CRD Flashcards

1
Q

EO 1 - Purpose of CRD system

A

Control Rx power

Reactivity Control based on CRDM and soluble boron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

EO 2 - List functions of each control rod group.

A

CRDM Groups 1-4: Safety Groups, fully withdrawn during s/u
CRDM Groups 5-7: Regulating Rods, withdrawn in sequence
CRDM Group 8: Axial Power Shaping Rods, shape the flux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

EO 3 - Differentiate normal power supplies for the rod groups.

A

A train from B631
B train from breaker A501 and X8 xfrmr

6 phase xfrmr steps down 480 VAC (3 phase) to 120VAC (6 phase) THEN diode or SCR into 120VDC (6 phase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

EO 3 cont’d - Breakdown how each group is moved.

A

6 phases od DC through diodes give RIPPLE DC

Safety Groups 1-4: Diodes
Reg groups 5-7, APSRs, Aux power supply: SCR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

EO 4 - Reason for sequential operation of rod groups.

A

Safety (1-4) and APSRs are pulled 1 group at a time.

Reg Rods (5-7) are moved in sequence. top and bottom 20% of groups are overlapped. more even reactivity addition.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

EO 4 cont’d - Specify rod group configurations that satisfy the reason for sequential operation of rod groups.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which CRDM component is considered the RCS pressure boudnary?

A

motor tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

EO 6 - Interpret the operation of the CRDM motor, mainly how the DC input signal is translated into linear movement of the control rod.

A

3 phase 480VAC stepped down to 6 phase 120VAC, then rectified via SCRs to a ripple DC

Programmer has 6 banks of SCRs for DC magnetic fields (A, B, C, AA, BB, CC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

EO 8 - Describe power dist. system as it pertains to the CRDMs: connecting the major components from source of power to CRDM stator.

A

‘A’ AC breaker receives 480VAC from B631.

‘B’ AC breaker receives 480VAC from A501 and X8.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

EO 10 -How programmer control circuits control SCR gating to provide power to the CRDMs.

A

Uses solid state microcomputer to generate commands.

15VDC for programmer controls
24 VDC for gating power to the SCRs

Gates SCRs in 3-2-3-2 to move rods.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

List DC hold buses

A

A and CC phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

EO 11 - Analyze how an automatic or manual reactor trip
removes power from the CRDM’s, including the CRD and
RPS trip logic/interface.

A

All brkr trips use RPS actuation Undervoltage trip relay to de-energize the trip relays and OPEN the the breaker

“A” RPS to “A” CRD Breaker
“B” RPS to “B” CRD Breaker
“C” RPS to “CC” Breakers and “E” Relays
“D” RPS to “DD” Breakers and “F” Relays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe Trip Confirm Lamp

A

When lighted, indicates that power to the CRDM’s has

been interrupted allowing rods to drop into the core.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe asymmetric rods lamp.

A

any control rod 6.5% out of alignment from its group average

Sends signal to OUT INHIBIT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the ball check valves needed for?

A

They allow fluid movement through motor tube to prevent vacuum binding and slow drop times during control rod movements.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How many phases need to be energized to keep rod from dropping?

A

1 phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What method of sequencing is used to move rods in or out?

A

3-2-3 movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Max stator temp, requiring de-energizing the CRDM, is ____

A

180F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Max temp of cooling water entering the CRDs is _____

A

120F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Min allowable cooling water temp is _____

A

60F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Min allowable RC temp for ICW to be aligned to de-energized

CRD stators is _____.

A

200F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

During stator replacement, max stator temp w/o ICW flow is

_____

A

160F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Max CRD travel is ____ inches per hour

A

420in/hr

24
Q

Max CRD run time is ___ min per hour.

A

30 min per hour

25
Q

CRDM Stator High Temp Computer Alarm is set at ____F.

A

113F

26
Q

IF more than one CRD stator in Groups 1-7 exceeds _____,
THEN:
TRIP the Reactor

A

180F

27
Q

list both rod speeds:

A

RUN = 30”/min

JOG = 3”/minute

28
Q

Fail Safe Commands

A

IN commands override OUT commands

Both sides (P & S) OUT commands required

If both speed commands are present, then it is a HOLD command.

29
Q

DROPS actuation will only trip the ______ rods, however that requires an RPS failure.

A

Regulating rods

30
Q

What is a SHUNT trip?

A

An energized trip

31
Q

Undervoltage acutates a contact to supply ____ to the SHUNT trip relay to energize.

