Loss of IA Flashcards
State when a Rx trip is required for a loss of IA.
Reactor Trip Criteria:
- Unstable plant conditions (CRS option)
- Unable to restore air header in CTMT
- RCP Controlled Bleedoff is being directed to the RDT (towards the end of the AOP)
- Prior to manually isolating air to CTMT or the Aux Bldg
What are the actions if IAA-UV-2 closes and is unable to be opened?
Place LD isolation valves in CMNT to close 515, 516.
Re-open IA CIV (IAA-UV-2) if closed.
If unable to open, restore IA in CTMT service air cross-tie (3.6.3 admin controls / no CTMT entry) or by aligning N2 to IA inside CTMT (requires CTMT entry)
If unable to restore IA to CTMT:
Trip the reactor and perform SPTAs
Trip all RCPs.
Isolate RCP bleed off.
Align N2 to the CTMT IA Header. (AOP Appendix)
Vent the RDT to containment as necessary to prevent the Rupture disk from blowing out.
State the differences between App K, Service Air to containment and App J, N2 to containment.
App K is not a T mod and aligns service air to containment requiring 3.6.3 admin controls.
App J IS a T mod and aligns N2 to containment. This requires a containment entry.
State the TS implications for a loss of IA in containment.
TS’s 3.4.5, 3.4.9, 3.4.14 and 3.6.3
Lpzr, RCS loops Mode 3, RCS operational leakage and Containment.
State the major actions associated with a loss of IA.
Evaluate manual reactor trip or down power (ZZ05) based on degrading plant conditions.
If any of the following valves failed closed, place the HS is closed
CH-515/516, Seal Bleed Off AOV, or SGBD CIVs.
If SGBD isolates, ensure COLSS constants are updated
Re-open IA CIV (IAA-UV-2) if closed.
If unable to open, restore IA in CTMT service air cross-tie (3.6.3 admin controls / no CTMT entry) or by aligning N2 to IA inside CTMT (requires CTMT entry)
If unable to restore IA to CTMT:
Trip the reactor and perform SPTAs
Trip all RCPs.
Isolate RCP bleed off.
Align N2 to the CTMT IA Header. (AOP Appendix)
Vent the RDT to CTMT if needed to maintain < 10 psig
Shift air dryers if large ΔP exists between air receiver and pressure downstream of the dryer
Operate air dryers in parallel if:
Large ΔP exists between air receiver and pressure downstream of the air dryer
One instrument air dryer is in service and a standby is available
IA pressure is ≥ 80 psig
N2 automatically aligns if IA pressure < 85 psig
If N2 is supplying air header:
O2 deficient atmosphere may exist in valve galleries and rooms below 100’ elevation.
O2 monitors used when going below 100’ elevation.
Post warning signs, Danger Tape, people to warn of the danger
Start at least one Fuel Building Exhaust Essential AFU on the Auxiliary Building.
≤ 28 psig in Fuel Bldg: locally align back-up N2 bottles to the gates
When will N2 backup supply the system and what shoudl be monitored/placed in service when this occurs?
- N2 automatically aligns if IA pressure < 85 psig
- If N2 is supplying air header:
- O2 deficient atmosphere may exist in valve galleries and rooms below 100’ elevation.
- O2 monitors used when going below 100’ elevation.
- Post warning signs, Danger Tape, people to warn of the danger
- Start at least one Fuel Building Exhaust Essential AFU on the Auxiliary Building.
- ≤ 28 psig in Fuel Bldg: locally align back-up N2 bottles to the gates
What is the major impact of lowering IA pressure in the Fuel Bldg and when and how is it solved?
Main impacts are the gate seals.
No action is initially necessary due to each train has compressed air or N2 that will automatically supply. As IA pressure < 28psig, action is requried to isolate the seal panels from the rest of the IA system and each other. App G will:
isolate seals from IA
Align instrumentation to check for proper operation and re isolate seals.
Predict how the plant will respond as IA lowers from normal pressures.
90 psig: Demin Polisher flow will be bypassed
80 psig: CD Pump mini-flow valves fail open. (↓ MFP suction pressure)
80 psig: HDT Pump disch valves fail closed / HDT high level dump valves fail open (↓ MFP suction pressure)
80 psig: SBCVs fail closed
75-65 psig: MFP mini-flow valves fail open
50-60 psig: ECCVs, MSIVs, and Economizer Isolation valves fail as is.
Post trip: ADVs and AFW will be used
45 psig:
RCP Seal Bleedoff diverts to RDT (505/506 close)
Letdown isolates (515/516/523 fail closed)
LDHX NC TCV fails closed
