Systems Flashcards
Draw the Electric Plant down to 4160v busses
List loads on the L10 Bus
CW Pump C
MFP
Interbus LH-1-A
S/U supply to L11
S/U supply to L12
List loads on the L11 Bus
CW Pump A
B33 Recirc Pump A (Fast)
Interbus LH-1-B
LF-1-A/C/E/H
(ACEHOLE)
List loads on the L12 Bus
CW Pump B
B33 Recirc Pump B (Fast)
Interbus LH-1-C
LF-1-B/F/D/G
List loads on the H11 Bus
RFBP A/C
CBP A/C
HWP A
CVCW Chiller A
TBCW Chiller A
LFMG A
SY Load Center
List loads on the H12 Bus
RFBP B/D
CBP B
HWP B/C
CVCW Chiller B
TBCW Chiller B
LFMG B
U1 SA & IA Compressors
SW Pump A
List loads on the XH busses
Which XH Bus is not diesel backed?
XH11:
CRD Pump A
NCC Pump A
XH12:
CRD Pump B
NCC Pump B
SW Pump B
XF-1-A
XH21: (Not diesel backed)
NCC Pump C
SW Pump D
Regarding Aux Transfer Switch function:
What is the purpose of the Aux Transfer Switch?
Will the transfer still happen with the switch in “Off”?
Aux Transfer Switch will prevent powering an L bus from 2 seperate transformers, which would result in twice the fault current with a fault in the affected L bus.
With the switch in “Off,” the transfer still occurs.
Regarding Fast Bus Transfer of L and H busses:
What causes a fast bus transfer to occur?
From which sources (primary or alternate) does a fast bus transfer occur?
What will happen when a breaker tries to transfer to a faulted bus?
Breakers auto transfer to alternate power supply if primary power supply goes down.
Breakers will not return to primary source if alternate source is subsequently lost.
Breaker will land in the trip free position.
Regarding Stub Busses
What are stub busses?
What happens to stub busses on a LOOP? LOCA?
What happens to loads on the stub busses in these situations?
Diesel backed busses with not required but desired loads on them.
During a LOOP, stub busses stay tied to their source. During a LOCA, stub busses shed and will not be tied in until operators bypass with keylock switch.
In a LOOP, the stub bus loads react as follows:
CRD Pumps - Pumps trip, will remain off until operator intervention.
NCC Pumps - Pumps trip, will restart automatically when stub bus power returns.
SW Pump B - Pump trips, and will restart provided the control switch is in normal, the pump receives a LOOP signal, voltage is restored to the bus, and the pump discharge valve reposition sequence completes.
In a LOCA, these loads remain secured.
Define LOOP, SBO, and TLAC
LOOP - Loss of Offsite power and at least one RHR powering DG is supplying its bus.
SBO - Loss of Offsite power with only HPCS operating.
TLAC - SBO with HPCS not operating.
Regarding Loss of Offsite Power:
List conditions for degraded and lost voltage.
What protections do the Loss of Voltage and Degraded voltage signals provide?
What causes an EH bus Undervoltage signal?
What causes a divisional LOOP signal?
Explain how LOCA signal ties into this.
What will cause LOOP logic to initiate?
Degraded Voltage - < 3800v
Loss of Voltage - < 3000v
Loss of voltage prevents damage to running safety related equipment.
Degraded voltage ensures injection times and system alignments are accomplished.
< 3000v for 3 seconds, < 3800v for 4 mins, or < 3800v for 12 Seconds with a LOOP signal. This timer begins upon receipt of the undervoltage signal.
Bus undervoltage signal, Bus UF signal (59.1hz), or Divisional Test Switch to Test
AND
Opposite divisional bus UV < 75% (instant), or Opposite divisional bus UF (< 59.1hz).
Which 480v Buses can be cross-tied?
F1A - F1B
F1C - F1D
F1E - F1F
F1G - F2G
EF1A - EF1B
EF1C - EF1D
Explain how Div 3 480v differs from Div 1/2
Div 3 does not have load centers.
EF-1-E is comes straight from the transfomer to the MCC.
Where is the Div 3 Transformer located?
Where are the Div 3 MCCs located?
EHF-1-E - CC 620’ inside the Div 2 Room
EF1E-1 - CC 620’
EF1E-2 - ESWPH 586’
Where are the Non-Class 1E load centers located?
F-1-[A-F] -> TPC 647’
F-1/2-G -> SWPH 620’
F-1-H - ConstWPH 620’
XF-1-A - TPC 620’
Where are busses L10,11,12 located?
TPC 620’
Which Non-Class 1E MCCs have ABTs and which bus do they transfer to?
F1B08
F1C08
F1D08
F2A08
F2B11
F2C11
Transfer to XF1A
List the conditions required for an ABT to autoshift from Normal Source.
Which ABTs are normal seeking, and how long until they return to normal source?
MCC bus voltage < 85% rated
Alternate power supply voltage and frequency > 90%
No lockout on the XF1A bus.
F1B08, F1C08, F1D08 are normal seeking and will return to normal source with power available for >30 minutes.
What are the indications of a ground on a DC bus?
What action should be taken if a ground is discovered?
Positive or negative circuit ground light will extinguish.
If a ground is detected, loads should be secured to perform a ground isolation.
Which DC load centers have reserve chargers?
All except for D1B
List Safety Class DC buses and their locations.
ED1A & ED2A - CC 638’
ED1B & ED2B - CC 638’
ED1C & ED2C - CC/DG 620’ Inside the DG Panel
ED-2-C is in a room located at the exit of the RP Control Point
How many cells in the Div 1 and Div 2 DC buses?
How many volts per cell?
What is the design basis of this voltage and quantity?
Div 1 - 60, Div 2 - 61
1.75V Per cell
Designed to maintain a voltage above 105v with a loss of charger for 2 hours and one cell < 1.75Vdc.
Cells are for batteries, not buses. Div 1 has the extra cell (RCIC).
List all Non-Safety DC buses and their locations.
Which of these are diesel backed, and where do they get their normal power from?
