Chapter 4 Safety Structures, Systems, and Components

DOE-STD -3009-94

Chapter 4

Safety Structures, Systems, and Components

PU R P O S E . The purpose of this DSA chapter is to provide information necessary to

support the safety basis requirements of 10 CFR 830 for derivation of hazard controls.

This chapter provides details on those facility structures, systems, and components that are

necessary for the facility to protect the public, provide defense in depth, or contribute to

worker safety. Similarly, this chapter p rovides details on specific administrative controls

that are significant to specific accident risk reduction. Descriptions are provided of the

attributes (i.e., functional requirements and performance criteria) required to support the

safety functions identified in the hazard and accident analyses and to support subsequent

derivation of TSRs. Expected products of this chapter, as applicable based on the graded

approach, include:

Descriptions of safety SSCs and SACs including safety functions.

Identification of support systems safety SSCs depend upon to carry out safety

functions.

Identification of the functional requirements necessary for the safety SSCs and

SACs to perform their safety functions, and the general conditions caused by

postulated accidents under which the safety SSCs or SACs must operate.

Identification of the performance criteria necessary to provide reasonable

assurance that the functional requirements will be met.

Identification of assumptions needing TSR coverage.

Existing supporting documentation is to be referenced. Maximum advantage should be

taken of pertinent existing safety analyses and design information (i.e., requirements and

their bases) that are immediately available or can be retrieved through reasonable efforts.

Include a brief summary for each such reference that explains its relevance to this chapter

and provides an introductory understanding of the reference.

AP P L I C A T I O N O F T H E GR A D E D AP P R O A C H . Hazard Category 3 facilities

will not have safety-class SSCs and the number o f safety-significant SSCs and SACs if

any, will be less than that of a Hazard Category 2 facility due to the reduced magnitude of

hazards. As noted in Chapter 3, "Hazard and Accident Analyses," a possible exception to

this general guidance pertains to che mical hazards. The hazard classification mechanism

used in DOE-STD-1027-92 does not consider potential hazardous chemical releases. It is

possible that a Hazard Category 3 facility could need safety-class items for large chemical

hazards, although it is not typically expected.

Hazard Category 2 facilities have the potential for an accident resulting in significant

onsite consequences and may have offsite consequences. These facilities

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