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NLO Systems > GT/NE- Station Black Out Generators (SBOG) > Flashcards

GT/NE- Station Black Out Generators (SBOG) Flashcards

(NE is the electrical side of the SBOGs)

1
Q

What is the system designator for the SBOG’s?

A

GT

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2
Q

What does the NRC mandate in 10CFR50.63?

A

That each station must provide an alternate source of AC power to ensure that the reactor core is not exposed during a station blackout if one or more of the emergency diesel generators or battery back up systems fail.

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3
Q

Is off site power dependable? Preferred?

A

Dependable, no. Preferred, yes.

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4
Q

What is the NUMARC 87-00?

A

It’s a Coping Assessment, which is a study of how a plant will ‘Cope with’ situations such as fire or tornado.

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5
Q

What is a black out vs a station black out?

A

A black out is when a single unit loses off-site power and both diesel generators fail

A station black out is when all three units lose off-site power and both diesels fail.

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6
Q

How long do you have to start and load the SBOG’s in an emergency?

A

1 hour to start the SBOG

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7
Q

What is the only means of power during a black out until the SBOG’s are brought online?

A

Class and non-class battery systems.

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8
Q

What is the back up for the SBOG’s and does the NRC let us take credit for it?

A

Cross tying the 4160v busses between units through the switchyard. We cannot take credit for this.

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9
Q

What is used to reduce the turbine speed to the effective generator speed of 1800 rpms?

A

A reduction gear assembly.

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10
Q

What are the three main components of a gas turbine?

A

Compressor, combustor and turbine

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11
Q

How many fuel injectors are in the SBOG combustion chamber?

A

12 + Fuel Plug (13th)

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12
Q

What two services does the compressed air of the gas turbine serve?

A

25% (primary air) compressed is mixed with fuel used for combustion

75% (secondary air) is used for cooling for combustion gases & inner heat shield, as it enters hold in the liner-it keeps flame cone from touching the liner. It also ensures complete combustion and reduces gas temp prior to entering turbine section

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13
Q

What physically spins the turbine of the gas turbine?

A

Hot exhaust gases from the combustion process

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14
Q

Efficiency of a typical gas turbine?

A

20%

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15
Q

At what temp are the exhaust gases when they exit the silencer stack?

A

1000 F

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16
Q

What temps are the gas turbines usually exposed to?

A

1600-2300F

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17
Q

What are the four processes that comprise the Brayton Cycle (for gas turbine engine)?

A

1) Compression: atm air is drawn into compressor & compressed

2) Combustion: fuel injected and makes air/fuel mixture then ignited which creates rapidly expanding hot gases

3) Expansion: hot gases are directed through turbine to produce rotational movement of shaft

4) Exhaust: spent gases are discharged to atm

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18
Q

What components draws the air into the compressor section through the air inlet?

A

Compressor rotor

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19
Q

When does the bleed valve open and why?

A

At start up to vent some of the compressed air around the turbine blades

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20
Q

The variable guide vanes regulate air flow during start to avoid surge limits. When do they begin to open and when will they be full open?

A

Begin opening from minimum position at 90% engine speed and reach full open one or two seconds later

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21
Q

What is the purpose of the combustion process?

A

To increase the velocity of gases being directed to the turbine section by causing them to expand more rapidly

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22
Q

During the combustion process, do I expect a change in pressure?

A

No

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23
Q

How long will the SBOG’s supply AC power to the emergency loads of a blacked out unit?

A

16 hours

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24
Q

What are the three major components of the Taurus turbine-driven generator package?

A

Turbine engine, reduction gear assembly, generator

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25
Q

What is the output speed of the Taurus turbine engine?

A

14951 rpm

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26
Q

What is the reduction gear ratio?

A

8.3/1

Turbine speed 14951 RPM : Generator speed 1800 RPM

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27
Q

How is the SBOG lube oil system cooled?

A

An electric fan on the bottom of the cooler package

28
Q

Concerning the sbog lube oil system, what components maintain proper oil temp?

A

Oil reservoir, oil coolers, thermostatic oil control valves

29
Q

What is the sbog lube oil piping made of?

A

Stainless steel

30
Q

What services are provided by the sbog air system?

A

Pressurize oil seals, cool turbine rotor discs and first stage nozzles, supply air for proper fuel air mixture in combustion chamber, prevents surge conditions at critical speeds

31
Q

What is the purpose of the turbotronic control system

A

Provides for automatic starting, acceleration to operating speed, engine and generator monitoring during operation, and normal and emergency shutdown sequencing, control, protection and display

32
Q

How is automatic speed control accomplished?

A

By the combination generator control module which maintains generator frequency by controlling fuel flow to the turbine

33
Q

The air intake system for each Sbog unit consists of what components?

A

Air filtration/cleaner unit, silencer, ductwork

34
Q

How many pre-filter’s and high-efficiency filters are there in the air inlet and exhaust system?

A

20 prefilters and 20 high efficiency filters

35
Q

Concerning the start system, what are the two functions of the diesel engine?

