Editing SAPHIRE (section)

== Basic event probabilities ==

General basic event probability capabilities for SAPHIRE include:

* Four different Markov models to represent the failure of a single component
* A common cause module to determine a group common cause failure probability for groups of up to six redundant components
* A load-capacity calculation allowing the user to specify a load and capacity distribution to determine P(Capacity < Load)
* A human reliability analysis calculator to determine a human failure event probability based upon the task type and compounding performance shaping factors
* The use of template events which allow for failure information to be shared where applicable
* A seismic fragility method that uses an associated earthquake acceleration level to determine a components failure probability
* House events to set basic events to logically true or false or to ignore the event
* A module to determine the loss-of-offsite power frequency and recoverability

SAPHIRE has been designed to handle large fault trees, where a tree may have up to 64,000 basic events and gates.  To handle the fault trees, two mechanisms for developing and modifying the fault tree are available – a graphical editor and a hierarchical logic editor.  Analysts may use either editor; if the logic is modified SAPHIRE can redraw the fault tree graphic.  Conversely, if the user modifies the fault tree graphic, SAPHIRE automatically updates the associated logic.  Applicable objects available in the fault tree editors include basic events and several gate types, including: OR, AND, NOR, NAND, and N-of-M.  In addition to these objects, SAPHIRE has a unique feature known as “table events” that allows the user to group up to eight basic events together on the fault tree graphic, thereby compacting the size of the fault tree on the printed page or computer screen.  All of these objects though represent traditional static-type Boolean logic models.  Models explicitly capturing dynamic or time-dependent situations are not available in current versions of SAPHIRE.