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Flashcards in Mode 3 to Mode 5 Deck (37)
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Describe the scope of 40OP-9ZZ10 Mode 3 to Mode 5 operations


  • Stabilizes the plant in Mode 3 to set up for cooldown or start-up
  • Plant cool down to Mode 5.
  • Secondary plant shutdown while using the EOP



State the precaution associated with RCS heat addition or removal methods.


  • Changes to RCS heat addition or removal methods (RCPs, SGs and ADV/SBCS, etc.) should be made by only one method at a time and sufficient time allowed for accurate indication temperature change before making the adjustment.



State the precautions associated with performing dilutions while subcritical.

  • Anticipate criticality for any dilutions
  • Stop dilutions if power / count rate doubles
  • EOL: large dilutions required to achieve Estimated Critical Boron Concentration (ECBC).
    • Dilution is allowed to start as long as final Cb is maintain 50 ppm > ECBC or 50 ppm > SDM Cb.


State when PZR boron equalization is required to be performed.

  • RCS/PZR boron equalization started if RCS boron changed by 50 ppm. Maintain ≤ 10 ppm difference.


What is the SDM boron concentration admin limit and why is it in place?

  • Admin boron limit is maintain 100 ppm above required SDM boron.
    • Compensates for changes in NCW / letdown temperatures


State the auto features associated with PZR level temperature compensation.

  • LT-110X/110Y (hot cal) / LT-103 (cold cal) PZR level
    • LT-110X/Y: if colder than 653°F/2250 psia, indicated will be higher than actual (swaps < 20%)
    • LT 103: if hotter than 60°F/14.7 psia, indicated will be lower than actual (swaps < 20%)



WHen is LTOP required to be placed in service?

  • LTOP required when any Tcold is ≤ 221°F (Both SDC suction relief valves in-service)


State the temperature requirements associated with SDC:

  • SDC design limit:
  • LPSI pump seal temperature limit:
  • Extended SDC operations temperature limit:
  • CS pump to SDC temperature/pressure limits:

  • 350°F – SDC design temperature limit (FSAR)
  • To extend LPSI Pump seal life, SDC normally initiated when RCS is < 300°F. (SM permission to align > 300°F)
  • Extended SDC ops (> 4 days), should be performed at ≤ 135°F
  • CSP cannot be aligned to SDC until ≤ 200°F / ≤ 250 psia. (Limits prevent pump damage.)


What is a concern when venting from penetration rooms when in midloop conditions?

Venting may introduce air into SDC System.


State the CHP pulsation dampener precharge pressure limitations.

  • Charging Pump pulsation dampener precharge pressure should be maintained at ~ 60% of charging operating pressure and will always be maintained at 25-75% of charging system pressure.



State the requirements of LCO 3.6.6 CS system.

  • LCO 3.6.6 requires both trains of CS to be operable Modes 1-4 ≥ 385 psia.
    • One train of CS is required to be available until Mode 5 entry (PRA requirement)
    • Due to not having class CTMT HVAC. LOCA in Mode 4 < 385 psia may not be covered.



Why are generator PCBs limited to 2 hours of being energized and open?

  • Generator PCBs (935/938) should not be open and energized for > 2 hours.
    • Reduces life or causes premature break down of the surge capacitors which are shunted to the breaker contacts.
    • Reclose for SWYD reliability (ring bus)
    • U1: Switching may cause a drop in voltage (3kV). If SIAS present, it could load shed WRF.


What could occur if RCS pressure is lowered below the shutoff head of the RMW pump?

  • ↓ RCS pressure below shutoff head of RMW pump may allow an uncontrolled dilution of the RCS.



State the max amperage to the following MFW pumps:





It's steam driven...

151 amps

122 amps


What is a consequence of extended use of AFNP01 when SG lvl is < 27% NR?

How is this avoided?

  • Extended use of AFW to maintain ≤ 27% NR may damage the downcomer feed ring and piping. Lines become voided < 27%. Minimize voiding and water hammer.
  • Feed ≥ 250 gpm until > 27% NR
    • < 250 gpm – potential water hammer


D/C isolation block valve dP is limited to > 600psid.



It may prevent valve closure.


State the RCP operational limits associated with pump combinations.

