C34 - DFCS

Question 1

What will initiate setpoint setdown?

What will setpoint ramp up to?

What will happen to level control?

Answer 1

11.4” Rx water level

ramp up to 54” Rx water level

Goes to single element

Question 2

How much lower is actual level compared to level demanded when power is < 45%?

At 45-90%?

at 100%?

Answer 2

5”

11” steam flow per inch

0” (it should match)

Question 3

Can you go back to 3 element with steam flow sealed in?

Answer 3

NO

Question 4

Can you go back to 3 element with a feed flow transmitter failed downscale?

Answer 4

Yes, IF flow > 8.25 mlbm/hr

Question 5

When can you go to 3 element when raising power?

Answer 5

> 6.6 mlbm/hr

Question 6

When does DFCS auto swap to single element on a down power?

Answer 6

< 4.95 mlbm/hr

Question 7

What’s a hard failure for level?

Answer 7

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”

Question 8

When can a recirc pump be shifted to fast speed?

Answer 8

> 3.2 mlbm/hr

Question 9

When do they auto shift to slow speed when reducing power?

Answer 9

< 3.0 mlbm/hr (for 15 sec)

Question 10

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?

Answer 10

after 10 seconds or 12.4” it changes to 4”

Stays there until an operator changes it

Question 11

What channel does digital feedwater control system read when it’s in service?

Answer 11

Intermediate of 3 pressure channels

Question 12

What else does the pressure channel feed?

Answer 12

Upset range water density compensation and Annunciator Rx PRESS HI

Question 13

How many transmitters feed into RPV pressure?

Answer 13

2 narrow and 1 wide

Question 14

What provides data to estimate steam flow, besides pressure?

Answer 14

APRM channel 4

Question 15

Where is level in the reactor taken from?

Answer 15

downcomer

Question 16

What does too much carry over cause?

Answer 16

damage to turbine

Question 17

what does too much carry under cause?

Answer 17

Recirc pump cavitation

Question 18

Where does the FCV runback and Recirc pump NPSH interlocks come from?

Answer 18

C34 NOT B21 !

Question 19

If a Recirc pump trips, what does water level do?

Answer 19

level goes up

Question 20

what happens if one narrow range level fails?

Answer 20

C34 throws it out and inserts upset range (still uses the middle reading)

Question 21

what happens if 2 narrow range level fails?

Answer 21

C34 throws it out and uses the one narrow range left

Question 22

What happens if 3 narrow range levels fail?

Answer 22

It uses UPSET

Question 23

Will any trips come off of the UPSET range?

Answer 23

NO

Question 24

If equalizing valve is opened, how does level fail?

Answer 24

HI

Question 25

If only 2 narrow ranges are available, what does DFCS use?

Answer 25

the lesser of the narrow range

Question 26

What happens if no narrow range or upset range is available?

Answer 26

It auto-swaps to manual with the last “B” demand signal

Question 27

Can disabled channel be selected?

Answer 27

NO

Question 28

If a channel is selected, how does it respond?

Answer 28

De-selects auto and it responds to the reading of that channel

Question 29

What is the logic for level 9 turbine trip?

Will the high level auto-reset?

Answer 29

2 out of 3 logic, 58” with a 1 second TD

Yes

Question 30

What is the preferred source for the Entry panel?

Answer 30

1Y99

Question 31

What type of device is the entry panel?

Answer 31

Normal seeking

• Auto swap to alternate AND back to normal *

Question 32

What happens during a soft failure?

Answer 32

It still uses the middle value

Question 33

When will disable lights illuminate on the panel?

Answer 33

when there is a hard fail