DC busses and batteries have power available regardless of DG status.
D1A & D2A - Unit 1/2 TPC 620’
D1B & D2B - Unit 1/2 TPC 620’
D1A and D1B are diesel backed from F1D08 & F1B08 respectively. Their normal source is L12.
D1A and D1B are DC, not DG backed. (Their normal chargers are DG backed)
List the major loads on BOP System A - D1A & D2A
Inverter DB-1-A for Vital Loads
Dis Panel D1A06
Control Room Annunciators
C34 Chart Recorder Upset Range
Main Generator and Xfmrs Logic
RFPT A Trip, reset, and test logic
MFP Trip Logic
Main Turbine Trip Logic
Normal, Reserve, and Unit 2 Charger
These are smaller, less demanding loads, generally circuitry.
List the major loads on BOP System B - D1B & D2B
Main Turbine EBOP
RCIC Gland Seal Compressor
Emergency Hydrogen Seal Oil Pump
RFPT A and B EBOP
MFP DC Lube Oil Pump
Dist Panels D1B06 & D1B07 which include:
BOP Switchgear breaker control power (Control power for all non-safety buses including stub busses)
Emergency Lighting
Feedwater Control 24vdc for DFWCS
RFPT B Trip, reset, and test logic
DG Fuel oil booster pumps
LFMG Control and Interlocks
Local annunciators
Generator Field Breaker Control Circuitry.
L10,11,12 and H11, 12 remote control/trip functions.
Normal charger
No reserve charger
These are larger loads like DC pumps. B for “Big”
List the major loads of Div 1 and Div 2 DC system.
Make sure to differentiate any key differences between divisional busses
Normal Charger
Reserve charge
Divisional RHR valve control and indication
RCIC System Valve Motors (Div 1 only)
RCIC control and indication (Div 1 only)
RCIC Logic (Div 1 only)
ADS Logic
Leak Detection Logic
RPS Instrumentation
RRCS Logic
LPCS Logic (Div 1 only)
LOCA Logic
Remote Shutdown Logic
Divisional Control Room Indication
Divisional DG Controls and Field Flashing
Divisional B33 Pump breaker control logic
Divisional ATWS UPS
Divisional Breaker Control Power
Optical Isolators
List the major loads on Division 3 DC System
Div 3 Generator Control
Div 3 DG Field Flash control
HPCS Logic
Div 3 Breaker Control Power
Div 3 Control room indicators
Div 3 optical isolators.
Regarding the BOP inverter:
What is the purpose of the static transfer switch?
Are there any inhibitors on its functions?
Automaticall shift power supply from normal to alternate on the following:
Overcurrent - Can auto switchback
Undervoltage - Can auto switchback
Continuity OOS - Manually reset
Loss of power to battery - Manually reset - This switch will only occur after a 15 minute timer has elapsed and has detected that DB1A still has no normal or alternate source.
Regarding all Inverters
What is the purpose of the static transfer switch?
The static transfer switch automatically shifts the inverter from the normal DC source to an alternate AC source.
Regarding BOP Inverter
What are the purposes of the regulating and isolating transformers?
Regulating Transformer - Adjusts output voltage to maintain constant voltage during changes in load.
Isolating Transformer - Eliminate electrical noise.
What are the normal and alternate power supplies to the BOP Inverter?
Normal - D-1-A
Alt - F1D08
What are the loads on the ATWS UPS?
APRMs
LPRMs
NI Flow Instrumentation
ERIS Das Cabinet
What pumps water for the site fire water system?
Discuss their controls and interlocks.
Jockey Pump - Auto start at 130# and Auto Stop at 150#. An autostart of the Motor or Diesel fire pumps will trip this pump and prevent it from starting.
Motor Fire Pump - Auto start at 120# or control room pushbutton.
Diesel Fire Pump - Auto start at 105#, loss of battery charger, or control room pushbutton. During a LOOP, the diesel fire pump starts due to loss of battery charger for 10 seconds.
How is charcoal deluge actuated and why is it actuated this way?
Manual only, due to potential to overload floor.
List all areas supplied by CO2 Fire Control
Recirc pumps
DG Rooms
TLO Storage Rooms
TLO Purifier Rooms
Computer Room Subfloor
Control Room Subfloor
Hose Reels
What are the Master Control valves?
What is their normal position?
What position do they fail in?
Root valve from CO2 supply to selector valves in various locations of the plant.
Normally closed.
Fail open on loss of power.
What are the Selector Control Valves?
What are their normal positions?
What position do they fail in?
Isolations for supplied areas/components of CO2 Fire Control.
Normally Closed
Fail Closed on loss of power.
Regarding the CO2 isolations for Drywell/Containment
Explain logic of the containment outboard isolation valve, its normal position, and its isolation signal.
Must be opened manually.
Normally closed.
Closes on BOP LOCA/1.68# Drywell Pressure.
With an alarm indicating a B33 Recirc pump fire, the Recirc pump selector valve is open for 40 minutes. In this time, the outboard containment isolation valve must be actuated for at least 1 minute, otherwise no CO2 will reach the Recirc pumps in the event of a recirc pump fire.
List areas protected by Halon
SB 640’
Telephone Battery Room
Metrology Lab
SB 605
TSC
Radio Communication Room
Computer Room
Explain Halon Remote System Logic Panel Automatic System Actuation
Need 2 signals, 1 signal per zone.
What is the purpose of the Bioshield?
Provide radiation and heat shielding
What are the purposes of the Suppression Pool?
What is its normal operating band, low level setpoint, and design temperature?
Provide water seal from containment to drywell.
Provide heat sink for SRVs
Provide means to suppress pressure transients from a DBA
Source of water for ECCS
Normal level - 17.8’ - 18.5’
Low level setpoint - 16.75’
Design Temperature - 185F
Purpose of the guard pipe penetrations and when are they required?
Surround high energy systems. They prevent containment overpressurization by directing pipe breakage back to the drywell. Required at > 275# or > 200F
How are electrical penetrations in the containment sealed to prevent outleakage?
