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
