The SWR 1000 concept, which, based on boiling water reactor components that have been proven in service, combines inherently passive safety with aspects of economical power generation, also affects the core design. The aim is to provide as simple a core configuration as possible with a relatively small number of fuel assemblies and control rods The core has been designed for a reactor thermal output of 2778 MW and is equipped with 157 control rods and 648 fuel assemblies of the ATRIUM 12 type. Detailed core analyses have demonstrated the feasibility of this concept.