They are hermetically sealed with 28-30# of Nitrogen purge that prevent moisture intrusion and O-ring leakage.
List the containment and drywell internal and external pressure limits
Internal Containment: 15PSIG
Internal Drywell: 30PSIG
External Drywell: -21PSID
External Containment: -0.8PSID
At what suppression pool temperature must the Reactor be shut down?
At what temperature must it be emergency depressurized?
> 110F
120F
What is the difference between a Dedicated Air Lock Operator and an Airlock Monitor?
Dedicated Air Lock Operator is required to comply with tech specs and ensures only 1 door is open at a time.
The monitor is required per Shutdown Safety and is only in place to bottle up containment.
Effects of Loss of IA, LOOP, and LOCA on Containment Airlocks
Loss of IA - Electro-Mechanical locking pin does not engage. Door can be operated twice with the ammount of air available in the accumulators.
LOOP - Control power is gone. Electro-Mechanical locking pin does not function. Can manually operate without power.
LOCA - Bottom doors and upper outer door air isolates on BOP LOCA. Upper inner door air isolates on RHR LOCA
Where does the area between the airlock seals vent to?
Annulus
Explain the normal flowpath of the FPCC system
Skimmers
Isolation Valves (Reactor Pools Only)
Surge Tanks
Pumps
Heat Exchangers
F/D Inlet Valves
F/Ds
F/D Outlet Valves
Isolation Valves
Describe the normal flowpath in RWCU
Suction from Loops and RPV Bottom Drain
2 Pumps in service
RHX
NRHX
Filter Demins
RHX
Back to Feedwater system
When should Supp RHR Fuel Pool Cooling be used?
What restrictions are associated with this?
When Lower Pools can not be maintained < 150F
Unit must be in Cold S/D
Applicable RHR system is INOP
What is the upper pool temperature high limit and why?
< 110F in Modes 1,2, & 3 for SPMU to function as designed.
FPCC system response to BOP and RHR LOCA, LOOP.
What must be done in a LOCA or LOOP?
A BOP LOCA will isolate the containment isolation valve for the upper pools.
An RHR LOCA and LOOP will isolate NCC to the FPCC HXs. ESW can be manually aligned to support cooling FPCC system.
During a LOCA the FPCC F/Ds will isolate due to tank pressure ratings.
Explain how upper pool inventory is maintained in the event of a system leak.
Siphon breakers on the upper pool prevent the siphoning of the pool through the return headers when a leak develops.
Explain how system inventory and flow rates effect FPCC Surge tank
Inventory added - Tank level increases
Invetory removed - Tank level decreases
Flow rate increased - Tank level decreases
Flow rate decrease - Tank level increases.
FPCC pump trips
Surge tank level low 8.5”
Location of Fuel Transfer Tube Day Tank
Location of Fuel Transfer Tube Drain Pump
Fuel Transfer Tube Drain Pump Autostarts/stops
IB 574’
IB 574’
Will start and stop based on level in auto. In start, will start if low level is clear.
List the requirements for safe condition of fuel or core components
Properly seated in the reactor vessel
Seated in designated storage location
In IFTS carriage inclined in either CB or FB limit switch positions
Fuel Prep machines fully submerged
Properly seated in the designated location of the Hi-Storm
How does a loss of RPS Bus B effect FPCC system?
The inboard containment isolation valve for the upper pool suction line is isolated. This will cause the upper pool to overflow if the upper pool return line is not isolated.
The inboard inlet isolation valve is a check valve and will not isolate.
If SPCU is running, what systems can cause a trip of the SPCU Pump?
What trips exist for the SPCU pump?
What are the start permissives?
LPCS and RHR will cause a low flow trip if aligned to the full flow test return line.
HPCS can cause a low flow trip due to sharing suction piping in the suppression pool.
Low flow - 400 gpm for 5 seconds
High Demin Inlet Temp - > 120F
Permissives - Suction path 100% open.
SPCU system response to BOP and RHR LOCA
SPCU suction isolations close on a BOP LOCA
Demin outlet isolation closes on RHR LOCA
Restrictions of using RHR B Loop as a SPCU return to SP
RHR B Must be declared inoperable.
What systems does the SPCU system interact with and how?
HPCS - SPCU utilizes the HPCS suction piping.
FPCC & SPCU can be aligned to each other to support cleaning.
RHR - SPCU discharges into the test return lines back to the suppression pool.
LPCS - If SPCU RHR A return path is used, LPCS shares that return path.
Condensate - SPCU can be used to transfer water from the SP to the Hotwell or CST.
WCT - SPCU can be used to transfer water from the SP to the WCT
What does SPMU provide?
Can it ever be overridden?
Additional heat capacity for cooling to the suppression pool.
Yes, but NEVER IN A LOCA.
Explain SPMU logic
- LOCA Signal 30 Min Timer
OR - SP Lo Lo (16.5”) or Arm and Depress
AND
RHR LOCA signal or Test switch to Test.
How is the 30 Min SPMU LOCA timer reset?
Taking the SPMU Auto/OFF keylock to off.
What will cause the SPMU TRAIN A/B NOT NORMAL alarm to actuate?
If in Refuel and Mode switch is in Auto
If NOT in Refuel and Mode switch in Off
Will arm and depress of RHR LOCA switch cause the 30 min SPMU timer to actuate?
Where does SPMU receive its signal for 30 min timer?
No
The K110 relay in RHR LOCA logic.
The K110 relay is NOT the signal for the 30 minute timer!
Where does AEGTS treated air exhaust to?
Train A - Unit 1 Plant Vent
Train B - Unit 2 Plant Vent
What system provides the motive force for Backup Drywell Purge?
AEGTS
What is the purpose and flowpath of Backup Drywell Purge?
AEGTS fans drag air from the drywell through B/U Drywell purge piping.
Backup drywell purge provides pressure relieving and control capabilities to support startup and heatup and mitigates pressure build up from air leaks.
What will cause the backup drywell purge system to isolate?
