Determination of System and Subsystem Functions

DOE-STD-1052-93

Outputs cross the boundaries moving out of the component into other

components or systems. These outputs are directly related to the function(s)

that should be preserved.

A component interface block diagram may be used to illustrate inputs and

outputs.

7.5

Determination of System and Subsystem Functions

This section describes a method to determine the primary and auxiliary functions of a

system and subsystem and the ways these functions may fail. Determining functions is

an important step in this method since preserving these functions is the objective of the

PM task that should be selected.

7.5.1

Function definitions describe what the system or subsystem should accomplish.

Functions may be determined from the following:

system and subsystem interfaces that should be supported

internal interfaces that the system or subsystem should provide as input

to another subsystem

internal interfaces that the system or subsystem provides to support

itself

Examples of primary functions include the following:

normal and emergency cooling flow

auto-start signal to another system

compressed air at a sufficient pressure for downstream components to

operate properly

control room alarms, indications, and recordings

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