Condensate Transfer and Storage & Aux Feedwater Flashcards
What is design basis for Condensate Transfer & Storage system ?
-Initial fill for Condensate & FW system
-Help maintains level in Condenser hot wells
-Provide water for CD Demins for resin regeneration
-Backup water to Spent Fuel Pool
-Emergency makeup for EW,EW, & DG Jacket Water Surge Tanks
Why is the CST Tank reinforced with concrete ?
-Needs to meet seismic category 1 requirements to be functional during safe shutdown
-Protects against tornado borne missiles
What is 300,000 gallons of water dedicated to inside the CST Tank ?
-To use Aux. FW system and provide FW to maintain plant in hot standby for 8 hours
-Allows controlled plant cooldown at max rate of 75F/hr to shutdown cooling is initiated
What is the other 220,000 gallons dedicated for inside the CST Tank ?
-Dedicated to 3 days of normal makeup to Condensate & FW systems
-Used by Secondary Chemistry Control system without replenishment from DW
How are the penetrations into the CST Tank arranged ?
-Essential operations is everything below the 300,000 gallons
-Non-Essential has penetration above the 300,000gallons
What is the normal makeup to the CST ? How is it done ?
-DW is normal makeup and is normally done automatically based on CST lvl
-Makeup line has a bypass line that can be used when level control balance is isolated
What is the backup makeup water to the CST ? Why is this makeup water supply not normally used ?
-Recycled Monitor Tanks is backup makeup source to CST
-Not normally used because it can potentially be contaminated
What cover gas is used for the CST Tank ? How is regulated ?
-Nitrogen gas is used
-Regulated to 3.5 psig by a PCV
-Bypass line can be used when PCV is isolated
What’re the two breather valve used for?
-One breather valve is used pass nitrogen from atmosphere from failed open nitrogen supply line
-Other breather valve allows air into CST to prevent vacuum during Main Condenser Hotwell Makeup
What is the purpose for Tank Overflow & Loop Seal line ?
-Loop seal prevents nitrogen from leaking out
-Overflow is directed to north condenser sump
Why should the CST inventory not be <40F & >120F ?
-<40F precludes thermal shock to SGs
->120F is upper limit of design calculations
What is the primary supply line for the FLEX SG Makeup Pump ?
Pump draws from CST Drain Line
Where is the valve located that is used to align the FLEX SG Makeup Pumps used for ?
The valve to align is located in CST Drain Pit
What conditions must the CST Drain out be maintained in ?
CST Drain pit must be maintained locked by Operations & Security departments
What’re pre-requisites to placing CST in Normal Operation ?
-DW available
-LP Nitrogen is available
Where do the Condensate Transfer Pumps supply makeup water to ?
-DG Jacket Water Storage Tanks
-EC Surge Tanks
-EW Surge Tanks
-Spent Fuel Pool
Is there expected to be leakage from the Condensate Transfer Pumps ?
-Some leakage is expected both during operation & while secured
-Leakage will fall to pump skid and directed to floor drain
Where do the Condensate Transfer Pump recirc. lines discharge to ?
Recirc. lines will discharge back into CST from associated Train Aux FW Pump Recirc. Lines
Where are the Condensate Transfer Pumps powered from ?
Powered from class 480MCC (PH)
What ESFAS signals auto start the Condensate Transfer Pumps ?
-LOP (Train Specific)
-SIAS
-CREFAS
-CRVIAS
What do the CST Suction Isolation Valves to the ‘N’ Aux FW Pump do ?
Provides isolation for CST & Seismic break between Seismic Category 1 & Seismic Category 2 rated supply line
What conditions are the CST Suction Isolation Valves usually in ?
They’re normally closed
How are both of the CST Suction Isolation Valves interlocked with ‘N’ Aux Fw Pump ?
Provides low suction pressure protection
What position must the CST Suction Isolation Valves be in to start and run the pump ?
-Both valves must be >80% open
-If one valve drops below 80% open it will trip the ‘N ‘ Aux FW Pump
Where are the ‘N’ Aux FW Pump suction isolation valves powered from ?