Auto close CIVs on RHR LOCA - Can be overridden and will get an amber light.
Auto close CIVs on High Drywell Gas Radiation - Can be overridden and will get an amber light.
Explain how the AEGTS Electro Hydraulic Actuated Dampers Work
There are recirc and exhaust dampers that operate concurrently to regulate annulus pressure.
The standby system is aligned to full exhaust.
On a loss of power or hydraulics, recirc will fail closed, exhaust will fail open.
Consider the failure as “maximum vacuum”
AEGTS Fan Auto Starts
Which ones can be overridden?
What are the effects of a LOOP on these fans?
RHR LOCA - Can be overridden and will get an amber light
Low Flow Auto Start of STBY Fan (< 1500 cfm) - Can not be overridden
They will momentarily shutdown, then restart with the D/G
What are the trips and start permissives of the AEGTS duct heaters?
When do they autostart?
Trip on loss of any permissive
Permissives:
No Hi Hi Htr trip (>225F)
No Hi Htr Temp trip
<166.2F fan discharge temp
Exhaust fan running, and valid flow signal
Heating coil thermostat circuit closed.
Autostart on RHR LOCA. Can not directly override. Override by securing the applicable fan.
How does the exhaust/recirc damper controller function?
How does this controller fail and why does it fail that way?
0% - Full open exhaust, recirc closed - MAX VAC
100% - Full open recirc, exhaust closed.
Fails to maximum vacuum (0%) to ensure all leakage is filtered before release to the environment.
What is the Tech Spec atmospheric temperature limit in containment?
=< 95F
How many AHUs are in the containment vessel and what cools them?
How many fans per AHU?
How many normally operate and whats the maximum amount allowed to operate?
6, cooled by CVCW
1 fan per AHU
4 Normally operate, but 6 can be operated for maximum cooling.
Are the containment cooling system fan discharge dampers electric or pnuematic?
How are they controlled?
How do the Containment Cooling system fan discharge dampers fail?
Pnuematic
Automatically actuate based on fan operating/secured, prevents reverse flow.
Fail closed on loss of air or power to solenoid.
How many AHUs operate in the drywell?
How many fans per AHU?
What cools them?
3 AHUs
2 fans per AHU
Cooled by NCC
How is the Containment Cooling system effected by LOCA?
CVCW Containment Isolations close on BOP LOCA. System will no longer cool.
How is the Drywell Cooling system effected by LOCA?
DW AHUs are cooled by NCC and will isolate on an RHR LOCA. System will no longer cool.
Drywell fans are powered by the Stub Bus and will lose power until power is restored by operators.
Regarding the 2 cooling coils in a drywell AHU:
How is the operating cooling coil determined? What features provide redundancy?
The operating DW AHU coil is determined by a 3-way AOV selector.
The valve fails to the B coil on loss of air.
The valve also fails to the B coil on loss of solenoid power.
Where does Drywell AHU condensation drain to?
Are there any alarms associated with these AHU drains?
Upper and Middle AHUs drain to the Drywell Equipment Drain Sump. Control room has an alarm for excessive flow provided by Leak Detection System.
Low Drywell AHU drains to the Drywell Floor Drain Sump
What atmospheric temperature is the lower Drywell Cooling AHU designed to maintain and why?
< 120 F on the RPV Skirt but > 80F to avoid brittle fracture.
Drywell Cooling Fan auto starts and stops
Fan will autostart on running fan low flow if in standby.
Standby fan will autostop when low flow condition clears.
Running fan will not trip on low flow condition.
Containment and DW Vent Exhaust damper trips and logic
Radiation Hi-Hi or downscale
Inboard/Outboard logic
BOP LOCA
Explain the rotating red beacons for the DW purge surge tanks. What is the basis for this? When are they disabled? What actions must be taken if these beacons are illuminated?
Beacons will illuminate red if tanks are not full. If the tank is not full, it is possible that the DW purge lines are not completely filled with water, and this will create a nuetron radiation stream into containment.
This alarm can be disabled when in Mode 4 or 5.
Must contact the US and RO and notify them.
Where does the CDWP system exhaust to?
Unit 1 Plant Vent
Explain the modes of operation of CDWP system
Intermittent - 1 Containment purge supply fan and 1 CDWP Exhaust fan in operation. No drywell purge supply fans operating.
Refuel - 2 Containment purge supply fans, 2 CDWP exhaust fans, 2 Drywell purge supply fans operating.
DW Purge supply ductwork is drained.
Intermittent starts for 5 min in Flow mode, then switches to DP mode
How many air operated isolation valves are in the CDWP system and how do they fail on loss of air, loss of power, and LOCA?
14 Air operated isolation valves.
Fail close on loss of air and loss of solenoid power.
Will isolate on BOP LOCA and Hi Hi radiation.
There are 4 radiation detectors in the Exh Plenum with INBD/OTBD logic.
There is a 5th radiation detector, too that only activates the Containment and Drywell evacutation alarms.
How does CDWP Vortex Damper modulate flow?
Vortex damper can modulate flow based on a preset flowrate or a Containment DP signal (There is a 5 min time delay on this signal).
When the system supply fan damper switch is in normal, flowrate is controlled by the preset flowrate setting, then switches to the DP signal after the 5 minute delay.
What is the purpose of the Combustible Gas Control System?
Maintain LOCA Hydrogen concentration < 4% (Lower Explosive Limit)
What are the normal operating conditions and limitations of the Hydrogen Recombiner?
Minimum temp of 1150F
Will ramp at 1225F and 2% Hydrogen Concentration
Normal Operating Range 1225-1400F
Maximum operating power < 75KW
Must be shutdown if Hydrogen Concentration > 6%
If the Hydrogen Recombiners are inoperable, what must be available?
One division of Hydrogen Igniters
What locations are sampled for Hydrogen by the Hydrogen Analyzers?
Drywell Dome
Containment Dome
Drywell Head
Above the Suppression Pool
Explain the blue permissive light associated with the Hydrogen Analyzers
Light comes on after 3.5 mins to indicate a representative sample is achieved.
