Some fundamental questions of the safety nuclear power plants

The concepts of risk and acceptable risk based on their probability are defined and applied to nuclear power plants referring to the Rasmussen-Report (WASH-1400, USA, 1975). Some public related aspects concerning the safety of nuclear power plants are also dealt with. Four categories of operational events and emergencies their probabilities are discussed in the framework of which event-tree and fault-tree analyses for risk estimation and the so-called 'defence in depth' method are applied together in the course of design. Contrary to earlier estimations concerning on-planned but not excludable events, protection against core melt-down has been given the highest priority. (Sz.J.)