The mass transport of radionuclides in a multilayered medium

This document describes the mathematical formalism for calculating the rate of mass transport across interfaces in a multilayered medium for radionuclides in a decay chain. Two numerical algorithms have been developed, both based on Laplace transport techniques: a direct solution for concentrations and fluxes in a two-layer medium; and, an approximate solution based on a response function for the mass transport across a finite layer adjacent to a semi-infinite layer. A comparison of the two algorithms is presented. Results of sample calculations for a multilayered medium are also reported and compared with results based on the mass-transfer coefficient approximation