Rod Control System Flashcards
Auto Rod Control system is designed to
Keep Tavg consistent with Tref.
Uses Tavg and compares to First stage turbine pressure
When in AUTO is there any OUTER motion?
NO OUTER MOTION IN AUTO
1 step is how much movement?
5/8 inch
ITS Maximum time for rod drop?
1.8 seconds
CRDM Out Sequence
7 steps
CRDM in sequence
7 steps
How long does it take for a single step to be performed?
780 milliseconds (.78 seconds)
Rod Drive Motor Generator
Powered from, output?
480V Bus 2B/3
Outputs 260V at 58.3 hertz
Reading Power Cabinets
1AC is?
Group 1 in Shutdown Bank A
Group 1 in Control Bank A
Group 1 in Control Bank C
Reading Power Cabinets
2BD is?
Group 2 Shutdown Bank B
Group 2 Control Bank B
Group 2 Control Bank D
Power Cabinet Urgent Alarm does what?
- Energizes red light on affected Power Cabinet
- Stops all rod motion in affected Power Cabinet
- Loss Overlap in unaffected cabinets
- RTGB alarm
Power Cabinet Urgent alarm caused by?
MR. LLP
- Multiplexing Error
- Regulation Failure
- Logic Error
- Loose or missing Card
- Phase Failure
Can you still move rods on a Urgent Power Cabinet alarm?
Not on effected cabinet but if you select an infidivual bank you can move that bank but you loose designed overlap
If you misposition a rod bank out of overlap what must be done before returning to MANUAL OR AUTO on the selector switch
Whatever bank was moved must be moved back to correct postion per procedure
Power Cabinet Non-Urgent alarm does what?
Loss of Power supply causes an urgent alarm if INWARD rod motion is demanded. (causes a logic error)
If OUTWARD rod motion is demanded will ratchet or drop
We place rods in manual and do not attempt any motion until repairs comp
A Logic Cabinet Urgent alarm does what?
- Inhibits all rod motion
- Energizes red light at logic cabinet
- RTGB alarm
A Logic Cabinet Urgent alarm is caused by?
SLO
- Secondary Cycler
- Loose or missing card
- Osciallator
Power Cabinet and Logic Cabinet non urgent alarms are caused by?
Power supply failure
Overlap works how?
- Control Bank A out 128
- Control Bank A/B out 100
- A stops at 228 steps total
- B goes 28 steps (now its at 128 steps)
- B/C go out 100
- B Stops when its at 228 steps out
- C goes 28 more steps (128 steps)
- C/D goe 100 steps
- C Stops at 228 steps
- D goes 118 more steps (Stays at 218 steps out)
Total of 602 steps
Rod Control Logic compares what?
Median Tavg to Tref
How much difference does Tavg have to be above Tref before Rod movement? when does movement stop?
1.5 degrees F. starts Rod insertion, once Tavg and Tref are within 1 degree of each other Rod movement stops
Rod Insertion Limits setpoint comes from?
Linear function of Median Delta T
Rod Insertion Limits do what?
- Ensure adequate SDM
- LImit the worth of ejected rod
- Ensure Proper Axial Flux
Start up Push Button does what?
Resets
Primary Cycler counter
Secondary Cycler counter
P-A converter
Internal memory and alarm circuits
Group step counters on RTGB
Bank overlap counter
S/D Banks A & B move how fast?
Individual banks selected only
68 steps a minute
Control Banks move how fast?
Individual banks selected or in manual
45 steps a minute
When in auto how fast do Rods move?
- 8-72 steps a minute
- 8 steps from 1-3 degrees difference
- ramps up to 72 steps from 3-5 degree difference
DC hold cabinet supplies what? and holds how many rods?
125/70 VDC
125 for latching
70 fo holding
5 Rods can be held at one time
Define SDM
The instantaneous amount of reactivity by which the Rx is subcritical or would be subcritical from its present condition assuming all full-length rod cluster assemblies (shutdown and control) are fully inserted except for the single rod cluster assembly of highest reactivity worth that is assumed to be fully withdrawn.
