This report provides an overview of (1) the most important exposure pathways related to the releases of radionuclides and (2) of dispersion models. Sources considered are nuclear power plants under normal working conditions, laboratories, non-nuclear industries, the storage of nuclear waste and consumer products. Emission of radionuclides mainly takes place via air and water, after wich distribution can continue via air, (ground)water soil and the foodchain. Part 1 of this document gives an overview of the radionuclides that can be released by the selected sources and the resulting exposure pathways. Through the use or the consumption of contaminated water, plants, animals and animal products, the inhalation of contaminated air as well as through external exposure man can sustain a dose. In part 2 this report gives an overview of dispersion models for radionuclides that are available in the Netherlands. These models calculate the distribution of (radioactive) chemical substances through air, water and/or soil. Integrated models concerning more than one compartment and/or are capable of making dose calculations are categorized under the compartment for which it is most applicable. This overview have led to the description of a conceptual model for all compartments, the definition of parameters and the most implementable values.