Table 4.24. Fault Tree Symbols cont'd

DOE-HDBK-1100-2004

A fault event representing a component failure or

BASIC Event

human error that requires no further development.

A basic event is the lowest level of resolution in

a fault tree.

A fault event representing a failure or error which

UNDEVELOPED

is not examined further because information is not

Event

available or because further development is

beyond the scope of the study.

A fault event representing a condition or event

EXTERNAL or

that is assumed to exist either as a boundary

HOUSE Event

condition for the fault tree or because the event

always occurs unless a failure takes place.

The TRANSFER IN symbol indicates that the

TRANSFER

fault tree is developed further at a corresponding

IN/OUT Symbols

TRANSFER OUT symbol. Transfer symbols are

used to transfer off-page or to avoid repeating

identical logic (with identical events) in several

places in a fault tree.