State Space Method of Fault Tree Analysis with Applications

摘要

A widely used analytical tool for assessing safety, reliability, and risk both qualitatively and quantitatively for a broad spectrum of engineering systems is the fault tree. The fault tree is an assemblage of initiating events (the roots) that pass through an interconnected (branched) system of Boolean OR and AND gates, and ultimately lead to an undesirable TOP event. This tool has been very helpful in designing engineered safety and reliability subsystems for nuclear power plants. However, fault tree models do have some disadvantages: (1) common cause/common mode failure effects are not easily identified; and (2) temporal sequential dependencies and interdependent failure modes (intermodal coupling) cannot be depicted. The latter disadvantage can be alleviated somewhat by using an event-sequence type of analysis tool in conjunction with the fault tree. However, the former problem has required considerable clever tinkering with the minimal cut sets in a fault tree to identify and eliminate common cause/sommon mode dependencies systematically. (ERA citation 10:023367)