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LCO 3.7.6. Condensate Storage and Supply
LCO 3.7.6.: the combined useable volume of the condensate storage tank (CST) and primary makeup storage tank (T-81) shall be >/= 100,000 gallons
APP: Modes 1,2,3, and Mode 4 when S/Gs are relied upon for heat removal
NO </= 1 HOUR ACTIONS
A S/G level controller, LIC-0701 and related equipment power supplies?
- powered from Y-10
- -auto swaps to Y-30
- -auto swaps back upon restoration of Y-10
B S/G level controller, LIC-0703 and related equipment power supplies?
- Y-20 normal
- -auto swaps to Y-40
- -auto swaps back if power is restored to Y-20
Heater Drain Pump trips
- T-5 low level (2/2)
- -P-10B @ 22.5%
- -P-10A @ 12.8%
- --staggering of setpoints prevents emptying of T-5 on equipment malfunction
- you also lose E bus on loadshed
MFP recirc valve power supplies
Feed reg valve bypass failure modes?
- Loss of air-as is
- loss of power-closed
- feedback failure-valve will oscillate open and closed
Moisture seperator drain tank (T-5) level control
- normal level 60-65%
- CV-0608 (heater drain pump common discharge) modulates to control level
- CV-0608 goes open on MFP low suction pressure of 270 psig
- -increases MFP suction pressure
- T-5 high level dump opens @ 80% level
Conditions required to transfer from FRV bypasses to FRVs @15% power?
- differential pressure must be between 150-200 psid across the FRVs
- FRV bypass valves must be 50% or more open
Moisture seperator drain tank T-5 high/low level alarm setpoints
What happens when LIC-0701/0703 MFRV LICs lose power?
output goes to 0, FRVs go closed
HIC-0526/0529 K-7A/B speed control operation
- only uses manual/cascade
- bumpless transfer from cascade to manual
- -must have pump speed (red pointer) within 0.5% of setpoint (blue pointer), you will get PF(green) light to transfer from manual to cascade.
- very slow response in cascade
- setpoint determined by HIC-0525 output in cascade
- HIC-0525 output signal of 54.2%=3250rpm=0% on HIC-0526/0529
- auto/PF mode not functional
When do the MFP discharge recirc valves open/close? (%power)
- during a power reduction recircs open @ approx 45% power
- during a power escalation
- -1st pump: recirc closes @ 30-35% power
- -2nd pump: recirc closes @ 40-45% power
Air supply for CV-0522B P-8B steam supply valve?
supplied from instrument air w/ bottled nitrogen backup supply from N2 station #2.
FRV bypass valves CV-0734/CV-0735 auto closure
- S/G pressure @ 500 psia (affected S/G only)
- -can be defeated
Purpose and operation of CV-0730 condensate recirc control valve
- 12 inch valve maintains minimum flow of 6800gpm
- -1600 gpm to gland seal condenser
- -5200 gpm to air ejector condenser
- on a downpower, CV-0730 should start opening at approximately 25% power
- on an uppower, CV-0730 should be full closed @ 35-40% power
HIC-0525 (combined feed controller) feedwater control mode selector operation
- acts as an auctioneering circuit
- -takes highest signal from LIC-0701/0703 sent to individual MFP speed controllers
- bumpless transfer from cascade to manual
- -must be with in 0.5% (green PF light) to transfer from manual to cascade
- only used manual/cascade
- individual pump controllers must be in cascade
- blue pointer-highest signal from LIC-0701/0703
- red pointer- signal output
- 0-100% equivalent to speed of 0-6000rpm
Main feed pump recirc CV failure modes
fail open on loss of Y-10(P-1A) or Y-20(P-1B)
FRVs auto close when?
