Rod Control Flashcards
C-1 _______
Inputs_____
Purpose___
When blocked___
IR High flux rod stop
> 20% on 1/2 IR. Stops outward rod motion in auto and manual. Rod stop is blocked when the IR high flux trip is blocked.
C-2_____
Input____
Purpose___
When blocked ____
PR high flux rod stop
> 103% Prx on 1/4 PR
Stops outward rod motion in auto and manual. Rod stop is blocked when the rod stop bypass switch is selected to the PR channel causing the rod stop annunciator.
C-3 ____
Input____
Purpose____
Can it be blocked?
OT delta T high rod stop
2/4 delta T> OTdeltaT setpoint -3%
Stops outward rod motion in auto and manual.
Can not be blocked. Alarm on 1/4 channels.
C-4____
Input____
Purpose___
OPdeltaT high rod stop
2/4 delta T > OPdeltaT setpoint-3%
Stops outward rod motion in auto and manual. Can not be blocked. 1/4 gives alarm
C-5_____
Input____
Purpose____
Location of alarm____
Can this interlock be blocked?
Turbine low power interlock
Impulse pressure<15% turbine power.
Stops outward rod motion in auto ONLY. Can not be blocked.
Alarm is on the bypass permissive panel
C-11____
Inputs____
Purpose___
Alarm is generated by_______
Can this be blocked?
Control bank D rod stop
CBD=223 steps.
Stops outward rod motion in auto only. Can not be blocked.
Alarm is generated by the process computer.
Control rods are typically made of ____
Silver indium cadmium alloy
Bank overlap automatically overlaps control banks for _____ and _____
Uniform flux distribution
and
DRW
Continuity (is/is not) required through the rod stop circuit to allow control rods to auto or manually withdraw.
IS
If control rods can not be inserted or withdrawn, a problem exists not in the _____ but in the _____.
Rod stop circuitry
Rod drive system
All ____ rod withdrawal capabilities are lost when AC bus ___ is de-energized.
Failure of buses ____, ___, and ____ will prevent _______ rod withdrawal until the rod stop is bypassed on the affected NI channel.
Auto; 111
112, 113, 114; manual and auto
All _____ rod withdrawals capabilities are lost when AC bus ____ is de-energized with N35 or N36 above 20% power.
Manual
Bus 114
Rod speeds
Auto_____
Manual____
Bank select CB ____
Bank select SB_____
8-72 spm
48 spm
48 spm
64 spm
Rods are in _____ when power_____ with/without main gen synched.
Rods are in _____ when power _____ with/without main gen synched.
Auto; >15% with main gen
Manual <15% without main gen
Reactor control unit compares ______ and ______ to determine a power mismatch.
Validated 2nd highest Q (nuclear power)
-and-
Validated 1st stage pressure
The Tref programmer receives input from _______
validated 1st stage pressure
Summing unit compares _______ with ________ to determine rod speed program.
Validated 2nd highest Tave
-with-
Mismatch/T ref program
-and-
Q/Turb FSP
Effects of failures on rods
Tave high____
PR NI high____
P-imp Low____
P-imp High___
Tave low or PR NI low_____
Tave, no effect validated Tave signal
PR NI high Rod stop C2 will actuate
P-imp low, no effect validated Impulse pressure
P-imp high, no effect validated impulse pressure
Tave low or PR NI low- no effect
In automatic, rod speed is _____ at a ____temperature deviation. Rod speed is _____ at a _____ temperature deviation.
8 spm at 3F
72spm at 5F
The reactor control unit develops _____ and _____ signals for the logic cabinet.
Rod speed and direction
Alternate action for both _____ and ______ will block rods in and out logic, rods will move in manual.
Alternate action for _____ will zero the power mismatch and move in ____ only on temperature error.
RCS Tave and Turbine impulse pressure
NI power; Auto
Logic cabinet - non urgent alarm causes (5)
-Failure of one redundant power supply or redundant controller
- Failure of IO module not required to support rod motion
- Failure of network media converter
- High temperature
- High humidity
Logic cabinet urgent alarm causes- (2)
-Failure of coincident inputs
-Failure of IO module required to support rod motion
The power cabinet designations are ____.(5)
1AC
2AC
1BD
2BD
SCDE
Bypass Breakers are of identical construction to the Rx Trip Breakers Except:
SSPS does not energize the shunt trip coils on a trip signal.
A SSPS “General Warning” is generated when a bypass breaker is racked in and closed and a reactor trip will occur if ______.
A Reactor Trip will occur if both bypass breakers are racked in and closed.
An SSPS “P-4” (“P” stands for “Permissive”) signal is generated when _______.
A reactor trip breaker and its associated bypass breaker are open or racked out.
A P-4 signal causes the following:
-Turbine Trip
-Feedwater Isolation (FWI) when combined with low Tave of 564° F.
-Allows auto SI to be blocked after an SI.
DC hold cabinet energizes ________ coils in one power cabinet at a time with ____VDC (latch) or _____VDC (hold). ____VDC from cabinet is used to reset steps counters.
stationary
125VDC
70VDC
24VDC
Rod insertion limit comparator:
0% reference height_____
30% reference height_____
100% reference height_____
47 steps on control bank C
0 steps on control bank D
161 steps on control bank D
Rod insertion limit comparator also generates the ______ Interlock whenever _____. Resets____.
