.AR SPTAs (40EP-9EO01): Welch's Highlighted Notes

Question 1

(Actions):

Reactivity Control (Immediate Actions)

Reactor power ↓

• (1st) Manual reactor trip (B05)
• (2nd) Open NGN-L03/L10 supply breakers (B01)
• (3rd) Open RTBs locally
• (4th) Open MG set breakers at NGN-L03/L10

Negative SUR

All FSCEAs inserted

• Borate until adequate SDM established

(> 40 gpm)

• App. 103 RCS M/U / Emergency borate
• App. 10/11 CH pump alt suction RWT/SFP
• SI flow

Main Turbine tripped

• (1st) Manually trip the turbine
• (2nd) Stop EHC pumps (wait for accumulator to dump)
• (3rd) Close MSIVs

Answer 1

(Bases/Expectations):

Loss of PNC/PND (only one RPI available, emergency boration required)

Loss of NNN-D11 and NNN-D12: Core mimic rod bottom lights AND LEL/UELs lost:

• CEA positions have to be verified on CPCs (check CEAC 1 and 2)

Check at least 2 of the available indicators:

• Rod Bottom Lights
• LELs
• CEAPDS
• CEAC-1 or -2 as a back up

If CEA positions are doubtful or indeterminate, take action to borate.

L03/L10 breakers opened for > 5 seconds then re-closed.

Allows MG flywheel to taper off, interrupting power to CEAs and allowing the MG start contact to open.

Ensures reactor is shutdown.

Reduces heat input to RCS.

Acceptance criteria reflect conditions during the 10 minutes following a trip.

Several minutes after a trip, when power has significantly dropped, _SUR indicatio_n will experience large fluctuations due to a low input signal and circuit noise, and may not be a useful indication.

SDM maintained if most reactive rod stuck out. PVNGS: SDM indeterminate until a calculation is completed (Borate until SDM is verified). Boration continues until SDM calc performed or directed to be stopped.

Use at least one CH pump hard started. Normal boration flow path is preferred.

Emergency Boration TCAs:

• 10 minutes during an ATWS using SA 103-A
• 15 minutes if COLR SDM not met (any CEAs fail to insert)
• 30 minutes allowed if required to locally open CHN-V164 to bypass BA filters

Turbine trip prevents uncontrolled C/D (+ δk)

Question 2

(Actions):

Maintenance of Vital Auxiliaries

Ensure Generator PCBs are open (~ 9 seconds)

Check that loads have transferred to offsite power and all vital and non-vital AC and DC buses are powered

If PBA/PBB not powered from off-site:

• Ensure DG has started
• Ensure DG breaker is closed (use hard card)
• If not at rated speed/voltage, override and adjust.
  
  • 4080-4300V and 59.9-60.5Hz.
• Ensure SP pump running to cool the DG

Locally stop DG if unable to start SP

Answer 2

(Bases/Expectations):

Ensures power restored to at least one vital bus to fulfill subsequent safety functions.

DG Hz meters powered from NNN-D11(A) / D12(B).

• Use sync scope or ERFDADS as a back-up.

Do not start the DG if high priority trip alarm is present.

Do not close the DG output breaker if PB is faulted.

If DGs are running, always check spray pond support.

RO should report status of DGs, DG high priority trouble alarms, trips or safety bus faults.

DG time limits with no SP cooling:

• 2.5 minutes (Loaded)
• 15 minutes (Unloaded)
• SP pumps auto start 25 seconds after LOP

If trip occurs with MOD open and PCBs closed (turb off-line), do NOT open the PCBs. Obtain SM concurrence to deviate.

If turbine is manually tripped, allow enough time for PCBs to open on their own (reverse power).

If manually opened too quickly, NAN-S01/S02 FBT will be blocked.

Ensure turbine is tripped prior to opening PCBs to prevent turbine overspeed.