Stator Cooling Water Flashcards

1
Q

What are the SCW pump auto starts?

A
  • Low Disch # at 120#(U1) and 80#(U2)

- Low Flow at 845gpm (U2 only)

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2
Q

What are the Main Turbine and Unit Differential trips associated with SCW?

A
  • 2/3 RTDs at 95°C after 5 second delay
  • 2/3 Low Flow at 195 gpm (U1) and 666 gpm (U2)
  • 2/3 Low Pressure at 13#(U1) and 28# (U2)

(Each auto trip will actuate)

  • Main Turbine Trip after 10 seconds
  • Unit Differential Trip after 30 seconds.

Manual Actions

  • Conductivity at 9.9 mho/cm (reduce load)
  • MANUAL TRIP at 18 mho/cm conductivity
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3
Q

What cools the SCW coolers?

A
  • TACW
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4
Q

How is the SCW maintained to prevent water leaking in the Generator?

A
  • SCW # is maintained 3-4# < machine gas #
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5
Q

Why is the SCW maintained 3-4°C > Cold Gas Temp?

A
  • Prevent moisture from forming on the outside of the Stator Water Teflon tubes
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6
Q

What is the auto makeup to the SCW system?

A
  • Demin Water
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7
Q

What is the purpose of the SCW system?

A
  • Removes heat from the Main Gen stator armature conductors
  • Designed for continuous operation and must be in service to allow operation of the Main Generator
  • Cools U2 Output Bushings
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8
Q

How to you prevent channeling of the SCW Deionizer?

A
  • By maintaining < 100gpm flow through the deionizer
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9
Q

What temp must you maintain in the deionizer to prevent resin breakdown?

A
  • < 120°F to prevent breakdown of the resin
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10
Q

Why does the SCW system have deionizers?

A
  • To remove conductivity so transfer of electricity thru water is not possible
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11
Q

What is the backup source of makeup water to the SCW system?

A
  • Condensate (Manual only) (HWP Discharge)
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12
Q

Where is the U1 SCW tank vented to?

A
  • Atmosphere
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13
Q

How does U2s SCW Tank differ from U1s SCW Tank?

A
  • Unit 2 SCW tank has H2 cover pressure instead of being vented to atmosphere
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14
Q

What are the SCW Pump trips?

A
  • Unit Differential HEA
    (Prevents flooding of generator)
  • Overload/Overcurrent
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15
Q

What does 1-CRV-640 (SCW Reg Valve) do in U1 only?

A
  • Maintains Main Gen water inlet pressure at about 3# < machine gas pressure
  • Mechanical stops prevent flows < 340 gpm (25#) and > 550 gpm.
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16
Q

How will a loss of CCRP affect the SCW Sys?

A
  • A loss of CCRP blocks the SCW High Temp Turbine Trip

- When power is restored, the block is removed 15 seconds later.

17
Q

Which SCW Trips are blocked to allow Unit Backfeed operations?

A
  • Low # and Low Flow Trips are blocked to allow Unit Backfeed operations.
18
Q

In U1, how many SCW Coolers are in service?

A
  • Both are normally in service, if only one is available, you have to reduce Generator load to 80%