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Area 1/2/6 > Extraction Drain > Flashcards

Extraction Drain Flashcards

1
Q

What does the Bleeder trip valve do?

A
  • Prevents reverse steam flow on a MT trip

- Ensures turbine won’t overspeed

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2
Q

How does the Bleeder trip valve test work?

A

Pull on the handle and it equalizes pressure across operator piston to allow partial closing of the valve disc by spring force

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3
Q

If we lose IA to a bleeder trip valve what happens?

A

BTV will lose its open permissive and the valve would go partially closed. Steam pressure would keep it open.

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4
Q

Which FW heater has more then one BTV?

A

LPFW Htr #4

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5
Q

Where is the Heater Drain Tank?

A

120’ Turbine Building

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6
Q

Which valves in the ED system are direct acting?

A

Normal level control valves except #1 LPFW htr.

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7
Q

Which valves in ED system are reverse acting?

A

High level control valves and #1 LPFW HTR normal level control valve.

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8
Q

Where does the ED blowdown stack drain to?

A

North area condenser sump

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9
Q

What is the concern with MSR drain tank level?

A

If it back up to 3” below the associated MSR, the MT will trip.

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10
Q

Explain the when HDP’s start when starting the reactor?

A

1st pump starts at 25%

2nd pump starts at 40%

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11
Q

What cools the HDP LO coolers?

A

TCW

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12
Q

What are the trips on a HDP?

A
  • Lo-lo level in HDT
  • low flow (711 gpm for 15 seconds)
  • Electrical protection
  • High condensate line pressure (575 psig)
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13
Q

If we lose IA what happens to the HDP?

A

The discharge valve will fail closed and the pump will be put in recirc.

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14
Q

Explain the HDP?

A
  • Powered from NB
  • 5 stage centrifugal
  • Vertical suction
  • 6000-6500 gpm
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15
Q

Where does the HDP get seal water from?

A

Seal water is supplied from the condensate header (375-500 psig)

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16
Q

How is the seal water cooled at the HDP?

A

By the condensate service header. (50-100 psig)

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17
Q

Explain the purpose of the ED system?

A

Utilizes steam from the MT system to preheat CD/FW to increase overall plant efficiency

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18
Q

Where does the blowdown flash tank vent to?

A

HDT vapor space

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19
Q

Where does the BDHX cooling water discharge to?

A

discharge of HDP’s

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20
Q

Explain the operation of the normal level control valves for the reheat drain tanks. (1st stage/2nd stage)

A
  • Normal acting valves

- Send drains to associated FW heater

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21
Q

What happens to the normal level control valves on the 1st or 2nd stage drain tank on a loss of air or power?

A

Fail closed

22
Q

Where do the high level control valve send the drains from the 1st and 2nd stage drain tanks to?

A

Condenser on a high level or loss of air or power; which the high level control valves will fail open.

23
Q

How are the heater drain tank and 1st stage reheater drain tank high level control valves operated during startup from 0%?

A

High level control valves will be open until 10% power is achieved.

24
Q

How are the 2nd stage reheater drain tank high level control valves operated during startup?

A

High level control valves will be open until 20% power is acheived

25
Q

How is level maintained in the FW heaters?

A

by the level control valves

26
Q

What is different about the #5 FW heater compared to #6/7?

A

No level control valve

No direct dump to condenser on high level

27
Q

Explain what happens on a hi-hi level in a HPFW Htr?

A
  • Supply isolation valve closes
  • Depressurize the BTV
  • Open ext. line drain valve
  • Closes normal level control valve of previous heater (if applicable)
28
Q

What is drain cooler approach used for?

A

used to measure heater performance

29
Q

How is DCA measured?

A

Drain temperature minus incoming condensate temperature

30
Q

What is a concern when a heater drain pump trips?

A

Hotwell level can lower 9 inches. (30” setpoint for CD pump trip)

31
Q

What kind of valve is the HDP dishcharge valve?

A

Air operated valve. Fails closed on loss of power or air.

32
Q

What kind of valve is the HDP recirc valve?

A

Air operated valve. Fails open on loss of power or air.

33
Q

Explain the operation of the HDP recirc valve?

A
  • closes when flow is greater than 3200 gpm
  • opens when flow is less than 1600 gpm
  • closes when HDP stops
34
Q

What is the HDT hi-hi level?

A

9 feet

35
Q

Why don’t the #1 and #2 LPFW heaters have BTV’s?

A

Due to low energy present.

36
Q

What do the #1 and #2 LPFW heaters have that the other FW heaters don’t?

A

Flow baffles in lieu of the BTV’s.

37
Q

Why are there two BTV’s in LPFW heater #4?

A

Because the energy in this LPFW heater is great enough to cause an overspeed if the BTV would fail to close.

38
Q

How is level maintained in the LPFW heaters?

A
  • by level control valves in the drain lines
39
Q

How do the drains flow from the #7 HPFW heater?

A

The drains are the result of differential pressure between the #7 HPFW heater and the #6 HPFW heater.

40
Q

What positions the HDP discharge valve?

A
  • Normal level controller of the heater drain tank to ensure adequate level and suction is maintained for the pump
41
Q

What is individual heater performance measured by?

A
  • DCA (Drain Cooler Approach)

- TTD (Terminal Temperature Difference)

42
Q

How is DCA measured?

A

Fluid draining from the heater subtracted by the temperature of the incoming condensate

43
Q

How is TTD measured?

A

How closely the exiting condensate temperature approaches Tsat of the extraction steam

44
Q

How does the plant react to a trip of a Heater drain pump?

A
  • Condenser level will drop
  • Reactor power could increase due to colder FW
  • Main Feedwater Pump suction pressure will decrease
  • HDT level will increase
45
Q

What is our target DCA?

A

10 degrees F

46
Q

What if our DCA is too high; what does it indicate?

A

Water level is too low which allows higher fluid velocities to cause tube fretting and vibration induced fatigue

47
Q

What if our DCA is too low; what does it indicate?

A

Water level is too high which reduces heat transfer

48
Q

When will the BTV’s for a HPFW heater close?

A
  • HPFW heater hi-hi
  • HDT hi-hi (9 feet)
  • Turbine trip
49
Q

Explain what happens on a hi-hi level in a LPFW heater?

A
  • MOV’s (inlet/outlet) automatically close
  • BTV’s in that train close
  • Normal level control valves close
  • High level dumps open to send drains to condenser
50
Q

Why do we want to minimize HDP mini-flow recirc ops?

A
  • oscillation of FWP suction pressure

- damage to the HDT from the hydraulic effects of recirculating water.

Area 1/2/6 (9 decks)

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