FR-Z.2 — Response to Containment Flooding¶
CSF containment — ORANGE path. Entered when containment sump level
exceeds the design-basis post-LOCA level (typically corresponds to ~85%
RWST + spray volume per Vogtle UFSAR §6.2.2). Sump flooding past
design level threatens: (1) submergence of safety-related equipment
mounted in lower containment, (2) buoyancy challenge to containment-
isolation valves, and (3) overflow into auxiliary building if any
penetration is degraded. Two scenarios drive entry: a continuing LOCA
inventory contribution beyond design-basis, or containment spray
running longer than spray-termination criteria require.
CSF: containment
Step 1 verify-flooding¶
Check: containment sump level «CTMT-SUMP-LVL» above post-LOCA design level (typically > 85% per Tech Spec 3.6 figure); containment temperature «CTMT-TEMP» and pressure «CTMT-PR»
Caution: high sump level alone is not flooding — must be ABOVE expected post-LOCA inventory accounting (RWST delivered minus expected RCS retention)
- Flooding confirmed → #identify-source
Because: ORANGE-path response: identify and mitigate
- False alarm or within expected envelope → E-0
Because: return to diagnostic flow
Step 2 identify-source¶
Decision: identify the source of containment flooding
1. Ongoing LOCA delivering RCS inventory beyond design-basis — RCS pressure «PT-455» continues to drop or RWST level «RWST-LVL» depleting faster than expected
2. Containment spray running past termination criteria — spray flow «SPRAY-FLOW» continues with «CTMT-PR» in normal post-accident band
3. Non-LOCA source — auxiliary building cross-tie leak, RWST level instrument failure, or other secondary inventory pathway
- LOCA source ongoing → E-1
Because: ongoing LOCA management takes precedence; flooding is a consequence not the leading issue
- Spray over-running → #stop-spray
Because: throttle / stop spray to limit flooding
- Other source identified → #stop-spray
Because: defensive action — limit further inventory addition while source identification continues
Step 3 stop-spray¶
Action: throttle or stop containment spray pumps «CSPRAY-A» / «CSPRAY-B» based on cessation of spray-actuation criteria (containment pressure has returned to within spray-termination band)
Action: align spray suction to containment sump (recirculation mode) if cooldown phase has reached recirculation transfer per ES-1.3
Caution: do NOT stop spray if containment pressure is still above spray-termination band — spray termination criteria are based on pressure, not on sump level
- Sump level stabilizing → E-0
Because: containment flooding controlled; return to diagnostic flow
- Sump level continues to rise → ES-1.3
Because: cold-leg recirculation transfer routes RCS injection via sump; reduces RWST contribution to flooding
Tags¶
-
id: CTMT-SUMP-LVL
description: containment recirculation sump level
sim-path: containment.sump.level
units: percent
equipment: containment
source: Vogtle UFSAR §6.2 -
id: CTMT-PR
description: containment building pressure
sim-path: containment.pressure
units: psig
equipment: containment
source: Vogtle UFSAR §6.2 -
id: CTMT-TEMP
description: containment average temperature
sim-path: containment.temperature.avg
units: degF
equipment: containment
source: Vogtle UFSAR §6.2 -
id: PT-455
description: pressurizer pressure (wide range)
sim-path: rcs.pressurizer.pressure_wr
units: psig
equipment: pressurizer
source: Vogtle UFSAR §5.4 -
id: RWST-LVL
description: refueling water storage tank level
sim-path: rwst.level
units: percent
equipment: rwst
source: Vogtle UFSAR §6.3.2 -
id: SPRAY-FLOW
description: containment spray total flow (header)
sim-path: ess.cspray.header_flow
units: gpm
equipment: containment-spray
source: Vogtle UFSAR §6.2.2 -
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