Main Feedwater Flashcards
What are the MFP trips?
- SI
- Rx Trip
- SG High-High Lvl (> 67% (P-14))
- Thrust Bearing
- Low Condenser Vacuum (< 20.0/20.3” hg)
- Low EHC # (2/3 < 800 psig)
- Low Suction # (< 180# for 5 sec)
- Overspeed (> 107%)
- IOPS (> 110%)
- Low Lube Oil Pressure (< 4# for 5 sec)
- Manual
What causes a Feedwater Isolation (FWI)? ***
- SG High-High level (P-14) (67% NR 2/3 on 1 SG)
- SI
- Rx trip (P-4) with low Tavg (Tavg < 554°F on 2/4 loops)
What supplies the normal steam supply to the MFPs?
- Reheat Steam (Norm)
- HP steam for start-up up to about 55%-60% but available up to 100% power if necessary
What are the FWI isolation actions?
- Closes FRVs (either train RPS)
- Closes FMO’s (train specific 1/4 SGs Trn A and 2/3 SG Trn B)
What must you do to clear a FWI that is associated with P-4 with Tavg < 554°F)?
- Cycle a Rx Trip Breaker
What are the power supplies for the MFP FMOs?
- 600v AC
What is powered by 600v AC on the Main FW system?
- MFP Discharge
- MFW FMOs
- Aux Oil pump
Will all 4 MFW FRVs close on loss of 250v DC ctrl pwr?
- Yes they will
If you get a FWI on either train, will it cause all 4 FRVs to close?
- Yes they close on either a Train A FWI or a Train B FWI. Do not need both to have a FWI signal
What is powered by 250v DC in the MFW system?
- Htr Valves
- MFP ELOs (Fail Open)
- DC Oil Pump
- HP Htr Bypass Valve (FMO-260) (Fails as is)
When will the MFP Seal Water Pump auto start?
- < 15 ΔP between CBP Disch # and MFP suction #
Where does the MFP seal water pump get its suction from?
- CST (U1)
- HWP Disch (Alt)
How does the MFP Seal Water FRV fail?
- Fails in the closed position but it has a mechanical stop to prevent full closure (5 gpm min) to maintain seal water leak off temp at 150°F
What is the FW designed to handle on a load rejection?
- Can handle 10% step change
OR - 5%/min ramp load change w/o steam dump
- Provides 3.55M lbm/hr (3.7M lbm/hr) of flow to each S/G
When is a MFP forced to Speed Ctrl?
- Both MS Press Xmitters Fail
- Both MFP Hdr Press Xmitters Fail
- MFP ΔP Setpoint Xmitter Fails
- Other MFP Trip when > 60% Power
(ΔP setpoint > 110 (112.5) ΔP) - MFP Speed > 5220 (5300) rpm
What flow do the MFP ELOs modulate to maintain?
- Modulate to maintain 4000 GPM (Suction flow)
How will the MFP ELOs respond if the ctrl switch is taken to close with the MFP Stop Valves open?
- ELO’s will go full open if Stop Valves are open
How will the MFP discharge valves respond when the MFP stop valves go closed?
- They will go closed if the MFP stop valves go closed. (They will not close on a FWI signal)
How much flow can each string of MFW heaters handle?
- 80% flow
How much flow can MFW heaters bypass valve (FMO-260) handle?
- 20% flow
Where does the E MFP ELO discharge to?
- B Condenser
Where does the W MFP ELO discharge to?
- A Condenser
Which FW heaters on Unit 1 receive HP steam?
- Heaters 5 and 6
Which FW heaters on Unit2 receive HP steam?
- Heaters 4, 5, and 6
Can you manually close the MFP ELOs?
- Yes, you can manually close MFP ELOs but only if the MFP stop valves are closed
What do the MFW FRVs have to ensure closure during a FWI?
- Control air lines contain redundant solenoids (Train A and B) to ensure closure during FWI*
What provides Seal Steam to the MFPs?
- They are self sealing at high power levels
What are the sources of MFP Seal water?
- CBP disch (Norm) ***
- U1 CST (via MFP Seal water pump) ***
- HWP Disch
How does the seal water to the MFP regulate temp?
- MFP seal water temp regulating valve sense temp on seal water drain and regulates to set point
How do the MFP seal water temp reg valves fail on loss of air?
- Open
Does the U-2 DC Lube Oil Pp go thru the Lube Oil Cooler?
- No, the DC Pump bypasses lube oil cooler
What is the purpose of the FW CIV Check Valves?
- Prevent complete blowdown of a SG due to a feed line break and ensure AFW flows towards the SGs
