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Shift Technical Advisor (STA)

The STA is the independent technical voice in the control room during emergencies. Established as a regulatory requirement post-TMI (NUREG-0578 Item 2.B.1, codified in 10 CFR 50.54(m)), the role exists specifically to provide diagnostic perspective that the EOP-executing team cannot — they're heads-down running the procedure.

What the STA does

  • Monitors the Critical Safety Function status trees in parallel with EOP execution. The STA owns the CSF tree evaluation independent of the SRO running the active EOP.
  • Calls procedure-change recommendations to the SRO when a CSF enters orange or red — the SRO holds the authority but the STA is the one who is supposed to see it first.
  • Provides technical analysis of plant transient behaviour beyond what the procedures cover (thermal-hydraulic intuition, system inter-dependencies the procedure doesn't make explicit).
  • Logs the technical narrative of the event separately from the RO's parameter log and the SRO's procedure log. The three logs cross-check in post-event review.

What the STA does NOT do

  • Manipulate controls. The STA is not licensed under 10 CFR 55 and cannot perform Action: steps.
  • Override the SRO. STA recommendations are advisory; the SRO decides. If the disagreement is critical, both escalate to the SS.
  • Take command of the EOP execution. The SRO runs the procedure.

Why the role exists structurally

TMI-2 (1979) showed that an EOP-executing team operating under high cognitive load loses peripheral awareness — they see what the procedure tells them to look at and miss what it doesn't. The STA is the deliberate counter to that: an independent observer with no procedure to execute, free to notice patterns the active team is filtering out. The role is one of the lessons learned that shows up in modern Conduct of Operations regulation in every NRC- regulated and IAEA-aligned plant.

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