After a shift, the sample is most accurate after 15 minutes due to purging of old sample.
List trips of the Combustible Gas Mixing Compressors that are always active
RHR Breaker Open
RHR Cooling Supply < 90% open
Compressor discharge < 90% open
C/S For compressor taken to stop
Effects of a loss of power to Hydrogen Igniters
Igniters will not function and will not re-energize without operator action once power is restored. This is to ensure operator can verify Hydrogen concentration low enough to allow for starting.
When must Hydrogen Igniters be operable?
If the Hydrogen Igniters are inoperable, what must be available?
What makes the Hydrogen Igniters inoperable?
How many igniters are there per division?
Both Hydrogen Igniter systems must be operable in Mode 1/2.
Both Hydrogen Recombiners and Mixing Compressors must be operable.
=< 90% of hydrogen igniters not functioning per division.
52 in Div 1, 50 in Div 2
<=90% of igniters cause inoperability.
Describe the flow paths for the Containment Vacuum and Drywell Vacuum relief systems
Drywell:
Containment -> Check Valve -> MOV -> Drywell
Containment:
Atmosphere -> Annulus -> MOV -> Check Valve
Tip: You can physically operate either check valve from inside containment.
Explain the Containment Vacuum Relief System MOV Logic
MOVs are normally open. They auto close on BOP LOCA as long as there is no vacuum in containment.
They can not be closed if vacuum condition exists.
They can not be opened if positive pressure exists in containment.
They will always open if containment is under a vacuum and always close if containment is under pressure.
The last two statements are only true if a LOCA signal exists.
Explain the DW Vacuum Relief System MOV Logic
They are normally closed valves. They will open when a DW Vacuum condition exists.
They will auto close on a BOP LOCA. If a vacuum condition exists, they will re-open and will actuate their override. At this point they must be manually closed to close, even if vacuum clears.
How many Cont and DW Vacuum reliefs must be operable?
Containment - 3 shall be operable and 4 shall be closed.
Modes 1,2,3, Movement of recently irradiated fuel
Drywell - 2 shall be operable.
Modes 1,2,3
What are the consequences of leaving having 2 supply fans running in the FHB ventillation system?
Areas of the IB that are contaminated will become positively pressurized.
FHB Ventillation response to a high airborne radiation alarm?
Sensed in the exhaust duct upstream of the exhaust plenum will trip the supply fans.
Exhaust fans will continue to operate.
Barometric dampers will pop open to provide air supply.
Explain the FHB C Exhaust fan power supply setup
Powered by EF2D, which is powered by either EF1B or EF1D with a kirk key interlock in the access control area.
List the control modes of DFWC
Low Flow
Single Element
Three Element
Speed Control
How does low flow control work?
What restrictions are associated with low flow control?
Valve position controlled based on Level error and Low Flow Control Valve Flow
Used when < 3% Prx
Capacity is 1400 GPM
Can not be used with MFP, as MFP control valve and this valve will not work well in unison.
How does single element control work?
When is it typically used?
What restrictions are associated with Single Element
Controls MFP Flow Control Valve &/or RFPT Speed demand based on Level error only.
Used when Prx is 3-15%.
Must have a RFPT running/available and its controller in AUTO or a MFP running/available and its controller in auto.
AND
Reactor level signal GOOD
AND
RRCS FW Runback not active
AND
Operator disables transfer to 3 Element
How does three element control work?
When is it typically used?
Why is three element preferred to single element in this range?
What restrictions are associated with Three Element control?
Adjusts RFPT Speed demand &/or MFP flow control valve position based on Level, Total Steam Flow, and Total Feed Pump Flow.
Typically used above 15% Prx
At least one RFPT running/available and its controller in AUTO or MFP runnin/available and its controller in AUTO
AND
Reactor level signal good
AND
RRCS FW Runback not active
AND
Steam Flow signal good
AND
Feed flow signal good
AND
Operator enables transfer to 3 element control.
The reactor is at 40% power when the operator shifts from 1E to 3E. The output Steam flow/Feed Flow Error circuit is failed HIGH.
What will happen when the transfer is enabled?
What should the operator’s actions be?
Initially, DFWCS would sense a high steam flow - feed flow error and increase feed rate significantly. This would cause a rapid rise in Reactor Level.
The operator should take Manual control of the RFPTs IAW ONI-C34.
If the operator transfers back to single element control with level significantly higher than required, the follow will happen:
Recirc pumps are in fast speed. When transferred back to slow, feed flow may drop to < 3.43 mlbm/hr. If it does, the B33 cavitation interlock will trip and cause the recirc pumps to automatically downshift to slow speed.
What are the two methods of controlling RFPT speed?
DCS
Manual Potentiometer
Which range of level detectors does the RFPT trip get its signal from?
How many of these range detectors are there?
How many are required for a trip?
What else does this range input to on the DFWCS?
How can these detectors effect the main turbine and RFPTs?
What else are these detectors used for in regards to providing trips?
Narrow Range
3 detectors, 2 required for trip.
Also inputs into L8 alarm circuit and Median Level Circuit.
They provide the L8 trip to the main turbine and RFPTs.
They also provide the L7/L4 alarm trips, the L4 B33 FCV runback trip, the L3 downshift, and setpoint setdown.
How does 3 element control work?
What instruments does it get its signals from?
3 Element control receives input from the narrow range level instruments, steam flow detectors, and feed flow (Feed flow venturis) to generate an error that adjusts RFPT speed and/or MFP flow control valve position to adjust level to its programmed setpoint.
What is the median level circuit?
What are automatic trips associated with failures in this circuit?
One bad signal, two bad signals, and three bad signals.
Median level circuit is part of three element control that determines which level to use in the program error. With 3 detectors, the median level is chosen for the program error level variable.
One bad signal will be disregarded and the lower of the two good signals is used.
Two bad signals will transfer to manual and the last signal from the Median Level circuit is propagated.
With three bad signals, automatically transfers to manual and level signal forced to low scale of 165” and propagated.
What level deviations cause trips in the DFWCS?
