CONTROL ROD DRIVE

Question 1

What action is required if the CRD trip breaker is INOPERABLE?

Answer 1

Place in trip within 1 hour or 3.0.1 applies.

Question 2

What is the restoration time for an INOPERABLE shunt trip?

Answer 2

Restore within 48 hours or trip the breaker.

Question 3

What are the criteria for rod OPERABILITY?

Answer 3

Trip insertion time, misalignment <9” (<6.5%), rod can be exercised, and rod can be located with API/RPI.

Question 4

What is the acceptable rod overlap range?

Answer 4

25% ± 5%.

Question 5

What is the composition of control rods?

Answer 5

80% Ag, 15% In, 5% Cd.

Question 6

What is the DSS actuation requirement?

Answer 6

Energize to actuate, RCS >2500# (2 of 2 logic).

Question 7

What happens if the first rod reaches the out limit in API?

Answer 7

The rest of the group is allowed to withdraw for up to 12 seconds or until reaching out/in limit.

Question 8

What does RPI do during rod misalignment correction?

Answer 8

Inhibits withdrawal of any rod >1% from the minimum RPI position in the group.

Question 9

What triggers an Out Inhibit?

Answer 9

> 2 DPM SUR on Source Range, >3 DPM SUR on Intermediate Range, >60% power with 9” asymmetric and diamond in AUTO, or safety rods not out.

Question 10

What causes a Sequence Inhibit?

Answer 10

3% deviation from overlap setpoint, shifting diamond to MANUAL and SEQUENCE OVERRIDE.

Question 11

What causes an AUTO Inhibit?

Answer 11

Loss of ICS AUTO power, safety rods not at out limit, or neutron error > ±1%.

Question 12

What does Source Interrupt protect against?

Answer 12

Stator damage (high temperature) and ratchet trip (low voltage).

Question 13

What happens during Hi-Hi AC on 2 phases?

Answer 13

Shunt trips A/C (or B/D).

Question 14

What happens during Lo-Lo AC on 2 phases on both trains?

Answer 14

Shunt trips all 4 AC breakers (Rx Trip).

Question 15

What happens during Lo-Lo DC on 1 phase on both SRPS?

Answer 15

De-energizes both rods.

Question 16

What triggers an Asymmetric Rod Fault alarm?

Answer 16

7” difference; 9” difference removes the rod from the average.

Question 17

What conditions trigger a runback due to asymmetric rod fault?

Answer 17

9” asymmetric and in-limit or 0%, or safety rod group off out-limit and 9” asymmetric.

Question 18

What does the Asymmetric Fault Bypass do?

Answer 18

Ignores all asymmetric faults, removes out inhibit if due to asymmetric fault, and stops dropped rod runback.

Question 19

What are the PIP power sources?

Answer 19

PIP Left → VBC, PIP Right → VBD, Green LED SBO Lights → VBB.

Question 20

What does “Rx Trip Confirmed” indicate?

Answer 20

It is sensed by 52 breaker contacts on CRD breakers OPEN or electronic trip from DSS, and it places the system in MANUAL and Sequence Override.

Question 21

What happens during a total loss of P1?

Answer 21

A reactor trip occurs.

Question 22

What is the consequence of losing the PG/M module?

Answer 22

It causes two control rods to drop.

Question 23

What are the RCS pressure/temp limits for CRD designed to ensure?

Answer 23

They ensure hydraulic buffer action during a reactor trip.

Question 24

What is the required action if regulating rods are in the RESTRICTED region?

Answer 24

Restore them within 24 hours.

Question 25

What is the required action if regulating rods are in the UNACCEPTABLE region?

Answer 25

Initiate boration within 15 minutes and restore to the restricted region within 2 hours.

Question 26

What does a blinking red light on a slice indicate?

Answer 26

It indicates a non-critical fault, but the slice is still functional.

Question 27

Why do you open CRD-CB-1A before reclosing 1G-2A after maintenance?

Answer 27

To avoid large current swings.

Question 28

Why is API used at 55% power?

Answer 28

It allows immediate verification that all control rods are fully inserted post-trip.

Question 29

What happens when a sequence fault occurs?

Answer 29

The diamond transfers to MANUAL.

Question 30

What does a solid red light on the PG/M module indicate?

Answer 30

On the second solid red light, the PG/M module goes to failed-safe and drops two rods.

Question 31

What does a solid red light on SRPS indicate?

Answer 31

It indicates a fatal failure and that the system is no longer performing its function.

Question 32

What is the operability status of a safety rod stuck at 97% but able to move between 94% and 97%?

Answer 32

The rod is considered operable since it is misaligned by less than 6.5%.

Question 33

Why is Absolute Position Indication used at 55% power?

Answer 33

It allows immediate verification that all control rods are fully inserted following a trip.

Question 34

What triggers AUTO inhibit?

Answer 34

A neutron error of ±1%.

Question 35

What is the first indication of a rod stuck during insertion?

Answer 35

The PI panel fault indication for the affected rod will be illuminated yellow.

Question 36

Is DCRDCS Zone 25% monitored or available on the PIP?

Answer 36

No, it is not monitored or available on the PIP.

Question 37

Solid Red Light on SRPS

Answer 37

Indicates a fatal failure and the SRPS is no longer performing its function.

Question 38

First indication of a rod stuck during insert

Answer 38

The PI panel fault indication for the affected rod will be illuminated YELLOW (API PIP screen does not detect it).