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There is today a wide range of pubLications avaiLabLe on the theory of reLiabiLity and the technique of ProbabiListic Safety AnaLysis (PSA). To pLace this work properLy in this context, we must recaLL a basic concept underLying both theory and technique, that of redundancy. ReLiabiLity is something which can be designed into a system, by the introduction of redundancy at appropriate points. John Von Neumann's historic paper of 1952 'ProbabiListic Logics and the Synthesis of ReLiabLe Organisms from UnreLiabLe Components" has served as inspiration for aLL subsequent work on systems reLiabiLity. This paper sings the praises of redundancy as a means of designing reLiabiLity into systems, or, to use Von Neumann's words, of minimising error. Redundancy, then, is a fundamentaL characteristic which a designer seeks to buiLd in by using appropriate structuraL characteristics of the 'modeL" or representation which he uses for his work. But any modeL is estabLished through a process of de Limination and decomposition. FirstLy, a "Universe of Discourse" is delineated; its component eLements are then separated out; and moreover in a probabiListic framework for each eLement each possibLe state is defined and assigned an appropriate possibiLity measure caLLed probability.
Sommario
Treatment of Common Cause Failures. The Nordic Perspective.- Classification of Multiple Related Failures.- Design Defences against Multiple Related Failures.- Design-Related Defensive Measures against Dependent Failures - ABB ATOM's Approach.- Design Defences against Common Cause/Multiple Related Failure.- Measures Taken at Design Level to Counter Common Cause Failures. A Few Comments Concerning the Approach of EDF.- Analysis Procedures for Identification of MRF's.- Dependent Failure Modelling by Fault Tree Technique.- Treatment of Multiple Related Failures by MARKOV Method.- Parametric Models for Common Cause Failures Analysis.- Estimation of Parameters of Common Cause Failure Models.- Pitfalls in Common Cause Failure Data Evaluation.- Experience and Results of the CCF-RBE.- Analysis of CCF-DATA-Identification. The Experience from the Nordic Benchmark.- Some Comments on CCF-Quantification. The Experience from the Nordic Benchmark.- Analysis of Common Cause Failures Based on Operating Experience: Possible Approaches and Results.- Multiple Related Failures from the Nordic Operating Experience.- The Use of Abnormal Event Data from Nuclear Power Reactors for Dependent Failure Analysis.- MRF's from the Analysis of Component Data.
