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ZZ LOIT CWS Systems 2018 > ED: Extraction Drain > Flashcards

ED: Extraction Drain Flashcards

1
Q

Where does Stage #9 extraction steam from the Low Pressure Turbine go?

A

LPFW Heaters #3 (A,B,C - cross connected)

Gland Steam Supply

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2
Q

What are the operational flowrates associated with the Heater Drain Pump Recirc Valve?

A
  • Opens at 1600 gpm and on a pump stop

- Closes at 3200 gpm

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3
Q

When will Extraction Steam Block Valves re-open if they automatically closed?

A

They will re-open when the Hi-Hi Level that initiated the closure clears.

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4
Q

How do the BTVs fail on a loss of air?

A

Closed

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5
Q

How do the High Level Drains on a loss of air or power?

A

Open on a loss of both

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6
Q

What happens on a Hi-Hi level in a LPFWH?

A
  • LPFWH train isolations close
  • BTVs (for #3 and #4) close
  • Extraction Steam low point drains open
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7
Q

Where does Stage #5 extraction steam from the High Pressure Turbine go?

A

HPFW Heaters #6 (A and B)

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8
Q

How do the BTVs fail on a loss of IA?

A

Closed

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9
Q

To where do the 2nd Stage Drain Tanks A and C vent?

A

Normally to the #7A HPFWH (via 711A)

Alternate to the Main Condenser (via 711B)

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10
Q

What happens on a Hi-Hi level in a HPFWH (or HDT for 5A/B)?

A
  • All inputs’ Normal Level Control Valves close
  • Inputs’ vents swap
  • Extraction Steam Block Valve closes
  • Bleeder Trip Valve closes
  • Extraction Steam low point drain opens
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11
Q

What level in the MSR Drain Tank will trip the Main Turbine?

A

-3” in the MSR

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12
Q

What valves in the ED System does the 1st Stage Scavenging Mode Selector Switch (EDN-HS-615) control?

A

It controls the operation of the 1st Stage Drain Tank Vent Valves to the #6 HPFWHs and the Main Condenser.

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13
Q

What are Extraction Steam Block Valves?

A

Each HPFWH steam line has a motor operated block valve that will:

  • for #6/#7 HPFWHs isolate on Hi-Hi level in that HPFWH
  • for #5 HPFWHs isolate on Hi-Hi level in its associated HDT

Extraction Steam Block Valves will re-open when the Hi-Hi level clears.

LPFWHs do NOT have Extraction Steam Block Valves.

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14
Q

To where do the HPFWHs vent?

A

Continuously vented to the Main Condenser. All join to a common header.

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15
Q

What would cause the Feed Water Heater low point drains to auto open?

A

Turbine Trip
Hi-Hi level in the associated Feed Water Heater

Of course, they can be operated from the Control Room as well.

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16
Q

What is special about the BTV’s on the #7 HPFWHs?

A

7 HPFWHs BTVs are located upstream of their MOVs. Allows isolation for maintenance while maintaining 1st Stage Reheat in service.

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17
Q

How do the Normal Drains fail on a loss of air or power?

A

Closed on a loss of both

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18
Q

What are the Heater Drain Pump power supplies?

A

HDP A - NBN-S02

HDP B - NBN-S01

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19
Q

How do the BTVs and drain valves behave on a Turbine Trip?

A
  • BTVs close (they will reopen once the trip is clear)

- Drain valves open (they will not reclose when the trip clears)

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20
Q

Do LPFWHs have Extraction Steam Block Valves?

A

No

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21
Q

To where does the MSR Drain Tank vent?

A

Hot Reheat (discharge from the MSRs)

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22
Q

What is the status of the MSR Drain Tank High Level Control Valve when power is <10%?

A

It its failed open until Hot Reheat steam pressure reaches a pressure equivalent to ~10%

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23
Q

What is special about HPFW Heater #5?

A

It has no level control due to being connected to the Heater Drain Tank.

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24
Q

The Normal Level Control Valve for the 1st Stage Drain Tank will auto close on what?

A

Hi-Hi level in the #6 HPFWH

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25
Q

Where can the 2nd Stage Drain Tank send water?

A

To the #7 HPFWHs or the Main Condenser

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26
Q

Where does Stage #11 extraction steam from the Low Pressure Turbine go?

