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Flashcards in Auxiliary Feedwater System Deck (50):
1

.What is the purpose of the Auxiliary Feedwater System?

Designed to provide a supply of feedwater to the steam generators during start‑up operations and to remove primary system sensible and decay heat during initial stages of shutdown operations.

2

What is the functional design of the Auxiliary Feedwater System?

Consists of two motor driven pumps and one steam turbine driven pump configured into two trains.

The system is normally aligned for fully automatic operation.  When at least 2 S/G level safety channels associated with an S/G reach a pre-determined setpoint (30%), an AFW pump starts and its associated flow control valves open to deliver the required flow (165 gpm) to both Steam Generators.

3

What quantity of condensate must be available for the Auxiliary Feedwater System?

Total combined capacity between T-2 and T‑81, Primary Makeup Storage Tank, must be greater than 100,000 gallons.

This exceeds the amount needed for 8 hours of auxiliary feedwater pump operation for decay heat removal following a reactor trip.

4

What is the design/power supplies for P-8A/B?

Horizontal, split case, single suction, double volute, nine-stage centrifugal pumps

Capable of delivering the minimum required flow for decay heat removal up to 1000 psia in the S/Gs with all four PCPs in service.

415 gpm design flow

P-8A is supplied Left channel power from Bus 1C

P-8B turbine driven with steam from E-50A

5

What is the design/power supplies for P-8C?

Horizontal split case single suction, double volute, seven-stage centrifugal pump.

Design flow of 330 gpm

P-8C is a converted HPSI pump.  It will deliver the minimum required flow for decay heat removal if S/G pressure is maintained at or below 900 psia with all four PCPs in service OR if S/G pressure is at or below 1000 psia with all PCPs secured.

Powered from Bus 1-D

6

What is the low suction pressure trip for P-8A/B?

Trips on low suction pressure (6.7 psig) on 2 of 3 switches.

Reset P-8A

  • Take control room handswitch or breaker cubicle switch momentarily to the TRIP position before pump can be restarted.

Reset P-8B

  • Take control room handswitch to close for CV-0522B

Power Supplies

Y-10 supplies switches, swaps to Y-30 in normal is lost

7

What is the P-8C Low Suction Pressure trip?

Trips pump on low suction pressure (8 psig) on 2 out of 3 switches.

Reset P-8C

  • Take control room handswitch or breaker cubicle switch momentarily to the TRIP position before pump can be restarted.

Switches powered by Y-20, no backup.

8

What trips an auxiliary feedwater pump?

P-A/C - Overcurrent

P-8A/B - 6.7 psig low suction pressure

P-8B - 8 psig low suction pressure

P-8B - overspeed at 110%. (3560 rpm rated, 3845-3916 rpm trip)

9

Motive force for CV-0522B, P-8B Steam Supply Valve

CV-0522B, P-8B Steam Supply Valve

Valve is air operated supplied by instrument air with bottled nitrogen backup supply from Nitrogen Station #2.  It is equipped with a manual operator for local control.

10

What are the left train flow control valves?

AFW Flow Control Valves are associated with left train AFW (P‑8A/B)

CV-0727 and CV-0749,

  • Four inch valves
  • CV-0727 – 'B' Steam Generato 
  • CV-0749 – 'A' Steam Generator
Instrument air operated. 
Backed up by bottled nitrogen from Nitrogen station #1.
Equipped with manual operators for local control.
Air to close (fail open on loss of air).

11

What are the right train flow control valves?

AFW Flow Control Valves are associated with right train AFW (P-8C)

CV-0736A and CV-0737A,

  • Four inch valves
  • CV-0736A – 'B' Steam Generator
  • CV-0737A – 'A' Steam Generator

Air to close (fail open on loss of air).

Instrument air operated.  NO backup nitrogen supply.

Equipped with manual operators

12

What are the right train flow control bypass valves?

CV-0736A and CV-0737A also contain 1.5" bypass valves:

CV-0736 and CV-0737

  • Allow continuous auxiliary feedwater at low flow rates during start-up and hot shutdown conditions.

Air to open (fail closed on loss of air).

Operated by instrument air system.  NO backup nitrogen supply

Equipped with manual operators for local control..

13

What are the FOGG valves?

