[en] A licensable waste package for a nuclear waste repository in basalt must control long-term radionuclide release to the host rock within approved limits as defined by regulatory criteria. Demonstration of satisfactory long-term performance requires experimental data that characterize radionuclide behavior in the expected geochemical waste package environment. Also, an accepted model is required to predict the long-term release of radionuclides from the waste package into the host rock. Experimental data are summarized that pertain to radionuclide behavior in the nuclear waste repository in basalt waste package (e.g., oxygen consumption, hydrothermal reactions, hydraulic conductivity). A simple, one-dimensional, composite media transport model is described that provides calculations of maximum radionuclide release rates and cumulative releases (over 10,000 y) at the waste package packing material/host rock interface on a radionuclide-by-radionuclide basis. The model demonstrates that radionuclide release from the waste package is linearly dependent on the solubility values chosen for the radionuclides of interest. The calculated releases are compared with Nuclear Regulatory Commission and Environmental Protection Agency criteria as well as the available experimental data. The experimental data indicate that the maximum release rates and cumulative releases of the radionuclides technetium, neptunium, and plutonium from the waste package should satisfy Environmental Protection Agency and Nuclear Regulatory Commission requirements. 12 references, 5 figures, 1 table