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 (< 5% U1) (< 22% U2)
- 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
- Condensate Hotwells
- ESW
What does the AFW flow conservation signal do?
- Conserves inventory and max flow to the SGs.
What happens on a 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 a 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 ***
What happens on a AFW flow retention?
- Pump discharge valves throttles back
MDAFP - 575 gpm
TDAFP - 955(975) gpm
Which AFW signal overrides the other? (Retention or Conservation)
- Flow Retention overrides Flow Conservation
How will the Unit 1 TDAFP FMOs to SG respond on an auto start signal of a TDAFP?
- 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
HOWEVER - They will not reposition if they are already throttled on when an auto start signal is received*
What is the trip and throttle valve powered by?
- N-Train
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 < 25% (3/4 feed flows)
Opening 1-FW-129 feeds what header from which pump?
- Feeds U1 2/3 SGs (East) from the U2 W MDADP
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
Are the AFW flow retention switches powered from N train?
- NO
- ELSC buss (Train B)
- AFW buss (Train A)
What does T.S. 3.7.5D (AFW System) state?
- If 3 AFW trains inoperable in Modes 1-3 (Mode 4 when relied upon for heat removal)
IMMEDIATELY - Initiate action to restore 1 AFW train to Operable status LCO 3.0.3 and other mode changes are suspended until 1 AFW train is restore to Operable status
What does T.S. 3.8.4D (AFW System) state?
- If Train N DC electrical power system 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
How can you tell which way the TDAFP has tripped?
- 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
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?
- Do NOT enter TS 3.0.3, restore 1 Train Immediately **
When is N-Train Required?
- Modes 1-3
What is also declared inoperable if N-Train is declared inoperable?
- TDAFP has to be declared inop
What valves isolate on a TDAFP start signal
- SG blowdown
- AFW Pump Test Valves
How is flow retention reset
Take both FMOs pull to stop
Does flow retention protect a cross tied AFW PP
No
What does AMSAC do
Trips the main turbine and starts all AFW pumps when C-20 is met
Describe C-20
Turbine 1st stage > 40% (2/2)
What is the time delay associated with AMSAC actuation
27 seconds to 220 seconds from 40%-100% power
How is ESW aligned to the AFW PP suctions
Locally by closing tell-tale drains AND opening associated manual valve