FOGG – Feed Only Good Generator

Disabled – not used at Palisades

Block valves are locked open with power removed:

  • MO‑0743 – P-8A/B to E‑50B S/G
  • MO‑0798 – P-8A/B to E‑50B S/G
  • MO‑0753 – P-8A/B to E‑50A S/G
  • MO‑0760 – P-8A/B to E‑50A S/G
  • MO‑0748 – P-8C to E‑50B S/G
  • MO‑0755 – P-8C to E‑50B S/G
  • MO‑0754 – P-8C to E‑50A S/G
  • MO‑0759 – P-8C to E‑50A S/G

14

What is Auxiliary Feedwater Actuation System (AFAS) C-187?

Auxiliary Feedwater Actuation System (AFAS) C-187

Provides automatic AFW pump starting on low level in either S/G of 30%

4 Sensor Channels with input from S/G safety channel level indication

  • SCA, SCB, SCC, and SCD
  • Y-10, Y-20, Y-30, Y-40

Sensor Channel Trips

  • Level in either S/G is +-30%.
  • Preferred AC Bus Trip
  • 2 out of 4 sensor channels activate both actuation channels when tripped

Actuation Channels (ACA - Left Train Actuation and ACB - Right Train Actuation)

  • Power supplies:
    • ACA - D11‑1
    • ACB - D21‑2

Loss of power prevents actuation channel from generating an AFAS.

 

15

What is required in order to bypass a sensor channel?

To bypass a tripped sensor channel requires power available to the sensor channel.  The bypass is not effective if sensor channel power has been lost.

16

What happens on a loss of Y-10 and Y-30?

Low Suction Pressure Trip (LSPT) on P‑8A/B

Loss of Y-20 results in LSPT on P-8B

17

What happens on a loss of D-11-1 or D-21-1?

No Channel Actuation

  • D-11-1: ACA - Left Train Actuation
  • D-21-1: ACB - Right Train Actuation)

CV-0522B opens to modulate supply pressure to ~250#, POC-0522B supplies via CV-0522G and H to run P-8B.  Position indication for CV-522B is lost.

18

How does the P‑8A Auto Start sequence function?

  1. AFAS signal present (occurs at < 30.0% in either S/G on a 2/4 safety channel logic.)
  2. P‑8A control room handswitch must be in AUTO.
  3. 2400V power available

If above conditions are met, a start signal is sent to P‑8A after 2.5 seconds.

Start is delayed 2.5 sec and only in for 5 sec since the anti pump feature requires removal of start signal.

19

How does the P‑8C Auto Start sequence function?

  1. AFAS signal present (occurs at < 30.0% in either S/G on a 2/4 safety channel logic.)
  2. P‑8C control room handswitch must be in AUTO.
  3. 2400V power available
  4. P‑8A not running or not delivering flow to A and B S/G.
  • Not delivering flow means:  At least 1 out of 2 flow switches to A S/G and B S/G sensing less than 100 gpm OR P‑8A breaker contact indicates P‑8A not running.

If, at any time, these permissives are met, a start signal is sent to P‑8C after 30.5 seconds.

20

How does the P‑8B Auto Start sequence function?

AFAS signal present (occurs at < 30.0% in either S/G on a 2/4 safety channel logic.)

P‑8B control room handswitch must be in AUTO.

P‑8A not running or not delivering flow to A and B S/G. Starts 112.5 sec counter.

If P-8C not delivering flow anytime after 112.5 sec, the P-8B Starts.

Not delivering flow means:  At least 1 out of 2 flow switches to A S/G and B S/G sensing less than 100 gpm OR P‑8A breaker contact indicates P‑8A not running.

21

How is AFAS reset?

Performed at panel C-187 (longer procedure process)

Prior to resetting AFAS, both S/G levels must be greater than 30%

22

What are the alternate water sources and which is preferred?

Fire Water can supply P-8A/B

Service Water can supply P-8C

Service water is the preferred source over fire water due to a check valve, CK-FW725, in the suction line between T-2 and service water.

23

What are the C-150, Auxiliary Hot Shutdown Panel indications and controls?

Enabling C-150/C-150A disables the corresponding instrumentation in the Control Room and on C-33.

  • P-8B – can open and close CV-0522B via HS‑0522C
    • P-8B will NOT trip on low suction pressure when CV-0522B is opened from C-150A
  • Can operate HIC‑0749C, P‑8A/B AFW flow to 'A' S/G if C-150 activated
  • Can operate HIC‑0727C, P‑8AB AFW flow to 'B' S/G if C‑150 activated

FI-0727B – Flow to 'B' S/G from P-8A/B

FI-0749B – Flow to 'A' S/G from P-8A/B

24

What are the C-33, Redundant Safety Injection Panel Controls and Indications?

