Glossary - Continued - std30240012

DOE-STD-3024-98

formally controlled. Revisions to controlled documents are uniquely tracked and implemented,

including mandatory page replacements and receipt acknowledgment. Controlled documents typically

include procedures for operations, surveillance, and maintenance, and safety basis documents such as

the SAR, TSRs, and hazard and accident analyses. [See Reference 5.]

Design Information. Design information is the combination of the requirements and the corresponding

basis information associated with the engineering design process. [See Reference 7.]

Engineering Design Process. The technical and management process that begins with the identification of

design inputs and constraints (e.g., mission objectives, commitments, applicable codes, standards,

regulations, procedures, and methodologies), processes this information, and results in the issuance of

requirements. This process defines and documents the inputs; adheres to the constraints; performs and

documents the necessary analyses, calculations, technical studies and evaluations; and ensures the

outputs of the process (i.e., the requirements that dictate a design that satisfies the inputs and

constraints) are documented and complete. [See Reference 7.]

Requirements. The results of the engineering design process that define what has been required.

Requirements are typically defined on design output documents (such as drawings and specifications)

that specify the functions, capabilities, capacities, physical dimensions, limits, setpoints, etc. for a

structure, system, or component. [See Reference 7.]

Safety Structures, Systems, and Components (Safety SSCs). The set of safety-class SSCs and safety-

significant SSCs for a given facility. The definitions for safety-class SSCs and safety-significant SSCs

and associated relevant information are provided in DOE-STD-3009-94. [See Reference 8.]

Subsystem. A combination of components, modules, devices, or software within a system which can

perform a function or an identifiable part of a function. A subsystem may be deemed to exist when

specific flow paths or equipment or functional capabilities can be correlated with different parts of the

system functions or system requirements. For example, if the system function statement were to say to

maintain negative differential pressures in various zones, there might be one flow path that could be

correlated with maintaining the negative differential pressure in one of these zones. In another example,

a general fire protection system might have one subsystem that detects fire conditions, another

subsystem that holds the fire water, and a third subsystem that delivers the fire water to the proper

location to suppress the fire. In some systems, programmable software is treated as a subsystem

associated with the system.

Support System. A system that provides a supporting service to another system that is necessary for the

supported system to be capable of meeting its system requirements. For example, an instrument air

system may be necessary for a ventilation system to meet its system requirements with regard to certain

dampers opening, modulating to maintain a specified negative pressure differential, or closing under

specified conditions. In another example, an HVAC system may be necessary to maintain the

temperature of the environment to within the limits for which some components are rated. In some

designs, components or the system may go to a so-called "Fail-Safe" condition upon loss of electric

power or some other supporting service, but that is a preferred failure mode. Preferred failure modes

do not negate the support system being necessary.

System. An interrelated set of structures, equipment, subsystems, modules, components, devices, parts,

and/or interconnecting items that is capable of performing a specified function or set of functions that

fulfill a purpose. Systems usually have defined physical boundaries, and systems often depend upon

human interactions. Some aspects of a system might be important to safety or programmatic mission,

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