Wk 2 Main turbine and auxiliaries
How many thrust bearings and what is their purpose?
1 thrust bearing and it provides axial support between the high and low pressure turbine sections.
How do MSVs 1,3, and 4 work with MSV 2?
1,3,4 are salve to MSV 2. They open when MSV 2 is ~98% open.
What sequence do the intercept valves open?
1,3,5 open first (master valves), 2,4,6 open when 1,3,5 are 95-100% open.
What are the requirements to start the turning gear, and what supporting systems are needed?
1. Main Shaft speed 0 RPM 2. >15# oil header pressure 3. When the piggy back motor switch is in position OFF the turning gear will auto engage Supporting systems 19-3 (29-3) and instrument air.
What are the design bases for main turbine?
1. Turbine inlet pressure is dictated by optimum reactor pressure. 2. Steam quality and exhaust pressure are selected for lowest blade erosion and max efficiency, respectively.
What is the gland seal flow path at high power operation?
1. at high turbine steam pressure turbine becomes self sealing 2. Steam from HP turbine seals provide steam to LP glands and excess leakage is vented to LP heaters. 3. GS unloading valve (AOV) maintains 2.5-5psig 4. Supply valve is controlled form the 7 panel 5. Unloader controlled by GS pressure regulator
What speed will all CIVs be closed?
107% rated speed.
What are the electrical overspeed trips?**
110% 110.3%
How many journal bearings are there and what is their purpose?
12 journal bearings, and the support rotor weight and provide radial stability.
What is the TGOP auto start?
15 psig oil supply header
What are the power supplies to both the above seat and below seat drains?
17-2
What is the power supply and auto start of motor suction pump (MSP)?**
17-2 and 10# main shaft oil pump suction pressure
What is the power supply for the turning gear oil pump?
19-3
What is the power supply and auto start of the turning gear oil pump (TGOP)?**
19-3 and 15# oil supply header pressure
What are the turbine oil filters?
2 100% capacity filters with normally on online. Supplied by 3 rotary gear PDPs (1 for each unit and a half) 50 gpm Pumps are powered from 17-1
What pressure is the gland seal header maintained at?
2.5-5 psig by pressure regulator and control valves
What is the loss of condenser vacuum turbine trip?**
20" Hg Vac
What is the power supply to the EBOP?
250 VDC non-essential.
What are the set points for the turbine inlet relief valves?
297-315
How does DEHC support the thrust bearing?
3 proximity probes monitor the axial movement of the turbine, this is sensed by DEHC. 32 mils movement in either direction (2 out of 3 logic) trips the turbine.
What is the discharge pressure of EBOP?
30 psig?
What is discharge pressure of turning gear oil pump?
40 psig
What are the generator electrical turbine trips?**
86 OR backup 86
When does the turning gear trip?
<10# bearing oil header pressure
What is generator load reject?
>40% mismatch between stator amps and cross over piping pressure. Also results in runback/load reject.
What is the piggy back motor?
A .7 HP motor that engages turning gear with the turbine shaft bull gear. Is a low torque motor designed to stall once engaged.
What is the glad seal unloading valve? (-123)
A PCV opens to discharge to feed water extraction lines if glad seal header exceeds 4 psig. This valve fails closed on a diaphragm rupture.
How are the extraction non-return valves operated?
A piston is held open by IA to allow valve operation, upon turbine trip air is bled off driving disc closed.
What is the emergency bearing oil pump (EBOP)
A pump located in te lube oil tank that supplies oil to the bearing oil supply header on loss of all AC power.
What is the turning gear oil pump?
A pump located in the lube oil tank that supplies oil to the bearing oil supply header when turbine is less than 90% rated speed.
When does the EBOP start?
Auto starts if MSOP discharge <135 psig AND TGOP discharge <25 psig.
Whats the purpose of hood spray?
Automatically provides cooling water from the condensate system to the condenser exhaust hood at low loads.
What are the remote electrical turbine trips?**
BOTH remote push buttons pressed.
What are the baffler valves?
Booster baffler valves maintains proper oil flow to the booster pump turbine Baffler bypass valves controls the oil flow to the lube oil coolers (about 50 psig)
What is the gland seal bypass feed valve (-S2)?
