Rod Ctrl

Question 1

What is the C-1 Conditional?

Answer 1

C-1, IR Rod Stop

• IRNI > 18% (16%) (1/2)
• AUTO and MANUAL rod withdrawal Stop
• Manually blocked above P10 (≥ 10% PR)
• Unblocked below P10

Question 2

What is the C-2 Conditional?

Answer 2

• PR > 103% (1/4)

- Auto and Manual Rod withdrawal stop

Question 3

What is the C-3 Conditional?

Answer 3

• Overtemp ΔT at 3% < trip setpoint (2/4)
• Gives auto and manual rod withdrawal stops and initiates turbine runback
• No Block!

Question 4

What is the C-4 Conditional?

Answer 4

• Overpressure ΔT at 3% < trip setpoint (2/4)
• Gives auto and manual rod withdrawal stops and initiates turbine runback
• No Block!

Question 5

What is the C-5 Conditional?

Answer 5

• MPC-253 < 15%
• Stops outward rod motion (while in Auto only)***
• No Block!

Question 6

What is the C-11 Conditional?

Answer 6

• Ctrl Bank D at 229 steps
• Stops outward rod motion (while in Auto only)***
• No Block!

Question 7

What does the Mismatch Rate Comparator do?

Answer 7

• Compares rate of change between MPC-253 and NIs. - Provides faster response to transients

Question 8

What are the Rod Ctrl Inputs?

Answer 8

• Auctioneered High Tave
• Auctioneered High PR NI
• MPC-253, Turbine 1st Stage Impulse #

Question 9

What is shutdown margin (SDM)?

Answer 9

• Reactivity worth must be sufficient to completely shut down the reactor with margin for all accident conditions, assuming the most reactive rod remains fully withdrawn

Question 10

How is the Ctrl Rod system designed?

Answer 10

• Maintain Tavg within 5°F of program and restore Tavg within 1°F following:
• 10% step load change
• 5%/min ramped load change
• 50% step load change with steam dumps (40%)

Question 11

Which control modes allow rods to move in a normal sequence with program overlap?

Answer 11

• Auto and Manual only

Question 12

Where are the MG Sets powered from?

Answer 12

• 11/21A and 11/21D busses

Question 13

What will trip the CRD MG Set Output Bkrs?

Answer 13

• Overvoltage
• Overcurrent
• Reverse Current
• Supply Bkr Open

Question 14

What will trip the CRD MG Set Supply Bkrs?

Answer 14

• Load Con

- Overcurrent

Question 15

What are the Pwr Cabinet urgent failures?

Answer 15

• Logic Error
• Regulation Failure
• Phase Failure
• Multiplexing Error
• Card Removed
• Pwr Cabinet failures affect groups for that cabinet **

Question 16

What is the Logic Cabinet urgent failures?

Answer 16

• Loose Card
• Oscillator
• Slave Cycler
• SDC circuit fail
• Logic cabinet failures affect all rods **

Question 17

What happens if you have an urgent failure on a Logic or Pwr Cabinet?

Answer 17

• Stops all rod motion

- De-energizes lift coil and energizes stationary and movable gripper

Question 18

During a power escalation, Control Bank C – Group 1 Rod B-8 dropped. At the time the event occurred, reactor power was 48% and Rod B-8 was fully withdrawn.

While recovering the rod per 1-OHP-4022-012-005, Attachment B, “Recovery By Positioning Single Rod,” a Rod Control Urgent Failure alarm occurred.
Which of the following explains why the alarm actuated?

a. A Multiplex Error has occurred in the Power Cabinet
b. An Oscillator Failure has occurred in the Logic Cabinet
c. A printed circuit card has been jarred loose from the Power Cabinet.
d. All Control Bank C – Group 2 rod lift coil disconnect switches are open.

Answer 18

d. All Control Bank C – Group 2 rod lift coil disconnect switches are open.

Question 19

Given the following conditions:
• Unit 1 is at 100% power
• A loss of power to CRP-3 occurs

What is the effect on the Rod Position Indication (RPI) system and the procedural action necessary, if any?

a. RPI indications are maintained since backup power supply (via ELSC) automatically energized the RPI Cabinets. Operation is allowed since RPI has been restored.
b. RPI indications are lost. Dispatch an operator to manually align backup power supply (via ELSC) to energize the RPI Cabinets. Operation is allowed since RPI has been restored.
c. RPI indications are maintained since backup power supply (via ELSC) automatically energized the RPI Cabinets. The CRP-3 power feed to RPI must be restored within 4 hours.
d. RPI indications are lost. Manually initiate a Reactor Trip and verify Reactor Trip by Wide Range power and negative start-up rate since the Rod’m Bottom Lights are NOT lit.

Answer 19

• b. RPI indications are lost. Dispatch an operator to manually align backup power supply (via ELSC) to energize the RPI Cabinets. Operation is allowed since RPI has been restored.

Question 20

What does the Variable Gain Unit do?

Answer 20

• Increases the output at low pwr

Given reactivity change at lower pwr has a smaller effect on pwr than at high power

Question 21

At what speed do the shutdown banks move?

Answer 21

• 62 SPM

Question 22

At what speed do the rod ctrl banks move in auto?

Answer 22

• 8-72 SPM

Question 23

At what speed do the rod ctrl banks move in manual?

Answer 23

• 48 SPM

Question 24

What is Differential Rod Worth?

Answer 24

• The change in reactivity resulting from a unit change of rod position. (pcm/step)

Question 25

What is Integral Rod Worth?

Answer 25

• Reactivity inserted by moving a control rod from a reference position to any other rod height

Question 26

When does the Rod dropped/Rod Bottom alarm clear?

Answer 26

• When Control Bank A gets to 20 Steps

Question 27

If MPC-253 fails low, what happens with rods in automatic?

Answer 27

• Rods will move in on PR rate change and temp error

Question 28

What Power Input feeds into the Rod insertion limit comparator?

Answer 28

• RCS ΔT

Question 29

1.5-3 degrees - 8 steps
3.5 degrees - 24 steps
4 degrees - 40 steps
4.5 degrees - 56 steps
5 degrees - 72 steps

Answer 29

1.5-3 degrees - 8 steps
3.5 degrees - 24 steps
4 degrees - 40 steps
4.5 degrees - 56 steps
5 degrees - 72 steps