to be implemented (i.e., important procedural features, including interfaces with sensors, etc.)
should be presented. Pertinent aspects of the SAC that relate directly to the safety function,
such as qualifications of personnel required and time available to perform associated tasks,
should be described. Finally, an evaluation of the SAC that demonstrates its capability to
perform the expected safety function should be described for each SAC.
The DSA should provide information (generally Chapter 5 of a DSA based on DOE STD-3009)
to support the derivation of hazard controls described in the TSR document. This Chapter
content is the linking document between the DSA hazard analysis that results in the designation
of SACs and their required safety functions and attributes, and the TSR document. TSR and
SAC procedure writers will refer to the DSA through this chapter to identify the accident
scenarios that generated the need for the SAC (in Chapter 3), and information on its safety
function and required attributes. Chapter 5 should provide a summary description of this
information and references to the supporting information in Chapters 3 and 4.
The concepts of validation and verification are important to the formulation of SACs. These
concepts, as they apply to SACs, are discussed below.
Validation: The functional requirements and performance criteria for safety SSCs are
identified to support the safety functions identified in the DSA and to support subsequent
derivation of TSRs. The formulation of SACs should include a similar process that validates
plant operators can perform the task(s) called for in an SAC within the timeframes assumed
in the DSA. If SACs require operator action and perform a function similar to a safety SSC,
assurance should be provided that the operators can adequately perform their required
tasks by analyzing the following human performance factors at a minimum:
Adequacy of the description of the task in facility procedures
Level of difficulty of the task
Design of the equipment and feedback, e.g. indicators, alarms, etc.
Time available to do the task or recover an error
Stress levels induced by the external environment, e.g. noise, heat, light and
protective clothing worn.
Formal engineering calculations may be necessary to ensure that plant operators have the
appropriate time and resources to carry out the required tasks. For example, if it is
assumed that operators will take actions to detect and isolate a leak, flow rate calculations