AF- Auxiliary Feedwater Flashcards
What is the basis for the amount of water level in the CST that is reserved for AF use in the plant during an emergency situation?
Provides sufficient reserve of feedwater to permit the plant to operate in Mode 3 for 8 hours followed by an orderly plant cool down at a rate not to exceed 75F/hr, to the point where Shutdown Cooling may be placed in operation (RCS ~350F)
What is the capacity of the CST and RMWT?
CST – 550,000 gallons
RMWT – 480,000 gallons
How is HA affected by a high water level in either AF pump room? What temp is maintained in the AF pump rooms?
Aux Building Normal AHU dampers isolate the Aux Building HVAC from the AFP rooms
50-104
What is the purpose of the AFN pump? How is ‘N’ AFP self-lubricating?
multi-stage centrifugal pump that delivers auxiliary feedwater to the S/Gs for the control of RCS temperature during startup, hot standby, shutdown, and initial fill and makeup
Uses dipper rings to throw oil onto the bearings
What provides cooling water for the AFN pump lube oil coolers? Where is the cooling water returned to?
Pump’s first stage discharge
pump suction
Where is ‘N’ AFP powered from? Control power?
PBA-S03
Control power from two sources: PKA-D21 or the output of the “A” Train Class Battery Charger
(there is a selector switch behind the load center to swap power supplies)
Why does ‘N’ AFP have two class powered suction valves?
Where are these valves located?
Provide class and seismic protection boundary for CST inventory, separating it from the non-seismic piping to ‘N’ AFP downstream of the isolation valves
CST pump house
What is the interlock associated with ‘N’ AFP and its suction valves? Purpose?
If either of the valves is less than 80% open, the pump will not start and will trip if running
To provide protection from a low suction pressure condition, which could damage the pump
Where is ‘N’ AFP located? Where is it controlled from?
100’ Turbine Building, NW corner
control room or pump breaker
Where are all non-seismic Category 1 penetrations located on the CST?
Above the level of the Safety related storage volume (300,000 gallons, or ~28 ft)
The construction and design of ‘B’ AFP is effectively identical to that of ‘N’ AFP, with what exceptions?
‘B’ AFP is designed to meet seismic category 1 requirements
‘B’ AFP is equipped with a larger horsepower motor (125% larger)
‘B’ AFP is equipped with an automatic start feature from the ESFAS load sequencer module for AFAS, CSAS, LOP
What else starts when the ‘B’ AFP starts?
Essential air cooling unit automatically starts
Where is ‘B’ AFP located?
80’ of the MSSS
In regards to the ‘A’ AFP, what is the purpose of the worm drive gearbox?
Coupled to an oil pump and the turbine’s governor actuator, and driven off of the turbine
What provides the cooling water to the ‘A’ AFP lube oil cooler?
First stage of the AFP
What is the minimum speed of the ‘A’ AFP to provide adequate lubrication and cooling?
1000 rpm
How do we maintain the cleanliness of the ‘A’ AFP governor control system?
Renewable cartridge filter that has a built in dirt alarm that will automatically bypass the filter when it becomes clogged
What drives the ‘A’ AFP?
Steam turbine
How does ‘A’ AFP respond to an AFAS?
the main steam supply valve bypass valves open first to bring the turbine up to 870 rpm in a slow and controlled manner
30 seconds later the main steam supply valves open to allow maximum steam flow to the turbine, and as the turbine approaches nominal speed, governor begins to throttle governor control valve to ~3400 rpm
Regarding the A AFP, why is there a large condensate pot installed in the Aux Building?
To allow for continuous draining of the moisture that can accumulate in the steam supply line to the AFA pump turbine
Without it, moisture could accumulate in the steam supply line which would greatly increase the chance of turbine overspeed during startup
Where is ‘A’ AFP located?
80’ MSSS
Where can I trip the Trip Throttle valve, AFA-HV-54, electrically?
Board 6 in the Control Room
‘A’ Remote Shutdown Panel
Local control panel
What is the one way for the trip throttle valve, AFA-HV-54, to trip automatically?
Mechanical overspeed device
can also trip manually by electrical trip, from pushbuttons, and a manual mechanical trip
What is the purpose of the essential AF pump Regulating and Isolation valves? When do they auto open? Where are they controlled from?
To provide means to regulate and isolate flow, respectively, to the steam generators from the Essential AF pumps
AFAS
Control Room, Remote Shutdown Panel, or
locally at the valves.
What powers the regulating and isolation valves associated with ‘A’ AFP? Turbine governor valves? What powers the same valves for the AFB pump? AFN?
All are PK
PH
this pump does not have those valves
What happens when an AFAS is received?
Both Essential AF pumps start, and the affected steam generator(s) regulating and isolation valves open