C34 - DFCS Flashcards
What will initiate setpoint setdown?
What will setpoint ramp up to?
What will happen to level control?
11.4” Rx water level
ramp up to 54” Rx water level
Goes to single element
How much lower is actual level compared to level demanded when power is < 45%?
At 45-90%?
at 100%?
5”
11” steam flow per inch
0” (it should match)
Can you go back to 3 element with steam flow sealed in?
NO
Can you go back to 3 element with a feed flow transmitter failed downscale?
Yes, IF flow > 8.25 mlbm/hr
When can you go to 3 element when raising power?
> 6.6 mlbm/hr
When does DFCS auto swap to single element on a down power?
< 4.95 mlbm/hr
What’s a hard failure for level?
Narrow range – Trip unit in cal OR channel not within 7.5” of the other 2.
AND
channel indicates < -3.75” or > 63.75”
UPSET RANGE
Channel < -11.25” or > 191.25”
When can a recirc pump be shifted to fast speed?
> 3.2 mlbm/hr
When do they auto shift to slow speed when reducing power?
< 3.0 mlbm/hr (for 15 sec)
On setpoint setdown, what will the master level controller change the setpoint to after the auto shift to 54”?
How long will it stay there?
after 10 seconds or 12.4” it changes to 4”
Stays there until an operator changes it
What channel does digital feedwater control system read when it’s in service?
Intermediate of 3 pressure channels
What else does the pressure channel feed?
Upset range water density compensation and Annunciator Rx PRESS HI
How many transmitters feed into RPV pressure?
2 narrow and 1 wide
What provides data to estimate steam flow, besides pressure?
APRM channel 4
Where is level in the reactor taken from?
downcomer
What does too much carry over cause?
damage to turbine
what does too much carry under cause?
Recirc pump cavitation
Where does the FCV runback and Recirc pump NPSH interlocks come from?
C34 NOT B21 !
If a Recirc pump trips, what does water level do?
level goes up
what happens if one narrow range level fails?
C34 throws it out and inserts upset range (still uses the middle reading)
what happens if 2 narrow range level fails?
C34 throws it out and uses the one narrow range left
What happens if 3 narrow range levels fail?
It uses UPSET
Will any trips come off of the UPSET range?
NO
If equalizing valve is opened, how does level fail?
HI
If only 2 narrow ranges are available, what does DFCS use?
the lesser of the narrow range
What happens if no narrow range or upset range is available?
It auto-swaps to manual with the last “B” demand signal
Can disabled channel be selected?
NO
If a channel is selected, how does it respond?
De-selects auto and it responds to the reading of that channel
What is the logic for level 9 turbine trip?
Will the high level auto-reset?
2 out of 3 logic, 58” with a 1 second TD
Yes
What is the preferred source for the Entry panel?
1Y99
What type of device is the entry panel?
Normal seeking
- Auto swap to alternate AND back to normal *
What happens during a soft failure?
It still uses the middle value
When will disable lights illuminate on the panel?
when there is a hard fail
