Abstract: A compressible nuclear waste disposal contamination in porous media is modeled by a coupled system of partial differential equations. The approximation of this system using a finite element method for the brine, radionuclides, and heat combined with a mixed finite element method for the pressure and velocity are analyzed. Optimal order error estimates in H¹ and L² are derived. This paper improves upon previously derived estimates in two aspects. Firstly, the error analysis is given with no restriction on the diffusion tensors. That is, it has included the effects of molecular diffusion and dispersion.Secondly, the "complete compressibility" case is considered.

Key words: Mixed finite element, compressible, nuclear waste