On the Use of Non-coherent Fault Trees in Safety and Security Studies

Non coherent fault trees characterised by non monotonic structure functions allows easier modelling of complex top events. The availability of tools based on the Binary Decision Diagrams approach allows extending the fault tree analysis to applications requiring the construction of non coherent functions as well high basic events probabilities. Two examples are described in this paper. The first one, from the field of safety, shows that the possibility to use non coherent trees reduces the modelling effort for complex Top events. The second example refers to a simple problem in the new field of security where the need of dealing with intentional actions implies the modelling of mutually exclusive events to which high probability values are associated. Some considerations about the interpretation of the importance indexes of basic events are also briefly described.

COJAZZI Giacomo;  RENDA Guido; 

CONTINI Sergio; 

2006-10-30

Taylor & Francis Group

JRC33575