6.2 Efficient Decomposition and Aggregation Approach
Different from the explicit method where the system model is developed with the consideration of contributions from CCs, in the implicit method, the system model and reliability expression are developed without considering CCFs. However, special treatments must be performed to include the contributions of CCs in the expression evaluation [ 2 , 13 ,15]. This section introduces such an implicit method called the EDA approach. Based on the “divide and conquer” principle, the basic idea of the EDA method is to decompose an original reliability problem with CCFs into a number of reduced reliability problems without CCFs according to the total probability theorem [16,17].
6.2.1 Three‐Step Method
The EDA method can be applied in three steps:
- Step 1: Construct common‐cause event (CCE) space. Assume m CCs exist in the system. The m CCs form 2m disjoint combinations, each called a CCE:
CCE 0 = CC 1