Regulating Rod Control System Flashcards
TRA00087
What are the basic functions of the Reg Rod Control System?
- Control and maintain power between NL and NF
- Provide ability to change reactor power at a controlled rate.
- Provide mechanism for the reactor slow setback power reduction.
How does Reg Rod Control measure reactor power?
Via Ion Chamber instruments.
Describe ATR Ion Chambers.
Saturation region operation.
Argon/Nitrogen filled pressurized to 1 atm
1 inch in diameter
Boron lined to detect thermal neutrons
Where are the regulating rod ion chambers located in the thimbles?
T-3 and T-10 instrument thimbles
List limit switches associated with reg rods.
0 inches - lower limit of travel stops servo drive
12 inches - initiates auto insert of oscc
20 inches - auto insert oscc stops. withdraw permit locked out
42 inches - enables interlock for servo control to enter AUTO
48 inches - upper limit of travel stops servo drive
What is the approximate worth of an operating reg rod?
~0.25$ (0.01$ per inch)
What is the max rate of travel for a reg rod?
up to 50 inches/second
What parameter controls reg rod position when system is selected to MANUAL?
Controller moves the rod to match demand.
What determines the speed at which the reg rod moves?
Determined by degree of mismatch from controller to rod position (0.8 inches per second to 50 inches per second.)
What are the different functions of the reg rod control system?
Controls and maintains power
Provides mechanism for slow setback
What characteristic of the ATR allows control of total power by a single control rod?
ATR reactor is tightly coupled
What parameter controls reg rod position when control is in auto?
Controller positions the reg rod to maintain selected power.
How would the reg rod respond to a PALM experiment that added 0.1$ when inserted?
Inserting approximately 10 inches every time the PALM experiment moved in core.
How would the reg rod respond to a slow steady increase in PCS temp?
Slowly withdraw due to the negative temp coefficient of the reactor.
Where in ATR would the reg rod controller be found?
Two separate units for each reg rod system:
1. Dist Processor instrument rack in RCR behind uprights
2. Dist Processor located in the South 2nd basement
What components are located in the Distributed Processor Instrument Rack?
Ether net hub, controller, HMI, Ion Chamber chassis
What components are located in the Motor Driver/Brake Interface Chassis?
Circuit breaker panel, Termination panel, Reg Rod Brake Power Supply, Reg Rod Motor Driver
Where is the motor driver/brake interface chassis located?
South 2nd basement next to stairs to Rod Access
What is the function of the motor driver?
Provides input signals to the reg rod motor in response to velocity demand and direction signals from the controller.
What conditions will cause the motor driver’s protective circuitry to disable itself?
Short circuit, excess current, excess voltage
How does the Reg Rod Motor Brake operate?
Must be energized for brake to release.
Power causes it to release.
Interruption of voltage causes it to lock.
Reg Rod Brake will lock after a 1-5 second time delay following what?
Any Fatal Failure
Controller selected to HOT STANDBY
Controller in MANUAL with no insert or withdraw signal
What is the power supply to Reg Rod 1?
E-117 Instrument UPS to E-82
What is the power supply to Reg Rod 2?
E-117 Instrument UPS to E-83
Where are E-82/83 located?
Behind amplifier cabinets in the ATR RCR
What are the functions of the Ion Chamber interface chassis?
HV PS
Preamp
Pulse emitter
Output analog to digital converter
What reg rod info is sent to RDAS?
Rod position
Reactor power
Controller demand
Controller status
What is the function of the Relay Interface Panel?
Isolation between power and Reg Rod System
Communicate permissives and interlocks
Provides controller info to permissive bus.
What affect does Slow Setback have on selected reg rod system in AUTO?
Power reduced from Nf to Nl over 480 seconds
What is the effect of a slow setback signal on selected reg rod system in MANUAL?
Slow setback converted to a reverse and all OSCC and neck shims insert.