A

LPFW Heaters #2 (A,B,C)

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27
Q

Where is Cold Reheat extraction steam sent?

A

HPFW Heaters #5 (A and B)

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28
Q

To where do the 2nd Stage Drain Tanks B and D vent?

A

Normally to the #7B HPFWH (via 712A)

Alternate to the Main Condenser (via 712B)

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29
Q

What happens on a Heater Drain Tank high level?

A
  • Comes in at 9’
  • 2 associated MSR Drain Tanks Normal Level Control Valves close
  • Associated #6 HPFWH Normal Level Control Valve closes
  • Associated #5 BTV and Extraction Steam Block Valve close
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30
Q

Do #1 and #2 LPFWHs have BTVs?

A

No. They have flow baffles. There’s not enough pressure in these FWHs to warrant protection from a Main Turbine Overspeed.

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31
Q

How do the Normal Level Control Valves fail?

A
  • Closed

- The one exception is the Normal Level Control Valve for the #1 LPFWHs which fail open to the Main Condenser.

32
Q

Where does Stage #3 extraction steam from the High Pressure Turbine go?

A

HPFW Heaters #7 (A and B)

1st Stage Reheat in the MSRs

33
Q

Why do #4 LPFWHs have two BTVs?

A

Because there’s enough energy in the #4 LPFWHs alone to cause a Main Turbine Overspeed

34
Q

The Normal Level Control Valve for the 2nd Stage Drain Tank will auto close on what?

A

Hi-Hi level in the #7 HPFWH

35
Q

How are the BTVs distributed across the Feed Water Heaters?

A

One on each HPFWH and #3 LPFWH

Two for #4 LPFWHs

36
Q

The Normal Level Control Valve for the MSR Drain Tank will auto close on what?

A

Hi-Hi level in the HDT

37
Q

Where can the 1st Stage Drain Tank send water?

A

To the #6 HPFWHs or the Main Condenser

38
Q

Where can the MSR Drain Tanks send water?

A

To the Heater Drain Tanks or the Main Condenser

39
Q

What is the sequence of events on a Heater Drain Pump start?

A
  • Motor Starts
  • 5 seconds later, recirc opens
  • 2 minutes after pump start the discharge valve will open (starting current)
40
Q

Where does Stage #8 extraction steam from the Low Pressure Turbine go?

A

LPFW Heaters #4 (A,B,C - cross connected)

41
Q

What are the Heater Drain Pump trips?

A
  • HDT Lo-Lo Level - 4’
  • HDP Lo Flo - 711 pm for > 15 sec
  • LPFWH outlet pressure Hi - 575#
42
Q

What will cause the BTVs to trip closed?

A
  • A Turbine Trip
  • Hi-Hi Feedwater Heater Level
  • a redundant signal is supplied to all BTVs (through the Turbine Critical Relay Dump Pressure Switch Low [EDN-PSL-76]) to ensure BTVs close on a Turbine Trip
43
Q

The 2nd Stage Scavenging Mode Selector Switch (EDN-HS-715) is in AUTO. In what position will the controlled valves be placed and what is the requirement for these valves to move?

A

Vent to #7 HPFWH opens and the vent to the Main Condenser closes.
These valves will only reposition if the associated Extraction Steam Block Valve is full open.

44
Q

What cooling water is sent to the Blowdown Stack?

A

Domestic Water (DS) cools the Blowdown Stack.

45
Q

How do the High Level Dump Valves fail?

A

Open

46
Q

What do LPFWHs have instead of BTVs?

A

Installed Flow Baffles

47
Q

What valves in the ED System does the Steam Blanketing Mode Selector Switch (MTN-HS-519)control?

A

It controls the operation of the 1st and 2nd Stage Drain Tank High Level Control Valves.

48
Q

Why do we have MSRs?

A

Improved cycle efficiency and minimizes LP turbine blade erosion.

49
Q

What happens to the Heater Drain Tank when its Heater Drain Pump is secured?

A

The Heater Drain Tank will fill all the way to its high level dump. (Basis for keeping hotwell level at 41”)

50
Q

What supplies 2nd Stage Reheat in the MSRs?

A

Main Steam

51
Q

What type of valves do the HPFWHs have for low point drains upstream of the BTVs?

A

MOVs

52
Q

How does the BTV Test Valve work?

A

It equalizes air pressure to allow the disc to fall into the steam flow, resulting in a partial closure.

53
Q

What purpose do the Bleeder Trip Valves serve?

A
  • Prevents reverse steam flow on a turbine trip (overspeed)

- Prevents moisture carryover on Heater Drain Tank or Feed Water Heater Hi-Hi Level (blade damage)

54
Q

When does the High Level Control Valve for the 2nd Stage Drain Tank close on a startup?

A

It its failed open until Hot Reheat steam pressure reaches a pressure equivalent to ~20%

55
Q

How does the Heater Drain Pump Recirc Valve fail on a loss of air or power?

A

Open

56
Q

Where does the Blowdown Flash Tank vent?

A

Primary is the Heater Drain Tank. Secondary is LPFW Heater #3.

57
Q

How does the Heater Drain Pump Discharge Valve fail on a loss of air or power?

A

Closed

58
Q

To where do the Heater Drain Pumps vent their suctions?

A

Back to their respective Heater Drain Tanks

59
Q

When does the High Level Control Valve for the 1st Stage Drain Tank close on a startup?

A

It its failed open until Hot Reheat steam pressure reaches a pressure equivalent to ~10%

60
Q

Where does the Blowdown Stack drain?

A

To the North Condenser Area Sump

61
Q

What is special about how the BTVs close?

A

It’s spring assisted

62
Q

Where do all the High Level Dumps put water?

A
  • The Main Condenser

- The one exception is the #5A/B HPFWHs. They don’t have level controllers and dump directly to the Heater Drain Tank.

63
Q

Where does the cooling water go after it leaves the SGBDHX?

A

To the Heater Drain Pump discharge

64
Q

To where do the 1st Stage Drain Tanks A and C vent?

A

Normally to the #6A HPFWH (via 611A)

Alternate to the Main Condenser (via 611B)

65
Q

What valves in the ED System does the 2nd Stage Scavenging Mode Selector Switch (EDN-HS-715) control?

A

It controls the operation of the 1st Stage Drain Tank Vent Valves to the #7 HPFWHs and the Main Condenser.

66
Q

To where do the 1st Stage Drain Tanks B and D vent?

A

Normally to the #6B HPFWH (via 612A)

Alternate to the Main Condenser (via 612B)

67
Q

Why do all the vents for the #7 HPFWHs go closed if there’s a Turbine Trip coincident with a loss of power to the 2nd Stage Reheater Isolation Valves (RSS)?

A

Without this, a flowpath would exist through the second stage heaters directly to the condenser.

68
Q

What type of valves do the LPFWHs have for the low point drains upstream of the BTVs?

A

AOVs

They fail open

69
Q

Where does Stage #12 extraction steam from the Low Pressure Turbine go?

A

LPFW Heaters #1 (A,B,C)

70
Q

The 1st Stage Scavenging Mode Selector Switch (EDN-HS-615) is in AUTO. In what position will the controlled valves be placed and what is the requirement for these valves to move?

A

Vent to #6 HPFWH opens and the vent to the Main Condenser closes.
These valves will only reposition if the associated Extraction Steam Block Valve is full open.

71
Q

What is special about HPFWH #5A in regards to low point drains upstream of the BTVs?

A

HPFWH #5A doesn’t have low point drains upstream of the BTVs due to the short pipe run from the turbine to the 5A HPFWH.

72
Q

When do the 1st and 2nd Stage Drain Tank vent valves swap to the Main Condenser?

A

The circuitry is run off of the Extraction Steam Block Valves. If they come off of their open seats, the vents will swap.

73
Q

To where do the Heater Drain Tanks vent?

A

To its associated #5 HPFWH

74
Q

How are the Turbine Critical Air Relay Dump Valves aligned to the Bleeder Trip Valves?

A
  • ARDV #1 is aligned to the two BTVs on the #4 LPFWHs (Critical)
  • ARDV #2 is aligned to all other BTVs (Non-Critical)
75
Q

How do the BTVs behave on a HPFWH Hi-Hi Level?

A

The BTV associated with the Hi-Hi level will go closed.

76
Q

How do the BTVs behave on a LPFWH Hi-Hi Level?

A

BTVs for #3 and #4 LPFWH go closed.

ZZ LOIT CWS Systems 2018 (35 decks)

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