With Analysis Results you are able to calculate the probability of an unwanted event occurs

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Fault Tree Event Tree Analysis Results Example

Analysis Results

Here are some typical questions that can be answered when using fault tree and event tree analysis:

How safe are my day-to-day operations and which are my systems weaknesses?

You are able to calculate the probability of an unwanted event occurs.
The probability is a dimensionless value, for example 1.0E-03 (which means one in a thousand). You get a list of events and combinations of events (Minimal Cut Sets) that lead to the unwanted event. The list is ranked according to probability so you may determine which event or combinations of events that are the most significant.

You will also get importance and sensitivity measures for each event included in the analysis. The importance and sensitivity measures are indicators of how important and how sensitive the results of the analysis are to variations in component failure or event probabilities.

What is the availability of my system and how reliable is it?

Companies supplying power often get the question: " What is the availability of your system and how reliable is it?" or "How many hours per year will you not be able to deliver power and how often will this happen?".

Using the mean unavailability (dimensionless value), Q, you can calculate the number of hours for any time period that your system is likely to be unavailable. Let's say Q=1.0E-03 for your system. This means that, on average, your system will be out of order approximately 8 hours and 45 minutes (1.0E-03*8760=8,76) per year.

Calculating the unconditional failure intensity (W) for an event in your fault tree model tells you how often your system is likely to fail. The unconditional failure intensity is a frequency. Let's say that W=5.0E-04/h in your system. This means on an average year, it is likely that your system will fail approximately 4,38 times (5.0E-04*8760=4,38).