- CHP (both valves)
- S/G pressure @ 500 psia (affected S/G only)-can be defeated
- S/G high level override @ 84.7% (affected S/G only)
LCO 3.7.3 Main feedwater regulating valves (MFRVs) and MFRV bypass valves
LCO 3.7.3.: 2 MFRVs and 2 MFRV bypass valves shall be operable
APP: Modes 1,2, and 3 except when both MFRVs and both MFRV bypass valves are either closed and deactivated, or isolated by closed manually actuated valves
Notes: seperate condition entry is allowed for each valve
NO </= 1 HOUR ACTION
LIC-0701/0703 main feed reg valve level indicating controller operation
- normal 65% level @ power
- recieves S/G downcomer level, steam flow, feed flow signals
- sends output signals to FRVs and HIC-0525 MFP combined speed controller
- auto/manual modes only
- transfer to auto blocked on turbine trip
- controller swaps to manual on turbine trip
- bumpless transfer
- -manual tracks auto-so bumpless from auto to manual
- -must be with in 5%(green light) to allow manual to auto transfer
MFRV bypass valve controller LIC-0734/0735 power supply?
MFP automatic trips?
- thrust bearing axial thrust
- low bearing oil pressure (9 psig)
- low governor oil pressure (25 psig)
- overspeed (5500 +/- 50 rpm)
- low suction pressure (250 psig 2/3 logic 3 second time delay)
HED system interlock on turbine trip
- on a turbine trip, the control valves are automatically closed to prevent flooding the reheater drain tanks and feedwater heaters E-6A/B.
- -reduces the possibility of water hammer
Main feed pump ratings
- 13,600 gpm each with discharge head of 1920 ft@ 5000 RPM
- rated @ 7000HP @ 5000 RPM
Purpose of moisture seperator drain tank pressure controller (DPIC-0609)
- monitors the differential pressure between T-5 and E-5s.
- on a loss of turbine load the E-5 pressure will drop
- DPIC-0609 will close CV-0610 and open the subcooling valves to the heater drain pumps
- also check valves in the line between E-5s and T-5 that close on loss of E-5 pressure to isolate T-5
Purpose of LIC-0735/0734 FRV bypass valve LICs?
enables finer control of S/G level @ low flow conditions (0-25% power)
Operation of LIC-0735/0734 FRV bypass valve LICs?
- auto/manual only
- -slide bar control
- -compares level to level setpoint
- blue-desired setpoint
- red-actual S/G level
FRV failure modes
- as is on loss of air
- closed on loss of power
- valve positioner failure-variable
- feedback failure-valve will oscillate open and closed
Consequences of 4" condensate reject valve failing open?
valve operates only by the level controller and cannot be closed by the operator, an open failure could result in condensate pump damage due to lowering hotwell level, and/or T-2 damage due to over filling
Why should condensate pumps not be operated for a prolonged period of time above 150F?
prevents damage to journal bearings due to overheating
Consequences of starting a feed pump with hand indicating controller set @ maximum?
- speed rises to 5250 rpm before the governor can assume control
- -could result in excess feed to the S/Gs (add positive reactivity)
What must be done to bypass an E-6 feedwater heater?
- power must be reduced 3%
- -prevents exceeding max permissible power due to colder feedwater to the S/Gs
MFP speed controller power supply?
powered from Y-01
What must be done to bypass an E-5 feedwater heater?
- must bypass associated E-6
- -limited to 600 MWe
- -lowers FW temps in E-6
- -excess extraction steam flow in E-6 heater
- -floods E-6 heater
Main feed pump reset permissives
- suction valve open
- condenser vacuum >/= 15" Hg
Mode of failure for a MFP?
fails to 3250 rpm on loss of air or loss of Y-01
How is hotwell level normally maintained?
- 3 inch makeup modulates open @66%
- 6 inch manually opened
- isolated 12 inch makeup would open on low level @ 58% but is not used
- 4 inch reject valve opens automatically @ 76%
MFRV 0701/0703 position indication power supplies
Interlock between CV-0710/0711 (MFP discharge recirc valves) and the trip and throttle valves?
- with both trip and throttle valves closed, the recircs are closed
- if any trip and throttle valve opens, recircs modulate based on suction flow
- interlock removed if D-11-1 is lost
- valves operate based on suction flow
What must be done and why when any 2 stages of FW heaters are bypassed?
