A detailed three-dimensional model (3-D) has been developed for the divertor cassette in the ITER design. The layered configurations of the dome PFC and vertical targets were modeled accurately with the front tungsten layer modeled separately. 3-D neutronics calculations have been performed to determine the detailed spatial distribution of the neutron flux in the divertor cassette. A detailed activation analysis has been performed for zones representing the different critical components of the divertor cassette. The calculations have been performed for two operational scenarios. Special attention has been given to the top 1 cm tungsten layer of the divertor dome. The radioactivity generated in the tungsten layers of the divertor is mostly dominated by W during the first day after shutdown. The GlidCop copper and 316 SS-LN parts of the divertor also generated considerable levels of activity and decay heat. Nevertheless, the analysis showed that the tungsten Plasma Facing Component (PFC) is clearly the most critical part of the divertor from the decay heat generation point of view.