SBCS (Steam Bypass Control System) Flashcards
Unit 1 is operating at 82% power.
All systems are in normal lineup when the generator trips due to a loss of field.
SBCV #4 is OOS.
CEA’s are not selected for large load reject.
A. Insert CEAs in manual sequential.
B. Trip the reactor.
C. Start a rapid shutdown per 40OP-9ZZ05, Power Operations.
D. Immediately select CEAs for large load reject and manually initiate a cutback.
B. Trip the reactor.
Unit power is being lowered due to a Main Condenser Circ Water Leak.
CRS is currently performing actions in accordance with 40AO-9ZZ10 (Cond Tube Rup).
Plant systems are aligned per 40AO-9ZZ10.
Rx power currently 65%.
Secondary Operator reports an EHC malfunction resulting in currency Tave being 5 F off program low.
What circumstances would cause a Quick Open block to be generated..... A. Main Feed Pump ‘B’ Trip B. Loss of NNN-D15 C. Reactor Trip D. Main Turbine Trip
C. Reactor Trip
Note: RTO is placed in-service ~70%
Immediately after the trip, the Secondary Operator got involved with the B01 report.
Due to a small SGTR, SBCS Valves 1007 and 1008 have been selected to OFF.
When this operator returned to B06, condenser backpressure was 8.5” HgA (Highest Shell)
Steam Generator levels are both 65% WR.
What condition is the Secondary Plant?
A. No feed with SBCS maintaining SG pressure.
B. No feed with Main Steam Safety Valves maintaining SG pressure.
C. Main Feed Pumps feeding in RTO with SBCS maintaining SG pressure.
D. Main Feed Pumps feeding in RTO with Main Steam Safety Valves maintaining SG Pressure
D. Main Feed Pumps Feeding in RTO with Main Steam Safety Valves maintaining SG pressure.
(Note: RTO- Reactor Trip Override)
The reactor was tripped due to a degrading condenser vacuum.
Immediately after the trip, the Secondary Operator became involved with the B01 report.
When this operator returned to B06, condenser backpressure was 9.0” HgA (Highest Shell).
Steam Generator levels are both 65% WR.
Assuming no other operator performed actions of B06, in what condition can this operator expect to find the secondary plant?
A. No feed with SBCS valves 1007 and 1008 maintaining SG pressure.
B. No feed with SBCS valves 1001 and 1004 maintaining SG pressure.
C. Main Feed Pumps feeding in RTO with SBCS valves 1001 and 1004 maintaining SG pressure.
D. Main Feed Pumps feeding in RTO with SBCS valves 1007 and 1008 maintaining SG pressure.
D. Main Feed Pumps feeding in RTO with SBCS valves 1007 and 1008 maintaining SG pressure.
Power to Steam Master Controller is lost for 30 seconds and then restored.
The steam bypass controller was in REMOTE AUTO before the power loss.
Which of the following is true of the SBCS when power is returned?
The SBCS master controller may return in_________and the system________be in EMERGENCY OFF.
A. Manual, will
B. Manual, will NOT
C. Automatic, will
D. Automatic, will NOT
A. Manual, will
The plant is operating at 100% power.
RCS pressure is 2250 psia.
Pressure control channel selector (RCN-HS-100) is positioned to ‘100X.’
Pressurizer heater control level trip channel selector (RCN-HS-100-3) is selected to ‘BOTH.’
PZR pressure transmitter ‘100Y’ failing high will result in:
A. All pressurizer heaters energizing.
B. All pressurizer heaters de-energizing.
C. The SBCS valves receiving an auto permissive signal.
D. The SBCS valves receiving an auto modulation signal.
C. The SBCS valves receiving an auto permissive signal.
Plant startup is in progress using 40OP-9ZZ04.
Reactor Power is 12%.
The Main Generator has just been placed on line (synchronized).
The Steam Bypass Control System (SBCS) is in LOCAL-AUTO control with valve 1001 open 40%.
Describe the normal method for getting SBCV 1001 fully closed in support of continuing the Generator Synchronization evolution.
A. Place SBCV 1001 valve controller to manual and manually close SBCV 1001.
B. Raise turbine load until the SBCV 1001 just closes.
C. Place the SBCS Master Controller in REMOTE-AUTOMATIC and verify that SBCV 1001 closes.
D. Lower the SBCS Master Controller set point 1150 PSIA and verify SBCV 1001 closes.
B. Raise turbine load until the SBCV 1001 just closes.
The plant is at 100% power when the operator notices Steam Bypass Valves inadvertently opening and selects EMERGENCY OFF.
Which one of the following identifies the response of the Steam Bypass Valves?
A. The valves modulate closed, then instrument air is applied to the top of the actuator to hold all the valves closed.
B. The bottom of the valve actuator is vented, N2 is applied to the top of the actuator forcing all valves to close.
C. Only valves 1001 through 1006 receive a close signal, valves 1007 and 1008 (the atmospheric steam bypass valves) will still operate.
D. The bottom of the valve actuator is vented, instrument air is applied to the top, forcing the valves to close with spring and air pressure.
D. The bottom of the valve actuator is vented, instrument air is applied to the top, forcing the valves to close with spring and air pressure.
Unit is operating at 15% rated power.
Steam flow transmitter SGN-FT-1011 fails LOW.
Which one of the following describes the impact (if any) on the SBCS?
