Main Turbine / Gen Iso Phase Bus Cooling (GML) Flashcards
What is unique about TSV2 (MSV1D)
Has an internal bypass to allow equalization for turbine warmup.
What is Critical Speed value?
900-1300 RPM (this is where turbine vibrations should be at peak value. Therefore, it is desired to minimize time at Critical Speed.)
What is the capacity of the Turbine Bypass Valves?
5 valves = 18.5% (20% on test questions)
When is it required to manually trip the Turbine?
- > 9mils w/ >3mil/min rate of change.
- > =10mils for 15min
- > =12mils for 2 consecutive readings.
- Vacuum <24.6”Hg and <30% load.
- > 2”Hg between any Condenser Box.
What is the Open sequence of the TCVs?
CV-1,2,3 open together to 57% then CV-4 begins to open
What is the Valve sequence for Turbine Overspeed?
- At 100% CV’s begin to close and are fully closed by 105%.
- At 105% CIV’s begin to close and are fully closed by 107%.
What do the Moisture Separators reheat the steam too? (Temp comparison to initial live steam)
Reheats dry steam to within 25°F of initial live steam temperature
What are the Master-Slave valve combinations?
1 & 4
2 & 6
3 & 5
What is the Master-Slave valve Opening and Closing sequence?
- When master valve reaches 90% open, slave valve receives signal to full open
- When master valve reaches 50% closed, slave valve receives signal to full close
When do Exhaust Hood Sprays open?
Opens automatically if LP turbine A or C exhaust hood temperature reaches 120°F
What actions need to be taken when resetting the Turbine and DEHC Speed automatically selects 1800 RPM?
Operator has approximately 10 seconds to select ALL VALVES CLOSED to prevent NSSS MSIV isolation on low vacuum trip due to Turbine Stop Valves opening.
What is the auto Main Turbine Trip on Vibrations?
There isn’t one!!!
Hence the reason for the manual trips. (See P&L D27)
When should the Turbine be manually trip for low condenser vacuum?
The Turbine should be manually tripped whenever Turbine load is <30% (410 MWe) and condenser vacuum is less than 24.6” Hg.
What happens if a NRV (Non-Return Valve) fails to close?
There is potential Turbine Overspeed on a Turbine Trip.
When MSIVs close, why does the Turbine Trip?
Turbine trips on reverse power
What are the requirements on a failure of TSV/TCV pressure permissive
1 Hr to restore then 4 Hrs to get <26%.
What happens to Chest Warming if the Turbine Trips?
Chest Warming is secured
What happens on a loss of Gland Sealing Steam?
Turb trip on low vacuum…eventually
When must Cond Vacuum Breakers be opened?
If it is projected that Bearing Vibration following a turbine trip will exceed 30 mils.
What initiates a RPS TSV SCRAM?
TSV <95% open when >26% Rx Pwr (sensed off of 1st stage shell pressure)
What lift oil pump pressure and what turbine speed is required for Turning Gear to engage?
- > 1000 psig
- <2 rpm
When do LP exhaust hood diaphragms rupture?
5 psig
MAIN TURBINE TRIPS
- L8 (202.3”)
- RCIC Initiation seal-in w/ MOV126 not fully closed and 4min TD.
- Pri Overspeed: DOPS >109.4% (1969rpm)
- B/U Overspeed: TCS 110.5% (1989rpm)
- Low EHC Hydraulic Pressure (1100#)
- Condenser Vacuum Low (22.1”Hg)
- Electrical Protection Trip (86 device)
- Low Bearing Oil Pressure (8#)
- MSR Hi-Hi Lvl (10sec)
- Main Shaft Pump Low discharge pressure (105#) w/ Turbine >1300rpm.
- Thrust Bearing wear Detector Ecessive Clearance (36mils)
- Loss of Stator water
- Emerg Trip Sys Pressure Low (800# for 2sec)
- Manual Push Buttons
- Soft Button (HMI Screen)
- Loss of both speed signals w/ Turb Speed >100rpm.
