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5.1 INTRODUCTION
5. SAFETY STRUCTURES, SYSTEMS, AND COMPONENTS
The objective of this chapter is to identify and classify those structures, systems, and
components (SSCs) that ensure the functions necessary for safe facility operation. The
preventive and mitigative safety features necessary to protect the maximum [exposed] off-site
individual (MOI), the collocated worker (CW), the immediate worker (W), and the
environment, or to provide significant defense-in-depth functions, are identified in the hazard
evaluation and accident analysis sections of NSTR-0 1 1-98, Safeiy Anabsis for the Building 991
Complex Final Safety Anaiysis Report (Ref. 1). This chapter correlates those identified safety
features to the Building 991 Complex SSCs capable of providing the necessary safety functions.
This chapter then categorizes each of the safety SSCs according to their importance to safety
and their operability requirements to perfom their identified safety function.
Development of System Evaluation Reports (SERs) was not accomplished for the
Building 991 Complex SSCs. Therefore, this chapter provides the safety functions of the SSCs,
their boundaries, the support systems required to be operable so the safety SSCs maintain their
safety functions, and the functional requirements of the SSCs (the acceptance criteria for each
SSC, including surveillance requirements and frequencies, is detailed in Appendix A,
Building 991 Complex Technical Safety Requirements). This information is presented in a
tabular’ format. In most cases the system descriptions provided in Chapter 2 will suffice,
therefore, this chapter will not provide additional SSC description information unless required
to supplement the Chapter 2 information. The SSCs determined most significant for the safe
operations of the facility are covered by Technical Safety Requirements (TSRs).
Safety SSCs for the Building 991 Complex are categorized in two ways to accommodate
Site methodology and Department of Enerm Standard 3009-94 (DOE-STD-3009) (Ref. 2)
methodology. These two methodologies do not correlate with each other. The Site
methodology provides System Category (SC) levels for the SSCs so procurement requirements
can be specified. The Site methodolom classifies SSCs as SC-1:’2. SC-3. or SC-4 depending on
their importance in protectinz the MOL CW, and W. The DOE-STD-3009 methodology
classifies SSCs as either safety-class or safety-significant depending on their importance of
protecting the MOI and the environment. or if they are mdor contributors to defense-in-depth
Section 5.2 discusses categorization of the SSCs Der the Site methodoionv and Section 5 3
discusses categorization of the SSCs per the DOE-STD-3009 methodolow.
Safety SSCs were identified during three phases of the hazard evaluation and accident
analysis process. The first phase wits during the hazard evaluation process. This process
qualitatively evaluated the hazards associated with the activities being conducted at the
Building 99 1 Complex. Assumptions, protective features, and requirements were identified
during this phase. These assumptions, protective features, and requirements could involve SSCs
specifically credited to eliminate a potential accident scenario from further evaluation.
Revision I
Saprernher 1999
5- 1 Building 991 Complex FSAR