出來，繼而對假設的模式進行驗證。依據固相分析與批次實驗結果，成功地以一雙吸附元Langmuir動力模式描述銫於合成地下水環境中在粉碎花崗岩的動力吸/脫附行為。另根據對非反應性氚水管柱實驗結果的分析，提出一包含流動帶與滯留帶液相的傳輸模式，藉以描述管柱系統中主要的傳輸過程。然而，結合此二模式而架構的反應性傳輸模式，並無法對多階段管柱實驗中銫的結果提供滿意的擬合。因此有必要在未來對此模式作進一步的修正。因而，建議先修改現行的管柱裝置，減少管柱連出端體積，以將因此體積所導致的額外延、擴散減到最小，期能針對主要的傳輸行為進行有效地分析。此外，也有必要藉由更多實驗來繼續深入探討不同核種在管柱中的反應機制與傳輸行為。

ABSTRACT
In order to assess the safety of a underground radwaste repository, reactive transport models suitable for evaluating the fate and transport of radionuclides need to be established based on experimental observation and analysis. The goal of this study is to construct adequate models simulating the reactive transport of cesium (Cs) in crushed granite through a systematic analysis, where synthetic groundwater (SGW) and synthetic seawater (SSW) were employed as the liquid phase. To build such models, this study applied N2-BET, x-ray diffraction (XRD), polar-microscopy/auto-radiography, and solid-phase digestion for the analysis of granite, kinetic batch tests for the characterization of sorption/desorption of Cs, and multi-stage advection-dispersion column tests for the determination of major transport processes and the calibration/validation of hypothesized reactive transport models. Based on the results of solid phase analysis and batch tests, a two-site Langmuir kinetic model has been determined capable of appropriately describing Cs sorption/desorption under test conditions. From the results of non-reactive HTO column tests, a mobile/immobile transport model was proposed to capture the major transport processes in our column system. However, the combination of the two-site Langmuir model and the mobile/immobile transport model failed to provide numerical breakthrough curves matching the Cs experimental breakthroughs. It implied that our model needs to be further refined. To achieve this, the setup of our column test needs to be modified first to reduce the volume of column connecting space, so that the effect of extra diffusion/dispersion on breakthroughs would be minimized and major transport characteristics can be clearly revealed. Moreover, more investigations on the reaction mechanisms and transport processes of the reactive transport system must be conducted.

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