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Systems > Main Turbine > Flashcards

Main Turbine Flashcards

1
Q

What valves are operated by PACs ?

A

-Stop Valves
-Control Valves
-Combined Intermediate Valves(CIVs)

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2
Q

What’re the two types of Control PACs ?

A

-PACs for controlling steam valves
-PACs for non-controlling steam valves

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3
Q

What valves use a Controlling PAC ?

A

-Stop Valve #2
-Control Valves 1,2,3,4
-Intercept valves 1,2,3

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4
Q

What Valves use Non-Controlling Valves ?

A

-Stop Valves 1,3,4
-Intercept Valves 4,5,6
-Intermediate Stop Valves 1,2,3,4,5,6

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5
Q

How fast do the Control PACs normally open & close valves ?

A

10% per second

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6
Q

How fast do the PACs close valves on a Turbine Trip ?

A

Will rapidly close valves in 0.2 seconds

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7
Q

What is the difference between PAC Controlling Valves & PAC NON-Controlling Valves ?

A

Controlling valves- Have a servo-valve that regulates EHC Oil flow

NON-Controlling Valves- Test solenoid admits full flow to the valve maintain them fully open during normal operation
Test Solenoid used during MT valve testing

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8
Q

What is the Maintain Turbine Stop Valved used for ?

A

-Allow steam to Main Turbine during normal conditions
-Quickly isolates steam during emergency conditions

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9
Q

How is the Steam Chest formed by the Stop Valves ?

A

Outlet of each Stop Valve is welded to the inlet of each Control Valve & below sets of stop valves is welded together to form Steam Chest

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10
Q

What does Stop Valve #2 provide ?

A

-Bypass valve that can open across pressure drop across valve
-Slowly warms steam chest & HP Turbine
-Pressurizes steam chest to minimize DP across Stop Valves to open rest of the Stop Valves

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11
Q

When control room tests each Stop Valve one at a time, what is the AO supposed to be looking for ?

A

Supposed to monitor valve stroke during closing & opening of Stop Valve

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12
Q

Why aren’t Control Valves affected when the Stop Valves are being tested ?

A

Steam chest supplies all 4 Control Valves so it has little impact

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13
Q

What is the Steam Chest used for ?

A

Used as equalization line to maintain steam flow through all 4 Steam lines to the HP Turbine

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14
Q

Above 50% power, what system receives steam leakoff from the Stop Valves ?

A

Stop Valve leakage provides steam to Gland Sealing Steam

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15
Q

What’re the Main Turbine Control Valves used for ?

A

-Controls steam flow during startup& shutdown
-Regulates steam flow for load requirements during normal operation
-First line of defense to prevent over speeding during emergency condition

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16
Q

Where is the inlet of the Control Valve directly welded to ?

A

Directly welded to the outlet of the Stop Valves

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17
Q

While at rated power the Main Turbine Control Valves normally maintained at ?

A

Maintained 40-50% open

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18
Q

How do we test the Main Turbine Controls Valves if it’s going to affect on Main Turbine operation?

A

-Turbine temporality reduced so control valves are less than 40% open

-As each control valve is closed, other control valves will auto open to maintain supply to Main Turbine

-Once control valve is fully closed & opened, other control valves throttle back to original position

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19
Q

After 50% power where do the Control Valves leak off to ?

A

Leaks off to the Main Turbine Gland Sealing Steam

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20
Q

What does the HP Turbine Shell provide for the turbine ?

A

-Pressure barrier between Turbine internals & turbine building
-Maintains alignment of turbine

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21
Q

What is provided to the HP Turbine Shell to prevent Main Steam from leaking out at Low-Load operations ?

A

Gland Sealing Steam is applied to HP Turbine Shell to prevent main steam from leaking out Shell Joints

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22
Q

What speed does the turbine spin at ?

A

1800 rpm

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23
Q

What is the Turbine Rotor geared to inside the Front Standard ?

A

Geared to the:
-Main Shaft LO Pump
-Permanent Magnet Generator
-Also extends to the ‘A’ LP Turbine Rotor

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24
Q

Where does extracted steam from the 3rd stage of the HP Turbine go ?

A

-Goes to the #7 HPFW Heater
-Goes to the 1st stage of the MSR

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25
Q

Where does extracted steam from 5th stage of the HP Turbine go ?

A

Goes to the #6 HPFW Heater

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26
Q

Where does the Exhaust Steam go after it exits HP Turbine ? What is the HP Turbine Exhaust called?

A
  • Cold Reheat goes to the MSRs
    -Exhaust is called Cold Reheat
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27
Q

What two valves are in the Combined Intermediate Valves ?

A

-Intercept Valve
-Intermediate stop valve

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28
Q

What does the Intercept Valve do inside the CIVs?

A

-Regulates steam flow into LP Turbine
-Rapidly isolates steam from cross around piping

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29
Q

What do the Intermediate Stop Valves do inside the CIVs ?

A

-Second line of defense against energy stored in the Cross Around Piping in event of Intercept Valve failure

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30
Q

Why’re the CIVs located as close as possible to the LP Turbine ?

A

Limits amount of uncontrolled steam in the cross around piping to prevent overspending during a Turbine Trip

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31
Q

What happens to the CIVs during Normal Operation, Normal shutdown, & Turbine Trip

A

-CIVs are wide open during Normal Operation
-BOTH valves close during Normal Turbine Shutdown or Turbine Trip

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32
Q

Which Intercept Valves are Controlling Valves ? What do they do ?

A

IVs 1,2,3 regulate steam flow to the LP Turbine

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33
Q

Which IVs are NON-Controlling Valves? What’re they supposed to do ?

A

4,5,6 respond to the positioning of IV 1,2,3

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34
Q

What happens when the Controlling Intercept Valves reach 90% ?

A

NON-Controlling IVs for LP Turbine will fully OPEN

35
Q

What happens when the Controlling Intercept Valves closes to 50%?

A

NON- Controlling Intercept Valves for the LP Turbine will go fully CLOSED

36
Q

Which valves inside the CIVs can open against pressure ?

A

-Intercept valve can open against pressure
-Intermediate Stop Valve can’t open against pressure

37
Q

Since the CIVs Intermediate Stop Valves can’t open against pressure, how are you supposed to open them ?

A

When opening CIVs the Intermediate Stop Valve must be opened first,
THEN Intercept Valve will be opened second

38
Q

Why do we try minimizing time having the CIVs closed?

A

Uneven steam flow to the LP Turbine causes unequal heating which leads to High Vibration

39
Q

What is provided to the CIVs to prevent leakage from valve casing ?

A

Gland sealing steam is supplied to both Intercept Valve & Intermediate Stop Valve

40
Q

Where do the LP Turbine receive there steam from ?

A

Received hot reheat from MSRs

41
Q

What is used to control temperature of the LP Turbine Hood during startup & Low Load operations ?

A

Has spray nozzles that spray water from condensate system

42
Q

How is the flow of water to the spray valve controlled ?

A

Temperature transmitters & local temperature indicators will automatically adjust the spray valves

43
Q

When is the manual bypass used for the Spray Nozzles for the LP Turbine ?

A

Used when the automatic system malfunctions

44
Q

What are the rupture discs on each of LP Turbines used for ?

A

Protects LP Turbine exhaust hood & Condenser, during a loss of CW to the Condenser

45
Q

How do the Rupture discs on the LP Turbine Exhaust Hood work ?

A

-If LP Turbine Exhaust Hood pressure rises to 5 psig, it forces rupture disc diaphragm into a cutting knife

-Relieves to Turbine Building Atmosphere

46
Q

What’re the Main Turbine Bearings used for ?

A

-Absorbs Axial thrust on turbine & generator rotors

47
Q

What’re the Main Turbine journal bearings used for ?

A

Supports weight of the Main Turbine Rotor

48
Q

Where are the Journal Bearings located at ?

A

At the end of each:
-HP Turbine Rotor
-LP Turbine Rotor
-Main Generator Rotor

49
Q

What’re the Main Turbine Bearings cooled by ?

A

Cooled by Main Turbine Oil fed into 25psig

50
Q

What should the temperature rise across the bearings be?

A

Should be <45F

51
Q

What is considered abnormal when it comes to the Main Turbine Bearings ?

A

ANY sudden increase in oil temperature across bearing is abnormal

52
Q

Where is the oil that cools the Main Turbine Bearings drained to ?

A

Drained to Main Turbine Lube Oil Reservoir

53
Q

Where is the lube oil drained to from the Main Generator ?

A

Drains into Aux. Detraining Section, then drains into Main Turbine LO Reservoir

54
Q

What is the Sight Box used for on the Lube Oil system ?

A

Portion of Lube Oil from each heating passed through Sight Box that allows visual inspection & oil temperature

55
Q

When is the Main Turbine Turning Gear used ?

A

Rotates Main Turbine Rotor slowly during shutdown periods when Rotor temperature changes occur

56
Q

How does the Turning Gear prevents temporary bowing of the Main Turbine Rotor ?

A

Provides means to obtain uniform state of temperature in the Turbine Rotors

57
Q

How is the Turning Gear used during Main Turbine Startup ?

A

Ensures no temporary rotor bow, which could affect:
-Shaft Clearances
-Unbalanced rotor weight causing vibration during startup

58
Q

What does the Turning Gear
Pre-Engagement Motor do ?

