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  1. How does modulate mode control the ADVs and TBV?
    • The steam dump controller on a turbine trip modulates the ADVs and TBV based on a Tave/Tref error signal
    • They try to maintain Tave at 532F
    • On a lowering Tave
    • -Tave at 556.9F (25F error signal) ADVs and TBV are full open (on quick open signal)
    • -Tave at 535F (3F error) ADVs and TBV are full closed
    • On an increasing Tave
    • -ADVs and TBV modulate open from full closed at 540F(8F error) to full open at 556.9F (25F error)
  2. ADVs Capacity?
    • 30% total steam flow
    • -4 valves at 7.5% each
    • Adequate to prevent lifting of the MSSVs following a turbine and RX trip
  3. When must the MSIV bypass valves be closed?
    When Rx power is >/= 2%
  4. Purpose of the MSIVs(CV-0501/0510)?
    • Isolate S/Gs to prevent uncontrolled release of radioactivity to the atmosphere in the event of a S/G tube rupture
    • Prevent the release of the contents of the 2nd S/G into containment in the event of a steam line rupture inside of containment
    • Prevents the uncontrolled C/D of the PCS
    • Designed to close within 5 seconds during no steam flow conditions and within 1 second during full steam flow conditions
  5. Turbine bypass valve, CV-0511, capacity?
    -4.5% of rated steam flow
  6. Main steam safety valves purpose?
    • Designed to provide overpressure protection for the shell side of the S/Gs and the main steam line piping up to the inlet of the turbine stop valves
    • 23 code safeties will pass 102% of rated steam flow, limiting secondary steam pressure to 110% of design
  7. Power supply for the ADV controller?
  8. What closes the MSIVs?
    • Main steam isolation signal (MSIS)
    • -2/4 low S/G pressures of 500psia on either S/G closes both MSIVs
    • -also closes the affected S/G FRV and the FRV bypass

    • CHP at 4 psig 2/4 logic
    • -1 channel of CHP closes both MSIVs
    • -left channel also closes
    • --E-50A S/G FRV and FRV bypass
    • -right channel also closes
    • --E-50B S/G FRV and FRV bypass
  9. LCO 3.7.1. Main Steam Safety Valves (MSSVs)
    LCO 3.7.1.: 23 MSSVs shall be operable as specified in table 3.7.1-1

    APP: Modes 1-3

  10. What is required to block MSIV auto closure on low S/G pressure?
    • 3/4 S/G safety channels within 512-548 psia
    • Block automatically removed when you go above 548psia on 2/4 channels
    • Block allows the MSIVs to remain open while using the TBV to C/D the plant, this conserves water inventory that would be lost using the ADVs
  11. LCO 3.7.2: Main Steam Isolation Valves (MSIVs)
    LCO 3.7.2.: 2 MSIVs shall be operable

    • APP: Mode 1
    • Modes 2 and 3 except when both MSIVs are closed and de-activated

  12. Explain quick open as it pertains to ADVs and the TBV?
    • When a turbine trip causes the 386 AST relay to energize you generate a quick open signal
    • If Tave >/= 556.9F, the steam dump control relay (SDCR) is energized and closes contacts to align quick open solenoids to the ADVs and the TBV
    • When Tave <556.9F, SDCR deenergizes and quick open solenoids deenergize and remove the quick open signals
    • -this puts you into modulate mode
  13. LCO 3.7.4: Atmospheric Dump Valves (ADVs)
    LCO 3.7.4: 1 ADV per S/G shall be operable.

    APP: Modes 1,2,3 and Mode 4 when the S/G is being relied upon for heat removal

  14. Turbine bypass valve solenoids power supply?
  15. ADV power supplies (solenoids)
    • CV-0779/0781-D-11-1 left train
    • CV-0780/0782-D-21-1 right train
  16. MSIV power supplies?
    • Left channel solenoids
    • -D-11-1

    • Right channel solenoids
    • -D-21-1

    • Normally deenergized
    • Energize to close MSIVs
  17. How does PIC-0511 turbine bypass valve controller operate?
    • Controls S/G pressure at 900 psia (532F)
    • Full open at 905 psia (532.6F)
    • Full closed at 895 psia (531.6F)
    • Auctioneered from PIC-0511 and HIC-0780A (steam dump controller)
    • -takes the higher of the 2 signals
  18. PIC-0511 and PM-0511 turbine bypass valve controller and auctioneering circuit power supply?
  19. Power supply for MSIV bypass valves?
    • MCC-3
    • -fail as is on a loss of power and position indications are lost
  20. Why must the MSIV bypass valves be closed when >/= 2% power?
    Bypasses do not have automatic isolation capability for CHP or S/G low pressure.
  21. Main steam safety valve setpoints?
    • 24 valves, 12 on each line
    • RV-0717-0724
    • -985 psig (1000 psia)
    • RV-0709-0716
    • -1005 psig (1020 psia)
    • RV-0701-0708
    • -1025 psig (1040 psia)
  22. What must be done on a reactor trip due to an inadvertent MSIV closure?
    • Notify the duty and call superintendent
    • Do not re-open MSIVs or make the RX critical with out plant manager approval
    • Contact system engineering to evaluate the need for MSIV internal inspection.
    • -the MSIVs are susceptible to damage when closing under high steam flow conditions.
  23. Air supply for the turbine bypass valve?
    • Instrument air with an accumulator
    • Accumulator normally isolated by a solenoid valve
    • -done to allow enough air pressure to give a quick open signal on a loss of instrument air
    • Valve fails closed on a loss of instrument air
  24. What interlock is associated with the turbine bypass valve?
    If main condenser vacuum is less than 5 inches of vacuum, you can't open the TBV and it will automatically close if it was open.
  25. What happens on a MSIV not full open signal?
    Turbine trip
  26. Air supplies for the ADVs?
    • Normally instrument air with an air accumulator
    • N2 backup from bulk N2 tank
    • No adverse effect on a loss of instrument air
  27. Why are MSIV hand switches returned to the open position after operation?
    Prevents burning up the trip solenoids
  28. What is the precaution associated with the aux hot shutdown panel C-150A/ control room indication transfer switch?
    • Prior to transferring to AHSP ensure average temperature display select on C-02 is in loop 2
    • -ADVs will get a quick open signal if the switch is left in loop 1 position and the transfer is made (Tave will fail high)
    • --only a problem if you have a turbine trip
  29. What are the consequences of improper MSR startup?
    • Operator manually ramps temperature IAW table
    • -if done improperly possible LP turbine damage could occur due to differential expansion of the turbine casing and rotor.
  30. What is the purpose of the 400oF pushbutton on C-01 for the Moisture Seperator Reheaters?
    • Used when turbine load is reduced to 10% or less for periods exceeding 15 minutes. This pushbutton functions to position the reheater steam control valves to maintain LP turbine inlet steam temperature at 400oF.
    • -the concern is overheating in the last 2 rows of blades on the LP turbine at continuous operation below 10% load.
  31. What does the ramp pushbutton do on the reheater control console?
    Normally used at 30% load after the shutoff valves are opened.  This button energizes the circuit that regulates the opening of the 6" Reheater steam control valves CV-0594, 0595, 0597 and 0598 to MSRs E-9A, B, C and D respectively over a period of two hours. The ramp feature assures an acceptable rate of differential expansion between the LP turbine casing and rotor

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2015-11-24 15:36:18
MAINSTEAM advanced systems

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