C-11
CBD >223 steps
221 steps
To calculate an expected CBD RIL approximately
CBD RIL=(Prx-30%)*2.3
RIL Basis (3 items)
Provides adequate SDM
Acceptable power distribution
Potential effects of a rod misalignment minimized (ejected rod worth)
How blown fuses affect the gripper coils.
Stationary____
Lift_____
Movable_____
S-Affected rod drops
L-Affected rod will not move
M-Affected rod(s) will ratchet into core when withdrawn or inserted
If a Lift coil or movable fuse blows how many rods are impacted?
What if a stationary fuse blows?
More than one rod may be affected.
Only one rod can be affected.
RIL calculator uses ______ to determine calculated RIL.
Validated delta T (2nd highest)
Rod control non-urgent failure:
DRPI (LEAF)
Power cabinet (F)
Logic cabinet (FFFHH)
Will any of these prevent rod motion in auto or manual?
DRPI: Loose or missing card, error in data A or B, Accuracy mode switch not in A+B, Failure of one redundant PS
PC: Failure of one redundant PS
Logic cabinet: Failure of one redundant PS or controller, Failure of a IO module not required for rod motion, failure of network media converter, high temp >=110F, high humidity >=95%
None of the above will prevent rod motion
Rod control urgent failure in DRPI (will or will not) prevent rod motion.
Power cabinet urgent failure (will or will not) prevent rod motion.
Logic cabinet (will or will not) prevent rod motion.
DRPI will not prevent rod motion.
PC will prevent rod motion only in affected cabinet.
LC will prevent ALL rod motion.
Startup reset switch (4 functions)
Where located?
Possible alarms if actuated?
-Reset power cabinet alarms
-Reset total group count/total bank count
-Reset master cycler
-Reset rod group step counters
-Possible RIL low and RIL low-2 alarms
MCB and soft key
Alarm reset pushbutton (3 functions)
Where located?
-Reset power cabinet alarm
-Reset logic cabinet alarm
-Cause stationary gripper full current for 160 msec
MCB and soft key
RIL low alarm comes in at ______ and RIL low-2 @______.
within 10 steps of calculated delta T rod position
Low-2 comes in when < delta T rod position
3.1.4 Rod Group Alignment Limits
LCO 3.1.4 All shutdown and control rods shall be OPERABLE.
AND
Individual indicated rod positions shall be within________
of their group step counter demand position.
APPLICABILITY: MODES 1 and 2.
12 steps
LCO times for the following:
A.1.1 Verify SDM is within
the limits specified
in the COLR.
OR
A.1.2 Initiate boration to
restore SDM to within
limit.
AND
A.2 Be in MODE 3.
Within one hour
Within one hour and mode 3 within 6 hours
One rod not within alignment, what are the LCO actions and times?
B.1.1 Verify SDM is within
the limits specified
in the COLR. one hour
OR
B.1.2 Initiate boration to
restore SDM to within
limit. one hour
AND
B.2 Reduce THERMAL POWER
to <= 75% RTP. 2 hours
3.1.5 Shutdown Bank Insertion Limits
LCO 3.1.5 Each shutdown bank shall be within the insertion limits
specified in the COLR.
<=16 steps below the RIL for SD banks determine SDM and initiate boration if not met
3.1.6 applies to ______
CB RILs
3.1.7 DRPI
LCO 3.1.7 The Digital Rod Position Indication (DRPI) System and the
Demand Position Indication System shall be OPERABLE.
What are the 3 electromagnets which act together to accomplish rod motion?
Stationary gripper, moveable gripper and lift coil.
What two parameter comparisons are made to determine rod speed and direction?
Tave vs. Tref.
Rate of Rx power change vs. rate of turbine load change
What is the function of the Power Mismatch Rate Comparator?
Speed up response of Rx control unit during transients
What two signals are provided by the logic cabinet to the Power Cabinets?
Current orders and multiplexing signals
The rod drive motor trips on ______ and the generator trips on ______.
Overcurrent
Overcurrent, Overvoltage, Directional Overcurrent
Lift coil disconnect switches are used for ______.
Individual rod movement or rod recovery.
Rod Deviation Power Range Tilt alarm causes (5)
Any Bank Greater than All Rods Out (ARO)/PARK position in COLR.
C/B D >223 steps.
Rod Sequence or overlap error >1 step (Group Misalignment) on demand.
Digital Rod Position (DRPI) vs Demand (RD System) > 12 steps.
How many CRDMs?
53 total, 28 SDB and 25 CB
Summing unit error signal to the rod speed programmer determines rod speed and direction.
Magnitude of error_____
Polarity of error________
Speed
Direction
The non linear gain unit ______. The variable gain unit______.
Converts the power mismatch signal to a temperature error signal and compensates for larger errors by increasing the output.
Compensates for the power mismatch from a given reactivity change at various power levels. Gain goes down as power rises.
The startup reset switch performs which functions?
Reset power cabinet alarms
Reset total group count/total bank count
Reset master cycler
Reset rod group step counters
Possible RIL low and RIL Low-2 alarms