Bypass gland seal feed valve when turbine throttle pressure is less than 250 psig. Operator is cautioned to close at reactor pressures >250 psig due to likelihood of lifting RB downstream of -S2 (120 psi set point) (This relief valve lifting is what caused the moisture resulted in our cable fire)
What do the CIVs stop valves do on a turbine trip?
CIV stop valves close on a turbine trip.
What is the purpose of the main turbine?
Converts thermodynamic energy of reactor steam in rotational mechanical energy to drive the main generator.
What is the discharge pressure of motor suction pump?
Discharge pressure of 40 psig.
Where do the bypass valves discharge?
Each bypass valve discharges through pressure reducing orifices to a different main condenser section to allow load equalizing.
Where is the extra steam sent from glad seal at high power?**
Excess steam is routed of the steam seal unloading valve to the 1A-1 and 1A-2 (2A-2, 2A-3) low pressure FW heaters.
What are the gland exhausters?
Exhausters that create vacuum of 10-15" water. Provides exhaust flow through the glad exhaust condensers and to exhaust non-condensable to chimney via offers system 1.75 minute holdup volume.
How does the glad seal steam seal unloading valve fail on loss of IA.
Fails closed, but it is not supplied by instrument air. it is spring to close.
What is the motive force for turbine control valves?
Hydraulically opened and closed with a spring assist on closure.
What is the motive force for main stop valves?
Hydraulically opened and closed with a spring assist on closure. (Hydraulics supplied by EHC)
What are the purposes of the relief valves in the gland steam system?
If PCVs fail, these relief valves maintain gland seal header at safe pressure. There are 2 relief valves set at 20 psig on the gland seal supply header. There is one more relief valve on the gland seal steam supply bypass line. This relief is at 120 psig.
What will happen when the piggyback motor switch is in off?
If main shaft speed is 0 RPM and there is >15# oil header pressure the turning gear will auto engage.
Why should motoring of the generator be avoided?
If the generator remains synced to the grid, but steam is not being admitted to the turbine, the generator become a motor and drives the turbine. This results in overheating of the turbine.
What happens if MSOP discharge pressure drops to <105 psig.
If turbine speed is greater than 1300 rpm the turbine will trip.
What is the gland seal steam feed valve (-S1)?
Inlet to glad seal feed PCV (-124). It is used during system start-up or shutdown to aid in maintain gland seal steam pressure.
What is used to engage the turning gear?
Instrument air
What is the oil driven booster pump?
It is located in the lube oil tank and is driven by the MSOP discharge oil. the booster pump supplies oil to MSOP suction at about 20 psig when turbine is at speed.
What is the glad seal exhaust vent?
It is maintained at vacuum by glad steam exhauster. The vent removes air in leakage and steam leak off from outermost stages of turbine shaft packing.
What is the turbine vacuum breaker MO-4901?
It opens to break make condenser vacuum before sealing steam can no longer be maintained. It is operated from MCR. The valve pis physically located on turbine floor, east side of bio wall.
What controls hood spray?
Its controlled by DEHC. When DEHC senes turbine speed >900 rpm and <10% turbine load the hood spray valves full open. (valves are normally closed)
What speed is the MSOP driven?
Its driven at 3636 rpm.
What is special about Main stop valve 2?
Its the only throttling valve. It admits steam to warm the steam chest on start up and to equalize the pressure across the stop valves prior to opening (via an internal pilot valve) Opens with a Dp <120 psig
What is the power supply to turbine lift pumps?
MCC 19-3
What are the below seat drains for CVs?
MO 3005- drains condensate from HP turbine inlet piping directly to main condenser. Normally closed during plant operation. There is an orificed bypass line continuously drains this area when the valve is closed.
What is the EBOP auto start?
MSOP discharge pressure <135 psig and TGOP discharge pressure is <25 psig
What flow and pressure is the MSOP?
MSOP provides sufficient oil pressure and flow when operating at or above ~90% of rated speed. Normal discharge pressure is 225 psig.
What is the auto start of MSP?
MSOP pump suction pressure of 10 psig. Operationally this happens at about 90% speed.
What is the MSP and what does it do?
Main suction pump auto starts at 10psig MSOP suction pressure to prevent loss of suction. (this corresponds to about 90% rated turbine speed)
What are the above seat drain for the CVs
Mo 3004 A/B/C/D drain condensation from the steam chest directly to the main condenser. These valves can be throttled to equalize pressure between the steam chest and HP turbine inlet.
How many bypass valves are there and what is their purpose?