A signal > 8” from median level - CAD Alarm
Any signal > 15” from any other level signal - RX CH ERROR HIGH alarm
Two signals > 8” from mediau - System trips to manual control.
One signal > 8” from median and another signal BAD/Bypassed - System trips to manual.
Explain the program level circuit.
What kind of shennanigans does this cause with level related trips?
Program level is 196” to 201”. Level remains at 196” until approx. 45% Prx, at which point it increases linearly to 201” at 95% Prx.
Certain trips are not based off of static reactor levels, like Reactor Level 4 Trip. These trips will vary in setpoint based on Prx.
What inputs do the steam flow detectors have in the DFWCS?
Input to level programming circuit.
Inputs to steam flow recorder.
Input to 1E/3E level controller.
Inputs to feed flow/steam flow mismatch.
What will cause an auto transfer to 1E control when in 3E?
Loss of any steam flow transmitter
Loss of 2 suction transmitters
2 suction transmitter with a 5% deviation
Loss of recirc flow signal on running pump
What are the suction flow transmitters?
How do they work?
What trips are associated with them?
Two flow transmitters on the suction side of each Feed Pump.
With 2 good transmitters, flow is averaged to an output.
If one transmitter is BAD or bypassed, only the good transmitter is used for output signal. DFWCS will remain in 3 element.
With > 5% deviation in the transmitters or both transmitters fail, DFWCS will auto transfer to 1E control.
With both transmitters failing, the FWP recirc valves will trip to 100% open as well.
Explain the flow path from the MS Header through the main turbine
Stop Valves -> EQ Header -> TSV -> TCV -> HP Turb -> MSR -> Cross Around Piping -> CIVs -> LP Turbine -> Condenser
What is the minimum flow requirements for the MFP and RFPT?
How are the RFPT and MFP recirc valves controlled?
What restrictions are on the operator when controlling in manual?
What happens if a flow control transmitter fails?
MFP - 4000 GPM
RFPT - 7000 GPM
Normally controlled by the operator to maintain Feed flow in program band according to error.
Operator may open the recirc valve further than program, but can not close further than demand signal.
The recirc valve associated with the flow controller will fail open to 100% and the pump will shift from three element to one element control.
What is the purpose of the TSVs?
Which TSV has an internal bypass and what is its purpose?
What is the purpose of the equalizing line in the TSV?
2 TSV has an internal bypass used for chest warming and equalizing dp across all TSVs
Quickly stop steam to the HP turbine in emergency or turbine trip situations.
Allows even flow through TSVs regardless of how many TCVs are open
What is Setpoint Setdown in DFWCS?
What does it do?
What is the purpose of this feature?
A hot button on the DFWCS display.
Automatically initiates on a L3 Scram and any time you go below L3 after.
For 10 seconds, it will maintain RPV level setpoint due to shrink (usually 196”) and then lower the setpoint to 178”.
This prevents a level 8 trip from over feeding and cold water swell.
At L8, all FWPs trip. It is undesirable to lose these pumps in a Scram if they are available for level control.
Regarding the Main Turbine System
How many CIVs are there?
What is the purpose of the CIVs?
6 CIVs. They protect the main turbine from overspeed (energy stored in the MSR) after trip.
How is thrust bearing wear tracked?
What setpoint will cause a main turbine trip?
Thrust bearing wear detector.
Will trip when the sensed oil pressure drops to 8# and lowering.
What are the start permissives of the turning gear?
When will it auto start?
What alarms come off the turning gear?
In reference to the recent OE where turbine rotor bowed:
“Oh my god they never even looked.”
One Bearing Lift Pump (> 265 psig)
Main Lube Oil Pressure (15 psig)
Generator OP Bkr(610/611), disconnect S112, or S111 open
Turning Gear CS not in off
No quill shaft failure as sensed by EHC
EHC Confirmation <100 rpm
Low speed switch picked up (1.5 rpm)
Auto starts at < 1.5 RPM shaft speed
TURNING GEAR NOT RUN/NOT ENGAGE
Normal Operating Parameters of Main Turbine and Turning Gear system
What are the turbine oil temperature limits?
Condenser Vac < 5” HgA
Turbine Oil Pressure (Bearing Header) 20-35 psig
Turbine Oil Pressure (Shaft Oil Pump) 220-265 psig
Main Turbine LO Temp 110-120F
Turbine Bearing Vibration < 5 mils
80-95F oil supply when on turning gear
90F min supply when rolling
110F min when operating normaly
List all Turbine Trips
RCIC Initiation
Generator Lockout
Thrust Bearing Wear
Manual trips
“Two fast” - Overspeed (110%, 1980 rpm) and B/U Overspeed (110.5%)
“The High Threes (Like High Seas)” - Hi Rx Lvl (L8), Hi MSR level
(1 - 195”, 2 - 217.5”), Hi vibes (12 mils)
“Loss 4 Words” - Loss of 125VDC (Active below 75% Turbine Speed), Loss of 24VDC, Loss of Stator Water Cooling (81C or 42.5 psig header pressure), Loss of Speed Sensors (Active when > 100 RPM)
“5 B-Low” - Low Vacuum (8.1” HgA), Low EHC Pressure (1100psig), Low ETS Pressure (400 psig), Low MSOP d/c pressure (100 psig, active above 75% Turbine speed), Low Bearing Header Pressure (12 psig)
Which turning gear interlocks does the Jog Pushbutton bypass?
Reverse Power Interlock and Turning Gear Oil Pump Discharge pressure
What are normal causes of Turbine vibrations and the reasons associated with them?
Critical Speed - 1500 rpm - Harmonics of the turbine amplifies vibration.
Packing Rub - Operation at low power, bypass steam, and packing adjusting to temperature can cause a temporary bow of the rotor resulting in imbalance.
Oil Whip - When bearing is lightly loaded, formation and collapse of oil wedge can cause vibrations.
Thermal Sensitivity - Magnitude and phase angle changes with load
Mechanical Unbalance
What is a quill shaft?
