Skip to content

Three-way communication and verification levels

Control-room communication uses verbal protocols structured to catch errors at the moment of action. Four levels of verification underlie EOP execution; the right level depends on the safety significance of the action.

Three-way communication

Every directive between roles uses three exchanges:

  1. Sender states the directive ("Trip Reactor Coolant Pump 1.")
  2. Receiver repeats it back ("Trip Reactor Coolant Pump 1.")
  3. Sender confirms ("That is correct.")

Read-back-confirm catches mis-hearing. The protocol is mandatory for every parameter callout during EOPs, every breaker manipulation, and every valve operation that changes plant alignment.

Four verification levels

  • Self-check — the operator who is about to perform the action pauses, identifies the component by tag and unit, confirms the action against the procedure step, then performs it. Default for routine actions.
  • Peer-check — a second qualified operator in the same control area visually confirms the component and concurs with the action before the first operator performs it. Required for actions that change critical-safety-function-bearing system state (HHSI start, CCW alignment).
  • Concurrent verification — two qualified operators simultaneously verify the component AND the action; both must agree before either acts. Required for irreversible plant manipulations (rod insertion, manual SI actuation).
  • Independent verification (IV) — a second qualified operator verifies the action after the fact, on the same or a different shift. Used for tag-outs and configuration changes that took effect before the IV occurred.

Why this matters for EOP authoring

EOP Check: and Action: lines do not declare the verification level — that's the SRO's call at execution time. But a step with a Caution: block flagging an irreversible action is implicitly guiding the SRO toward concurrent verification. Authors should write Caution: blocks at exactly those moments.

Cross-reference