Nine bypass valves permit steam flow to the condenser for starting up the turbine-generator
What is the power supply and auto start of the emergency bearing oil pump (EBOP)?**
Non Essential 250 VDC <135# MSOP discharge pressure AND TGOP discharge pressure <25#
What are the 1 hour actions for Tech Spec 3.7.7 - The main turbine bypass system?
None
What is the normal position of the intercept valves?
Normally full open, they ramp open when turbine speed is selected.
What is the main shaft oil pump and what is its purpose?
Oil pump that is physically driven by the turbine shaft. In conduction with booster pump it supplies all system requirements when the turbine is at operating speed. It is located at the front standard.
What happens at high hood spray temperature?
Operator must do a manual trip at >225F
What instrumentation is available in the control room?
Position recorder on 7 panel. When not synced to grid it indicates RPM When synced to the grid it indicates control valve position First stage pressure is also available at 7 panel. This signal is used for 38.5% scram bypass Throttle pressure is used for DEHC as well as <785# GP 1 signal.
What is the power supply for motor suction pump (MSP)?
Powered rom 17-2
What is the purpose of the combined intermediate valves (CIVs) and what is special about them?
Prevent overspeed which might occur if CVs and stop valves are closed, due to flashing of water in moisture separators. Each CIV consists of an intercept valve and a stop valve in a common body.
What are the turbine inlet relief valves and where do they discharge?
Seven LP relief valves protect the LP (crossover) piping and moisture separators from over pressure. They discharge to the main condenser.
What is the purpose of the turning gear and where is it located?
Slowly rotate rotor (3 to 5 rpm) to prevent rotor bowing. Located between LP turbine section C and generator
What is the glad seal flow path at lower power or shutdown operation?
Steam is supplied to gland seal feed valve from D-ring and is reduced to 2.5-5 psig
What is the normal position of the stop valve in the CIVs?
Stop valves are normally open, and close on turbine trip
Where do the turbine lift pumps take suction from?
Suction from the bearing oil supply header
What is the purpose motor suction pump (MSP)?
Supplies oil to the MSOP suction when turbine is less than 90% of rated speed.
What is the purpose of the turbine lift pumps?
Supply high pressure oil to the bottom of each journal bearing to lift the rotor off the bearings 3-5 mils when on turning gear
What is the suction source for hood spray?
Takes from condensate booster pump suction line.
How are the turbine seals sealed when at high pressure?**
The HP provides steam to itself and the LP turbines. ( it is self sealing)
What are the lube oil coolers and what is the cooling medium?
The cool the turbine lube oil, 2 100% capacity coolers with one valved in at a time. The coolers and cooled by SW ( approximately 3500 gallons per minute)
What gives the motive force to the booster pump?**
The discharge of the MSOP.
To close the stop valves what position must the intercept valves be in?
The intercept valves must be fully closed for the stop valves to close.
What prevents the CVs from popping off their seat when opening?
The internals of the valve are balance with an internal pilot valve and balance chamber to prevent disc from popping off seat when opened.
What is the fail position of the TCV to the lube oil coolers?
The lube oil cooler TCV fails open which maintains SW outlet to 110-120F. (Normally 115F) Verify this info if you think its important
What is the LCO statement for Tech Spec 3.7.7 - The main turbine bypass system?
The main turbine bypass system shall be operable OR LCO 3.2.2, MINIMUM CRITICAL POWER RATIO (MCPR), " limiter for an inoperable Main Turbine Bypass System as specified in the COLR, are made applicable.
To open the intercept valves, what position must the stop valves be in?
The stop valves must be full open.
What is the power supply to main shaft oil pump (MSOP)?**
The turbine
What is the TGOP and when does it start?
The turning gear oil pump auto starts at 15 psig bearing supply header pressure to supply the turning gear and the turbine bearings.
When does the turning gear engage?
The turning gear will auto engage at 0 RPM
What happens if piggy-back motor switch is left in on (not auto)?***
The turning gear will continue to try to engage even after turbine roll. When the switch is in position off the turning gear will auto engage.**
How many stop valves are there and what is the purpose of them?
There are 4 main stop valves ( one per steam line) and they shut to protect the turbine from dangerous operation.
How many turbine control valves are there and what is their purpose?
There are 4 turbine control valves (CVs) and they regulate steam flow to the turbine, thereby controlling reactor pressure.
What are the extraction non-return valves and what is their purpose?