What is the effect of Run Relay lost on reg rods if in AUTO?
Reg Rod will enter MANUAL mode
Brake locks
RO controls power with OSCCs
How would reg rod system react if the operator entered a command for which the prerequisites were not met?
Controller would do nothing.
Where can the position of selected reg rod be viewed?
Reactor uprights, control console
System #1 controls the reg rod in what core position?
Southeast
How is the desired reg rod control system selected?
System 1/2 selected on two-position switch
What different modes of Reg Rod operation are available?
AUTO/MANUAL/HOT STANDBY
What thimble is the ion chamber for Reg Rod 2?
Thimble 10
How does reg rod position bar graph change color for position?
<12 or >42 inches - RED
12-20 inches - YELLOW
20-42 inches - GREEN
What determines what control pop-ups appear in the aux display/entry area?
Controller mode change commands
Selected actions
How to determine if reg rod CPU is active and working correctly?
Atom animation (disappears and red circle appears on failure)
Define normalized power
Power assigned to the operator that relates ion chamber output to a percent of Nf
Define demand power
Power the controller is presently calling for
Define target power
Desired power level assigned by the operator
Unselected Reg Rod controller can operate in what modes?
Hot Standby or Manual
Reg rod controller in AUTO will change to what mode when deselected?
Manual
Unselected reg rod controller in hot standby will change to what mode if selected?
Manual
Can both reg rod controllers be set to Manual at the same time?
Yes
How fast in the reg rod driven when manual motion switch is toggled if selected to hot standby?
Won’t move.
What limitation are placed on magnitude of power normalized changes?
Done in steps of a factor of 5 or less.
What is indicated by mode change select button for AUTO grayed out?
Prerequisites are not met.
How does the operator know when the reg rod controller has changed modes?
Display changes
What conditions must be met to enter AUTO mode?
Reactor power 1E-3 Nf
Selected reg rod >42 inches
Run permissive relay energized
Neck shim shutdown test block installed
No fatal or non-fatal failures
Rate of change is linear or exponential?
Exponential
While positioned within its operating range the reg rod is considered to be worth…
0.01$/inch
What are the two general types of reg rod control system failures?
Fatal, non-fatal
What is the basic difference between the two failure types?
Manual control still possible in non-fatal.
How does reg rod system react to a non-fatal error?
Transfer to Manual, lock the brake
What is the RO’s primary responsibility following a fatal or non-fatal failure?
Control power.
What is required after a fatal failure to withdraw reg rod?
Management Approval
How does the reg rod in AUTO respond to a scram.
Withdraws fully. At 1E-3 Nf Run relay is lost, reg rod goes to MANUAL and the brake locks
How would the Regulating Rod Control system in AUTO respond to a reverse?
Controller goes to MANUAL and the brake locks
How does reg rod in manual react to scram?
No change
How does reg rod in Manual react to slow setback?
No change to controller mode or reg rod position. Setback would convert to a reverse and insert OSCC and neck shims.
How would reg rod in AUTO react to slow setback?
Lower power at slow rate until the cause of the setback clears
If the origin of a setback originated from experiment loops how would this change the response?
Auto power reduction would terminate at 3 Nl
Expected response to reg rod controller failure?
Deselect failed channel.
Select alt channel in AUTO
Threshold for abnormal reg rod movement?
3 inches or more abrupt, unexplained and sustained movement
Greater than 10 inches during insertion of HSIS
What is the expected response to abnormal regulation rod movement?
Reduce power to <90% in 30 minutes
What is expected operator response to a 16 inch or greater sustained and unexplained reg rod movement?
SCRAM immediately
Two types of power variation surveillances at ATR?
Brush recording power variation checks
Power spectral density measurements
What prevents manual reg rod withdrawal?
START
Safety rods or test block out
No fission chamber motion
Reverse
48 inch limit switch
What kicks you out of AUTO?
Loss of RUN
Reverse
Fatal/non-fatal
