RADIONUCLIDE TRANSPORT AND RETARDATION IN ROCK FRACTURE AND CRUSHED ROCK COLUMN EXPERIMENTS

Transport and retardation of non-sorbing tritiated water and chloride and slightly sorbing sodium was studied in Syyry area SY-KR7 mica gnei ss, in altered porous tonalite and in fresh tonalite. Experiments were performed using dynamic fracture and crushed rock column methods. Sta tic batch method for sodium was introduced to compare retardation valu es from static and dynamic experiments. The C-14-PMMA method was used to study the pore structure of matrices, The pore aperture distributio n was evaluated from Hg-porosimetry determinations and the surface are as were determined using the B.E.T. method. The flow characteristics a nd transport behavior of tracers were interpreted using a numerical co mpartment model for dispersion. The effect of matrix diffusion was cal culated using an analytical solution to the advection-matrix diffusion problem in which surface retardation was taken into account. Radionuc lide transport behavior in rock fractures was explained on the basis o f rock structure. (C) 1997 Elsevier Science B.V.