Turbine Cooling Water System Flashcards
Describe Turbine Cooling Water Loads.
Turbine Lube Oil: (12” header)
* TLO Coolers (2) – 2nd largest load
Turbine Equipment: (16’ header)
* H2 Coolers (4) – Largest Load (50% of all TCW flow at 100% power)
* H2 Air side Seal Oil HX
* H2 Oil side Seal Oil HX
* Exciter Air Coolers (2)
* Isophase Bus Duct Coolers (2)
* Condensate Polisher Air Compressor
* {H2 Dryer}
* {Unit 1 Condensate Pump 1C Motor Bearing Cooler}
Auxiliary Equipment: (4” header)
* Instrument Air Compressors - (Water jackets & Aftercoolers)
* Instrument Air Dryer - (Aftercooler)
* {Instrument Air Emergency Cooling Water Cooler} – Described later
* Service Air Compressors - (Water jackets & Aftercoolers)
* DEH Coolers (2) - Flow is manually throttled to maintain EH temperature between 110°F and 130°F.
* Main Feedwater Pump Oil Coolers -TCW at 20 gpm and read in a sight glass
* Condensate Pump Motor Bearing Coolers – {Unit 1 Condensate Pumps 1A &1B} / [Unit 2 – Condensate Pumps 2A, 2B & 2C.] Normal TCW flow rate is 10 gpm. Low flow alarm at < 4.5 gpm
* Heater Drain Pump Seal Coolers
* Chemical Sample Coolers - Provides 10 gpm of flow to the Secondary Chemistry Sample Panel
Describe the Turbine Cooling Water Surge Tank.
- Located at NW corner of RAB roof above Control Room
- Allows for system thermal expansion/contraction and provides pump NPSH
- 1000 gallon tank, vented to atmosphere
- Auto make-up is from the Demin Water System via Level Control Valve LCV-13-1.
Describe the TCW Pumps.
- START/STOP switches on RTGB 102 [202] and local
- 5100 gpm each, 152 feet head (70-95 psig) discharge
- Power from 4kv A2/B2 buses,
- Normal suction pressure is 10-25 psig.
- 1 pump & 1HX (can handle 100% load) / 1 pump & 2 HX’s (100% load normal operations)
Describe the TCW Standby Pump Selector Switch.
Used to designate which TCW pump will auto-start on low TCW flow (<1550 gpm)
3-position switch
“TCW PP A” - Enables auto-start of A TCW pump
“TCW PP B” - Enables auto-start of B TCW pump
“Manual” - Disables auto-start feature for both pumps
Describe the TCW Heat Exchangers.
- Horizontal, single pass, counter flow, shell & Tube.
- Shell side – TCW
- Tube side – ICW
- TIC on TCW HX Outlet controls TCV on ICW at outlet of HX.
- TCW HX TCV’s are currently bypassed – they have been broken forever
- Heat Exchanger Temperature Control Valves Fail OPEN on Loss of Power (Full Cooling)
- ICW to TCW is isolated on Safety Injection (SIAS)
Describe the fail position of TCW TCVs.
All Fail open (ie fail to max cooling) on loss of air or power, with exception of H2 Coolers
Describe H2 Coolers as related to TCW.
- TCV-13-15 H2 Coolers Outlet - (115F)
- Largest load. First load affected by TCW problems
- Reduce load if Temp increases
- Fails as is on loss of air. Fail open on loss of power.
- Mechanical stop to prevent full opening on loss of signal due to controller or positioner failure.
- Both of these prevent a failure of TCV-13-15 robbing flow from the rest of TCW System
Describe the actions required for a Total Loss of TCW.
No running pumps – Rapid Down Power Unit, VARS to minimum, but will NOT need to trip the Rx / Turbine.
Describe the effects of a loss of Instrument Air on TCW.
For loss of Instrument Air to TCV’s, the TCV’s fail open (Except TCV-13-15 which Fails As-Is) for maximum TCW (and ICW) flow. TCV-13-15 fails as is to prevent robbing other components of TCW if it loses air. Shift instrument air compressors to emergency cooling. This action is mandatory for a Loss of Offsite Power due to loss of electrical buses.
List the TCW TCVs with setpoints.