They’re BOTH powered from ‘A’ train
Which condenser hotwell does CST provide makeup water for ?
‘A’ Main Condenser Hotwell Halves
What controls the makeup to the ‘A’ Main Condenser hotwell ?
Makeup is controlled by ‘C’ Main Condenser Hotwell half level
When is condensate rejected from the Main Condenser ?
High lvl in ‘C’ condenser will open Condenser Hotwell Draw Off Level Control Valve and return it to CST
What is the most common use of the CST system ?
-CST is used for Condensate Demins
What do the Regenerate Water Transfer Pumps in Secondary Chemistry control system used for ?
Transfers water from CST to Condensate Demins during regen process to:
-Trasnfer resin between vessels
-Rinse vessels after resin is transferred
-Dilute acid and concentration during chemical cleaning of cation resin
-Backwash resin
-Fill service vessel after transferring resin back into them
What’s status are the CST pumps during normal operation ?
-Condensate pump are normally in standby
-If makeup water is needed then Control Room can manually start it
How does Essential Lighting interface with CST ?
QB provides lighting for CST Pump House
How many CST gallons is designated for a controlled shutdown & cooldown ?
300,000 gallons designated to supply Essential Aux FW Pumps
What should CST level be ?
> 29.5 ft
What should CST have sufficient cooling for?
-Must have sufficient cooling to remove decay heat for 4hrs following reactor trip from 102%
-Then cooldown RCS for Shutdown Cooling entry conditions
Why must there be a volume of 300,000 gallons ?
This 300,000 gallons will hold unit in mode 3 for 8 hours followed by cooldown to SDC entry conditions at 75F per hour
What is the design basis for Aux. Feedwater system?
-Provide flow for RCS temp. during Normal startup, hot standby, & shutdown conditions
-Supports orderly ,controlled shutdown & cooldown of reactor
-Used to remove decay heat from RCS during Station Blackout
What are the UFSAR Design Bases ?
-RCS cooldown at max rate of 75F per hour to 350F during LOOP
-Hot standby for 8hours during LOOP
-RCS cooldown using SG following main steam line break,or Main FW Break inside containment during LOOP
When does ‘N’ Aux FW Pump deliver Feedwater to Steam Generator ?
-During normal startup, Hot Standby, & Shutdown conditions
-Also provides chemically treated water to SG for initial fill
How are the ‘N’ Aux FW motor & pump bearings lubricated ?
Bearings are self lubricated using slinger rings to throw oil on bearings
How are the ‘N’ Aux FW Pump motor bearings cooled ?
Motor bearings cooled by shaft mounted fan
How is the ‘N’ Aux FW Pump bearings cooled?
-Pump bearings cooled with discharge of pumps 1st stage through integral oil cooler
-After 1st stage cools bearings it’s then sent back to suction of pump
Where is the ‘N’ Aux FW Pump powered from ?
Powered from 4.16kv PBA-S03
What’re the two class control power sources for main break operation for the ‘N’ AF Pump ?
-Normal source is: PKA-D21
-Alternate source is: ‘A’ Class Battery Charger PKA-H11
How do you select a control power source for the ‘N’ AF Pump ?
A 3 position switch for Control Power Transfer Switch for ‘N’ AF Pump
What does ‘N’ AF Pump do during normal startup ?
-Provides FW to steam generator until power reaches 2%, then Main FW pump will start
-Also used for SG chemistry by injecting ammonia & hydrazine at suction of pump
What’re the two suction isolation valves provide for ‘N’ AF Pump ?
-Provide protection from low suction pressure condition
-Interlocked with pump if valves less than 80% open it will trip pump
What ESFAS Signal will trip the ‘N’ AF Pump ?
-SIAS
-LOP
What is the different between ‘N’ AF Pump & ‘B’ AF Pump ?
Difference is ‘B’ AF Pump has:
-Seismic category 1 requirements
-Larger horsepower motor
-Delivers 650gpm to intact SG @1270psia
What is the power supply for ‘B’ AF Pump ?
