CEDMCS Flashcards
To where does CEDMCS send signals on a Reactor Trip?
Main Turbine for tripping DFWCS for RTO SBCS for QOB ERFDADS for indications SRP Downtown
How long does it take to drop rods 90%?
4 seconds
What powers the CEDMCS cooling fans?
NGN-L17
How many CEAs are in a subgroup?
4
Except the one that has 5
What does the Plant Computer supply to CEDMCS?
Upper Group Stop Lower Group Stop Sequential Permissive Upper Sequencing Limit Lower Sequencing Limit
What does RRS provide to CEDMCS?
Rate and Direction Signals
How many reed switch assemblies and voltage ladders are there per CEA?
2
How far apart are the reed switches on a CEA?
1.5 inches
How far is one step for a CEA?
0.75 inches
At how many steps does the Upper Electrical Limit occur?
200 steps
At how many steps does the Lower Electrical Limit occur?
1 step
What functions does the Dropped Rod Contact serve in CEDMCS?
- The rod bottom light on B04
- Tells the Plant Computer to zero the pulse counters.
If the Upper Latch Coil on a CEA is at a reduced voltage, is it holding or latching/moving?
Holding
What does CWP stand for?
CEA Withdraw Prohibit
What does AMI stand for?
Automatic Motion Inhibit
What does AWP stand for?
Automatic Withdraw Prohibit
Which rod inhibition can be bypassed?
CWP
When is a CWP enacted?
2/4 High Pressurizer Pressure Pre-Trip 2/4 Low DNBR Pre-Trip 2/4 High LPD Pre-Trip RPCB CEA Misalignment from CPCs/CEACs
When is an AMI enacted?
- > 5% deviation between redundant indicators for TLI, Reactor Power, and Tave when AVERAGE is selected on RRS
- Whenever Reactor Power < 15%
- When TLI < 15% and Reactor Power is below the lesser of
- SBCS availability + TLI or…
- AMI threshold setpoint.
When is an AWP enacted?
- Tave > Tref by 6F
- Tc > 575F
- SBCS Demand
What are the power supplies to the CEDMCS MGs?
NGN-L03
NGN-L10
What is the voltage output of the CEDMCS MGs?
240V
Is one CEDMCS MG enough for control rod operation in Manual Group?
No. But it is enough for Manual Individual operation
When does SPS open the CEDMCS MG output contactors and open the Trip Circuit Breakers?
2409 psia
Where can you see Trip Circuit Breaker position indication?
PPS
SPLA Cabinet
Locally
Are the Trip Circuit Breakers safety related?
Yes, but power through them is not
From where can you open the Trip Circuit Breakers?
- B05
- Locally
- PPS Cabinets (testing)
- SPLA Cabinets (testing)
From where can you close the Trip Circuit Breakers?
- PPS Cabinets (normal)
- Locally (testing)
- SPLA Cabinets (not OPS)
What, specifically, happens to the Trip Circuit Breakers on a trip?
They are tripped by the concurrent actuation of both shunt trip (energize to trip) and under voltage (de-energize to trip) devices.
What is the purpose in the CEDMCS MG flywheels?
They provide stored energy for 1 second of operation with no power.
What causes the Continuous Gripper High Voltage alarm?
A loss of subgroup logic power
If a Continuous Gripper High Voltage alarm is received, what must be done?
The affected subgroup must be placed on the hold bus within 10 minutes or the CEDM coil could burn up resulting in a dropped CEA
What results from any CEA subgroup being placed on the Hold Bus?
- CEDMCS Trouble Alarm
- Rods on Hold Bus won’t move in Manual or Auto
When rods move IN in MANUAL, what speed do they move?
30”/min
When rods move OUT in MANUAL, what speed do they move?
30”/min
When rods move IN in AUTO, what speed do they move?
3”/min or 30”/min
When rods move OUT in AUTO, what speed do they move?
3”/min
What is the trip logic for the Undervoltage Relays which monitor the CEDMCS bus voltage?
- 2/4 logic
- each relay will trip at 180V
When the trip logic is met for the CEDMCS UV Relays, what happens?
- Turbine Trip to EHC
- RTO to DFWCS
- PC and RK annunciators
- Sequential Trip/Coastdown Trip signal to Main Generator
- QOB to SBCS for X valves on Low Tave and RX TRIP combo
From where do the Digital Group and Individual Position Indication on B04 come?
Pulse counts
What does Manual Sequential require to work?
The Plant Computer
What alarm will be received if an Out of Sequence from the Plant Computer is detected?
CEA TECH SPEC VIOLATION
What will bring in the CEDMCS TRBL alarm?
- CGHV
- MG Set Overload
- Continuous CEA motion
- Any Subgroup on the Hold Bus
- local alarms
What will bring in the Continuous Motion Alarm?
30 seconds in high speed
60 seconds in low speed
What will bring in the CEA TECH SPEC VIOLATION alarm?
- Major/Minor deviations in CEA positions
- Out of Sequence condition
What happens to CEDMCS on a loss of PNA or PNB?
The associated RTCBs open (A and C or B and D) but power is maintained to the CEAs
What happens to CEDMCS on a loss of PNC?
- RTCBs A and C open
- Pac-Man on Core Mimic
- Pulse Counters for the lit Rod Bottom Lights will zero
- MI only method available for moving the remaining 1/4 of the rods
What happens to CEDMCS on a loss of PND?
- RTCBs B and D open
- Reverse Pac-Man on Core Mimic
- Pulse Counters for the lit Rod Bottom Lights will zero
- MI only method available for moving the remaining 3/4 of the rods
What happens to CEDMCS on a loss of NNN-D11 or NNN-D12?
Nothing
What happens to CEDMCS on a loss of NNN-D11 and NNN-D12?
- All CEAs will drop into the core.
- No Core Mimic, UEL, or LEL lights (during a Station Blackout, theres no easy way to verify that the rods are on the bottom)
What happens to CEDMCS on a loss of the Plant Computer?
- Only methods available for moving rods are MI and MG.
- Rods will not automatically stop at UGS and LGS
- Pulse counters are lost
- PDIL alarms are lost (out-of-sequenc, deviation, and exercise limit)
What happens to CEDMCS on a loss of CEDM Cooling?
CEDM Coils may be damaged if cooling is not restored or the coils de-energized within 40 minutes if RCS temperature is > 300F
What happens to CEDMCS on a loss of Aux Building HVAC?
Could cause rods to slip, drop, or move around randomly as the CEDMCS Cabinet Room heats up.
What does LCO 3.1.5 say?
- All full strength rods have to be operable
- All full and part strength rods aligned within 6.6” in their group - of not, then reduce power and restore alignment
- if 2 or more CEAs are > 9.9” = Trip immediately
- if 1 or more CEAs are untrippable = M3 in 6 hrs