HR: 13:40h
AN: H43I-01    [Abstracts]
TI: Determining Sorption Coefficients in Intact Rock Using an Electrical Potential Gradient as a Driving Force for Migration
AU: * Andre, M
EM: magnusa@ket.kth.se
AF: Department of Chemical Engineering and Technology, Royal Institute of Technology, Stockholm, SE-10044 Sweden
AU: Malmstrom, M
EM: malmstro@ket.kth.se
AF: Department of Chemical Engineering and Technology, Royal Institute of Technology, Stockholm, SE-10044 Sweden
AU: Neretnieks, I
EM: niquel@ket.kth.se
AF: Department of Chemical Engineering and Technology, Royal Institute of Technology, Stockholm, SE-10044 Sweden
AB: The transport of radionuclides in indigenous rock is greatly affected by the sorption of cations in the porous rock matrix. Radionuclides escaping from a repository for nuclear waste can be subjected to such conditions. Because of this, accurate sorption data is needed for the performance assessment for deep geological disposal of nuclear waste. For the determination of sorption coefficients, batch experiments have traditionally been used to reduce the experimental time. For batch experiments, the rock sample is crushed into fine particles, increasing the surface area of the sample. The small particle diameter makes batch experiments time efficient but the increase of surface area has been shown to have an effect on the sorption coefficients measured (Skagius et. al., 1982, Byeg$\aa$rd et. al., 1998). It is also probable that the crushing and sieving of the rock sample causes a differentiation of the minerals present in the rock, which could further impair the measurement of sorption coefficients. A new method for measuring sorption coefficients in intact rock is being developed. The method was proposed by L$\ddot{o}$fgren and Neretnieks (2003) and uses electromigration as a mean to speed up the transport process allowing for faster equilibration between a rock sample and an electrolyte. A potential gradient acts as a driving force in addition to the concentration gradient and forces the cations through the rock sample towards the anode. By measuring the change in chemical composition of the electrolyte the sorption coefficient can be determined. Preliminary experiments using cesium as a sorbing tracer were performed using cylindrical rock samples with a diameter of 50 mm and a length of 15 mm. The results from these experiments have shown that it is possible to measure sorption capacity using this method.
DE: 5114 Permeability and porosity
DE: 5120 Plasticity, diffusion, and creep
DE: 5139 Transport properties
DE: 5194 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting