CRD Flashcards
How are regulating rods sequenced?
The top and bottom 20% of groups 5,6,7 are overlapped.
What are the main and secondary power supplies for CRD Rod Groups?
A (Main): B631
B (Secondary): A-501/ X-8
What phases are used to ‘Hold’ a CRDM?
‘A’ and ‘CC’
How many phases are needed to ‘Hold’ a CRDM?
1, but we provide 2 for redundancy
What is the purpose of the ball check valves on the motor tube?
Ball check valves are only with the control rods (Safeties, and Control Groups 1-7) Required
for water volume replacement during a reactor trip.
What is the purpose of the synchronizing bearing?
Ensures the segment arms are equally pulled apart
for magnetic coupling and full engagement of the roller nuts.
What is the purpose of the torque taker?
Prevents the Leadscrew from rotating to provide
linear motion in and out of the core.
What is the order for rotating the CRDM to generate IN or OUT rod motion?
3-2-3-2 (2-3-2-3)
What is CRDM max stator temp?
180F
What is max cooling water temp entering the CRD?
120F
What is the min allowable cooling water temp?
60F
What is allowed max CRD travel? (hi temp implications)
420”/hr
What is allowed max CRD run time? (hi temp implications)
30min/hr
What is the CRDM Stator Hi Temp Computer Alarm setpoint?
113F
How many CRD Stator Group temperatures above 180F require tripping the reactor?
> 1
What are the 2 rod speeds?
“RUN” is 30”/minute
“JOG” is 3”/minute
What would happen if rod control receives simultaneous IN and OUT commands?
IN commands override OUT commands
What would happen if rod control receives simultaneous commands for 2 different rod speeds?
HOLD command
When will Diverse Reactor Overpressure Prevention System (DROPS) de-energize the CRDM gate drives?
RCS pressure >2430psig
To ensure all Control Rod Drives are de-energized on a reactor trip, what are all of the possible combinations of CRD breaker/electronic positions to remove all power from the CRDM’s?
A and B or C&E and D&F or A and D&F or B and C&E
What are 2 separate means of tripping a CRDM breaker?
UV and Shunt
What are 2 separate means of tripping a CRDM breaker?
UV and Shunt
How many rod position indications are required to be operable per Tech Specs?
1 of 3
API
RPI
Zone
What conditions generate an ‘OUT’ Inhibit?
- Loss of System Power (24VDC, 15VDC, 5VDC: Comes from RS-3, RS-4)
- Loss of power to DC Hold
- Loss of air flow in the DC hold cabinets
- Overheat of the 480VAC Voltage Regulator
What conditions generate ‘Sequence’ Inhibit?
GR6>5% AND GR5<80% GR7>5% AND GR5<80% G7>5% AND GR5<95% GR6<95% AND G7>20% GR5<95% AND GR6>20%
What will prevent the Diamond Panel from going to AUTO?
- Auto Inhibit
- Sequence Inhibit
- Reactor Trip Confirmed
What will reject the Diamond Panel to MANUAL?
Loss of ICS Power
What condition will light up the APSR OVERLAP Light?
Group 6 within 2% of the top of the poison section of Group 8 (Power Peaking Concern)
What interlocks are the Safety Rods Out Limits tied to?
- Asymmetric Rod Runback
- Auto Inhibit
- Out Inhibit
- Feed and Bleed
- Sequence Enable
- Out Command
How many rod out limits are needed to stop outward rod motion of that group?
1 (Out Limit Light on the Diamond and PI panel)
What does it mean when the CONTROL ON Light is illuminated on the Diamond Panel?
Command Enabled or Selected for Transfer
What is the purpose of the IN LIMIT BYPASS (LATCH) Switch on the Diamond Panel?
Bypasses IN LIMITS for latching (Groups 1-7)
After transferring a rod group back to the group power supply from the aux power supply, what completes the logic to allow another rod group to be selected?
Transfer Reset (TR CF light must go out)
How do you know there are no rods or rod groups on the Aux Power Supply?
TR CF light will be out
FAULT RESET will reset what faults?
- Asymmetric Rod Fault
- Out Inhibit
- System Power
- Motor Power
TRIP RESET resets the CRD trip condition and energizes rod motors if what conditions are met?
- GR 1-7 In Limits
- RPS Reset
- CRDM Cooling Flow
What is required to bypass Safety Group Out Limit interlocks with GR 5-7 for an OUT command or SEQ?
Keyswitch upstairs in the Comp Room
What does MAN TRANS accomplish on the Diamond Panel?
Pulses the rod transfer switches to change power supplies
What does the SY light being illuminated mean?
Phases between the Aux Supply and Group Supply match
What is the purpose of the SEQ OR button?
Enables rotary selector switches (excl. GR8)
What is the purpose of the GROUP/ AUXIL button?
Refers to the Group or Aux Power Supplies
What will cause Auto Inhibit if ICS is in Manual?
- > +-1% Neutron Error
- Loss of ICS Power
- Loss of Safety Group Out Limit
What causes the Fault Light on the PI Panel?
5% Asymmetric Alarm
As indicated in the CRD system logic cabinets, each CRDM has ________ absolute zone reference switches, NOT counting the “out limit” and an “in limit” switches
5
If breaker B631 opened while operating at 100% power, the response of the Control Rod Drive system would be:
No effect on regulating rods, safety rods held by a single phase (CC)