HIC-0727, 0749, 0736A, 0737A

Can operate associated flow control valve in "Manual" only.

  • Indicates flow to associated S/G
  • "Cascade" has no function
  • In "Auto," signal from associated FIC in control room is passed to control valve

Signal output will track when being controlled from control room but will not track when being controlled from panel C-150

25

What are the control room controls and indications?

C-01

AFW Pumps, P-8A, P-8B, P-8C

  • P-8A/C - Handswitches
  • Keyswitches, SS-1/P8A and SS-1/P8C are installed in Panel C-11 to prevent automatic opening of associated flow control valves when AFW pumps start.  This is used for testing.
  • P-8B, Control Switch position are CLOSE, OPEN, AUTO

26

How does a loss of D-11-1 impact P-8B?

P-8B will start.

  • Designed to limit the effects of an ATWS condition
  • SV-0522G/H are energized all the time and held closed (P&ID shows de-energized position).
  • On loss of D11-1 SVs fail open so air is directed to open CV‑0522B.

27

How do AFW Flow Controllers FIC-0727, FIC-0749, FIC‑0736A, FIC-0737A function?

AFW Flow Controllers FIC-0727, FIC-0749, FIC‑0736A, FIC-0737A

  • Control signals from FICs at C-01 are sent through respective HIC at C-33. 
  • HIC must be in AUTO in order to pass signals on to the valves.
  • Controllers are NOT considered operable in MANUAL.  If any HIC or FIC is in MANUAL, AFAS will have NO affect on valve position

28

How do FIC-0727/0749 function?

FIC-0727/0749

Control flow from P-8A/B through 4” lines.

Placed to Auto with P-8A/B off: Blue Pen drops to zero, operator can then set desired flow rate.

P-8A/B Running

  • If FIC is in AUTO, valve opens to BLUE setpoint flow rate
  • If FIC is in CASCADE, valve opens to obtain 165 gpm.
  • If FIC is transferred from CASCADE to AUTO, setpoint remains at 165 gpm

FIC will transfer to AUTO and track the HIC if:

  • FIC was originally in MANUAL
  • HIC is then swapped from AUTO to MANUAL

29

What is the power supply to  FIC-0727/0749?

FIC-0727/0749 P-8A/B 4 inch line power supply

Y-10, transfers to Y-30 on loss of Y-10.

30

What are the FIC-0727/0749 Operability Requirements?

FIC-0727/0749 Operability Requirements

NOT operable if FIC or HIC in MANUAL

Considered operable if

  • In CASCADE, or
  • In AUTO AND no MFW in service AND S/G levels and PCS temps maintained within bands required for decay heat removal

31

How are FIC-0737A/0736A operated?

Operation of FIC-0737A/0736A - P-8C

  • Can control either the 1 ½” bypass valves (CV-0736/CV-0737) or the main 4” valves (CV-0736A/CV-0737A).
  • PF Mode (Program Function) controls the small bypass valves for finer control of AFW flow
  • If in AUTO or PF Mode, and an AFAS occurs, the controller auto swaps to CASCADE, and the bypass valves close
  • P-8C must be operating before FIC can be swapped to AUTO.  If you try to select AUTO with P-8C OFF, the FIC swaps to CASCADE!

32

What are the power supplies to FIC-0737A/0736A?

FIC-0737A/0736A

Y-20, no swapping

Loss of Y-20 also TRIPS P‑8C since the pressure switches lose power for the low suction pressure trip.

33

How do you determine if FIC-0737A/0736A is in PF Mode?

FIC-0737A/0736A PF mode

a)      PF light on solid.

b)      Controller in AUTO.  Cannot select MANUAL or CASCADE

c)      ARP-36, 2-10 “AFW BYPASS VALVE OPEN” status array light

d)      BLUE and RED pens don’t match.

34

When are FIC-0737A/0736A operable?

FIC-0737A/0736A Operable

Operable if in CASCADE, AUTO, or in PF Mode. 

NOT operable if FIC or HIC in MANUAL

35

Why are FIC-0736A/0737A controllers operable in AUTO always but FIC-0727/0749 controllers have restrictions?

FIC-0736A/0737A controllers will automatically swap to CASCADE upon an AFAS and FIC‑0727/0749 controllers will not.

36

What controls and indications are on C-01?

