AB.4KV-0003 — Loss of 2C 4KV Bus
Purpose
Provides operator actions for response to a loss of the 2C 4KV vital bus. The 2C bus supplies 22 Charging Pump, 22 SI Pump, 22 Containment Spray Pump, and other safeguards loads.
Key Actions / Information
Exam — 2020 Q29
Charging pump power supply alignment following loss of 2C 4KV bus: 22 CV Pump is supplied from the 2C 4KV bus and is lost. Available charging pumps: 21 CV Pump (2B 4KV bus) and 23 CV Pump (2A 460V bus). If 22 CV Pump was in service, place either 21 or 23 CV Pump in service. 23 CV Pump is powered from the 2A 460V bus, NOT from 2C 4KV — it remains available on loss of 2C.
Exam — 2020 Q91
A bus differential fault on 2C 4KV Bus prevents the 2C EDG from re-energizing the bus. AB.4KV-0003 verifies 2C bus energized from EDG and starts/stops loads as necessary, but this path is unavailable when the bus fault is a differential fault — the EDG output breaker will not close onto a faulted bus. With all Unit 2 charging pumps unavailable, the CRS enters AB.CVC-0001, not AB.4KV-0003, to address loss of charging.
Connections
- Related systems: 4KV, CVCS, ECCS, Containment Spray
- Related procedures: S2.OP-AR.ZZ-0009 — Overhead Annunciators Window J
- Related exam questions: 2020 Q29, 2020 Q91
- Related exam: 2020 NRC Written Exam