RRS Malfunctions Flashcards
Describe the actions required if a Temp instrument fails.
Temperature Instrument Failures (Tcold, Thot, or Tavg circuit)
- Ensure CEDMCS is not in AS (place in standby)
- Check PLCS controlling to the programmed level (take manual control if needed)
- Charging Pumps may cycle and letdown perturbations may occur when PZR level setpoint deviates from actual level or when the setpoint is restored to match actual level.
- If letdown isolates, perform loss of letdown AOP
- Determine if Tcold, Thot, or Tavg circuit has failed
- Failure of a temperature instrument could affect COLSS if the failed instrument is still reading within its normal range.
- Select the unaffected instrument at RRS cabinet
- Ensure Tavg/Tref mismatch is < 3°F
- Restore PLCS / CEDMCS to auto
Describe the effects of a Tc or Th failing HIGH.
Tc or Th Fails High (100% power)
Tavg selected to average
- AWP
- AMI
- PZR Level setpoint goes to max (52.6%) (Capped)
Tavg selected to affected channel
- AWP
- CEA auto insertion demand (High Rate)
- PZR Level setpoint goes to max (52.6%) (Capped)
Tavg selected to unaffected channel.
- AWP (Tc > 575° F) [Tc failure only]
Any Position
- Prevents SBCS Quick Open Block for Group X valves on reactor trip
- Prevents turbine runback demand on a cutback
- Max feed flow if in RTO until NR reaches 51.9%
- COLSS input is affected
- RC Loops Temp Hi alarm and test panel light
Describe the effects of a Tc or Th fails LOW.
Tc or Th Fails Low (100% power)
Tavg selected to average.
- AMI
- PZR level setpoint ↓ (letdown flow ↑ / CHP stops)
- Thot low: 33%
- Tcold low: 38%
Tavg selected to the affected channel.
- PZR level setpoint ↓ to 33% (letdown flow ↑ / CHP stops)
- CEA withdraw demand (move if not ARO)
- Depending on CEA position may cause CWP on DNBR, LPD or High PPZR pre-trips.
Letdown will isolate on high temperature (letdown flow ↑ / CHP stops) in ~ 90 seconds. Hard start the pump or take manual control.
Any Position
- SBCS: Quick Open Block for Group X valves on reactor trip
- Sends turbine runback demand to RPCS on a cutback
- No feed flow if in RTO
- COLSS input is affected
- RRS test panel light.
Describe the actions required for a TLI failure.
Turbine Load Index (TLI) Failures
- Ensure CEDMCS is not in AS (place in standby)
- If SBCS responds to the TLI failure or CRS directs, remove SBCS from Remote-Auto:
- Place SBCS in Emergency Off, Local-Auto, or Manual
- Rapid changes to SBCS Master Controller signal when in 1E control could cause perturbations in DFWCS which may result in a Rx trip.
- Determine affected TLI and unselect the instrument
- Restore Tavg/Tref to < 3°F
- Restore CEDMCS and SBCS to normal
Describe the effects of TLI failling HIGH
TLI fails high [Tref fails to 587°F]
TLI selected to average.
- AMI
- Prevents SBCS Quick Open Permissive.
- No SBCS AMI Permissive. No AMI until NI is < 15%.
- SBCS sends continuous runback signal (> 60% TLI).
TLI Selected to the Failed Transmitter.
- CEA auto withdraw demand (move if not ARO)
- CEA position may cause CWP on pre-trips.
- Prevents SBCS Quick Open Permissive.
- No SBCS AMI Permissive. No AMI until NI is < 15%.
- Continuous runback signal on a cutback (SBCS).
No cutback signal sent on main turbine trip.
Note: Any movement of TLI switch could affect DFWCS 1E control (potential trip
Describe the effects of TLI failing LOW
TLI Fails Low [Tref fails to 564°F]
TLI selected to average.
- AWP
- AMI
TLI selected to Failed Transmitter.
- AWP
- CEA high rate auto insertion demand
Any position
- SBCS Quick Open Permissive generated for ~10 seconds.
- TLI < 15% generates SBCS AMI Permissive
- Any movement of TLI switch could affect DFWCS 1E control (potential trip)
TLI Selected to Unaffected Transmitter (Hi/Lo failure).
- RRS test panel light only
Describe the required actions for a Control Channel failing.
Control Channel NI Failures
- Ensure CEDMCS is not in AS (place in standby)
- Determine affected NI and unselect the instrument
- Restore Tavg/Tref to < 3°F
- Restore CEDMCS to normal
- Ensure NI is in maintenance bypass on FWCS (use ARP)
Describe the effects of a NI failing LOW
NI Fails Low
NI selected to average.
- AMI, may see pulse to withdraw (rate of power change)
NI selected to affected detector.
- AMI generated by SBCS if failed to < 15%.
- May cause CEA withdrawal. (If no AMI, AS and not ARO)
- Only until rate of change power error goes away
Any position:
- DFWCS uses canned NI value for ATUN
- DFWCS could go through valve swapover if the 2nd NI fails low while one is in maintenance bypass.
Describe the effects of NI failing HIGH.
NI Fails High
NI selected to average.
- AMI
- May see pulse to insert (rate of power change)
NI selected to affected detector.
- May cause CEA Insertion until rate of change power error goes away if CEDMCS is in AS Mode.
Any position:
- Low power AMI can NOT be generated in SBCS
- DFWCS uses canned NI value for ATUN
