Slide 152 of 161

## Analyzing the Fault Tree

## 1. Determine the minimal cut-sets to simplify the tree (qualitative analysis).

## 2. Determine the probability of each input event

## 3. Combine the probability inputs to logic gates as follows:

## a. AND Gate - The probability of output is the product of the probabilities of the inputs (P0=Pi1� Pi2...�Pin)

## b. OR Gate - The probability of output is the sum of the probabilities of the inputs (P0=Pi1+ Pi2...�Pin)

## 4. Combine the gate input probabilities until the probability of the top event is determined.

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