A

Supplies rotational power to drive a hydraulic pump which provides the pressure to drive a hydraulic motor which provides rotational force to start the turbine

Supplies a source of atomizing air from an External compressor attached to the diesel engine to the air assist accumulator of the turbine engine. Used to pressurize the air assist tank to 120 PSIG for Sbog start

36
Q

Start command has been initiated. What are the nine steps that occur for the Sbog start up?

A

30 second pre-lube 24 V DC pump cycle begins,

diesel engine starts and accelerates to operating speed’s within seconds,

engine driven pre-charge pump begins operation,

loading solenoid valve is energized and pressure positions pump to maximum stroke,

hydraulic motor rotates, sprag clutch engages outer race, And gas turbine engine begins to rotate,

combustion occurs, speed increases and turbine engine begins to drive gear train,

when gear train speed exceeds start motor speed, Spraggs disengage, permitting clutch to free wheel,

turbine reaches 66% NGP, loading solenoid deenergizes, and hydraulic pump goes to minimum stroke,

as turbine accelerates to 100% speed, diesel engine continues to run in no-load condition for five minutes, then shuts down

37
Q

What are used as the engine seals?

A

Labyrinth seals

38
Q

Where does the turbine cooling air come from?

A

Bleeds from the compressor 11th stage of compressor section

39
Q

What type of valve is the compressor bleed air valve?

A

Motor-driven roller screw actuated butterfly (trunion) valve

40
Q

During the start cycle, the PLC commands an actuator to open the bleed air valve. When will it shut?

A

Approximately 90% speed

41
Q

During deceleration, when will the bleed valve open?

A

90% engine speed

42
Q

What lets the PLC know how much air is available for combustion?

A

PCD (pressure compressor discharge)

43
Q

What is the operation sequence of the air system?

A

Engine begins cranking

Compressor begins building pressure

Cooling air is supplied to the turbine

Combustion occurs

PLC controls acceleration fuel schedule (1% every 2 seconds, while not exceeding programmed 3rd stage rotor inlet temp increase(T5))

Air/oil seals are pressurized

Bleed air valve closes and variable guide vanes open at 90% speed

Engine is at 100%

44
Q

What is the function of the lube oil system?

A

Provides lubrication and cooling of engine rotating elements and provides operating medium for hydraulic-actuation of the bleed air valve, variable guide vanes and fuel valve actuator

45
Q

When does the thermal bypass valve bypass the oil coolers?

A

When oil cooler DP >50 psig

46
Q

What pressures are associated with the oil pressure transducer?

A

Alarm @ 42 psig

Shutdown @ 25 psig

Start permissive @ 6 psig

47
Q

What is the purpose of the pre/post lube oil pump?

A

Supplies oil to the engine and gearbox for 30 seconds prior to engine rotation, during “crank” mode, and for 55 minutes post lube cooling cycle after engine shutdown

48
Q

What temp set points are associated with the lube oil heater temp detector?

A

Alarms @160F

Shutdown @ 165F

49
Q

What are level alarm set points associated with the lube oil tank? (EXPLANATION Question)

A

Low level alarm @ 279 gal

Low level shutdown @ 182 gal

50
Q

Briefly describe the sbog fire protection system

A

Light sensors called “fire eyes” which sense a fire by sensing wavelength within the sbog enclosure and dump the CO2 injection to stop fires. Must be disabled prior to opening enclosure doors.

51
Q

Who needs to be informed prior to inhibiting fire system?

A

Unit 1 control room and fire protection dept

52
Q

What are the basic steps in the start up sequence of the sbogs?

A

Press start button

Diesel starting engine starts

Ignition

Acceleration

Generation

53
Q

At what speed does the fuel purge valve close?

A

15% speed

54
Q

What is the fuel purge for?

A

To burn off any remaining fuel in the system prior to start up

55
Q

When do the sbogs reach self-sustaining speed and why?

A

66% speed because the energy produced by the hot gases from the combustor is enough to maintain turbine speed

56
Q

At what speed does the voltage regulator flash a generation field? (EXPLANATION Question)

A

80% speed

57
Q

When will the Ready to Load light come on? (EXPLANATION Question)

A

10 seconds after turbine speed reaches 90%

58
Q

When does the combination generator control module assume control of the turbine?

A

90% speed

59
Q

Approximately how long is the start up sequence? (EXPLANATION Question)

A

2 min 15 seconds

60
Q

While the sbog is operating, what would happen if ‘fast stop’ is used? (EXPLANATION Question)

A

This immediately closes the fuel cutoff valve and trips the generator output breaker

3 minute cool down period will be eliminated

61
Q

How many stages are on the compressor rotor?

A

12 stages

62
Q

How many stages on the compressor rotor have variable guide vanes?

A

1 on the compressor inlet and First 3 stages of the rotor

63
Q

What components are in the front of the Taurus turbine engine?

A

Air inlet assembly, generator

64
Q

Where is 480VAC power to auxiliary equipment powered from?

A

AE-NHN-M56

65
Q

Do the SBOG’s have a stand alone DC battery system for emergency start up?

A

Yes

66
Q

What type of fuel is used in the gas turbines?

A

No. 2 fuel oil

67
Q

When does the SBOG ignition system switch off? (EXPLANATION Question)

A

when T5 temperature reaches 400*F

NLO Systems (66 decks)

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