Condenser Air Removal
Function
Maintains condenser vacuum by removing non-condensable gases. Includes air ejectors and vacuum monitoring.
Exam — 2018 Q36
Excessively high Vacuum Pump Seal Water Temperature can cause Main Condenser vacuum to degrade — as seal water temperature increases, vacuum pump performance decreases. Excessively LOW TAC supply temperature, excessively HIGH seal water flow, and separating tank overflow all cause seal water temperature to LOWER, which would actually IMPROVE condenser vacuum (not degrade it).
Exam — 2020 Q63
When swapping condenser vacuum pumps per S2.OP-SO.AR-0001: if the AR25 (Air Ejector Suction Isolation Valve) remains OPEN when a vacuum pump is stopped, condenser backpressure rises (loss of condenser vacuum). Per the procedural caution, contingency plans include restarting the vacuum pump OR immediately manually closing the AR23/AR25 valve. Backpressure rising = vacuum lowering. These are the same condition described differently. A rising backpressure means worsening condenser vacuum, not improving it.
Scenario — 2022 #1
Event 2: 24 Vacuum Pump trips during load reduction. PO enters AB.COND-0001. PO starts all available vacuum pumps — 22 Vacuum Pump trips after starting, 25 Vacuum Pump starts but 25AR25 (vacuum pump discharge AOV) fails to open. PO manually opens 25AR25 from the control room. Condenser backpressure recovers.
Connections
- Related systems: Main Turbine
- Related procedures: AB.COND-0001 — Loss of Condenser Vacuum, S2.OP-SO.AR-0001 — Condenser Air Removal System Operation
- Related exam questions: 2018 Q36, 2019 Q92, 2020 Q63
- Related scenarios: 2019 Scenario 3 — ATWS / Stuck-Open PORV, 2022 Scenario 1 — Load Reduction / LBLOCA
- Related exam: 2018 NRC Written Exam, 2019 NRC Written Exam, 2020 NRC Written Exam, 2022 NRC Operating Exam