Facility Vulnerability with VISAC

Edit the Logic Models

The logic models tell VISAC how to propogate damage from the basic events, through the plant safety systems to a final consequence for each aspect of the plant.

Individual basic events (which correspond to the geometric critical components) are connected using "and" and "or" gates to form fault trees for plant subsystems. These fault trees are then connected together using an event tree. Paths through an event tree, sequences, are determined by which fault trees have been failed due to basic event damage. Each sequence in an event tree ends with with either another event tree or a consequence. Several event trees are then grouped together to form an aspect of facility operation.

The logic models are all editable by using the choices under the Models/Edit Logic Model menu option:

Event/Fault Trees - EFTed in its Edit mode to set up or change basic events, fault trees, event trees, consequences
Analysis Parameters - aspects (groups of event trees)
Calculation Parameters - how EFcalc will perform the calculations
Gate Downtimes - supercede downtimes calculated by EFcalc from propogating event downtimes
Accident Definitions - list which top-level fault trees are failed

The logic models can also be edited by selecting them from the expandable tree structure, under the Logic Model tab.

Oak Ridge National Laboratory, 2004

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