Power supply is 4.16kv PBA-S04
What is the normal water supply to the ‘B’ AF Pump ?
CST supplies water to pump through normally locked open valve
What water supply is used when CST isn’t available for ‘B’ AF Pump?
RMWT is backup, this is done by unlocking & closing normal water supply from CST & opening normally closed water supply valve
What will automatically start ‘B’ AF Pump ?
-AFAS 1/2
-CSAS
-SIAS
-‘B’ Train LOP
What else will start in the same room when ‘B’ AF pump starts?
Essential ACU will start for pump operability
What’re pre/post start checks for ‘B’ AF Pump ?
-Oil levels
-Leakage
-Physical obstructions
-abnormal conditions
-Oil Temperature
What is different about ‘A’ AF Pump ?
Doesn’t need AC power to operator because it’s steam driven
Why does ‘A’ AF Pump provide reliability ?
Provides reliability during Blackout and is capable of deliver water to SG at different flow rates & pressures,as the RCS cools down to SDC entry
Where does the steam used to drive ‘A’ AF Pump exhaust to ?
Exhaust out to atmosphere, instead of a condenser
Where does ‘A’ AF Pump turbine receive its steam from ?
-Receives steam from BOTH steam generator main steam lines
When will ‘A’ AF Pump automatically start ?
Will start on AFAS and will auto open Main Steam Supply Valves & bypass valves
When would we use Aux. Steam to drive ‘A’ AF Pump ?
-Testing
-Performance of standard appendix
What is the Governor on the ‘A’ AF Pump used for ?
Used to regulate steam control valve to control speed of turbine, and therefore the pump
What does the Governor consist of ?
-Automatic control box
-Manual Speed Potentiometer
-Hydraulic Actuator
-Governor Valve
What does the Governor control box do ?
Control box senses shaft speed & sends control signal to Hydraulic actuator (EGR)
What is the Governor EGR used for ?
Uses system oil to position Governor Valve
What does the Governor Valve do ?
It regulated steam going into the turbine
What is the Governor Potentiometer used for ?
Used to manually control this process
Where is the Governor powered from ?
Powered from Class 125VDC Control Power (PKA-D21)
What will happen to the ‘A’ AF Pump if governor loses control power ?
The governor fails open which causes turbine to trip on overspeed
Where is the Oil Pump attached to on the ‘A’ AF Pump?
Oil pump coupled to a worm gearbox driven by the AF Turbine Shaft
Where does the Oil Pump supply oil to ?
Supplied oil to Turbine bearings & to Turbine Hydraulic Actuator (EGR)
What does the ‘A’ AF Pump oil cooler used for ? Where does it get its cooling water from ?
-Oil cooler maintains oil temp
-Receives cooling water from 1st stage of AF Pump,discharges water back to suction of pump
What happens when the Governor control system cartridge filter gets clogged ?
Has a dirt alarm that’ll bypass filter when it gets clogged
What is the eight glass used for on the ‘A’ AF Pump ?
Sight glass on each end of turbine to indicate oil level
What’re are the Min. Operating Speed & Min. Sustained Speed ?
Min. Operating Speed-800rpm
Min. Sustained Speed- 1000rpm
Why is operating ‘A’ AF Pump with speed less than 1000 rpm, greater than 5 minutes prohibited ?
Operating below 1000rpm doesn’t allow adequate Oil Pressure & Cooling Water to Oil Cooler
Where can the ‘A’ AF Pump be operated from ?
-Control Room
-May be operated locally for testing or during Emergency Operating Procedures
How is the ‘ A’ AF Pump operated WITH & WITHOUT control power ?
-With control power available: indications & controls on local control panel are used
-Without control power available:
Manually throttle steam to turbine
Opening isolation valves to each SG
Throttling regulating valve to control discharge pressure
What happens if the overspeed mechanism actuates for the ‘A’ AF Pump ?
Overspeed will trip the Trip Throttle Valve stopping steam supply to turbine
What is the normal supply water to the ‘A’ AF Pump ? What is alternate water supply ?
