Rod Ctrl Flashcards
What is the C-1 Conditional?
C-1, IR Rod Stop
- IRNI > 18% (16%) (1/2)
- AUTO and MANUAL rod withdrawal Stop
- Manually blocked above P10 (≥ 10% PR)
- Unblocked below P10
What is the C-2 Conditional?
- PR > 103% (1/4)
- Auto and Manual Rod withdrawal stop
What is the C-3 Conditional?
- Overtemp ΔT at 3% < trip setpoint (2/4)
- Gives auto and manual rod withdrawal stops and initiates turbine runback
- No Block!
What is the C-4 Conditional?
- Overpressure ΔT at 3% < trip setpoint (2/4)
- Gives auto and manual rod withdrawal stops and initiates turbine runback
- No Block!
What is the C-5 Conditional?
- MPC-253 < 15%
- Stops outward rod motion (while in Auto only)***
- No Block!
What is the C-11 Conditional?
- Ctrl Bank D at 229 steps
- Stops outward rod motion (while in Auto only)***
- No Block!
What does the Mismatch Rate Comparator do?
- Compares rate of change between MPC-253 and NIs. - Provides faster response to transients
What are the Rod Ctrl Inputs?
- Auctioneered High Tave
- Auctioneered High PR NI
- MPC-253, Turbine 1st Stage Impulse #
What is shutdown margin (SDM)?
- Reactivity worth must be sufficient to completely shut down the reactor with margin for all accident conditions, assuming the most reactive rod remains fully withdrawn
How is the Ctrl Rod system designed?
- 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%)
Which control modes allow rods to move in a normal sequence with program overlap?
- Auto and Manual only
Where are the MG Sets powered from?
- 11/21A and 11/21D busses
What will trip the CRD MG Set Output Bkrs?
- Overvoltage
- Overcurrent
- Reverse Current
- Supply Bkr Open
What will trip the CRD MG Set Supply Bkrs?
- Load Con
- Overcurrent
What are the Pwr Cabinet urgent failures?
- Logic Error
- Regulation Failure
- Phase Failure
- Multiplexing Error
- Card Removed
- Pwr Cabinet failures affect groups for that cabinet **
What is the Logic Cabinet urgent failures?
- Loose Card
- Oscillator
- Slave Cycler
- SDC circuit fail
- Logic cabinet failures affect all rods **
What happens if you have an urgent failure on a Logic or Pwr Cabinet?
- Stops all rod motion
- De-energizes lift coil and energizes stationary and movable gripper
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 At the time the event occurred, reactor power was 48% and Rod B-8 was fully withdrawn.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.
Which of the following explains why the alarm actuated?
a. A Multiplex Error has occurred in the Power Cabinet
b. An Oscillator Failure has occurred in the Logic Cabinet
c. A printed circuit card has been jarred loose from the Power Cabinet.
d. All Control Bank C – Group 2 rod lift coil disconnect switches are open.
d. All Control Bank C – Group 2 rod lift coil disconnect switches are open.
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 maintained since backup power supply (via ELSC) automatically energized the RPI Cabinets. Operation is allowed since RPI has been restored.
b. 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.
c. RPI indications are maintained since backup power supply (via ELSC) automatically energized the RPI Cabinets. The CRP-3 power feed to RPI must be restored within 4 hours.
d. RPI indications are lost. Manually initiate a Reactor Trip and verify Reactor Trip by Wide Range power and negative start-up rate since the Rod’m Bottom Lights are NOT lit.
- b. 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.
What does the Variable Gain Unit do?
- Increases the output at low pwr
Given reactivity change at lower pwr has a smaller effect on pwr than at high power
At what speed do the shutdown banks move?
- 62 SPM
At what speed do the rod ctrl banks move in auto?
- 8-72 SPM
At what speed do the rod ctrl banks move in manual?
- 48 SPM
What is Differential Rod Worth?
- The change in reactivity resulting from a unit change of rod position. (pcm/step)
What is Integral Rod Worth?
- Reactivity inserted by moving a control rod from a reference position to any other rod height
When does the Rod dropped/Rod Bottom alarm clear?
- When Control Bank A gets to 20 Steps
If MPC-253 fails low, what happens with rods in automatic?
- Rods will move in on PR rate change and temp error
What Power Input feeds into the Rod insertion limit comparator?
- RCS ΔT
1.5-3 degrees - 8 steps
3.5 degrees - 24 steps
4 degrees - 40 steps
4.5 degrees - 56 steps
5 degrees - 72 steps
1.5-3 degrees - 8 steps
3.5 degrees - 24 steps
4 degrees - 40 steps
4.5 degrees - 56 steps
5 degrees - 72 steps
