On the Fundamental Continuity Equation for Material Transport in Fractured Media and Retention Factor for a System of Joints

Transport of radioactive nuclides through a system of joints is discussed including a linear sorption isotherm. The expression for the effective retention factor is derived for (a) a single joint, (b) a system of identical joints separated by a given distance, and (c) a system of joints with arbitrary apertures and sorption characteristics. It is shown that the retention factors for cases a and b are the same. In the limit of dense fractures, the retention factor for the porous medium is recovered. Relevance to the one-dimensional geosphere transport problem in the heterogeneous geology is pointed out. An arbitrary number of joint sets can now be included in such a problem.