Systems Exam 4 - Main Feedwater Flashcards
(21 cards)
SG Normal Level Setpoints
→Unit 1: 67%
→Unit 2: 64%
→controlled by SGWLC
→Level Dominant System, but steam flow/feed flow mismatch will overcome level dominance
SG Lo-Lo Level Setpoints
→Unit 1: 38%
→Unit 2: 35.4%
→causes Rx Trip
→causes AFW Auto Start (1/4 SGs for MDAFWPs, 2/4 SGs for TDAFWP)
SG Hi-Hi Level Setpoints
→Unit 1: 84%
→Unit 2: 81.5%
→P-14:
→MFPs trip
→turbine trips
→Feedwater Isolation signal
→2/3 detectors on any 1 SG (ch 1 not used SGs 1&4; ch 2 not used SGs 2&3)
Main Feed Pump Trips (10)
→Manual
→SI from either train (also trips Main Turbine and causes FWI)
→Low Turbine Bearing Oil Pressure - U1 ≤5.5 psig, U2 ≤4 psig; (2/3) 2 sec TDPU
→Low Pump Bearing Oil Pressure - U1 ≤10psig, U2 ≤7 psig; (2/3) 2 sec TDPU
→Low Vacuum Aux Condensers (2/3) ≤17.5” Hg on 2 detectors OR <21” Hg on one detector and 17.5” Hg on another detector; 2 sec TDPU
→Low MFP Suction Pressure ≤190 psig (2/3); 30 sec TD MFP A, 45 sec TD MFP B; staggered trip
→Low MFP Suction Pressure ≤170 psig (2/3); 4 sec TD (trips both simultaneously)
→Thrust Bearing Wear ≥32 mils (2/3)
→Electrical Overspeed ≥5600 rpm (2/3)
→Mechanical Overspeed ≈5720 rpm (5663-5773 rpm, 5720 ± 57 rpm or ±1% tolerance)
→P-14 SG Hi-Hi Level (2/3 on any one SG); also trips Main Turbine and causes FWI
How does loss of uD2 affect MFP’s?
Loss of uD2 will prevent an electrical trip of the MFPs due to loss of the control system.
Quickly shut down the MFPs if:
→radial bearing metal temp >225°F
→any other bearing metal temp >215°F
→any oil temp >215°F
→radial bearing vibration >5 mils
What produces a Feedwater Isolation Signal (FWI) signal?
→Hi-Hi S/G Water Level (P-14), resettable <P-14 by cycling trip breakers
→P-4 AND Low T-ave of 564°F or ΔT ≥20°F between Ave T-ave and T-ref (2/4), resettable via reset/latch switch (1 per train), blocks input signal
→SI, resettable by cycling trip breakers and clearing SI signal
Note: P-14 and SI trip MFPs; P-4 does NOT.
Feedwater Isolation Signal (FWI) closes the following valves:
Feedwater Isolation Signal (FWI) closes the following valves:
→u-FCV-510 through 540 Flow Control Valves
→u-LV-2162 through 2165 Flow Control Bypass Valves
→u-HV-2134 through 2137 Feedwater Isolation Valves
→u-HV-2185 through 2188 Feedwater Isolation Bypass Valves
→2-FV-2193 through 2196 Feedwater Pre-Heater Bypass Valves (U2 only)
→2-FV-2181 through 2184 Feedwater Split Flow Bypass Valves (U2 only)
Valves Close in Order To:
→prevent excessive RCS cooldown
→prevent uncontrolled SG filling
→limit mass addition to CNTMT in event of DBA
What action must be taken if LEFM is lost?