A. All valves quick open then close.
B. This failure will have no noticeable impact.
C. The modulation set point will increase.
D. The modulation set point will decrease.
B. This failure will have no noticeable impact.
Note: Due to 15% power is <50% power the setpoint is stable and you just move left on the graph
SBCS valves are in operation following a reactor trip.
Valve 1001 is open 40%, controlling steam header pressure at approximately 1170 psia.
The Secondary Operator inadvertently opens an ADV, causing steam header pressure to rapidly drop by 50 psia (and remains 50 psia lower).
Based on these conditions, you should expect the MODULATE PERMISSIVE light to…
A. Extinguish immediately.
B. Remain on, with SBCS valve 1001 remaining at its present position.
C. Remain on, with SBCS valve 1001 throttling closed to approximately 10%.
D. Extinguish in approximately 15 seconds.
A. Extinguish immediately.
The Unit SBCS valves will modulate open at a lower steam pressure when:
A. Pressurizer pressure is decreasing rapidly below set point (2250 psia).
B. Pressurizer pressure is increasing rapidly above set point (2250 psia).
C. X1 and Y1 are received and a quick open occurs.
D. Steam header pressure transmitter (PT-1027) fails low.
B. Pressurizer pressure is increasing rapidly above set point (2250 psia).
A reactor trip occurs from rated power. Which of the following identifies the response of the SBCS to the transient?
A. Quick open is blocked on all eight valves.
B. Only the group Y valves quick open.
C. Only the group X valves quick open.
D. All eight valves quick open.
C. Only the group x valves quick open.
Unit 1 has tripped form 100% power due to a Loss of Offsite power.
The following report is made for B01 electric plant status:
-13.8 and 4.16kVAC non class buses are de-energized.
-4.16kVAC class busses are energized by their respective DGs.
-Class and non-class DC buses are energized.
-120 vac non class instrument buses were de-energized but have transferred to their class backup sources.
-120 vac class instrument buses are energized.
Assuming no Operator action, which one of following Reactor Coolant system temperature responses should the crew expect to see in the 10 minutes following the LOOP.
A. T-cold is stabile at 564F with T-hot approximately 3F hotter.
B. T-cold is stable at 564F with T-hot approximately 30F hotter.
C. T-cold increases to 572F with T-hot approximately 3F hotter.
D. T-cold increases to 572F with T-hot approximately 30F hotter.
D. T-cold increases to 572F with T-hot approximately 30F hotter.
(Note: On the loss of power the SBCS comes back in manual with 0% output. With no operation action, Tcold will be controlled by the safeties at 1250 (572 degree) as Thot increases in Natural Circulation conditions. If SBCS was working it maintains 1170 (564 degrees). 30 degree delta T is a reasonable number for nat’l Circ conditions. On loss of power the SBCS comes back in manual and possibly emergency off.)
Unit 1 is operating at 100% power.
Steam pressure transmitter SGN-PT-1027 has failed low.
The Steam Bypass Control System (SBCS) is aligned for Remote/Auto operation.
The Main Turbine trips.
After the Quick Open has cleared and assuming NO operation action, which one of the following is correct regarding the SBCS and main steam pressure?
A. The SBCS will not function and the main steam header pressure will increase to Main Steam Safety Set point.
B. Only SBCVs 7 and 8 will function and the main steam header pressure will be controlled at the automatic set point.
C. All SBCVs will function and the main steam header pressure will be controlled at a slightly higher than normal set point due to the bias applied to the failure of SGN-PT-1027.
D. All SBCVs will function and the main steam header will be controlled approximately 20 psia below the automatic set point due to the ‘locked in’ permissive signal.
A. The SBCS will not function and the main steam header pressure will increase to Main Steam Safety set point.
(Note: SBCV are locked out due to a loss of permissive signal pressure increases to MSSV set point)
The Reactor is stable at 50% power.
The Main Turbine has tripped.
The Steam Bypass Master controller, SGN-PIC-1010, is in Auto/Remote operation.
Normal CEA overlap has been established.
Subsequently
CEAs are withdrawn 10 inches in Manual Sequential.
You have been directed to monitor the ‘D’ channel instrumentation for RCS temperature, pressure and power.
Which one of the following correctly describes the expected response and location of these instruments?
A. Reactor power increases, RCS T-cold increases but returns to program, Pressurizer pressure remains unchanged. The ‘D’ channel indications can be monitored from B05 only.
B. Reactor power increases slightly but returns to 50%, RCS T-cold increases and remains higher, Pressurizer pressure increases and remains higher. These indications can be found on B05 only.
C. Reactor power increases, RCS T-cold increases and remains higher, Pressurizer pressure increases and remains higher. The ‘D’ channel indications can be monitored from either QSPDS or B05.
D. Reactor Power increases slightly but returns to 50%, RCS T-cold increases but returns to program, Pressurizer pressure remains unchanged. The ‘D’ channel indications can be monitored from either QSPDS or B05.
A. Reactor power increases, RCS T-cold increases but returns to program, Pressurizer pressure remains unchanged. The ‘D’ channel indications can be monitored from B05 only.
(Note: SBCS in auto means it is controlling temperature not power. Examines may confuse 100% power response with what happens when SBCS is maintaining the plant. This is an old PBVGNS event, in an attempt to raise the temp post cutback the RO pulled CEAs until a VOPT trip occurred. Only A and B instruments feed the QSPDS system.)
