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NLO Systems > AF- Auxiliary Feedwater > Flashcards

AF- Auxiliary Feedwater Flashcards

1
Q

What is the basis for the amount of water level in the CST that is reserved for AF use in the plant during an emergency situation?

A

Provides sufficient reserve of feedwater to permit the plant to operate in Mode 3 for 8 hours followed by an orderly plant cool down at a rate not to exceed 75F/hr, to the point where Shutdown Cooling may be placed in operation (RCS ~350F)

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2
Q

What is the capacity of the CST and RMWT?

A

CST – 550,000 gallons

RMWT – 480,000 gallons

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3
Q

How is HA affected by a high water level in either AF pump room? What temp is maintained in the AF pump rooms?

A

Aux Building Normal AHU dampers isolate the Aux Building HVAC from the AFP rooms

50-104

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4
Q

What is the purpose of the AFN pump? How is ‘N’ AFP self-lubricating?

A

multi-stage centrifugal pump that delivers auxiliary feedwater to the S/Gs for the control of RCS temperature during startup, hot standby, shutdown, and initial fill and makeup

Uses dipper rings to throw oil onto the bearings

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5
Q

What provides cooling water for the AFN pump lube oil coolers? Where is the cooling water returned to?

A

Pump’s first stage discharge

pump suction

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6
Q

Where is ‘N’ AFP powered from? Control power?

A

PBA-S03

Control power from two sources: PKA-D21 or the output of the “A” Train Class Battery Charger

(there is a selector switch behind the load center to swap power supplies)

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7
Q

Why does ‘N’ AFP have two class powered suction valves?

Where are these valves located?

A

Provide class and seismic protection boundary for CST inventory, separating it from the non-seismic piping to ‘N’ AFP downstream of the isolation valves

CST pump house

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8
Q

What is the interlock associated with ‘N’ AFP and its suction valves? Purpose?

A

If either of the valves is less than 80% open, the pump will not start and will trip if running

To provide protection from a low suction pressure condition, which could damage the pump

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9
Q

Where is ‘N’ AFP located? Where is it controlled from?

A

100’ Turbine Building, NW corner

control room or pump breaker

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10
Q

Where are all non-seismic Category 1 penetrations located on the CST?

A

Above the level of the Safety related storage volume (300,000 gallons, or ~28 ft)

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11
Q

The construction and design of ‘B’ AFP is effectively identical to that of ‘N’ AFP, with what exceptions?

A

‘B’ AFP is designed to meet seismic category 1 requirements

‘B’ AFP is equipped with a larger horsepower motor (125% larger)

‘B’ AFP is equipped with an automatic start feature from the ESFAS load sequencer module for AFAS, CSAS, LOP

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12
Q

What else starts when the ‘B’ AFP starts?

A

Essential air cooling unit automatically starts

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13
Q

Where is ‘B’ AFP located?

A

80’ of the MSSS

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14
Q

In regards to the ‘A’ AFP, what is the purpose of the worm drive gearbox?

A

Coupled to an oil pump and the turbine’s governor actuator, and driven off of the turbine

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15
Q

What provides the cooling water to the ‘A’ AFP lube oil cooler?

A

First stage of the AFP

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16
Q

What is the minimum speed of the ‘A’ AFP to provide adequate lubrication and cooling?

A

1000 rpm

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17
Q

How do we maintain the cleanliness of the ‘A’ AFP governor control system?

A

Renewable cartridge filter that has a built in dirt alarm that will automatically bypass the filter when it becomes clogged

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18
Q

What drives the ‘A’ AFP?

A

Steam turbine

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19
Q

How does ‘A’ AFP respond to an AFAS?

A

the main steam supply valve bypass valves open first to bring the turbine up to 870 rpm in a slow and controlled manner

30 seconds later the main steam supply valves open to allow maximum steam flow to the turbine, and as the turbine approaches nominal speed, governor begins to throttle governor control valve to ~3400 rpm

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20
Q

Regarding the A AFP, why is there a large condensate pot installed in the Aux Building?

A

To allow for continuous draining of the moisture that can accumulate in the steam supply line to the AFA pump turbine

Without it, moisture could accumulate in the steam supply line which would greatly increase the chance of turbine overspeed during startup

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21
Q

Where is ‘A’ AFP located?

