ECA-1.1 — Loss of Emergency Coolant Recirculation¶
Entered from ES-1.3, ES-1.4, or E-1 when transfer to cold-
or hot-leg recirculation fails — sump suction unobtainable, pump trip
during transfer, or strainer blockage. Without recirculation, RWST
inventory is finite (typically depletes in 60-90 minutes at full SI
flow per Vogtle UFSAR §6.3.2). This procedure exercises every
alternate-recirculation path before falling through to inadequate-core-
cooling response.
CSF: core-cooling
CSF: rcs-inventory
Step 1 verify-recirc-failure¶
Check: RWST level «RWST-LVL» at or below low-low setpoint AND cold-leg recirculation flow not established («LO-HEAD-FLOW» low or zero); sump-strainer differential pressure «SUMP-SCREEN-DP» (high indicates blockage); RHR pump status «RHR-PUMP-A» / «RHR-PUMP-B»
Caution: a momentary flow disturbance during transfer is NOT recirculation failure — confirm that the recirc path has been attempted AND failed
- Recirculation failure confirmed → #attempt-restoration
Because: extreme-conditions response engages
- Recirc actually established (transient flow disturbance only) → ES-1.3
Because: return to normal recirculation procedure
Step 2 attempt-restoration¶
Within: 5 minutes of failure confirmation — RWST depletion is the dominant clock
Action: attempt alternate-suction recirculation — containment-spray pump «CSPRAY-A» / «CSPRAY-B» can serve as ECCS makeup via cross-tie if the spray-pump train is otherwise available
Action: if sump strainer is the blockage cause, attempt strainer backflush (if procedure allows)
Action: align any remaining ECCS path (high-head SI from sump via piggyback if RHR train is partially recoverable)
Caution: cross-tie operations can defeat single-failure protection — coordinate with SS; train separation may be lost
- Alternate recirculation path established → ES-1.3
Because: return to normal cold-leg recirc procedure with the alternate path
- All restoration attempts failed → #core-cooling-fallback
Because: no recirc available; fallback to direct core-cooling management
Step 3 core-cooling-fallback¶
Action: maximize remaining core-cooling resources — any working SI pump injecting from any source; isolate non-essential flow paths to conserve RWST
Action: manage RCS pressure «PT-455» — lower pressure widens the SI injection window from accumulators and low-head pumps; balance against subcooling margin
Action: prepare for transition to SAMG-territory if RWST depletes without recirc — coordinate with SS/EC for EAL escalation
Caution: this step is a holding pattern — no good answers exist when recirc fails; the goal is to maintain cooling until either recirc is restored OR SAMG entry is required
- Adequate cooling maintained (subcooling, vessel level, CETs all stable) → #monitor-recovery
Because: holding pattern; continue monitoring for recirc-restoration opportunity
- Cooling inadequate → FR-C.1
Because: inadequate-core-cooling response — the final EOP path before SAMG
Step 4 monitor-recovery¶
Check: ongoing recirculation-restoration efforts; RWST level; ECCS flow status
Within: re-evaluate every 15 minutes
- Recirculation path restored by any means → ES-1.3
Because: resume normal recirculation
- Recirc not restored → #monitor-recovery
Because: continue holding pattern
Tags¶
-
id: RWST-LVL
description: refueling water storage tank level
sim-path: rwst.level
units: percent
equipment: rwst
source: Vogtle UFSAR §6.3.2 -
id: LO-HEAD-FLOW
description: low-head SI / RHR header flow
sim-path: ess.lo_head.header_flow
units: gpm
equipment: si-system
source: Vogtle UFSAR §6.3 -
id: SUMP-SCREEN-DP
description: containment sump strainer differential pressure
sim-path: ess.sump.strainer.dp
units: psid
equipment: si-system
source: Vogtle UFSAR §6.3.2 -
id: RHR-PUMP-A
description: residual heat removal pump A status
sim-path: ess.rhr_pump.a.status
units: enum[STOPPED,RUNNING,FAULT]
equipment: rhr-system
source: Vogtle UFSAR §5.4.7 -
id: RHR-PUMP-B
description: residual heat removal pump B status
sim-path: ess.rhr_pump.b.status
units: enum[STOPPED,RUNNING,FAULT]
equipment: rhr-system
source: Vogtle UFSAR §5.4.7 -
id: CSPRAY-A
description: containment spray pump A status
sim-path: ess.cspray_pump.a.status
units: enum[STOPPED,RUNNING,FAULT]
equipment: containment-spray
source: Vogtle UFSAR §6.2.2 -
id: CSPRAY-B
description: containment spray pump B status
sim-path: ess.cspray_pump.b.status
units: enum[STOPPED,RUNNING,FAULT]
equipment: containment-spray
source: Vogtle UFSAR §6.2.2 -
id: PT-455
description: pressurizer pressure (wide range)
sim-path: rcs.pressurizer.pressure_wr
units: psig
equipment: pressurizer
source: Vogtle UFSAR §5.4