In the Federal Republic of Germany – following corresponding studies in the USA – a comprehensive study designed to evaluate the risk from nuclear power plants has been prepared. The study was aimed at determining the risk involved in incidents and accidents in nuclear power plants, taking account of German conditions. Phase A was completed in August 1979 which involved initial risk investigations mainly aimed at assessing the risk involved in accidents in nuclear power plants and comparing it with other risks of civilization and nature. In Phase B of the German risk study, extensive research into the incident behaviour was carried out. In this context, the time sequence of the incidents, the impact involved and the intervention of the safety systems provided to control the accident or incident were thoroughly analysed. These investigations showed the importance of in-plant accident management. The analyses demonstrated that in many cases nuclear power plants still have safety reserves when the safety systems do not intervene as intended and safety-related design limits are exceeded. These safety reserves can be used for in-plant accident management to further reduce the risk resulting from accidents. risk analyses are suitable to identify in-plant accident management and to show how far they can reduce the risk involved in accidents. Investigations on in-plant accident management occupy a central position in the work during phase B of the study. The “German risk Study on Nuclear Power Plants Phase B” was published by the GRS (Company for Industrial Plants and Nuclear Safety) in June 1989.