Rod Control & IRPI (RQ-C-4732) Flashcards
Which one of the following parameters typically has the greatest effect on the shape of a differential rod worth curve?
A) Core radial neutron flux distribution
B) Core axial neutron flux distribution
C) Core xenon distribution
D) Burnable poison distribution
B) Core axial neutron flux distribution
Consider a nuclear reactor core with four quadrants: A, B, C, and D. The reactor is operating at steady state 90% power when a fully withdrawn control rod in quadrant C drops to the bottom of the core. Assume that no operator actions are taken and reactor power stabilizes at 88%.
How are the maximum upper and lower core power tilt values (sometimes called quadrant power tilt ratio or azimuthal power tilt) affected by the dropped rod?
A) Upper core value decreases while lower core value increases.
B) Upper core value increases while lower core value decreases.
C) Both upper and lower core values decrease.
D) Both upper and lower core values increase.
D) Both upper and lower core values increase.
Given the following events and conditions:
- Unit 1 is operating at 80% power, steady state.
- Rod control is in manual for testing.
- Control bank D is at 175 steps.
- AP #110, Drop 34 - BANK D LOW alarm actuates
- AP #110, Drop 39 - BANK D LOW-LOW alarm actuates.
Which ONE of the following conditions could be the cause of these two alarms?
A) MPC-253 failed high
B) N42, Power Range NI channel failed high
C) Loop 2 Narrow Range Thot instrument failed high
D) Loop 2 Narrow Range Tcold instrument failed high
C) Loop 2 Narrow Range Thot instrument failed high
Unit 1 is operating at 100% power when a rapid failure low of turbine impulse pressure (MPC-253) occurs with rod control in automatic.
Which ONE of the following describes the expected response of the rod control system?
A) Rods will initially move in due to power mismatch, but will then start to withdraw due to developing a temperature error.
B) Rods will initially move in due to power mismatch, and will then continue to move in once a temperature error develops.
C) Rods will move in due to power mismatch and due to a temperature error.
D) Rods will move in due to temperature error with an offsetting power mismatch trying to move rods out.
C) Rods will move in due to power mismatch and due to a temperature error.
Unit 1 was operating at 100%, with Control Bank D at 218 steps. 01-OHP-4030-112-015, Full Length Control Rod Operability Test is in progress. The RO selects CBD on the Bank Selector Switch and inserts rods to 208 steps. The RO then selects MANUAL on the Bank Selector Switch and restores Bank D to 218 steps.
Which ONE of the following is the Control Bank D position when Control Bank C will begin to insert if this condition is left uncorrected?
A) 80 Steps
B) 90 Steps
C) 100 Steps
D) 110 Steps
B) 90 Steps
Unit 2 was operating at 20% power when a Control Bank A rod dropped into the core. During recovery of the dropped rod, an URGENT FAILURE alarm was received.
Which ONE of the following is the reason for this alarm?
A) Output voltage to the moveable and stationary grippers has excessive ripple.
B) Moveable and stationary grippers attempt to energize at the same time.
C) Current signals to moveable and stationary grippers are lost at the same time.
D) Current to the lift coils does NOT match the current command signal for an entire group.
D) Current to the lift coils does NOT match the current command signal for an entire group.
The following plant conditions exist:
- Control Rods are in Manual
- Reactor/Turbine Power is 12% and stable
- Tave is 3°F less than Tref
Which ONE of the following conditions would prevent AUTOMATIC rod control from restoring Tave?
A) C-1, Intermediate Range High Flux Rod Stop.
B) C-3, Overtemperature Delta-T High Rod Stop.
C) C-4, Overpower Delta-T High Rod Stop.
D) C-5, Turbine Low Power Interlock
D) C-5, Turbine Low Power Interlock
Reactor power at 75 percent Rod control in automatic. Xenon transient in progress.
Assuming no operator action, no changes in nuclear or turbine power.
Control rods will begin to move in the _________ direction when Tavg > Tref by more than ____, and will continue to move until Tavg is within ____ of Tref.
A) Inward; 2.0°F; 1.5°F
B) Inward; 1.5°F; 1.0°F
C) Outward; 1.5°F; 1.0°F
D) Outward; 2.0°F; 1.5°F
B) Inward; 1.5°F; 1.0°F
Unit 2 reactor startup is about to be performed, commencing with the withdrawal of Control Bank “A”.
The “Rod Dropped or Rod Bottomed” annunciator should clear when ____ are greater than ____ steps.
A) Control Bank “A” group demands; 35
B) Control Bank “D” group demands; 35
C) Control Bank “A” individual positions; 20
D) Control Bank “D” individual positions; 20
C) Control Bank “A” individual positions; 20
Unit 2 is operating at 100% power when loop 2 Tcold fails low with rod control in automatic.
Which ONE of the following describes the expected response of the rod control system?
A) Rods initially move in due to an instant temperature error, with an offsetting power mismatch attempting to move rods out as reactor power decreases.
B) Rods initially don’t move, but as a power mismatch signal develops, rods will start to move out.
C) Rods initially don’t move, nor will they move due to this failure.
D) Rods initially move out due to an instant temperature error. Power mismatch will not be affected initially or later.
C) Rods initially don’t move, nor will they move due to this failure.
Reactor power is 35% - startup is in progress. All control systems are in AUTOMATIC. Control Bank D rods are at 150 steps.
The lower detector for power range nuclear instrument channel N41 fails HIGH, causing channel total power indication to increase to 70%.
Assuming no operator action is taken, what will be the response of the rod control system?
A) Rods will not move.
B) Rods will drive all the way in.
C) Rods will drive in some distance then stop.
D) Rods will insert, and then withdraw.
D) Rods will insert, and then withdraw.
Reactor power is 90%. All control systems are in AUTOMATIC. Control Bank D rods are at 200 steps.
The lower detector for power range nuclear instrument channel N41 fails HIGH, causing channel total power indication to increase to 110%.
Assuming no operator action is taken, what will be the response of the rod control system?
A) Rods will not move.
B) Rods will drive all the way in.
C) Rods will drive in some distance then stop.
D) Rods will insert, and then withdraw.
C) Rods will drive in some distance then stop.