What indications show that the quill shaft is functional?
A type of shaft coupling that spreads torque over a longer distance on adjoining components.
Low speed switch picks up (1.5 rpm)
EHC Confirmation < 100 rpm.
How are TSV, TCV, Turbine Steam Drains, and CIVs positioned during turbine warm up?
TCVs are open, CIVs closed, all Turbine drains but 1 are closed, and #2 TSV poppet is thorttled to maintain pressure 60-100#.
Explain how the turbine reacts to a change in reactor power.
For a power increase:
Pressure Increase
Voids collapse, adding reactivity
Fuel temperature rises, adding negative reactivity
TCVs respond to maintain constant reactor pressure
Turbine load increases
What are the three branches of the EHC circuitry?
Which circuits are removed from the process when the system is placed in Bypass?
Speed, Load, Pressure
Speed and Load circuits are bypassed.
How is the turbine protected from overspeed?
Which of these systems satisfies criteria in ORM for overspeed protection?
Mechanical Overspeed Trip
Backup Overspeed Trip
The mechanical overspeed trip satisfies the ORM requirements. This includes the TSVs, TCVs, Bypass Valves, and CIVs.
What functions does the BOST provide?
What is the BOST relationship to the Speed Control Unit?
For any trips, what logic and setpoints are utilized?
The BOST provides turbine trips for the following:
A backup to mechanical overspeed trip utilizing its own speed sensing, independent of the Speed Control Unit.
Provides the arming for the Low MSOP discharge pressure trip, loss of 125vDC trip, and the loss of speed sensing trip.
BOST is independent of the SCU.
Overspeed - 110.5% in normal, 105% in standby. Utilizes 2 out of 3 logic.
MSOP Discharge pressure Low - < 100# AND > 75% rated turbine speed.
Loss of 125vDC AND > 75% rated turbine speed.
Loss of Speed Sensing - Both speed sensing units out of service AND > 5.5% rated turbine speed.
What is the wobbulator circuit?
When turbine speed is set to 1500 rpm, speed is varied between 1450 and 1550 rpm over a 12 minute cycle to minimize vibrations due to natural resonance of the turbine.
How does the EHC system respond to a loss of one Speed Control unit?
How will it respond to a loss of both speed control units?
How will it respond to these situations with the Speed Control Unit in standby?
A loss of one speed control will cause the turbine to accelrate at twice the normal speed.
With a loss of both speed control units, the turbine will trip if > 100 RPM.
With the unit in standby, these functions are defeated and nothing will happen.
What is Load Set? How is it determined and what is its normal value?
Load set is a value determined by the operator as the initial input for the Load Control Unit. It is controlled with a pushbutton on the panel and generally set to 120MW above the generator output.
What is a Load Set Runback? What conditions will cause this? What are the setpoints for these conditions?
A signal override of the load set when certain conditions exist.
Conditions:
Loss of Stator Cooling - Either SWC outlet temp > 81C or SWC inlet pressure < 42.5 psig. This runback will cause a turbine trip if Generator Amps are >75% @ 2 mins or >25% @ 3.5 mins into the runback.
Sync Speed Not Selected - 1800 RPM not selected (You only care about this during startup).
Power Load Balance - Difference between tracking of Reheated Steam and Generator Current is >40%.
How does the load set runback for stator water cooling work?
Load set reduces speed by 1% every 3 seconds. If the condition clears, the runback will stop. If not, the runback will continue until either the condition clears or TCV closure.
During the runback, if the condition is still active at 2 minutes with > 75% generator load (approx 30,000 AMPS), or still active at 3.5 minutes with > 25% generator amps (approx 9,900 AMPS), the turbine will trip.
What is a Load Limit Setback?
What does it do?
What is it designed to protect?
What are its trip setpoints?
Protective circuit that inputs a reduced steam flow limit into the pressure control circuitry when its set value is eclipsed.
It inputs a value into the Pressure Control Unit circuitry that causes the TCVs to close and the Bypass valves to open in order to reduce steam flow through the turbine. It sets back at a rate of 3% per second down to 75% rated steam flow.
It is designed to protect the condenser from an overpressure condition.
Setpoints are the same as the FCV Runback from B33:
> 5.6” HgA with < 3 Circ Water pumps running OR #1 Bypass full open.
What is the pressure regulator?
What signal does it provide?
How many channels does it provide?
How can a failure of the pressure regulator effect the plant?
Circuit that calculates an error signal (3.33% per every 1 PSI) that outputs to the flow demand signal.
There are two channels, a normal and alternate.
If a pressure regulator channel fails, it will auto shift to the alternate channel. If the regulator is in test, it will not shift - instead the bypass valves will open.
If the pressure regulator fails High, RPV pressure lowers.
If low, RPV pressure rises.
Can also fail as-is.
1 Bypass valve has an important feature that the other bypass valves don’t. What is it?
1 bypass valve provides the signal when full open for FCV Runback and Load Limit Setback.
How many CIVs are there and how are they distributed?
How do they normally work?
What arrangement do they operate in and why do they operate this way?
There are 6 CIVs.
The CIVs (Combined Intermediate Valves) are arranged on opposing sides of the low pressure turbines to emit steam for operation.
They are normally full open or closed, and only throttle in an overspeed condition.
They are paired in a Master/Slave arrangement that prevents a single LP turbine from being completely isolated from steam while other turbines still have steam emission. This prevents a significant overtorque condition on the turbine shaft.
During steam chest warm up and shell warm up, how are the TSVs, TCVs, and CIVs arranged positionally?
What allows for controlled warm up of this equipment?
The TSV is closed for both warm ups.
The TCV is open for Shell warm up.
The CIVs are closed for shell warm up and open for chest warm up.
The #2 Poppit allows for this controlled warm up.
What do generated trip signals for the turbine utilize to actuate trips on the TSVs and TCVs?
What component causes the fast acting close of the TCVs to actuate?
The Disc Dump Valve will dump hydraulic pressure and cause the valves to close due to heavy spring pressure.