There is one on each extraction steam line from LP turbine to B,C and D feed water heaters. Protects the turbine from overspeed which might occur when the turbine is tripped and water in heaters flash to steam.
What are the modes of applicability for Tech Spec 3.7.7 - The main turbine bypass system?
Thermal Power ≥ 25%
How do the stop valves open?
They open sequentially and when all are open they bypass 33% of rated steam flow.
what happens with a generator electric trip (86 device) trips?**
Turbine trip
What happens on high moisture separator level?**
Turbine trip 15 seconds after alarm point
What happens on an electrical overspeed?
Turbine trip at 110% and 1103%
What happens on low EHC pressure?
Turbine trip at 1100# supply (FAS) header
What happens on a loss of condenser vacuum?
Turbine trip at 20" Hg
What happens on high thrust bearing wear?
Turbine trip at 32 mills?
What happens on low bearing oil pressure?
Turbine trip at 8#
What happens on low MSOP discharge pressure?
Turbine trip at <105# with turbine at >1300 rpm
What happens on a failure to runback on stator amps?
Turbine trip at the following setpoints >27,242 amp after 105 seconds >9,121 amp after 195 seconds
When does the turning gear auto start?
Turning gear auto starts at 0 RPM if bearing oil pressure >15 psig
What critical speeds should be avoided in relation to harmonic vibrations?
U1 critical speed is ~950 rpm and U2 critical speed is ~1100 rpm. At these speeds harmonic vibrations will have the most destructive effect.
What is the cooler transfer valve?
Valve that controls which cooler is online, has two hand hand wheels. Upper handwheel selects the cooler the lower helps seat the valve.
How do speeds greater than 100% effect the CIVs?
When speed reaches 105% of rated speed, CIVs 1,3,5 being to close. (CVs start closing at 100% and are full closed at 105%) When 1,3,5 are 50% closed then 2,4,6 close.
What is the POWER LOAD UNBALANCE TRIP alarm?
a >40% unbalance between power and load. Detected by measure stator output current (load) and cross over piping pressure (power). CVs and CIVs close on this
What is normal lube oil flow path?
a. Booster pump supplies oil to the Main Shaft Oil Pump (MSOP) suction at 20 psig b. MSOP supplies the booster baffler and baffler bypass at 230-250 psig c. Booster baffler supplies the booster pump at 200 psig d. Baffler bypass supplies the oil coolers at 50 psig e. Booster pump turbine exhausts oil to the oil coolers at 50 psig f. Oil exits coolers to bearing supply header at 40 psig g. Service water is throttled to maintain oil out of the cooler at about 115F h. Motor Suction Pump (MSP), Turning Gear Oil Pump (TGOP), and Emergency Bearing Oil Pump (EBOP) and bearing lift pumps are not running when Turbine is in operation
What is the general flow path after steam leaves the vessel?
a. D-Ring/Turbine Throttle/Equalizing header through the Main Stop Valves (also goes to Bypass valves, gland seal steam regulator, SJAE regulator, off-gas) b. Into the Steam Chest and through the Control Valves into the HP Turbine. c. HP Turbine exhaust flows through 4 Moisture Separators into 6 crossover pipes d. Through 6 Combined Intermediate Valves (CIVs) into the 3 LP Turbine sections. e. The LP Turbines exhaust directly to the Main Condenser Throttle pressure ~ 930 psig, Steam chest ~ 900 psig, HP inlet ~ 820 psig
General precautions for the turbine:
c. Turbine should not be run < 800 rpm for more than 5 minutes d. Breaking vacuum at rated speed (1800 rpm) induces extreme stress on last stage blades. This should be completed until turbine speed is 2/3 rated. e. The turbine should not be operated at 2/3 rated speed with condenser vacuum < 26" Hg f. HP turbine shell is limited to 150F inside to outside metal delta T to prevent excessive thermal stresses. All start-ups shall have heat-up rate < 150F/hr. g. All startup rates are according to turbine first stage bowl temperatures 250-350F (medium, 90 rpm/minute) or > 350F (fast, 180 rpm/minute) h. High temperature alarm for turbine bearing temperatures (pt 1-12) is 225oF i. Metal temperature is 250 oF - Manual scram
What happens on FASTC low pressure?
scrams at <460# with ≥ 38.5 steam flow
What happens on a high Rx level (+48")?**
turbine trip
