Question

Develop a single or set of event trees to describe the escalation mechanism that would lead to an impairment of a TR from a fire or explosion in an adjacent module. Your event tree(s) should include the direct effects of fire and explosion and escalations which may lead to impairment of the TR by fire, smoke or structural failure. Present your event tree(s) and discuss all underlying assumptions

Answer 1

Fault tree analysis (FTA) techniques were first developed at Bell Telephone Laboratories in the early 1960's. Since this time they have been readily adopted by a wide range of engineering disciplines as one of the primary methods of performing reliability and safety analysis.FTA is a top down, deductive failure analysis in which an undesired state of a system is analyzed using boolean logic to combine a series of lower-level events. This analysis method is mainly used in the field of safety engineering and reliability engineering to determine the probability of a safety accident or a particular system level (functional) failure. Fault trees graphically represent the interaction of failures and other events within a system. Basic events at the bottom of the fault tree are linked via logic symbols (known as gates) to one or more TOP events. These TOP events represent identified hazards or system failure modes for which predicted reliability or availability data is required. Fault tree diagrams (FTD) are logic block diagrams that display the state of a system (top event) in terms of the states of its components (basic events). Like reliability block diagrams (RBDs), fault tree diagrams are also a graphical design technique, and as such provide an alternative to methodology to RBDs. An FTD is built top-down and in term of events rather than blocks. It uses a graphic "model" of the pathways within a system that can lead to a foreseeable, undesirable loss event (or a failure). The pathways interconnect contributory events and conditions, using standard logic symbols (AND, OR etc). The basic constructs in a fault tree diagram are gates and events, where the events have an identical meaning as a block in an RBD and the gates are the conditions. FTA involves five steps. Obtain an understanding of the system, Define the top event to study, Construct the fault tree, Evaluate the fault tree, qualitative analysis and reliability evaluation.