A

125 VDC

32
Q

Undervoltage is ____________ to trip.

A

de-energized

33
Q

Transformer over-voltage of ____ VAC has an alarm.

____ VAC for 10 seconds trips the respective ‘A’ or ‘B’ brkr.

A

130

140

34
Q

Source Interruption Device (SIR) provides additional system protection, how?

A

AC overvoltage on the output of the xfrmr

DC undervoltage on the DC hold busses

35
Q

DC undervoltage must occur on which side to trip its respective breaker?

A

both sides

36
Q

describe absolute position indication (API)

A

2 ind reed switch strings that actuate a 5 volt divider circuit

closing the reed switches as the permanent magnet attached to the torque taker passes the reed switches

37
Q

Describe function of Relative Position Indication (RPI).

A

Uses the “A” “C” and “BB” “PHASES” to drive a stepping motor

direction of the phases being energized and de-energized
determine the indication “IN or “OUT”

RPI only works when the rod is being moved, if the RX trips RPI
indicates full out

RPI is reset by running a stepping motor on the PI panel and selecting the specific group once the RX is shutdown and prior to
startup

38
Q

distances for asymmetrical rod fault

A

Hi fault >9’ (6.5%)

Lo rod fault 7” (5%)

39
Q

RPI provides:

A
  • Individual indication
  • Group average in the CRD room
  • Sequence fault
  • Computer indication
40
Q

Describe Out Inhibit Lamp

A

control rods will not respond to any out command.

<10% power AND >2DPM SR OR >3 DPM IR
OR
>40% power AND EITHER
Asymm Rod Fault 6.5% OR
Loss of any safety group out limit
41
Q

Describe Sequence Inhibit Lamp

A

indicates excessive overlap between regulating groups (>25%).

42
Q

Describe Auto Inhibit Lamp

A
IF Diamond in manual:
-Loss of any safety group OUT limit
- >+-1% neutron error
-Loss of ICS power
IF Diamond in AUTO:
-only loss of ICS power will bring in lamp and shift diamond to manual
43
Q

Describe APSR Overlap Fault Lamp

A

bottom of group 6 within 2% of the top of the poison section of group 8

44
Q

Describe Out limit lamps

A

Groups 1 - 8 (red): Indicates that at least one rod out of its respective
group is at the out limit.
This will stop rod withdrawal for all rods within that group.

45
Q

What feeds sequence inhibit lamp

A

RPI

46
Q

Describe Control On lamps

A

White lights that indicate a particular group has been selected for transfer OR
they have aux power

47
Q

Describe In Limit Lamps

A

Group 1 - 8 (green): Indicates that at least one rod in that group is at the “in limit”.
This will stop rod movement in the “In” direction for that group.

48
Q

Asymmetric Runback Req’s

A

–>40% power and in AUTO

  • Loss of any Safety group OUT limit
  • Group 5 in limit and asymmetric fault
  • Group 6 in limit with Group 5 > 80% and asymmetric fault
  • Group 7 in limit with Group 6 > 80% and asymmetric fault
49
Q

TS 3.1.4 Control Rod Group Alignment

A

Each CONTROL ROD shall be OPERABLE and
aligned to within 6.5% of its group average height.

Modes 1 & 2

50
Q

TS 3.1.5 Safety Rod Insertion Limits

A

Each safety rod shall be fully withdrawn.

Modes 1 & 2

51
Q

TS 3.1.6 APSR Alignment Limits

A

Each APSR shall be OPERABLE and aligned
within 6.5% of the group average height.

Modes 1 & 2

52
Q

TS 3.1.7 Position Indicator Channels

A

The API channel and RPI channel for each
CONTROL ROD and APSR shall be OPERABLE.

Modes 1 & 2

53
Q

3.2.1 Regulating Rod Insertion Limits

A

Regulating rod groups shall be within the physical
insertion, sequence, and overlap limits specified in
the COLR.

Modes 1 & 2

54
Q

3.2.2 APSR Insertion Limits

A

APSRs shall be positioned within the limits
specified in the COLR.

Modes 1 & 2

55
Q

TS 3.3.4 CRD Trip Devices

A

The following CRD trip devices shall be OPERABLE:

a. Two AC CRD trip breakers;
b. Two DC CRD trip breaker pairs; and
c. Eight electronic trip assembly (ETA) relays.

Modes 1 & 2
Modes 3, 4, 5 with any CRD trip brkr in closed position & the CRD system capable of rod withdrawal.