This subsection provides performance criteria imposed on the safe ty-class SSC
so it can meet functional requirement(s) and thereby satisfy its safety function.
Performance criteria characterize the specific operational responses and
capabilities necessary to meet functional requirements.
Engineering judgment may be used to develop performance criteria for
existing safety SSCs (i.e., already designed) where documentation of design
and operational responses may not exist. In determining performance criteria
for safety-class SSCs, existing criteria traditionally associated with safety-class
designation, such as single failure criteria, should be considered in the
judgment process. However, for existing SSCs, formal design comparison and
compliance with traditional safety-class performance criteria is not required.
Evaluate the capabilities of the SSC to meet performance criteria. The
evaluation should be as simple as possible, and rely on engineering judgment,
calculations, or performance tests as opposed to formal design reconstitution.
would exceed its interlock trip point. Such a pass- fail test would typically
bound the needed equipment performance as response time is not a highly
This subsection id entifies those assumptions requiring TSRs to ensure
performance of the safety function.
S A F E T Y-SIGNIFICANT STRUCTURES, SYSTEMS, AND
Relevant information is provided, in the following SSC specific subsections, with
descriptions sufficiently detailed to provide an understanding of the safety function
of safety-significant SSCs. Descriptions for each safety-significant SSC must be
complete enough to allow for verification of the accuracy of the safety analysis
inputs and assumptions.
Provide a summary list of safety-significant SSCs. This summary list should
identify, in tabular form, safety-significant SSCs, the rationale from Chapter 3 for
which safety-significant designation was made, safety functions, functional
requirements, and performanc e criteria judged to require TSR coverage. The
remaining subsections provide details that correlate to the summary list.
Note: The following format is repeated sequentially for each ("X") safety
significant SSC. The examples provided are for illustration purposes only, and
should not be construed as a requirement to designate such systems safety-class or