S2.OP-IO.ZZ-0007 — Cold Shutdown to Refueling
⚠️ DRAFT — Reconstructed from exam materials
Purpose
Provides guidance for transitioning from cold shutdown to refueling mode, including reactor disassembly and defueling sequences.
Key Actions / Information
Core Alteration Definition
A CORE ALTERATION is the movement of any fuel, sources, OR reactivity control components within the reactor vessel with the vessel head removed and fuel in the vessel.
Exam — 2022 Q94
The first defueling activity requiring direct supervision of the Refueling SRO in Containment because it is a CORE ALTERATION is unlatching RCCAs (performed before fuel moves). Moving fuel assemblies is also a core alteration but occurs after RCCA unlatching. Lifting upper internals and disconnecting CRDMs are NOT core alterations — they do not involve movement of fuel, sources, or reactivity control components within the reactor vessel.
MODE 6 Entry (Reactor Head De-tensioning) Requirements
Exam — 2020 Q94
Before de-tensioning the first Rx Head Stud (entering MODE 6), IOP-7 Attachment 1 requires:• At least two source range neutron detectors OPERABLE (NIS source range and/or Gamma-Metrics) per TS 3.9.2.2
• Completion of S2.OP-ST.ZZ-0007(Q), verifying each unborated water source isolation valve secured closed per TS 3.9.2.1
NOT required before de-tensioning (common traps):
• 168 hours subcritical — TS 3.9.3 applies to movement of irradiated fuel, not de-tensioning. Also, 168 hours applies only May 16 – Oct 14; for Oct 15 – May 15 only 80 hours is required.
• Continuous communications between CR and refuel floor — required 1 hour prior to CORE ALTERATIONS, not de-tensioning.
Connections
- Related systems: Refueling, Control Rod Drive
- Related tech specs: TS 3/4.9 — Refueling Operations
- Related exam questions: 2022 Q94, 2020 Q94
- Related exam: 2022 NRC Written Exam, 2020 NRC Written Exam