  • Flow to each Train can be read on the associated flow control valve
  • PI-0789 – P-8A/B discharge pressure
  • PI-0750 – P-8C discharge pressure
  • EAI-1104 – P-8A amps
  • EAI-1209 – P-8C amps
  • P-8B steam supply pressure is indicated on PI‑0521A.  Note that this indicates pressure downstream of CV-0522B
  • CV-0522B DC control power available light  Indicates that control power is available from D11-1.

37

What controls and indications are on C-13?

T-2, Condensate Storage Tank, level

  • LIA-2021 – C-13L
  • LIA-2022 – C-13R

38

How do Auxiliary Feedwater and Main Steam interact?

  • AFW system is primary source of water level control during plant heat-up and cooldown. 
  • AFAS is automatically actuated on low steam generator water level.  If Auxiliary Feedwater System malfunctions such that no flow is available, Steam Generators will experience a dryout condition.  This will lead to an overheating condition of the PCS and Reactor Core.
  • 'A' Steam Generator is the source of steam for K-8, P-8B Turbine Driver

39

How do Auxiliary Feedwater and Service Water?

Preferred backup source of water to right train AFW (P-8C)

40

How do Auxiliary Feedwater and Fire Water interact?

Alternate backup source of water to left train AFW (P-8A/B)

41

How do Auxiliary Feedwater and instrument air interact?

Operating air for steam supply CV-0522B, and

AFW flow

CV-0727, CV-0749 -  Fail Open

CV-0736/CV-0737 - Fail Closed

CV-0736A?CV-0737A.- Fail Open

42

How do Auxiliary Feedwater and Compressed Gas interact?

Backup source of operating gas for steam supply CV-0522B and AFW flow control valves CV-0727 and CV-0749.

43

When are CV‑0736 and CV-0737 not used?

Auxiliary feedwater bypass valves CV‑0736 and CV-0737 shall NOT be used to initiate Auxiliary Feedwater flow to the steam generators unless either:

Steam Generators are cold (<212°F) OR;

Steam Generator level is 60% or greater.

44

What are the limits on recirculation of P-8C?

Auxiliary feed pump P-8C recirculation flow is ~ 30 gpm.

Operating the pump in RECIRCULATION mode should be limited to

<2 minutes and shall be limited to <5 minutes,

(due to hydraulic instability and potential impeller damage).

45

What are the AMP limits on P-8A and P-8C?

P‑8A = 112 amps

P‑8C = 99 amps

This ensures that full load current amps will not be exceeded which would cause winding overheating and insulation degradation

46

How do steam traps affect operability of P-8B?

Steam line water hammer for P-8B turbine driver is prevented by use of steam traps and a moisture separator.

Malfunction of the moisture removing equipment can render P-8B inoperable

47

How is water hammer on the Auxiliary Feedwater lines prevented?

Feed line water hammer is prevented by use of check valves on the AFW discharge near the Steam Generators.  These valves are checked for proper operation during Operator rounds by verifying the piping is cool to the touch.

48

What is the minimum flow requirement for P-8C?

Due to hydraulic instability at low flow, P-8C should NOT be run with a total flow of less than 75 gpm to S/Gs

49

What are ramifications of SS-4/P-8C in TEST?

SS-4/P-8C in TEST

Keyswitch SS-4/P-8C in TEST position prevents Control Valves CV-0736A and
CV-0737A opening upon manual pump starts. AFAS automatic response is NOT
affected by SS-4/P-8C.

50

What are the required positions for the flow controllers in Mode 4?

In Mode 4, only one AFW train including a motor driven AFW pump is required to
be OPERABLE when a steam generator is being relied upon for heat removal.

Therefore in Mode 4 the AFW control valve controllers and AFW pump hand
switches for the motor driven AFW pump associated with the train being credited,
must be positioned as defined in this step.

FIC-0727/0749 (flow controllers from P-8A/B AFW pumps) are considered operable if operated in the following modes:

  • Cascade
  • Auto, such that steam generator levels and PCS temperatures are being maintained within required bands to satisfy decay heat removal requirements (main feed is not supplying flow to steam generators in addition to aux feed).

FIC-0736A/0737A (flow controllers from P-8C AFW Pump) are considered operable if operated in cascade, auto, or in PF (bypass valve) mode.

FICs-0727/0749, FICs-0736A/0737A are not considered operable if in manual mode.

HS-P-8A, HS-0522B, and HS-P-8C (AFW pump hand switches) must be in AUTO for their associated AFW pumps to be considered operable.