-CST provides water to ‘A’ AF Pump through normally locked open valve
-Alternate supply is from RMWT, unlocked and close valve. Then open RMWT valve
What else will start with the ‘A’ AF Pump ?
Essential ACU
Why is it important for the ‘A’ AF pump to receive steam upstream of the MSIV’s ?
Ensures steam for ‘A’ AF pump during Main Steam Isolation Signal
What is the 1in steam supply valves used for on the ‘A’ AF Pump ?
-1in stems supply line will get the AF turbine up to speed(1000rpm)
-Allows oil pressure to increase for Governor to control steam
-Provides pressure for 1st stage cooling water to oil cooler
When does the 6in Steam Supply Valves open to the ‘A’ AF Pump ?
-30seconds after 1in line is opened, the 6in line will open to admit full steam
-Governor will now be in control of speed
What’re the Critical steam traps in the supply lines to the ‘A’ AF Pump used for ?
They’re used to remove condensate from supply lines to the ‘A’ condenser just above condenser reheat trays
What happens if the condenser reheat trays flood into the Steam Trap line ?
-Steam traps won’t remove moisture in lines
-If moisture reaches AF Turbine it could overspeed the turbine
What is the Condensate Pot used for ?
-Used to drain moisture from critical steam trap supply line
-Collects drainage & leakoff from trip throttle valve
What would happen if we didn’t have Condensate Pot ?
-Would greatly increase chances of overspeed trip
-Overspeed challenges the design function of fast starts from cold condition
How do the two thermostatic vent valves work on the Condensate Drain Pot ?
-When AFA pump is started some steam will release, but vent valves will close after they’ve been heated up
-Vent valves have a bellows
What happens to AFA Pump if vent valves or steam/floats traps aren’t a operating correctly ?
AFA Pump will not be operable if these things aren’t operating
What is the Trip Throttle Valve used for ?
-During normal operation is used as a trip valve
-Throttles steam flow if control power is lost to Governor
Where can the AFA Pump MOV in the steam supply line be operated from ?
-B06 in Control Room
-‘A’ Remote Shutdown Panel
-Local Control Panel in AFA room
What do the red & green lights indicate on the local control panel ?
-Green for closed/red for Open
This is for BOTH:
-Trip Throttle Valve Operator
-Trip & Throttle Valve
When would the Trip Throttle Valve be operated manually ?
This will be done when starting up AFA Pump, this is performed for testing or Emergency Operating Procedures
What will trip the Trip Throttle Valve closed ?
A mechanical overspeed or a electrical protection signal
What controls regulating valves to open or close?
Regulating valves open and close based on SG level between 25.8% & 40.4%
What will ESFAS auto open the Regulating Valves & Isolation Valves ?
Both valves will open upon a AFAS
Where can regulating & isolation valves be operated from ?
-Control room
-Remote shutdown panel
-Locally at valves
Where is AFA Pump discharge regulating and isolation valves powered from ?
Powered from Class 125VDC from buses PKA & PKC
Where is AFB Pump discharge Regulating & Isolation Valves powered from ?
Powered from Class 480VAC MCC
Why does the ‘N’ AF Pump not have any dedicated regulating or isolation valves ?
It uses the Feedwater Downcomer line stop valves and control valves
Why is there multiple isolation barriers at the discharge of the AF Pumps ?
This is to prevent back flow of Feedwater which could cause steam to form at AF Pump and while starting the pump can steam bind it
What device do you we use at the AF Pump Discharge piping to identify if there is any steam formation at pipe?
We use a temperature plate recorder that’ll change color to identify if there is steam at the AF Pump
How do we know if gas binding has occurred ?
AF Pump doesn’t develop discharge pressure or flow
What does filling and venting the AF Pump do ? What happens to AF pump when filling & venting ?
Fill & vent pump with CST water & this process makes AF Pump inoperable
What is a differential pressure lockout ? What causes it ?
-Differential pressure between SGs is 185psid
-This indicated a Main Steam Line Break or Feedwater Line Break affecting SG with lowest pressure
What happens during a Differential Pressure Lockout ?
Closes regulating valves & isolation valve & prevent them from reopening