TLO Coolers:
* TCV-13-28 TLO Temperature Control Valve - (110F)
* 2900 gpm
* Fails open
TCW HX Outlet:
* TCV-13-2A (B) Heat Exchangers (90F)
* Fails open
Exciter Coolers:
* TCV-13-8 Exciter Cooler Outlet (110F)
* Fails open
Air Side Seal Oil Cooler:
* TCV-13-21 Air Side Seal Oil Cooler Outlet (110F)
* Fails open
* Relief Valve set at 100psig to preclude leakage of TCW into Seal Oil System.
H2 Side Seal Oil Cooler:
* TCV-13-22 H2 Side Seal Oil Cooler Outlet (106F)
* Fails open
* Relief Valve set at 100psig to preclude leakage of TCW into Seal Oil System.
{Instrument Air Compressors Emergency Cooling Water}:
* {TCV-13-31 Backup Compressor Aftercooler}
* {TCV-13-32 Backup Compressor Jacket Cooler}
* {Fails Open}
Isophase Bus Coolers
* Line taps off the Equipment Header.
* Combined flow through the coolers. No TCV
* Approximately 150 gpm each cooler
* Inlet Temp ~ 100°F
* Outlet Temp ~ 120°F
Instrument Air Compressors
* 2” Line supplies the IA Compressor 1A/1B [2A/2B] After-Coolers and Jacket Coolers.
* Manual Temperature Control Valve.
* Normal after-coolers outlet temperature is ~ 140°F.
* Normal jacket outlet temperature is ~ 120°F.
* A recirculation pump with a head tank and a fan cooler.
* Used as a cooling water backup system.
* The recirculation pump and fan powered from AB MCC.
* Manually aligned during a loss of normal turbine cooling water supply.
* Another two inch line taps off the auxiliary equipment header and supplies 1C/1D [2C/2D] instrument air compressor inner coolers, oil coolers and after coolers.
Chemical Feed Pot
* 100 gallon tank filled from Demin water, Located above the TCW Surge Tank
* Taps into the pump suction piping, used for adding chemicals to inhibit corrosion.
Describe Off Normal Operation of TCW.
- If TCW pump overload and/or high temp alarm (Loss of one TCW Pump while unit is at 100% power)
- Open the system cross-tie and reduce turbine load w/i the capabilities of 1 pump (approx 60%).
- Degraded ICW flow:
- Ensure ICW to TCW valves are open (MV-21-2/3), Isolate blowdown, manually close TCV’s to OBHX’s.
- If TCW HX TCV’s not responding properly:
- Shift TCV’s to manual or open the bypass valves.
- High Differential Pressure on TCW HX inlet strainers:
- Backwash the TCW HX strainers IAW the procedure,
- C & D Instrument Air Compressors must be secured due to a loss of TCW
- Air in TCW system:
- Vent pumps and suction header as needed.
- Total loss of TCW requires tripping the Turbine
- For loss of Instrument Air to TCV’s, the TCV’s fail open (Except TCV-13-15 which Fails As-Is) for maximum TCW (and ICW) flow. TCV-13-15 fails as is to prevent robbing other components of TCW if it loses air. Shift instrument air compressors to emergency cooling. This action is mandatory for a Loss of Offsite Power due to loss of electrical buses.
- If surge tank makeup flow control is not proper: Manual bypass control if needed.
- Excessive make-up water usage to Surge Tank (totalizer): indication of leak. Attempt to locate/isolate
Discuss TCW Abnormal Operation.
Total loss of TCW:
* No running pumps – Rapid Down Power Unit, VARS to minimum, but will NOT need to trip the Rx / Turbine.
For loss of Instrument Air to TCV’s, the TCV’s FAIL OPEN for maximum TCW (and ICW):
* EXCEPT: TCV-13-15 FAILS AS-IS to prevent robbing other components of TCW if it loses air.
Shift instrument air compressors to emergency cooling.
* This action is mandatory for a Loss of Offsite Power due to loss of electrical buses.
If surge tank makeup flow control is not proper?
* Go to manual bypass control if needed
High Differential Pressure on TCW HX inlet strainers
* Backwash the TCW HX strainers IAW the procedure
1C/1D [2C/2D] Instrument Air Compressors must be secured due to a loss of TCW
* TCW AOP is used to align Emergency Cooling to the A & B Air Compressors.
* TCW AOP is used to align service water to the C & D Air Compressors
