Auxiliary Feed (AF)

Question 1

What is the purpose of the Auxiliary Feedwater System?

Answer 1

AFW and CST can maintain Mode 3 for 8 hours with subsequent 75°F/HR cooldown to 350°F.

Question 2

What is the normal and backup suction source for the Aux. Feedwater pumps?

What is the concern using the backup suction source?

Answer 2

Normal is Condensate Storage Tank (CST), 300,000 gallon (29.5 ft) minimum (LCO limit)

Backup source of water for AFA/AFB pumps is Reactor Makeup Water Tank (RMWT). Need to manually align (valves in AF pump rooms).

Mini-flow for AF go to CST. Pumps do not recirc to the RMWT (creates** potential for CST contamination**)

Question 3

What are the amperage limits for the Auxiliary Feed pumps?

Answer 3

(AFN-P01) (PBA-S03)
* **122 amp limit **

(AFB-P01) (PBB-S04)
* 151 amp limit (Bacardi 151)

Question 4

What autostarts the Auxiliary Feedwater pumps?

Answer 4

AF - B starts on SLAC
SLAC

SIAS
AFAS-1 or AFAS-2 (No time delay)
SIAS (B train)
CSAS (B train)
LOP (PBB only)
(10 sec time delay from load sequencer for SIAS/CSAS/LOP only)

AF N has no auto starts

AF A auto starts on AFAS only

Question 5

What will trip the AF N pump?

Answer 5

SIAS (Channel A)
Suction valves less than 80% (CTA-UV-1 or 4)
Load shed on PBA-S03 (LOP / does NOT auto restart)
Electrical fault (SEIS alarm) (86 can be reset from Control Room)

Question 6

What is the normal and alternate control power supplies for AF N pump?

Answer 6

Control power:
o Transfer switch on the wall by PBA-S03
o Normal: PKA-D21
o Alternate: A train PK battery charger

Question 7

What is the flow path for AF N pump?

Answer 7

Supplies SGs thru MFW downcomer control valves or downcomer control valve bypass MOVs.
o Normally use bypass MOVs in manual control (better control)
o Flow path is isolated on MSIS signal. Can be overridden.
o** Downcomer MOVs powered from NHN-M71 (SIAS load shed MCC)**
o Downcomer Isolation valves fail open on loss of power (PK)

Question 8

When will the Essential Aux Feed pump room chillers auto start?

Answer 8

• Pump room ACUs auto start when pump starts (Manual or Auto)
  o AFA ACU auto starts when either Main Steam Admission Valve opens (SGA-134 or 138 not full closed)
  o AFB ACU auto starts when pump breaker is closed
  Remains running for 5 minutes following pump shutdown.
  Maintain pump rooms < 104º. (analyzed environmental parameters)
• Aux Bldg Normal AHUs provide room cooling during standby conditions.
• Dampers between the rooms auto isolate if flooding occurs (3.5 feet) in either room.

Question 9

What’s the minimum speed for AF A for lube oil concerns?

Answer 9

• Shaft driven oil pump (supplies bearings and governor actuator)
  o 1000 rpm provides adequate oil flow (< 1000 rpm for > 5 min is prohibited)
  o Sustained low speed may cause damage to pump sleeve bearings and pump internals due to loss of lubrication.
  o Lube oil cooler supplied from first-stage of the pump.

Question 10

What happens if the B05 AFAS initiate switch is left in the INITIATE position?

Answer 10

 If left in actuate, valves will remain full open and NOT cycle to control level.
o Manual BOP-ESFAS actuation will only start AFB pump (AFA/FCVs controlled from PPS)

Question 11

What happens if one Steam Generator is more than 185# below the other Steam Generator?

Answer 11

Delta-P Lockout:
* Automatic feeding of the SG assumes SG-1 and 2 ∆P < 185 psid. (no MSLB)
* ∆P Lockout prevents auto AFAS actuation on affected SG.
o Manual actuation (B05 or ARC) will still actuate AFAS with a ∆P lockout.
* ∆P Lockout closes isolations and FCVs on affected SG (lowest pressure)
o Does NOT affect the AF A steam supplies (manually isolated in the EOPs)

Question 12

Does an MSIS affect AF A Steam admission valves?

Answer 12

No

Main Steam Supply Valves (SGA-UV-134 / 138) and Bypasses (134A / 138A)
* 125Vdc MOVs (PKA-M41)
* Auto open: AFAS actuation. (Not affected by ΔP Lockout)
(upstream of MSIV’s)

• Supply valves interlocked with 1” bypass MOVs (Same open / close signals)
• Bypass valve opens first
  o Opens in ~ 6 seconds
  o Bypasses do NOT cause SEAS alarm if they fail.

Question 13

What causes the AF room essential ACU’s to stop running?

Answer 13

AFA ACU stops after 5 min after pump S/D, maintains 104F

Question 14

If AFA/B aligned to RMWT for suction, where does they recirculate?

Answer 14

Reactor makeup water tank (RMWT)
* Backup source of water for AFA/AFB pumps.
* Local manual valves aligned in AFW pump rooms.
* Pumps do not recirc to the RMWT (creates potential for CST contamination)

Question 15

What will the light indications be for the following Aux Feed A trips:
overspeed
tripped from B06

Answer 15

Trip and Throttle Valve (AFA-HV-54)
* Mechanical Overspeed trip (4008 - 4108 rpm)
o Unlatches trip linkage. Springs close the valve. Motor runs down. Opening power is blocked.
o White “overspeed” light lit in MCR (Blue locally / RSP) [Two Green / White light lit in MCR]
o Requires local manual reset.

• Electrical trip:
  o Manually actuated from push button (MCR, locally, or RSP)
  o Green top and Red bottom lights lit
  o Does not trip the linkage. Opening power not blocked. Motor does NOT run down.