FWLC - 1.0 Flashcards
What is the normal level that FWLC maintains the RX Level when operating?
Maintains Rx Level in normal band ~+35”
What are the modes of operation of the FWLC system?
- Auto – 650 – 5480 RPM
- Manual
- Warmup – 0-650RPM (Woodward Governor)
* DFCS Raises to 1000RPM for 30 minutes
RFPT SULC Steam Flow Mode
Auto Man >31.4% 3 Element
Auto Man <27.8% Single Element
Manual Auto <50%* SULCV Single Element
Auto Auto <50%* SULCV D/P
*Steam flow >50% transfer SULC to manual
Which component in the FWLC system compensates for a level error?
Master Level Controller
Which component in the FWLC system compensates for a D/P error?
Startup Level Controller
What method of FWLC is used at high power and what signals are used?
(>31.4%) 3 element control is used if available.
Looks at:
1. Steam flow feed flow mismatch – anticipatory changes
2. Level (ultimately controls.)
What happens when RPV water level transmitters fail?
Median Signal Select uses transmitter with the middle signal
On first transmitter failure, swaps to lowest remaining signal
On second transmitter failure, uses remaining transmitter
Third transmitter failure, locks in at last known good level
What occurs on a loss of of steam flow signal failure?
On a loss of any Steam Flow signal, the control circuit will transfer to single element control
What occurs on a loss of feed flow signal failures?
On a loss of any Feed Flow signal the control circuit will transfer to single element control
What happens on a loss of A,B, or C 483?
The associated RFP will trip
What happens on a loss of A,B, or CJ483?
Loss of the associated Digital Feed via a control signal failure in MCR and the turbine trip and reset logic(overspeed and shaft position detection)
What is a control signal failure?
A Control Signal Failure is initiated whenever the control signal out of the DFCS downstream of the respective RFP controller goes out of band.
What is a RFP set point set down and when does it occur?
RPV level 12.5” Reduces RFP control band to 14” to (attempt to) prevent over feeding on a scram/low level.
What points are sensed by the FWLC system to determine if a RFP is operating or not?
- Disch Valve 100% open
- Turbine reset (2/3 control oil pressure not low)
- Control valve poppets not 100% closed
What occurs on a loss of a RFP discharge pressure transmitter?
does not matter; however, if a discharge pressure header transmitter is lost, the SULC controller will switch to manual if in D/P mode.
Why do we use single element control?
Controlling element is used at lower power because vessel changes are slower and steam/feed flow is less accurate.
