Chapter 4. System Description

DOE-STD-3024-98

the system as a whole and to the components of the

suppose a requirement on the system is that the

system, and should identify any specific QA actions

centerline of a pump suction line be located more

deemed to be necessary. When the general QA

than 8 inches and less than 14 inches above the

category provides for options related to specific QA

bottom of a tank. This requirement might have been

activities, the SDD shall identify which options

based on a combination of net positive suction head

apply to this system.

When specific QA

considerations for the pump and avoiding debris that

requirements, such as witnessing vendor testing, are

may be on the bottom of the tank. In describing the

applicable only to certain components, those

system, do not simply repeat the 8 to 14inches

requirements should be identified (perhaps, in a

requirement, but rather describe the actual

table) in the SDD.

installation more specifically, such as the centerline

of the suction pipe is 11.25 inches above the bottom

of the tank. For a requirement that a valve be

3.5.5 Miscellaneous Requirements

provided with position indication that is displayed in

This part of the system requirements section of the

the control room, do not simply say that valve

SDD is for requirements and their bases that do not

indication is provided in the control room. State

fit conveniently into the other defined subsections.

more specifically that, for example, valve position

limit switches are provided on the valve that indicate

on the auxiliary systems panel in the control room

Chapter 4

when the valve is greater than 90% open (green

light) or greater than 90% closed (red light).

System Description

In addition, features of the system description that

The SDD shall include a comprehensive description

are related to the system requirements shall be

of the system, including both its safety features and

correlated. One method for this correlation which

non-safety features. The SDD description shall

has been found effective and convenient is to use

emphasize those features provided to meet the

footnotes. For example, a footnote to a particular

requirements on the system.

feature, characteristic, or performance capability

might say "This feature is related to System

This section of the SDD shall identify the

Requirement 3.3.4.15."

components of the system; describe how those

components are laid out physically and

4.1 Configuration Information

interconnected; explain the system flow paths;

identify the indicators, controls, and alarms

4.1.1 Description of System, Subsystems, and

provided; define the acceptable ranges for system

Major Components

performance and setpoints; and explain how the

system operates.

The detailed system diagram shall identify the

components in the system and their interconnections.

The manufacturer and model number for

This diagram should extend sufficiently to identify

components in the current system configuration

the interfacing equipment and systems. The

must be recorded in a controlled document for

boundary between the system being described and

several reasons including to facilitate identifying the

the interfacing systems shall be shown on the

applicable information in vendor-supplied

diagram in a distinctive manner. Similarly, the

documents. In some cases, the SDD may be the

subsystems that have already been shown in the

most appropriate place to record this information. In

simplified system diagram in Chapter 2 of the SDD

other cases, the SDD may reference a separate

should be identified in a distinctive manner that can

controlled document such as the MEL or Bill of

be correlated with the earlier diagram. For a very

Materials that contains this configuration

simple system, a single diagram may be used.

information.

A purpose of the system diagram is to illustrate

Describe the system with specific values, rather than

which components are needed to fulfill the system

simply repeating the requirements. For example,

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