Reliability data and safety evaluation of nuclear power plants - status and trends in the German Democratic Republic

System analysis covers structure investigations and methods of reliability analysis, which are the main points within the framework of probabilistic safety analysis. Collection, analysis and retrieval of reliability data had been found to be a field of increasing importance to safety analysis. Therefore both constructor and operational organizations in the GDR are legally bound to collect and analyse reliability data as well as to make changes of the technology of a NPP if data indicate a necessity. An independent system of data collection has been established by the National Board on Atomic Safety and Radiation Protection. Current data bases of the GDR involve generic data as well as plant specific reliability information. The paper presents the general approach used in the GDR to introduce reliability data into licensing decisions. Status and plans of data manipulation are discussed as well as the structure of data bases. In addition experiences gathered in using reliability data are presented. Some of them are the following: i) At the present status of reliability analysis and probabilistic safety analysis respectively generic data play an important role. ii) Plant specific data bases are to be improved to get more sophisticated probabilistic safety information. Special attention has to be paid on human errors and common mode failures. iii) Engineering judgement is the most important point in manipulating reliability data and using them in probabilistic safety analysis. (author). 8 refs, 3 figs