→reduce power to <98.6% if lost
→LEFM is a high accuracy flow measuring device which uses acoustic energy pulses to determine the final feedwater mass flow, and is used in calorimetric
Describe MFP Turning Gear Operation
→turning gear engaged via Instrument Air, driven by motor
→starts when speed ≤2 rpm (via low speed switch on MFP turbine) AND adequate lube oil pressure
Feed Water Isolation Valves
(HV-2134 through 2137)
Minimum N2 Pressure / Power Supplies / Minimum Temp
Feed Water Isolation Valves
(u-HV-2134/2135/2136/2137)
→hydraulically opened, nitrogen to close, 2040 psig minimum pressure to be operable
→pressure less than 2040 may result in exceeding surveillance stroke time
→provided with train related solenoids to dump hydraulic pressure and close valves within 5 secs
→hydraulic pumps powered from: uEB1-3 for SGs 1 and 3, uEB2-3 for SGs 2 and 4
→ maintain ≥90°F at all times per IPO-002, based on fracture toughness (TR 13.7.38)
Feed Pump Recirc Valves FV-2289/2290
Auto Operation
→in Auto, valves throttle to maintain 5,000 gpm suction flow (MFP trip reset will open if in Auto)
→driver card failure enables a separate solenoid which causes the valve to open at 4,275 gpm and close at 6,625 gpm
→at normal power this would keep it closed
→fails open on loss of air
→fails closed on loss of signal
→fails closed on MFP trip if both HP and LP steam supplies are shut
Feed Pump Discharge Valves HV-2109/2110 Interlocks
Feed Pump Discharge Valves HV-2109/2110
Interlocked with MFP status
→auto opens on feed pump turbine start signals
→auto close on a trip of the feed pump turbine OR closure of both HP and LP steam valves
→trip signal overrides start signal
→can auto open after trip signal reset
Water Hammer Interlocks
Water Hammer Interlocks are satisfied when:
→no Feedwater Isolation signals present
→FWIBV full open for 50 minutes
→IRC feedwater temp >250°F for 10 minutes AND feedwater ΔT across cntmt penetration <10°F
→total feedwater flow is >500,000 lbm/hr per SG
→admin limits: SG pressure >605 psig and NR level >5%
Once Water Hammer Interlocks are met it causes the following:
Water Hammer Interlocks met causes the following:
→allows opening FIV (will auto open if in Auto after Open)
→once FIV open, FIBV/FPBV auto close and FSBV auto opens
Water Hammer Interlocks - removed by any of the following:
Water Hammer Interlocks are removed by any of the following:
→Feedwater Isolation Signal is received
→both FWIV and FWIBV go full closed
→FSBV doesn’t have open signal and total FW flow to SG is <475,000 lbm/hr
→total FW flow to SG decreasing to <475,000 lbm/hr in conjunction with either IRC feedwater temp decreasing to <250°F OR ΔT across cntmt penetration increasing to >10°F
Split Flow Bypass Valves HV-2181 through 2184 Auto Close on:
→any MDAFWP auto start signal
→Feedwater Isolation
→Water Hammer Interlocks not met
Note: during normal, 100% power, split flow bypass is approx. 15% of total flow.
Full Flow Flush Interlocks
To open FWP flush bypass valves (HV-2122 & 2124):
→both FWPs tripped (both HP and LP steam valves closed)
→both FWP suction valves (HV-2321 & 2323) closed.
TR 13.7.32 - SG Pressure/Temperature Limitations
TR 13.7.32 - SG Pressure/Temperature Limitations
Establishes the temperature limits for primary and secondary coolants in the Steam Generators when the pressure of either coolant is greater than 200 psig. (requires the temperatures of the Primary and Secondary coolants to be > 70°F when the pressure of either coolant in the SG is > 200 psig)
Main Feedwater Pump Lube Oil Pumps
→2 AC oil pumps and 1 DC oil pump
→1 AC pump normally in service
→AC pumps are dual stage - 1st stage supplies 55 psig header; 2nd stage supplies 200 psig header
Main Feedwater Pump Lube Oil Pump Auto Starts
→standby AC pump starts at 175 psig header pressure on the 200 psig header
→DC pump auto starts at 25 psig bearing header pressure
→only supplies 55 psig bearing header; bypasses lube oil coolers and filter
What happens on a loss of 2EC1 or 2EC2?
FWIVs close and FWPBVs open due to loss of water hammer interlocks.
