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ARCH.067 Populate the fault tree
SM-2809
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Populate Confluence page for activity definition: ARCH.067 Populate the fault tree
IN PEER REVIEW
Goal | Visualize all logical combinations of system level deviations that cause one operational deviation in a fault tree and define initial probabilities for the system level deviations. |
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Requirements met by this process step | ISO 15288 6.4.3.3 c) |
Inputs | None identified |
Outputs | AMOD-004 Fault tree (per operational deviation) |
Methodology | Following prerequisite activities have been completed in ARCH.066:
In this activity the fault tree shall be generated as per AMOD-004., such that the logical combination of system level deviations that results into an operational deviation are shown. Further, the probabilities for the occurrence of an operational deviation shall be broken down to the causing system level deviations. At this moment of the process a meaningful breakdown of probabilities will be very limited, because the physical manifestation of the system of interest is needed to make this more meaningful, which is not existent yet. Because of that as first approach only the equal distribution of probabilities is suggested depending on the logical combinations applied:
Note The distribution of the probabilities among the system level deviation will become important in one of the following process activities, when external constraints that are implied on the system are considered. E.g. when an input is used from an actor/system of low safety integrity in a system of that requires high safety integrity. Then safety measures have to be incorporated to compensate for the input of low safety integrity. |
Tools and non-human resources | Team for Capella (tbd - possibly a further tool or plugin for modelling fault trees - ticketed ) |
Cardinality | Once per system capability per operational deviation, with allowed revisions after changes in the operational level risk model or the system function definitions |
Completion criteria | All system level deviations are included included in at least one fault tree for an operational deviation. |
Design review | |
Step done by (Responsible) | System architect |
Provides input to/assists (Contributes) | RAMS architect Security architect |
Uses outputs (Informed) | Independent safety assessor |