Loss 125V DC Flashcards
What major actions are taken for loss of D01 when transfer of D11 to emergency supply is succesful?
Check EFW off or operating properly, Vacuum pump running, SF cooling in service.
What major actions are taken for loss of D01 with transfer of D11 from emergency source unsuccessful and Gen Output Bkrs remain closed?
- Align SU2 to A-2/A-1/H-1/H-2 (SU2 preferred since load shedding remains available via backup DC power and cooling groups can operate automatically). Use SU1 if SU2 unavailable.
- Check RCPs in service, trip both GEN output bkrs and check SF cooling in service.
What major actions are taken when D11 transfer unsuccessful and Gen Output Bkrs tripped?
- Check DG2 started and energized A-4 and trip RCPs
- Override ESAS and secure Spray and LPI pump and isolate RCP seal bleedoff.
- Ensure B55/56 supplied from B6.
- Control RCS MU/HPI by aligning normal Makeup path (CV-1235) and set PZR lvl setpoint to 100”.
- Ensure P-7A running with SG levels rising to 300 - 320”.
- Align 4160V buses to SU2.
- Restore systems.
What actions are taken for Loss of D02
- Check unit at power (If not, close Letdown cooler outlet valves)
- Check SI and Seal cooling in service (if not, trip RCPs and isolate seal bleedoff)
- Swap D21 to D01
- Check RX tripped, vacuum pump running and OP HPI Pump in service
- Check 4160V buses energized.
What major actions are taken for loss of D01 and D02?
- Place turbine in manual and close GVs in fast speed. (If will not close, operator trip turbine locally)
- Align 4160V buses to SU1 (preferred)
- Trip Gen Output Bkrs
- Follow up Actions
What major actions are performed for loss of D01 and D02 with Gen Output Bkrs open?
- Trip Bkrs in CR (A-1/A-2 feeds from unit aux, P-8s, P-3s, P-75, Main Chillers, P-6A, P-2s
- Align SU1 to A-1/A-2 (SU2 if SU1 not available)
- Operator locally close breaker to SW pumps
- Ensure CV-1407 open and local operator close P-36A Bkr
- Align and start EFW Pump P-7B and crack open feed valves to raise level to 370 - 410”.
- Isolate L/D and establish SI (Temp < 180 deg F, open in 4 - 6 gpm increments to 30 - 40 gpm). If > 180 open in 4 - 6 gpm increments to 8 - 12 gpm for 30 minutes and then establish 30 - 40 gpm.
What events take place as a result of Loss of D01?
> 55% results in RX trip with loss of turbine trip solenoids/GEN LO relays/Power to A3 and odd train 480V breaker controls (A1 DC maintained by battery eliminator).
Turbine will not trip and power will not be transferred to SU transformer.
SG pressure lower and may actuate MSLI. P-7A will start and control levels.
Gen output breakers will not trip open due to loss of GEN LO relays.
DG2 will start and tie one. DG1 will not.
Turbine tied to auto xfmr will maintain voltages normal until turbine is tripped.
If AC power is lost as well, ESAS even channels will actuate due to loss of RS1 and RS3.
What events take place as a result of Loss of D02?
> 55%, RX will trip, Loss of power to A4 and 480V even train breaker controls, A2 will be maintained by battery eliminator, Loss of power to EOS stuff.
Offsite power will be transferred automatically. DG2 will not start.
If no AC power as well, power will be lost to RS2 and RS4 resulting in EFIC actuation of MSLI and EFW and loss of control power to P-7A. Control valves will fail open.
Letdown relief will lift due to loss of Y02.
What events take place as a result of Loss of D01 and D02?
RX trip with SG pressure rapidly lowering due to turbine failure to trip until gov valves are closed. Turbine will be placed in manual and governor valves closed in fast speed. MSIVs can only be closed by isolating and venting IA to the valves. Buses can be transferred to SU xfmr if gen output bkrs remain closed, otherwise will have to be stripped and closed locally. De-energizing vital AC buses with total loss of DC will result in loss of DH and loss of inventory through PZR code safety valves.
