Rod Ctrl Flashcards

1
Q

What is the C-1 Conditional?

A

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

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2
Q

What is the C-2 Conditional?

A

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

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3
Q

What is the C-3 Conditional?

A

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

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4
Q

What is the C-4 Conditional?

A

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

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5
Q

What is the C-5 Conditional?

A

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

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6
Q

What is the C-11 Conditional?

A

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

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7
Q

What are the Rod Ctrl Inputs?

A
  • Auctioneered High Tave
  • Auctioneered High PR NI
  • MPC-253, Turbine 1st Stage Impulse #
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8
Q

What is the Rod Control System designed to do?

A

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% dumps)

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9
Q

Where are the MG Sets powered from?

A

11/21A and 11/21D busses

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10
Q

What will trip the CRD MG Set Output Bkrs?

A
  • Overvoltage
  • Overcurrent
  • Reverse Current
  • Supply Bkr Open
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11
Q

What will trip the CRD MG Set Supply Bkrs?

A
  • Load Con
  • Overcurrent
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12
Q

If there is an urgent failure in the power cabinet, what is affected?

Rod Control

A

Rod groups for that cabinet

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13
Q

If there is an urgent failure in the logic cabinet, what is affected?

A

ALL RODS

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14
Q

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

A

Stops all rod motion by de-energizing lift coil and energizing stationary and movable gripper

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15
Q

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.

Why was this alarm actuated?

A

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

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16
Q

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 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.

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17
Q

What does the Variable Gain Unit do?

A

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

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18
Q

At what speed do the shutdown banks move?

A

62 SPM

19
Q

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

A

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

20
Q

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

A

48 SPM

21
Q

What is Differential Rod Worth?

A

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

22
Q

What is Integral Rod Worth?

A

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

23
Q

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

A

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

24
Q

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

A

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

25
Q

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

A

When demand is > 35 steps for that group

26
Q

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

A

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

27
Q

When do Rod Bottom lights clear for the control banks?

A

When the rods are withdrawn > 20 steps

28
Q

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

A

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

29
Q

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

A

Rods step in due to the temperature error

30
Q

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

A

NOTHING! Rod control uses auctioneered high Tavg

31
Q

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

A

Nothing! Rod control uses auctioneered high

32
Q

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

A

Rods step in due to the power rate of change.

33
Q

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

A

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

34
Q

What is the purpose of bank overlap?

A

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

35
Q

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

A

Shutdown Banks C and D

36
Q

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

A

Radial power distribution

37
Q

Will dropping a peripheral or center control rod have more of an effect on the radial power distribution?

A

Center Rod

38
Q

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

A

Axial

39
Q

What is the purpose of maintaining QPTR within limits?

A

It keeps radial power distribution within limits

40
Q

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

A

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

41
Q

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

A

RCS Delta-T

42
Q

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

A

120 VAC stepped down from Rod Drive MG Set Output

43
Q

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….

A

Step in until the power mismatch circuit output decays away