AFW Flashcards
What are the MDAFP Auto Starts?
- Both MFP Trips (in Auto)
- AMSAC (C-20)
- Load Shed
- Low-Low SG Lvl (2/3) on 1 SG
- SI
What are the TDAFP Auto Starts?
- Undervolt on the RCP Bus (2/4 RCP busses at 88v)
- SG low low lvl (2/3) on 2 SGs
- AMSAC (C-20)
What are the MDAFP Trips?
- Load Shed
- Overload/Overcurrent
What are the TDAFP Trips?
- Electronic Overspeed (108% at 4698 rpm)
- Mechanical Overspeed (111% 4829 rpm)
What is the purpose of the AFW system?
- Maintain a minimum area of heat transfer in the SGs in order to prevent loss of PW through the Pzr Safety or Relief Valves
- TDAFPs maintain tube sheet coverage of 10 feet
What are the suction sources of the AFW pumps?
- Own CST
- Other Unit CST
- ESW
What is the purpose of the AFW flow conservation signal?
Conserves inventory and max flow to the SGs
What happens on an AFW Flow Conservation signal?
- SG Blowdown Isolations Close
- AFW Pump Test Valves Close
- MDAFP FMOs OPEN (regardless of position)
- seals in for 45 seconds to ensure the FMOs OPEN
What causes an AFW Flow Conservation Signal?
Anything that starts MDAFW pump auto start
What does the AFW flow retention signal do?
Protect against run-out after steam/feed break by limiting flow from the AFW pumps that may be supplying the faulted SG
What happens on a AFW flow retention?
Pump discharge valves throttles back
- MDAFP 575 gpm
- TDAFP 955 (975) gpm
What causes an AFW Flow Retention Signal?
High AFW pump discharge flow
Which AFW signal overrides the other? (Retention or Conservation)
Flow Retention overrides Flow Conservation
Which AFW signal overrides the other? (Flow Retention or Flow Conservation)
- Flow Retention overrides Flow Conservation
How will the Unit 1 TDAFP FMOs to SG respond on an auto start signal of a TDAFP if in standby alignment?
U1 TDAFP FMOs will not move from their throttled position
How will the Unit 2 TDAFP FMOs to SG respond on an auto start signal of a TDAFP?
U2 TDAFP FMOs will full open if they are closed, but will remain as is if throttled
What is the trip and throttle valve powered by?
N-Train
What is the TDAFP Turbine oil Cooler and Governor Oil Cooler cooled by?
TDAFP discharge
If you put the TDAFP ELO switch in Manual what will the valve do?
Stay open
How do the TDAFP ELO fail on loss of air and ctrl power?
Open
Why are the U1 TDAFP outlets to SG valves throttled (FMO-211, 221, 231, 241)?
Prevent overfill of SGs on the event of a tube rupture
Where does the back up water supply to the suction of the MDAFPs come from?
East ESW Header
Where does the back up water supply to the suction of the TDADPs come from?
West ESW Header
What will cause an AMSAC Signal?
FW Flow less than 25% (3/4 feed flows)
WHat is the T.S. Minimum for the CST and what does it provide?
182,000 Gal
- Maintain the plant in Mode 3 for 9 hours with steam discharge to the atmosphere via PORVS with LOOP.
- OR-
- Capability of holding the Unit in MODE 3 for 2 hours followed by a 4 hour cooldown to RHR
Which SG(s) provide steam the TDAFPs?
2 and 3 SGs
What does T.S. 3.7.5D (AFW System) state if 3 AFW trains are inoperable in Modes 1-3 (Mode 4 when relied upon for heat removal)?
IMMEDIATELY Initiate action to restore 1 AFW train to Operable status. Do NOT enter LCO 3.0.3 change modes
What does T.S. 3.8.4D (AFW System) state if the N Train DC electrical power system is inoperable in Modes 1-4?
IMMEDIATELY Declare the TDAFW pump inoperable
What are the N Train loads?
- Trip and Throttle Valve
- Test Valve
- TDAFP to SG Supply valves
- Auto Start circuit
- Turbine Trip circuit
- Electr. Overspeed circuit
- ELO valve control power and solenoid
- AMSAC inverter
- N-Train Chargers are tripped by SSPS testing
Flow retention switches are NOT
How can you tell if it’s an electronic or mechanical overspeed on the TDAFP?
Electronic Overspeed
- Overspeed will bring in both alarms. (Drop 10 and 50) Drop 50 will clear when seal in alarm is reset
Mechanical Overspeed
- Overspeed will bring in both alarms. (Drop 10 and 50) But Drop 50 will not clear even if the seal in alarm is reset
What are the Safety functions of Aux Feed?
- Provides Feedwater to S/G’s when Main Feedwater Pumps are unavailable
- Removes Core Residual Heat
How many AFW Trains are required Modes 1-3 ?
3 Trains
Is AFW required in Mode 4?
Only when being used to supply SGs for heat removal
What do you do if you have all three AFW Trains Inop in mode 1?
Do NOT enter TS 3.0.3!! Restore 1 Train Immediately
When is N-Train Required?
Modes 1-3
What is the mission time for AFW?
7 days (for now)
Does the flow retention signal protect a AFW pump if it is cross-tied from the other unit?
NO
What is the Low Low SG Level for Unit 1?
5%
What is the Low Low SG Level for Unit 2?
22%
What does an AMSAC actuation do?
Trips the turbine and starts all AFW Pumps
What is C-20?
Enables AMSAC
2/2 Turbin 1st stage Impulse Pressures greater than 40%
What conditions cause AMSAC to actuate?
Feed flow less than 25% on 3/4
(1 channel from each SG)
(channels are 1, 2, 1, 2)
What is the time delay for AMSAC?
Variable. 27 secs - 220 secs from 100% to 40% power
What steps are taken to align ESW to AFW?
- Locally Close the Tell-Tale Drain
- Open associated manual isolation
- Open MOV from control room
When must the TDAFP be operable?
Greater than 350°F (MODE 3), regardless of SG Pressure
Describe the capabilities of the MDAFP with regards to the minimum AFW flow for RCS Decay Heat removal.
This flow meets the minimum required for RCS Decay Heat Removal
Which steam generators do the East MDAFP Feed?
2 and 3 on own unit
1 and 4 on opposite unit
Which steam generators do the West MDAFP Feed?
1 and 4 on own unit
2 and 3 on opposite unit
Which SGs do the TDAFP feed?
1-4 of own unit only
How do you resotre the N Train battery charger to service after a loadshed?
Send AEO to turn Battery Charger Control box switch on the I/S battery charger to Off then back to Auto
Which MDAFP auto start is NOT available if the control switch is in neutral?
Loss of both MFPs
What protects the Aux Feed Water Pumps from minimum flow conditions
Emergency Leak Off Valves