A

80’ MSSS

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22
Q

Where can I trip the Trip Throttle valve, AFA-HV-54, electrically?

A

Board 6 in the Control Room

‘A’ Remote Shutdown Panel

Local control panel

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23
Q

What is the one way for the trip throttle valve, AFA-HV-54, to trip automatically?

A

Mechanical overspeed device

can also trip manually by electrical trip, from pushbuttons, and a manual mechanical trip

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24
Q

What is the purpose of the essential AF pump Regulating and Isolation valves? When do they auto open? Where are they controlled from?

A

To provide means to regulate and isolate flow, respectively, to the steam generators from the Essential AF pumps

AFAS

Control Room, Remote Shutdown Panel, or
locally at the valves.

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25
Q

What powers the regulating and isolation valves associated with ‘A’ AFP? Turbine governor valves? What powers the same valves for the AFB pump? AFN?

A

All are PK

PH

this pump does not have those valves

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26
Q

What happens when an AFAS is received?

A

Both Essential AF pumps start, and the affected steam generator(s) regulating and isolation valves open

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27
Q

What happens if steam generator pressures differ by more than 185 psid?

A

Indicative of a main steam line break or feedwater line break affecting the steam generator with the lowest pressure

The D/P lockout will close the regulating and isolation valves for the affected steam generator, and prevent them from being reopened

28
Q

What is the power supply for ‘B’ AFP?

A

PBB-S04

29
Q

During startup, up to what power will we maintain S/G levels with AF?

A

2%

30
Q

What is the main purpose of the Aux. feed system?

A

provide sufficient flow to the steam generator(s) for the control of reactor coolant temperature during normal startup, hot standby and shutdown conditions, and for initial fill and makeup.

remove heat from RCS via S/Gs during a station blackout

31
Q

What powers the B train AFP MOV flow control and isolation valves?

A

PH

32
Q

What powers all valve position indicators in the AF system?

A

PN via aux. relay cabinet

33
Q

What is powered by NH in the AF system?

A

AFN-P01 MOV recirculation valve

34
Q

What system feeds the AFA-P01 turbine for testing purposes?

A

AS

35
Q

What is 300,000 gallons in the RMWT designated for?

A

non-safety related, alternate source of water for the essential AF pumps only

36
Q

What is the normal source of water for the essential and non-essential AF pumps?

A

CST, 300,000 gallons

37
Q

How does EC interface with the AF system?

A

AHU in each essential pump room starts on a pump start, cooled by EC

38
Q

How does FP (fire protection) interface with AF?

A

FP is connected to the discharge of the AFN pump as an additional source of make up to the S/Gs

(defense in depth)

39
Q

Where do the AF pumps tie-in to the main feedwater system to feed the S/Gs?

A

AFN is upstream of the downcomer FW regulating valve

AFA and AFB is downstream of the downcomer FWIV

40
Q

Where do the floor drains of the AF pump rooms route drainage to?

A

non-ESF sump

backflow into these rooms is prevented

41
Q

What signal from ESFAS trips the AFN pump? Essential pumps?

A

SIAS, LOP

LOP/LS (load shed)

42
Q

How does the SC system interface with the AFN pump?

A

while running, ammonia and hydrazine can be injected

43
Q

How does AF interface with SG?

A

SG provides steam to AFA pump after MSIS from either or both S/G

all three AF pumps feed S/G through DC FW lines

AFN pump is used to feed the S/G during initial fill and make up, startup, hot standby, and normal shutdown

44
Q

What FLEX connections are in place for the AF system?

A

provided to allow use of a FLEX SG Makeup Pump to supply feedwater to the Steam Generators

primary flow is AFB discharge

AFA discharge is alternate path

AFB suction line can also feed the FLEX AF pump

45
Q

Where does the AFN pump take suction and where does it discharge to?

A

CST only

feeds the S/Gs through the FW downcomer control valves or through the control valve bypass

46
Q

Does the AFn pump take suction from the CST at the same level as the essential AF pumps?

A

yes

47
Q

What is the purpose of the two parallel recirc lines back to the CST from the AF pumps?

