Study On FTA And AHP Based Reliability Allocation Method

Since Fukushima nuclear accident happened in2011, reliability of nuclear power plants has become an even greater concern in recent years. Reliability design is a significant process to increase reliability of complex systems. And reliability allocation is a vital step of reliability design, as a way to reduce cost as well as enhance public safety when the reliability of whole system is reached.Reliability allocation could allocate reliability goal of a system to its components and subsystems based on certain rules. However, the existing reliability allocation methods generally have some limitations such as efficiency is low, factors considered is not sufficient, the rationality and reasonability is not enough and stuff.To solve such problems, a method based on Fault Tree Analysis and Analytic Hierarchy Process is proposed. With this method, objective computed results from FTA and subjective evaluation from experts was combined to make the allocation results more accurate and more reasonable in an efficient way. Various factors and the whole system are considered to make this method applicable in complex system in nuclear power plant.This method includes minimal cut-sets allocation and basic events allocation. Compared with existing methods, this method has following merits:(1) making the allocation target more clearly through selecting appropriate minimal cut-sets and basic events based on certain rules,(2) improving reasonability and rationality by considering more factors,(3) enhancing the allocation efficiency by using data from quantitative analysis of fault tree.In addition, a reliability allocation system is developed based on this method, which could simplify the calculation, reduce required allocation time and increase allocation efficiency.