ABSTRACT

Risk analysis uses logic diagrams, which reflect the logic of the failures and processes needed to produce adverse Consequences. Their origin is to be found in the Cold War need to determine methods to test intercontinental ballistic missile launch systems up to the point of launch but being sure not to actually launch. Application to the design of aircraft quickly followed, then the nuclear power industry, rail, road and the petrochemical industry. Representative values of failure probability are fortunately available to the risk engineer, but actual failure probabilities depend on everyday management decisions about operating, maintenance, inspection, equipment renewal and training practices. Risk analysis makes use of two types of logic diagram, one to understand the logic of system faults, known as fault tree analysis (FTA), that lead to a significant Event, and the other to show what can follow the Event by describing the logical pathways that lead from it to Consequences.