- turbine load is restricted to <600MWe
- -prevents excessive extraction steam velocity in the next higher pressure heater
Why do we close the feed reg and bypass valves on nomal plant C/D?
prevents feeding S/Gs with condensate when S/G pressures lower to less than condensate pump discharge pressure
Condensate pump ratings
- 9250 gpm each @1000 ft
- limited to <30% power with 1 condensate pump
What happens at MFP suction pressure of 270 psig?
CV-0608, heater drain pump discharge valve, goes full open to ensure adequate NPSH for the MFPs
Consequence of allowing a MFP to warm up for an excessive amount of time?
dead heading pump until the trip and throttle valves are full open due to the recircs being closed
Relationship between MFP individual pump speed controller output signal and pump speed?
- 0% demand=4ma=3psig=3250rpm
- 100% demand=20ma=15psig=5250rpm
Heater drain pump capacity and power supplies?
- @ 100% power P-10A/B supply approximately 6100 gpm @ approximately 350 psig
- -roughly 25% of feed flow
- miniflow approximately 250 gpm per pump
- power supply-E bus
Purpose of the condenser, condensate, and feedwater system?
recover and preheat condensed steam for reuse as S/G feedwater
Effects of a heater drain pump trip @ 100% power?
- flow from heater drain pumps is reduced by 50% to MFPs
- MFP suction pressure lowers
- T-5 level increases due to loss of 1 heater drain pump
- plant trip
Effects of failure of the high level override function?
may result in moisture carryover due to a FRV failing to close
Normal Hotwell level
Limits on reheater outlet temperature during valve testing
- Control reheater C/D rate to <250F/hr
- prevents undue thermal stress and possible distortions to LP turbine stationary parts
Condensate pump motor starting limitations
- motor initially at room ambient temperature- 2 starts
- motor running continuously for > 30 minutes-1 start
- motor idle for > 60 minutes-1 start
Operation of MFP discharge recirc valves CV-0710 and CV-0711?
- modulate based on MFP suction flow
- -3000gpm (valve full open)
- -6500gpm (valve full closed)
- fail open on loss of air, loss of Y-10(Y-20)
T-4A/B high level alarm setpoint
35 1/2 inches from the bottom
What happens to the feedwater system on a turbine trip?
- -remain as is due to LIC-0701/0703 switching to manual
- -if in cascade HIC-0526/0529 shift to auto and ramp down speed
- -when in manual, pump rampdown is lost
What causes the BTVs to unlatch?
- Turbine trip
- -prevents overspeed
- High FW heater level
- -prevents damaging turbine blading
- Loss of air
LCO 3.4.17 Steam Generator (SG) Tube Integrity
- LCO 3.4.17 SG tube integrity shall be maintained.
- All SG tubes satisfying the tube repair criteria shall be plugged in
- accordance with the Steam Generator Program.
APPLICABILITY: MODES 1, 2, 3, and 4.
--------------NOTE-------------------------- Separate Condition entry is allowed for each SG tube.
- NO </= 1 HOUR ACTIONS
What are the S/G safety valve setpoints?
24 safety valves protect the shell side of the S/G and main steam headers from overpressure.
- 8 valves at 1000 psia
- 8 valves at 1020 psia
- 8 valves at 1040 psia
What indications are available for S/G D/P?
- 4 flow signals on C-12
- -one alarm if 2/4 channels indicate a flow less than setpoint, reactor is tripped
- All flow indicators must be within 5 % of each other
- 8 differential transmitters in each loop (16 total)
What is the function of the SGWLC system?
- To regulate S/G feed flow such that
- -feedwater flow matches steam flow
- -S/G water levels are maintained within normal limits
Describe the basic operation of the SGWLC system?
- 3 inputs are sent to LIC-0701/0703 (level/steam flow/feed flow)
- 1 signal from each LIC is sent to:
- -auctioneered to combined feed pump speed controller
- Combine speed controller sends a signal to each feed pump speed controller
- When LIC-0701(0703) output is 0%, you get a 3 psig air signal (FRV is closed)
- When output is 100%, you get a 15 psig signal (FRV is open)
- Linear relationship