  • RCPs 1A and 1B are the preferred pumps to leave running to maintain max Spray capability.
  • If SG forced cooldown will be performed, keep 1A/2A running or 1B/2B running.
  • Avoid running 1A and 2B or 1B and 2A. Minimizes RCP journal bearing damage.
  • To prevent lift, RCPs are limited to 3 or less when temp is < 500°F.
  • For P-T concerns, only two RCPs are allowed < 200°F


State the natural circulation flow indications and what successful nc flow looks like.

loop dT




dT between Thot and max CET

  • < 65°F Loop ΔT
  • Thot ↔ or ↓
  • Tcold ↔ or ↓ (should be at Tsat for SG pressure)
  • ≥ 24°F CET SCM
  • < 30°F ΔT between Thot and max CET


What shoudl automatically occur at < 1x10-4%?


What must be done prior to <1x10-5%

and <=2x10-6%?

  • < 1x10-4%: ensure high log power bypasses automatically removed (red/white lights off)
  • < 1x10-5%: bypass CPC trips
  • ≤ 2x10-6%: energize start-up channel NIs (select SU NI, press HV Permit/HV On button)
    • BDAS channel checks within 1 hour



State the major evolutions associated with staying in Mode 3 operation.

  • Re-ring the SWYD bus. (Close PCBs within 2 hours)
  • Maintain Tcold < 570°F
  • If Tcold is lowering, Close MS drains if MSIVs are open and stop SGBD
  • Align BFT to the condenser
  • Restart RCPs if required
  • Secure HDTPs if running
  • Cooldown feedwater lines if MFW is in-service.
  • Place an AFW pump in-service (AFN→AFB→AFA)
  • Secure the MFW pumps
  • Maintain SGWL 30-50% NR
  • Restore vacuum / CW if required
  • Restore the Main Steam lines / SBCS if required:
    • 75°F/hour steam line HUR limit
    • < 15°F/hour RCS CDR limit when warming the steam lines
  • Align Turbine / generator support systems
  • Stop all but one Condensate pump
  • Evaluate placing long path recirc in-service (short M3 entry followed by start-up, secondary pressurized, vacuum maintained)
  • Maintain SDM



What should be first bypassed during cooldown to Mode 5?





When are D/C control valves isolated and control of feed swapped to bypas mov's?

  • Isolate DCCV when control becomes unstable. Feed with bypass MOVs.


When do we begin establishing the correlary boron concentration for cooldown?


  • Prior to commencing cooldown, begin establishing initial RCS boron concentration for cooldown (Target ~270°F: SDC entry temperature - 20°F)



What is the preferred AFW pump operation?

  • Place AFW pump in-service (AFN→AFB→AFA)


How many MAIN spray valves should be used for RCS cooldown?




What method is used to initially cooldown the RCS?

  • Start RCS cooldown and depressurization
    • Use SBCVs or ADVs
    • Thottle open one spray valve to maintain constant pressure reduction (throttling will minimize thermal stresses when < 4 RCPs are operating).


What precautions associated with lowering Low Ppzr setpoints must be observed before lowering the setpoint?

  • If Tc is ≥ 485°F, maintain setpoint ≥ 140 psia above Tc saturation pressure. Ensures SIAS prior to upper head void formation in the event of RCS depressurization caused by a SLB. (LCO 3.3.5 bases)
  • If exceeded, raise RCS pressure or cooldown to < 485°F within 2 hours.
  • If pressure is too low for the existing temperature, and an accident occurs, saturation conditions could exist in the RCS before the new, lower SIAS setpoint is reached. When saturation conditions occur, the pressure drop due to the LOCA is greatly reduced as water flashes to steam and holds the pressure up. This could prevent (or delay) the SIAS actuation and HPSI injection. Maintaining the setpoint 140 psia above saturation pressure ensures proper SIAS and HPSI injection.


At what temperatures are RCPs nomrally stopped?

  • ≤ 505°F: Stop one RCP
  • ≤ 350°F: Stop the 3rd RCP


What must be adjusted on the CHPs during RCS depressurization?

  • Adjust charging pump pulsation dampener pressure as RCS pressure lowers
    • Pump is non-functional during adjustment



When is the second LD control valve placed in service?

  • < 1050 psia PZR: place the 2nd letdown control valve in-service