A

It engages the Turning Gear onto the Main Turbine Rotor

59
Q

What does the Turning Gear Driving Motor do ?

A

Supply torque for breakaway of Turbine Generator Rotor

60
Q

What are the Turning Gear automatic actuations ?

A

-Engages & starts when rotor drops below speed set point
-Disengages when Main Turbine Rotor is rolled with steam

61
Q

During turning gear operations where is the lubrication provided from ? Which pumps provide it ?

A

-Provided from Main Turbine LO system
-Turning Gear Oil Pump or Emergency Bearing Oil Pump for turning gear operations

62
Q

What’re the Pre-Engagement Motor & Driving Motor powered from ?

A

Powered from NH

63
Q

Does the Turning Gear have a shutoff valve for Lube Oil supply ?

A

No there is no shutoff valve from the Main Turbine Lube Oil supply header

64
Q

What does the Emergency Trip System contain ?

A

-Combines mechanical trip in front standard & electrical trip signals of Trip& Monitoring system
-Contains Air Relay Dump Valves used following Turbine Trip

65
Q

What does the Electro-Hydraulic Control Oil referred to as Emergency Trip Supply do ?

A

Allows Main Turbine Stop Valves, Control Valves, & Combined Intermediate Valves to open

66
Q

What does the Emergency Trip System do to the Emergency Trip Supply when it receives a mechanical or electrical trip signal ?

A

Emergency Trip System isolated Emergency Trip Supply oil to all Control PACs which will trip CLOSE all steam valves

67
Q

What’re the Air Relief Dump Valves used for? How do they work ?

A

-They’re kept opened by Emergency Trip Supply Oil
-Admit Instrument Air to Bleeder Trip Valves to overcome spring force to help maintain them open

68
Q

What Air Relay Dump Valves do during a Turbine Trip ?

A

-ETS oil is cut off causing ARDVs to close which isolates Instrument Air from Bleeder Trip Valves
-This causes bleeder trip valves to close & prevent back flow steam going back to Main Turbine from extraction lines

69
Q

When does the Main Turbine Overspeed Trip Device actuate ?

A

Actuated at 110% speed

70
Q

How does the Overspeed Trip Device work ?

A

-Normal speeds compressed spring holds ring in normal position
-Overspeed will centrifugal force will over come spring force activating Mechanical Trip Mechanism

71
Q

What does the Permanent Magnet Generator do ?

A

Provides AC power to Electro-Hydraulic Control Oil when Turbine is >95%

72
Q

What do the Turning Gear Low Speed Switches do ?

A

-Electro- Hydraulic device that activates turning gear when MT Rotor speed drops below setpoint
-Sensed by Aux. Control Rotor

73
Q

How do the speed sensors work ?

A

-Positioned around Aux Control Rotor
-Generates voltage proportional to shaft speed & provides it to Electro-Hydraulic Control Oil System

74
Q

What does Thrust Bearing Wear Detector do?

A

-Hydraulic device detects axial position of Turbine Rotor compared to Thrust Bearing Casing
-TBWD activates Emergency Trip System when Thrust Bearings Plates exceed set point

75
Q

Where do all the Main Turbine Valve drains routed to ?

A

Routed to the Main Condenser

76
Q

What’re the position of the Main Turbine Drain Valves during normal, startup, & shutdown operations ?

A

-Closed during normal operation
-Opened on main turbine trip to depressurize steam lines
-Maintained open during shutdown
-Closed during startup

77
Q

When is gland sealing steam provided to ?

A

-Stop & Control valves at low power
-High Pressure Turbine shell at low power
-Combined Intermediate Valves
-LP Turbine Shells

78
Q

Where does Main Turbine supply Gland sealing steam at high power ?

A

Supplied from:
-Stop& Control Valves
-High Pressure Turbine

79
Q

What will happen if the RCS gets to cold following a Main Turbine Setback ?

A

Main Turbine Runback is initiated to throttle Main Turbine Control valves & reduce Main Turbine loading

80
Q

What happens on loss of Electro-Hydrualic Control Oil ?

A

Main Turbine Trip will happen

81
Q

What is reactor power reduced to during a Main Turbine Trip or Load Rejection ?

A

Selected CEAs will drop into core reducing power level to 50%

82
Q

During a Turbine Trip or Load Rejection besides a Reactor Power Cutback, what other system is put into service ?

A

The Steam Bypass Control System will be initiated to control RCS Temperature & Pressure

83
Q

Where will Steam Bypass Control System dump steam to if there is no condenser vacuum ?

A

SBCS will dump steam to atmosphere to control RCS Temp. & Pressure

Systems (62 decks)

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