Experimental studies on colloid flow rate in geologic media; Colloid transport through columns packed with glass beads

*; Yui, Mikazu

PNC TN8410 97-125, 20 Pages, 1997/03

PNC-TN8410-97-125.pdf:1.02MB

To evaluate migration behavior of radionuclides in geologic media is one of the most significant issues for the performance assessment of geological disposal system for high level radioactive waste. For performance analysis, effects of micro particles such as colloids on the radionuclides migration should be considered; whether colloids enhance tansport of radionuclides in a geologic formation. Based on the theory of Hydrodynamic Chromatography(HDC), the average flow rate of colloids could be faster than that of the bulk water under the condition that the flow profile of bulk water is parabolic. Transport of radionuclides through geologic media could be accelerated when the radionuclides are sorbed on colloids. In order to investigate the transport behavior of colloids in geologic media, we used a column packed with glass beads as simulated porous geologic media and two types of colloid tracers of gold colloid and latex particle as simulated natural colloids. We compared the flow rate of colloids based on the HDC theory with the results of the column experiments. By this comparison, it is suggested that the flow rate of the colloid in porous geologic media is significantly slower than that predicted based on the HDC. The differences between them was explained by colloid retardation processes due to its sorption on the glass beads, that it is not strictly described in the HDC theory.