Rod Ctrl

Question 1

What is the C-1 Conditional?

Answer 1

Intermediate Range Rod Stop
- Stops AUTO and MANUAL Rod Withdraw
- 1/2 - IRNI > 18% (16%)
- Manually blocked above P10 (≥ 10% PR)
- Unblocked below P10

Question 2

What is the C-2 Conditional?

Answer 2

Power Range Rod Stop
- Stops AUTO and MANUAL Rod Withdraw
- 1/4 PR > 103%
- Blocked when ROD STOP BYPASS selected to alarming channel

Question 3

What is the C-3 Conditional?

Answer 3

OTΔT Rod Stop
- 2/4 PRNI 3% < trip setpoint
- Stops AUTO and MANUAL rod withdraw
- No Block!

Question 4

What is the C-4 Conditional?

Answer 4

OPΔT Rod Stop
- 2/4 PRNI 3% < trip setpoint
- Stops AUTO and MANUAL rod withdraw
- No Block!

Question 5

What is the C-5 Conditional?

Answer 5

Turbine Power Interlock
- MPC-253 < 15%
- Stops AUTO ONLY rod withdraw
- No Block!

Question 6

What is the C-11 Conditional?

Answer 6

Control Bankd D Rod Stop
- Ctrl Bank D at 229 steps
- Stops AUTO ONLY rod withdraw
- No Block!

Question 7

What are the Rod Ctrl Inputs?

Answer 7

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

Question 8

Where are the MG Sets powered from?

Answer 8

11/21A and 11/21D busses

Question 9

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?

Answer 9

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 10

What does the Variable Gain Unit do?

Answer 10

Increases the output at low power because reactivity change at lower power has a smaller effect on power than at high power

Question 11

At what speed do the shutdown banks move?

Answer 11

62 SPM

Question 12

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

Answer 12

8-72 SPM
- Error of 1.5-3 degrees = 8 steps per minute
- Error of 3-5 degrees = 32 steps per Degree + 8
1.5-3 degrees - 8 steps
3.5 degrees - 24 steps
4 degrees - 40 steps
4.5 degrees - 56 steps
5 degrees - 72 steps

Question 13

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

Answer 13

48 SPM

Question 14

What is Differential Rod Worth?

Answer 14

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

Question 15

What is Integral Rod Worth?

Answer 15

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

Question 16

When does the Rod dropped/Rod Bottom alarm clear for Control Bank A?

Answer 16

When all shutdown Banks are withdrawn AND Control Bank A gets to 20 Steps

Question 17

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

Answer 17

Rods will step in due to PR rate change and temp error

Question 18

When does the Rod Dropped alarm enabled for Control Banks B-C?

Answer 18

When demand is > 35 steps for that group

Question 19

When does the Rod Dropped alarm annunciate for Control Banks B -C?

Answer 19

When IRPI is < 20 steps with a demand > 35 steps, AFTER the alarm has been enabled.

Question 20

When do Rod Bottom lights clear for the control banks?

Answer 20

When the rods are withdrawn > 20 steps

Question 21

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

Answer 21

Rods step OUT due to power rate of change and temperature error

Question 22

If Tavg fails high, what happens with rods in automatic? Why?

Answer 22

Rods step in due to the temperature error

Question 23

If Tavg fails low, what happens with rods in automatic? Why?

Answer 23

NOTHING! Rod control uses auctioneered high Tavg

Question 24

If a Power Range NI fails low, what happens with rods in automatic? Why?

Answer 24

Nothing! Rod control uses auctioneered high

Question 25

If a power range NI fails high, what happens with rods in automatic? Why?

Answer 25

Rods step in due to the power rate of change.

Question 26

If you have a PR NI Failure high, will rods step back out due to the temperature error afterwards?

Answer 26

It depends. If C2 (103% on 1/4 PRNI) is met, NO. If the failure is less than that setpoint, yes, they will step back out

Question 27

What is the purpose of bank overlap?

Answer 27

Provides a more uniform axial power distrubtion as well as a more uniform Differential Rod Worth

Question 28

When moving which rods would you expect no indication on your rod speed indicator?

Answer 28

Shutdown Banks C and D

Question 29

If a rod is dropped, is the effect on axial or radial power distribution more noticable?

Answer 29

Radial power distribution

Question 30

If a rod is inserted 20 steps, is the greater effect on radial or axial power distribution?

Answer 30

Axial

Question 31

What is the purpose of maintaining QPTR within limits?

Answer 31

It keeps radial power distribution within limits

Question 32

What is the purpose of maintaining raidal and axial core power distribution within limits?

Answer 32

It keeps power density (kw/ft) and DNBR within limits

Question 33

What provides the Reactor Power input to the rod insertion limit comparator?

Answer 33

RCS Delta-T

Question 34

What is the normal source of power to the Rod Control Logic Cabinets?

Answer 34

120 VAC stepped down from Rod Drive MG Set Output

Question 35

Given the following conditions: Unit stable at 75% power w equilibrium Xe. Rod control is in auto. Rod height is 180 Steps on CB D. PR Channel N-44 fails High. Which one of the following describes the response of the Rod Control system? The control rods will….

Answer 35

Step in until the power mismatch circuit output decays away