A

minimum flow recirc and full flow recirc for testing

48
Q

What is the purpose of having a steam turbine with PK powered valves for the AFA pump?

A

to enable aux. feedwater supply on a SBO

is able to supply lower rates of flow to not overcool the RCS

49
Q

Describe the operation of the AFA pump turbine governor. How does the valve fail on a loss of power?

A

the governor valve is a steam control valve that actuates to set the speed of the turbine and pump

fails open, causing the turbine to overspeed

50
Q

How do the AFA pump and turbine bearings stay cool?

A

gear driven oil pump with an oil cooler, cooled from the first stage of the pump

51
Q

What is the purpose of the AFA trip throttle valve?

A

overspeed mechanism that stops the steam supply to the AFA turbine

can also control steam flow in the event that control power is lost to the governor

52
Q

What are the two places the Essential AF pumps can take suction from?

A

normal is CST

alternate is RMWT

53
Q

What is the flow path of the steam to the AFA steam turbine?

A

from the main steam line, upstream of the MSIVs, through an isolation valve and the trip throttle valve to the turbine

exhausted to the MSSS roof

54
Q

Why is the AF pump mini-flow recirc line returning to the CST above the 28’ mark?

A

to maintain tank integrity in the event of a steam line break

55
Q

Concerning the AF system essential pumps, how can the CST become contaminated during pump operation?

A

when suction is aligned to the RMWT

the AF pump recirculation lines cannot be aligned to the RMWT

56
Q

Why would a control room operator want to close the AFA turbine steam supply valves? where are these valves located?

A

main steam line break upstream of the MSIVs to ensure the turbine gets steam from a reliable source

steam generator tube leak, to minimize the radiological release to the environment

120’ MSSS

57
Q

What is important about the AFA pump turbine critical steam traps? Where are they located?

A

these steam traps are installed in the AFA turbine steam supply lines

drain to the A condenser, just above the reheater trays

high level in the reheater trays will flood these steam trap drain lines and potentially INOP the AFA Pump

100’ turbine building, west end (M23 from S/G1, M24 from S/G2)

58
Q

Concerning the AF system, What is the condensate pot equipped with and what is the purpose of them? Where is the condensate pot located?

A

two vent valves, a supply of steam to the AFA pump turbine during start up,

level gauge glass, to verify the steam trap is operating properly on startup

steam trap, to maintain level in the condensate pot during pump start

77’ aux building, unassigned room

59
Q

Concerning the AF trip throttle valve, what are the indications of an electrical trip and a mechanical trip?

A

elec:

  • Latch Lever and Trip Hook are engaged
  • Trip and Throttle Valve Operator red “Open” light will be lit
  • Trip and Throttle Valve green “Closed” light will be lit

mech:

  • Latch Lever and Trip Hook are disengaged
  • Trip and Throttle Valve Operator green “Closed” light will be lit
  • Trip and Throttle Valve green “Closed” light will be lit
60
Q

Where are the regulating and isolation valves for the essential AF pumps located?

A

80’ MSSS, respective pump rooms

61
Q

Concerning the AF system, where is the temperature tape recorder located and what is its purpose?

A

discharge piping of the AF pumps

changes colors to detect an abnormal increase in temperature

62
Q

What is in place in each feedwater line to the S/Gs to decrease the potential of steam back leakage into the AF essential pumps?

A

5 isolation barriers (valves)

63
Q

How can you tell if an essential AF pump is gas/steam bound?

A

steam binding is indicated on the tape recorder by the pump casing

gas binding in indicated by pump failing to maintain expected discharge pressure/flow

64
Q

Does venting the essential AF pumps make them inoperable? What water source do you flush the essential AF pump casing and discharge piping with?

A

yes

CST

65
Q

Concerning the AF system, what is the order of events that occur after an AFAS1 or 2?

A
  • S/G level drops to 25.8% in either S/G, the respective AFAS signal will actuate.
  • Both Essential pumps start and only the affected S/G’s regulating and isolation valves open
  • these valves will close when S/G level reaches 40.8%
  • these valves will continue to cycle in this range until control takes manual control

if both AFAS-1 and -2 actuate simultaneously, both sets of regulating and isolation valves will open

NLO Systems (66 decks)

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