CEA Malfunctions Flashcards
State when a Reactor Trip is required for CEA malfunctions.
A reactor trip is required when:
• CEA movement continues after CEDMCS has been taken to standby.
• IF one CEA is deviating from its group by greater than 6.6 inches, AND any CEA Reg Group
is below the Transient Insertion Limit.
• The Unit is in Mode 1 or 2, AND two or more CEAs are deviating by greater than 9.9 inches
from their associated group.
• The Unit is in Mode 1 or 2, AND 12 fingered CEA(s) misaligned from its group can NOT be
restored prior to receiving a DNBR or LPD trip.
• The Unit is in Mode 1 or 2, AND CPC ASI exceeds +/- 0.45 and trending to +/- 0.5 (Pt ID
0187) with the CPC Aux Trip on ASI still possible (above the Rule of 45), using Pt ID 0125.
For a CEA deviation prior to criticality, a reactor trip is required if ANY of the following conditions
exist:
• Two or more CEAs are deviating by greater than 9.9 inches from their associated group and
the CRS/SM determines a Reactor Trip is desired.
• Xenon transient adding positive reactivity and boration does not stabilize a rising count rate
For a CEA deviation prior to 1% power, a reactor trip is required if:
• The CRS/SM determines a reactor trip is desired.
• If any of the following conditions exist:
o Rising power results in any pre-trip alarm.
o Rising power challenges Mode 1 entry.
o Any operable High Log Power channel lowering to 1 x 10-4 % power.
What are the required actions associated with one or more trippable CEAs misaligned from its group by greater than 6.6 “ and <= 9.9” OR one trippable CEA is misaligned from its group by greater than 9.9”?
LCO3.1.5 requires the following actions and completion times when CEAs are misaligned from its group.
Reduce thermal power per the COLR within 1 hour AND realign the CEA within 2 hrs.
In order to do so, a power reduction must be started within 10 minutes and a target reached per the following:
Initially ↓ turbine load to ↑ Tavg 3°F above Tref
- > 80%: 20% reduction
- > 70% to 80%: 15% reduction
- > 45% to 70%: 10% reduction
- > 35% to 45%: 5% reduction
Borate ≥ 35 gpm
Charging pump suction (AOP App) OR emergency boration AOP
Once at target power level, stop the boration, start a dilution to maintain power and adjust turbine load as needed.
State the TCA associated with CEA malfunctions
Reduce power within 10 minutes of the dropped or slipped CEA.
UFSAR requires 15 minutes but the COLR states 10 minutes. LCO 3.1.5 requires a power reduction to be complete within 1 hour.
Not meeting the LCO requires a SD to mode 3 within 6 hrs.
Describe how the downpower required for a dropped or slipped CEA is initiated.
Log the time of the power reduction and reduce turbine load to raise Tave 3F > Tref.
State when a downpower for a dropped or slipped CEA is not required to be performed.
Down power NOT required if one CEA misaligned within 10” of top of core (per the COLR):
- One CEA misaligned
- CEAs > 142.5” (pulse counter)
- CEAs > 140.1” (RSPT)
- > 95% RTP
- COLSS / CEACs in service
- AZTILT
Down power NOT required if ≤ 35%
Following a required downpower due to a slipped or dropped CEA, discuss how the plant is stabilized.
When the App B requirements are met(downpower complete), adjust turbine load to maintain Tave/Tref mismatch. Stop the boration. Commence a dilution per the maneuvering box guidelines and STA worksheet to stabilize power due to effects of xenon.
If CEA recovery is not possible, what are the required actions of CEA malfunctions AOP?
The plan becomes to downpower the unit to < 20% power and perform a rx trip.
Describe how a CEA misalignment affects CPCs and COLSS.
POL calculations, Tq,
work in progress
A dropped CEA will cause DNBR and LDP POL alarms due to large penalty factors. If the radial peaking factor calculations are impacted heavily enough, then COLSS will cease calculations and the POL alarms will clear.
If the effects of a dropped or slipped CEA exceed the Tq constant in CPCs, then TS 3.2.3 needs to be addressed and action taken to ensure the plant is operated within Tq limits.
When a RG CEA(not RG5) slips or drops into the core, the affected quadrant CPC will trip LPD and DNBR channel trips due to penalty factors associated with OOS and subgroup deviation.
A 12 finger CEA will almost always result in a Rx trip due to the large PFs applied across multiple CPC channels.
Determine the minimum CEA withdrawal time for recovery of a slipped/dropped CEA.
Use of App C will assist in determining the MINIMUM time required for CEA recovery.
CEA recovery
- Recover within 2 hours or commence plant shutdown
- If the reason for the CEA deviation is known (e.g. ACTM actuation), an attempt to realign the CEA can be made.
- Determine withdrawal rate (based on CEA deviation and 1 hour since deviation)
- Withdrawal limits prevent over power conditions in the adjacent fuel
- Dropped (150’ deviation) for ≥ 1 hour: 30 minute withdrawal time (ranges from 0-30 min)
- Once recovered, maintain power stable for 1 hour to allow Rx Engineering to assess the core
If the CEA cannot be moved, align the group to the CEA:
- Only if RILs are maintained
- Move each CEA in MI and maintain 2 step overlap (1.5”)
