TMM

Question 1

The Thermal Margin Monitor measures the core Axial Shape Index and corrects that signal using the Shape Annealing Factor. The Axial Shape Index needs to be corrected for…

1 differences between the flux at the core periphery and the flux at the detectors.
2 axial neutron population flux distribution variances from top to bottom of the core.
3 differences between the flux at the incore detectors and at the excore detectors.
4 radial neutron population flux distribution variances from inside to outside of the core.

Answer 1

1 differences between the flux at the core periphery and the flux at the detectors.

Question 2

Referring to the TMM block diagram, which of the following explains the function the Power Peaking Function Generator in the Thermal Margin Monitor?

1 Calculates the setpoint for the Variable High Power Trip.
2 Provides the Axial Shape Index Function input for the TM/LP trip.
3 Generates the power portion of the DNB penalty calculation for the TM/LP trip setpoint.
4 Calculates the TM/LP trip setpoint using the radial and axial peaking factors.

Answer 2

3 Generates the power portion of the DNB penalty calculation for the TM/LP trip setpoint.

Question 3

Refer to the attached block diagram of the Thermal Margin Monitor. Which ONE of the following function generators defines the operating envelope for the core’s Axial Shape Index?

1 Axial Function Generator
2 Power Peaking Function Generator
3 Axial Shape Index Function Generator
4 Local Power Density Function Generator

Answer 3

4 Local Power Density Function Generator

Question 4

During 100% power operations with Battery Chargers #1 and #2 in service, DC Bus Tie Breaker 72-20 fails open. Which Thermal Margin Monitor channel will be without power due to this event?

1 A
2 B
3 C
4 D

Answer 4

4 D

Question 5

Which ONE of the following describes the purpose of the Thermal Margin/Low Pressure reactor trip?

A Protect the reactor core from exceeding a linear heat rate limit.
B Prevent exceeding DNB limits for slow reactivity addition accidents from low power.
C Protect the Primary Coolant Pumps from operating at low PCS pressure.
D Provides an adequate margin to core thermal limits for a loss of flow accident

Answer 5

B Prevent exceeding DNB limits for slow reactivity addition accidents from low power

Question 6

Which ONE of the following describes the purpose of the Variable High Power Trip (VHPT) reactor trip?

A Provides capability to limit transients quickly beginning at low power levels, without operator action.
B Protect the Primary Coolant Pumps from operating at low PCS pressure.
C Provides assurance the core axial flux shape is maintained within the boundaries of the safety analysis.
D Protect the reactor core from the effects of a Loss of Coolant Accident

Answer 6

A Provides capability to limit transients quickly beginning at low power levels, without operator action.

Question 7

How will the Thermal Margin Monitor ΔT (B) and ASI (L-U/L+U) input signals change in response to a boron dilution at full power?

A Both ΔT and ASI will rise
B Both ΔT and ASI will lower
C ΔT will rise and ASI will lower
D ΔT will lower and ASI will rise

Answer 7

A Both ΔT and ASI will rise

Question 8

During full power operations, CB1 Supply Breaker to the “A” Channel Thermal Margin Monitor (TMM) fails open. How will that impact the trip signals the TMM delivers to the Reactor Protection System?

A. Variable High Power will trip; TM/LP will not trip
B TM/LP will trip; Variable High Power will not trip
C Both Variable High Power and TM/LP will not trip
D Both Variable High Power and TM/LP will trip.

Answer 8

D Both Variable High Power and TM/LP will trip

Question 9

Which ONE of the following Control Room indications would validate that a Thermal Margin Monitor (TMM) channel has failed upon receipt of Annunciator EK-06D3, “Nuclear- ΔT Power Deviation/T-Inlet Off Normal/Calculator Trouble Channel A?“

A System Status screen shows Phi-B values are in trip.
B TMM Nuclear- ΔT Deviation Meter trips for >18 seconds.
C A TCOLD input to the TMM indicates failed off-scale high.
D TMM display screen blank except for an error message

Answer 9

D TMM display screen blank except for an error message

Question 10

The following plant conditions exist:
MODE 2 with reactor power stable below the point of adding heat.
2 Flux – Delta T channels are inoperable
Given references, determine which of the following describes the required ORM actions.

A Operation may proceed, but power must be limited to greater than or equal to 70% RTP.
B Operation may proceed, but power must be limited to greater than or equal to 25% RTP.
C Operation in MODE 1 is not permitted until the 2 channels are restored.
D Operation in MODE 1 is not permitted until at least 1 channel is restored.

Answer 10

C Operation in MODE 1 is not permitted until the 2 channels are restored.

Question 11

The Thermal Margin Monitor generates the core ΔT signal by taking the…

A auctioneered high THOT and average TCOLDS.
B auctioneered high of both TCOLDS and THOTS.
C auctioneered high TCOLD and average THOTS.
D average of both of the THOTS and the TCOLDS

Answer 11

C auctioneered high TCOLD and average THOTS.

Question 12

Which ONE of the following describes the Thermal Margin Monitor output signals?

A VHPT and Loss of Load reactor trips to all 4 RPS channels.
B VHPT, and Loss of Load to all 4 RPS channels and an ASI alarm.
C VHPT and TM/LP setpoint to all 4 RPS channels and an ASI alarm
D VHPT Pre-trip and trip to all 4 RPS channels and a quadrant power tilt alarm

Answer 12

C VHPT and TM/LP setpoint to all 4 RPS channels and an ASI alarm

Question 13

The following conditions exist:
Reactor Power is 100%
All RPS and TMM channels operable
Which ONE of the following describes the effect on the Thermal Margin/Low Pressure (TM/LP) Trip setpoint of the ASI value shifting from 0.0 to a –0.1 value due to a xenon oscillation?
The TM/LP trip setpoint, in psia, will:

A initially lower than rise.
B stay the same.
C rise.
D lower

Answer 13

C rise.

Question 14

If the VHPT RESET button is depressed with the below listed Reactor Power indications, which ONE of the following are the new Variable High Power Trip and Pre-trip setpoints?
Delta T power indicates 43%
Nuclear power indicates 41.8%

A VHPT = 55.3%, VHP pre-trip = 56.8%.
B VHPT = 58%, VHP pre-trip = 56.5%.
C VHPT = 56.5%, VHP pre-trip = 54.5%.
D VHPT = 58%, VHP pre-trip = 55%.

Answer 14

B VHPT = 58%, VHP pre-trip = 56.5%.

Question 15

The following plant conditions exist:
Reactor Power stable at 25% for 15 minutes
Control Rods withdrawn above PDIL
TAVE = TREF and stable
Pressurizer pressure = 2060 psia and stable
Pressurizer level at the programmed level
Which ONE of the following describes the criterion that must be met prior to manually resetting the VHPT setpoint?

A At least 3 PCPs operating.
B Both Steam Generator levels are between 60% and 70%.
C Reactor power above 28.5%.
D All four power range nuclear instruments operable.

Answer 15

B Both Steam Generator levels are between 60% and 70%

Question 16

Which ONE of the following would administratively prevent resetting the Variable High Power Trip setpoints during a normal power escalation from 23% to 50%?
A Power escalation rate is 12%/hour
B Control Rods are above PDIL
C TAVE/TREF deviation is 4.2°F
D Pressurizer Level is 47%

Answer 16

C TAVE/TREF deviation is 4.2°F