S2.OP-PT.AF-0002 — AFW Backleakage Testing
Purpose
Provides guidance for monitoring and determining auxiliary feedwater system backleakage from the main feedwater system. Backleakage of hot feedwater into the AFW piping can cause steam/vapor binding of motor-driven AFW pumps, disabling them when needed.
Key Actions / Information
Exam — 2018 Q18
Per P&L 3.1, this procedure shall be performed 30 to 60 minutes after an AFW Pump is shutdown in Modes 1-3. Per SOER 84-3, backleakage of hot feedwater has disabled AFW pumps due to steam binding (vapor binding). Trap: the procedure is NOT required to be performed immediately — the 30-60 minute window allows time for backleakage to develop and become detectable. Backward rotation is a concern for RCPs (which have Anti-Reverse-Rotation Devices), not AFW pumps — the AFW failure mode is vapor binding.
Connections
- Related systems: AFW, Feed & Condensate
- Related exam questions: 2018 Q18
- Related exam: 2018 NRC Written Exam