AB.SW-0005 — Loss of All Service Water
⚠️ DRAFT — Reconstructed from exam materials
Purpose
Provides immediate actions for responding to a complete loss of all service water flow, including reactor trip and RCP trip actions.
Key Actions / Information
Exam — 2022 Q90
On loss of all SW flow, immediately trip the reactor and stop all RCPs to limit heat input to the CCW system. Unit difference: on Unit 2, the 2A 4KV vital bus (which powers 21 and 22 SW Pumps) is different from Unit 1 power supply alignment. A 2A 4KV bus lockout loses both 21 and 22 SW Pumps — 22 SW Pump will NOT auto-start because it lost its power source. With 23 SW Pump already tripped, all SW flow capability is lost.
Exam — 2020 Q53
AB.SW-0005 entry criteria: requires actual loss of ALL service water flow. A 1A 4KV Bus Differential on Unit 1 with #3 SW Bay already C/Ted does NOT cause a loss of all SW because 15 and 16 SW Pumps (powered from 1A Bus) were already isolated for the bay outage. The 12 SW Pump auto-starts on C Bus to maintain flow. Correct procedure entry: AB.4KV-0001. Distractor: RCPs are stopped to limit heat input to the CCW system (not the RCS) in AB.SW-0005.
Connections
- Related systems: Service Water, EDGs, 4KV, CCW
- Related procedures: AB.SW-0001 — Loss of SW Header Pressure
- Related exam questions: 2020 Q53, 2022 Q90
- Related exam: 2020 NRC Written Exam, 2022 NRC Written Exam