Pre-course ILT RD Flashcards
What is the purpose and function of the Reactor Control Unit?
Maintains or restores Tave to programmed value
During auto control, develops rod speed and direction controls for logic cabinets
Develops error signals - Temperature and power rate of change mismatch
What is the purpose and function of the logic cabinet?
Receives command signals either from the RCU or the RO
Develops current command signal for use in the power cabinets
Controlled by two redundant ovation controllers
Logic cabinet power supplies: 120 VAC from MG set OR 120 VAC from 1LL785 lighting
cabinets with UPS
Sends out two signals to the power cabinets: Current orders to firing cards - supplies current in proper order to CRDM coils for rod movement
Multiplexing = Determine which group of rods to move
What is the purpose and function of the RD Power Cabinet?
Converts 3 phase AC from MG sets into sequenced DC current pulses
There are 5 power cabinets and each cabinet is designed to drive 3 groups of control rods
Only one group in a power cabinet can move at a time
What is the purpose and function of the DC hold supply cabinet?
Supplies DC power to energize the stationary coils on a rod group in the event work needs to be performed on a power cabinet:
Only one group of a single cabinet can be held or the hold cabinet will be overloaded
Reactor trip breakers will cause rods held by this cabinet to drop
Power comes from the RD generators downstream of the trip breakers
What is the purpose and function of control rod groups and banks?
There are 4 control banks and 5 shutdown banks; A & B banks have two groups while the rest have one group
What is the design basis of the rod control system?
Between 15-100% power be able to withstand a 10% step load change and 5%/min ramp without a reactor trip, steam dump, or pressurizer relief actuation
50% step load decrease IF steam dumps available
The system is capable of restoring coolant average temperature to within the programmed temperature deadband following a change in load
What are the control permissives that affect Rod Control System?
C-1 through C-5 and C-11
What is the setpoint and function of C-1?
1/2 IR >20% power
Stops outward rod movement in auto and manual
What is the setpoint and function of C-2?
1/4 PR >= 103%
Stops outward rod movement in auto and manual
What is the setpoint and coincidence of C-3?
OT delta T 2/4 channels within 3% of OTdT Trip setpoint
Stops outward rod movement in auto and manual
Initiates turbine runback
What is the trip setpoint and function of C-4?
OPdT 2/4 channels within 3% of OPdT trip setpoint
Stops outward rod movement in auto and manual
Initiates turbine runback
What is the function and setpoint of C-5?
Turbine low power
PT-505 <15%
Stops outward rod movement in auto
What is the function and setpoint of C-11?
CBD withdrawal limit
Rod insertion limit computer determines that CBD >=223 steps
Stops outward rod movement in auto
What are the actual and indicated rod speeds of automatic rod control?
No demand: Indicated 8 steps/min, Actual 0 steps/min
With demand: 8 - 72 steps/min
What are the actual and indicated rod speeds for manual rod control?
No demand: indicated speed 48 steps/minute, actual speed 0
With demand: 48 steps/min
