The Fukushima accident led to high radionuclide releases into the atmosphere for more than 3 weeks. This situation has not been assumed when the concepts of nuclear emergency preparedness were developed internationally. The results of simulations studying potential implications of Fukushima-like source terms on nuclear emergency preparedness are presented. Two hypothetical source terms are considered. Radiological consequences are assessed with the decision support system RODOS. Atmospheric dispersion calculations are based on meteorological monitoring data from June and December 2010, respectively, to study potential seasonal effects. Simulations are performed for two nuclear power plant sites in Northern and Southern Germany, respectively. These sites are chosen due to their differing meteorology and topography. Predicted radiation doses of members of the population are compared with dose reference levels actually recommended for initiating protective measures in Germany. Potential implications of general interest for nuclear emergency planning are discussed.