RADIOACTIVE WASTE DISPOSAL HEATING EFFECTS IN UNSATURATED FRACTURED ROCK

Abstract

Numerical techniques are described for modeling two-phase (liquid and gas), two-component (water and air) nonisotkermal flow in fractured porous media. Interphase mass transfer, latent heat, conduction, convection, gravity, and capillary effects are included. A rigorous method based on variable substitution is described to circumvent numerical problems associated with phase disappearance/appearance. Test calculations show that selection of primary variables for the Newton iteration has a profound effect on the number of nonlinear iterations required for convergence. Comparisons with previously reported compulations indicate that the method used here is very efficient. For a fractured waste canister problem, a previously unreported pressure pulse phenomenon is predicted. Comparisons of one- and two-dimensional simulations show that one-dimensional results can be misleading.