The Fast Acting Solenoid provides a bleed path that relieves hydraulic pressure and causes the TCV to close rapidly.
Describe the flow path through RWCU
Suction from 2 recirc loops and the RPV bottom drain
2 Pumps normally in service
RHX
NRHX
2 F/Ds
RHX
Feedwater
What is the purpose of circulating RWCU from the bottom head drain?
Prevents thermal stratification.
Regarding a RWCU isolation signal
The RWCU CIVs closure predicates a delay for the rest of the isolation. What is the duration of this delay and what is it for?
32 seconds to allow for the CIVs to close with a reduced differential pressure across them.
The leak detection signal for the RWCU system has a bypass. Which RWCU system trips are bypassed by this switch?
All except for L2, SLC initiation, and NRHX Demin outlet temperature.
List the RWCU Leak detection trips and setpoints
LVL 2 - 130”
SLC initiation
High Delta Flow (>59 GPM for 10 mins)
Loss of Power to E31 for > 1 second
High RWCU Equipment Room Temp
High Steam Tunnel Temp 156F
NRHX Demin Outlet 140F
List the RWCU Pump Trips and Setpoints. List any unique attributes of a trip if it has any.
CIV Close < 90% Open
Thermal Overload
High Stator Temp 275F
High Thermal Neck Temp 180F
Low Flow < 70 GPM for 3 seconds.
This trip is delayed for 120 seconds during the initial pump start. If the pump control switch is taken to start again, the 120 second timer will restart.
What are the auto close signals for the RWCU Blowdown line and basis behind them?
Upstream Pressure < 5 PSIG to prevent a leak from vacuum draining the system.
Downstream Pressure > 140 PSIG due to downstream piping not rated for higher pressure.
Explain the discrepancy in differential flow while performing a blowdown of the RWCU system to the main condenser or rad waste.
The blowdown line won’t register flow until blowdown flow is > 35 gpm. When performing a blowdown, differential flow will indicate higher than actual until the blowdown flow exceeds 35 gpm.
With both RWCU pumps operating, what will happen when a CIV closes?
Both pumps will trip.
What will happen if an operator positions both the blowdown line to the condenser and rad waste isolations open?
Vacuum on main engine will be broken and can damage waste collection tank.
What are the normal and alternate power supplies for RPS A & B?
A Normal - MG Set from F1B08
A Alternate - F1C08
B Normal - MG Set from F1C12
B Alternate F1D12
With a loss of L11, what will happen to the RPS system when in a normal lineup?
What will happen because of this?
RPS B normal supply does not have an ABT and RPS B will lose power.
This temporary loss of power to B RPS will input a half scram and an inboard NS^4 isolation.
What are the trip setpoints for the RPS MG sets?
Overvoltage 140V
Undervolt 60V
Underfrequency 54 hz
What is the purpose of the EPA breakers?
How are they arranged?
What are the trip setpoints for the EPA Breakers?
What are the consequences of an EPA breaker trip?
Protects the MSIV solenoids, scram solenoids, and RPS relays from voltage issues.
They are arranged 2 per circuit in series.
Overvoltage 132VAC
Undervoltage 108VAC
Underfrequency 57hz
If an EPA breaker trips, the RPS bus will lose power. This will cause a half scram and a BOP isolation for the applicable division.
What is the difference between the Scram and Backup Scram?
How do backup scrams function?
Scram signal opens scram pilot valves that vent CRD system to the scram discharge volume and cause the CRDs to rapidly insert.
The Backup scram signal vents the air header that controls the scram pilot valves to allow them to fail open in the event that they do not receive a proper signal. This is a redundancy mechanism.
Backup scram valves, unlike scram valves, are DC powered and energize to actuate.
What is the normal position of the Scram Discharge Pilot valves and how do they reposition in the event of a scram?
Normally open, they close when a scram signal is inserted to bottle up the SDV.
What are the lights above the 4 SCRAM arm and depress buttons?
If a single light is out above each switch, what does that indicate?
If both lights are out above a single switch, what does that indicate?
The lights are for the scram signals for that applicable rod group.
Illumination indicates that a scram signal is not present.
If a single light is out on each channel, a half scram is inserted.
If both lights are out above a single channel, that is a failure of equipment and a full scram on a single channel, 1/4 of the rods are inserted.
List the Modes of Operation, the mode switch position for each mode, and any requirements associated with them.
Mode 1 - Power Ops - Run - Usually 8-10% Prx
Mode 2 - Startup - Startup/Refuel - 0-10% Prx
Mode 3 - Hot S/D - Shutdown - > 200F with all RPV bolts tensioned.
Mode 4 - Cold S/D - Shutdown - < 200F with all RPV bolts tensioned.
Mode 5 - Refuel - Refuel or Shutdown - One or more RPV bolts untensioned.
What is the TSV Closure scram setpoint, when is it bypassed, and basis?
3 TSVs < 95% open based on 1st stage shell pressure of 212 psig.
Bypassed at < 38% RTP as indicated by 1st stage shell pressure (212 psig)
Bases is anticipated pressure increase and resultant power increase, prevents MCPR from being exceeded.
Draw or explain the electrical diagram for B33 pump power supplies
List all trips and actions associated with the various level set points.
How do OPRM inputs work?
In the generator capability curve below, describe the following:
What do the pressure curves represent?
What is the limiting issue from lines A-B?
What is the limiting issue from lines B-C?
What is the limiting issue from lines C-D?
The pressures on the curves represent the hydrogen volume pressure cooling the stator.
For A-B, curve is limited by field heating.
For B-C, curve is limited by armature heating.
For C-D, curve is limited by armature core end heating.
For the graph below, determine if the following parameters are acceptable:
Generator lagging 50 MVARS
Generator output 1200 MWe
Hydrogen Pressure 45 PSIG
No, these conditions fall outside the acceptable parameters of the Generator Capability Curve
List the serviced loads of the following stages of extraction steam:
List the D17 monitored areas and what trips are associated with each.
Which D17s do not have particulate and iodine sampling?
No P/I highlighted in yellow
