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Abnormals > AB.CVC-0001 — Loss of Charging

AB.CVC-0001 — Loss of Charging

⚠️ DRAFT

AB.CVC-0001 — Loss of Charging

Purpose

Referenced in 2023 NRC Operating Exam simulator scenarios. Details to be backfilled from source documents.

Key Actions / Information

Exam — 2022 Q6
Per step 3.109, if MFC malfunction: take manual control of 2CV55 or 23 Charging Pump. With 23 Charging Pump in service, 2CV55 has no effect on charging flow — must take manual control of 23 Charging Pump Speed Controller. 23 Charging Pump low speed stop maintains minimum 47 gpm for RCP seal injection.
JPM — 2018 Sim-b
Entered due to VCT level channel 2LT112 failing high at 100% power, MOL. CRS directs manual makeup of VCT to 53% per S2.OP-SO.CVC-0006 Section 5.2. VCT level monitored via 2LT114 on Plant Computer (P250 on 2CC1). RCS boron 900 ppm, BAST 6700 ppm.
JPM — 2022 Sim-b
Entered due to VCT level channel 2LT112 failing high. CRS directs manual makeup to VCT per S2.OP-SO.CVC-0006 Section 5.2 to restore VCT level to 53%. VCT level monitored via 2LT114 on Plant Computer (2LT112 unreliable due to failure).
Scenario — 2022 #3
PZR Level Channel I fails high. Charging flow lowers automatically. RO places Master Flow Control in Manual and raises charging flow to restore PZR level to program. CRS enters AB.CVC-0001. RO selects operable Channel 3 for control and operable Channel 2 or 3 for recorder. CRS evaluates TS 3.3.1.1 action 6 (72 hours to place channel in tripped condition).
Exam — 2020 Q91
With no Unit 2 Charging Pumps available (22 CV Pump lost on 2C bus fault, 23 CV Pump tagged, 21 CV Pump tripped on overcurrent), step 3.50 directs: "COORDINATE with Unit 1 to place 13 Charging Pump in service using U/1 RWST." Trap: the procedure does NOT direct tripping the reactor and initiating SI (that action is for PZR level uncontrolled). A bus differential fault prevents 2C EDG from re-energizing the bus, so 22 CV Pump cannot be recovered via AB.4KV-0003.
Exam — 2020 Q77
Loss of one charging pump (21 CHP trips, 23 CHP started): TS 3.1.2.2 (Boration Flow Paths) still met — two boration flow paths remain. TS 3.1.2.4 (Charging Pumps) still met — 23 Charging Pump counts for reactivity addition capability (two pumps still operable: 22 and 23). TS 3.5.2 (ECCS) is the only applicable entry — one ECCS subsystem inoperable (21 CHP is the high-head ECCS component for that train). 72 hours to restore, then Hot Shutdown within 12 hours (total 84 hours to MODE 4). The 23 Charging Pump (positive displacement) counts toward the reactivity TS (3.1.2.4) but is NOT an ECCS high-head pump.
Scenario — 2020 #1
PZR Level Channel 1 fails low — letdown isolates. RO takes manual control of charging flow, selects operable channel, energizes PZR heaters. Restores letdown: opens 2CV7, 2CV18 in Manual, opens 2CV2 and 2CV277 in Auto, ensures charging flow ~85-90 gpm.
Scenario — 2020 #3
VCT level channel 2LT-114 fails high — 2CV35 diverts to CVCS HUT, VCT level lowers. RO takes manual control of 2CV35 and positions to VCT. CRS directs maintaining VCT level by cycling 2CV35 or initiating manual makeup IAW S2.OP-SO.CVC-0006.
JPM — 2019 SRO-A3
12 Charging pump trips at 0700 while 1B EDG is CIT. Crew enters S1.OP-AB.CVC-0001, starts 13 Charging pump, restores letdown and PZR level. The CRS must then evaluate TS impact: TS 3.5.2.a action a (72 hours) for the inoperable ECCS subsystem (12 Charging pump), AND TS 3.8.1.1 action b.2 (4 hours) because the 12 Charging pump is a redundant required feature of the CIT 1B EDG.
Exam — 2018 Q52
Charging line leak diagnosis: seal injection flow lowering + PZR level lowering + 2R41 (Plant Radiation Monitor) rising + letdown line flashing = leak on the CVCS charging line. A charging line leak IS an entry condition for AB.CVC-0001. Trap: letdown line leak shows similar symptoms (PZR level lowering, radiation rising) but would NOT cause seal injection to lower or letdown line flashing. Letdown line leak is NOT an entry condition for AB.CVC-0001.

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