Sro Incore Nis Wk4

Front 1

Which one of the following describes why the Movable Incore Detector System (MIDS) poses a potential radiological hazard? A. The detector is a Geiger-Mueller type and has a tendency to leak after exposure to high flux fields.B. The fission chamber type detector becomes highly radioactive and area radiation levels increase when the detector is retracted.C. When the MIDS is inserted into the core during refueling, the fuel assemblies must remain in place or an overexposure may occur.D. A MIDS detector consists of an ion chamber which is a delicate instrument and very susceptible to damage.

Back 1

B

Front 2

Incore Thermocouple System temperature readings are input to which components/systems? A. Flux mapping console, PTS circuit, and KC-008B. SSPS, ESFAS, and KC-008C. RVLIS, Flux mapping console, and ESFASD. NPIS for information, SPDS for CSF monitoring, and Core Subcooling Monitor.

Back 2

D

Front 3

When containment temperature alone increases, the temperature indication from the Incore Thermocouple System _____________ due to ___________________________. A. increases / the increasing temperature at the measuring junction.B. increases / the increasing temperature at the reference junction.C. does not change / the location of the junction boxes.D. does not change / the compensating RTDs located in the junction boxes.

Back 3

D

Front 4

The plant is operating at 100% power with the incore temperature monitoring display for the hottest incore thermocouple reading 622 degrees F. Temperature in the area of the reference junction boxes for the thermocouples rises 15 degrees F over the duration of the shift. Reactor power level remains constant over the duration of the shift.How are the core exit thermocouple readings affected by the temperature change in the area of the reference junction boxes? A. Readings will remain the same since temperature change does not affect the signal from the reference junction.B. Readings will be lower due to lowered voltage differential between the metals at the hot junction.C. Readings will be higher due to higher voltage differential between the metals at the cold junction.D. Readings will remain the same because the temperature error is compensated for by the incore temperature monitor processor system.

Back 4

D

Front 5

What is the function of the incore thermocouple system?

Back 5

Measure the coolant temperature at the outlet of selected core fuel assemblies.

Front 6

How is the exit temperature of a fuel element that does not have an installed thermocouple determined?

Back 6

The exit temperature is estimated using data taken from adjacent fuel assemblies.

Front 7

Explain the operation of a fission chamber.

Back 7

Lined with U-235 enriched U3O8. Fission causes massive ionization. Fission pulse is greater than alpha and gamma signals. Current flow measured to determine intensity of neutron flux. Operates in ion chamber region of gas-filled detector characteristic curve.

Front 8

List the six transfer paths from the 6-path transfer device.

Back 8

1. NORMAL
2. CALIBRATE
3. ALTERNATE (3)
4. STORAGE

Front 9

MIDS contains two types of limit switches. What are they called and what do they do?

Back 9

Withdrawal limit switches - 1) Provides signal to console and manual control box indicating detector withdrawn; 2) Prevents operation of associated 6-path transfer until detector withdrawn from transfer so no jam occurs and; 3) Provides zero reference for measuring length of cable insertion for position measuring circuits in console.

Safety limit switches - Stops detector from entering drive box, in case of malfunction of withdrawal limit switch, by removing electrical power from drive assembly gear motor.

Front 10

What component forms the primary pressure boundary between the reactor coolant system and moveable incore detector system during normal operations?

Back 10

Swagelok seal at the seal table.

Front 11

An instrumentation thimble has ruptured. The detector and cable are inserted and jammed in the core and can not be withdrawn. What action will be required to stop the loss of coolant?

Back 11

The associated manual isolation valve will have to be closed.

Front 12

How many thermocouples are contained in the incore thermocouple system?

Back 12

50

Front 13

Explain the operation of a thermocouple.

Back 13

Whenever two dissimilar metals are joined at welded junction, a potential difference exists across the junction.

Front 14

What component(s) serve as the pressure boundary between the reactor coolant system and the incore thermocouple system?

Back 14

Two conoseals

Front 15

How many reference junction boxes for the incore thermocouple system are there and how many thermocouples does each serve?

Back 15

Two; 25

Front 16

What aspect of fission chambers makes them particularly hazardous?

Back 16

They become extremely radioactive during use and can make a significant contribution to radiation levels below the reactor.

Front 17

What three points concerning primary system leaks at seal tables should be remembered to minimize the risk of developing leaks at this location?

Back 17

1. Flux thimbles should only be cleaned when RCS is depressurized.
2. Mating parts of seal table pressure fittings should be from the same manufacturer.
3. Pressure fittings should only be tightened or loosened when RCS is depressurized

Front 18

A Reactor startup is in progress. The operator takes BOTH source range block switches to BLOCK, but fails to complete the circuit on the A train (NOT BLOCKED)What will occur if the startup continues? A. A rod stop will occur as power is increasedB. The source range high voltage will be automatically blocked at P-10C. A Reactor trip will occur as power is increasedD. The source range detector will be damaged due to high flux

Back 18

C

Front 19

While performing a reactor startup, the following readings are observed on the SR and IR indicators: NI31 - 5 x 104 CPS NI32 - 5 x 104 CPS NI35 - 5 x 10-11 AMPS NI36 - 1 x 10-10 AMPSWhich of the following is correct? A. NI35 is overcompensatedB. NI36 is overcompensatedC. NI36 is undercompensatedD. NI35 is undercompensated

Back 19

A

Front 20

The plant is at 15% power performing a shutdown when IR NI-35 fails high. What action should be taken? A. The only required action is to trip the reactor since the SRs will automatically energize after the trip.B. Place the Level Trip Switch in Bypass and manually reinstate the SRs when NI-36 goes below P-6.C. Since the failure will have no effect on the shutdown, continue the shutdown.D. Place the inoperable channel in the trip condition within six hours and pull the detector fuses.

Back 20

B

Front 21

Reactor power is at 100%. The lower detector for PR Channel N43 failed four days ago. Channel 43 was removed from service, and its associated protection bistables were tripped. PR channel N41 is gradually failing downscale (low) from a failure in the level amplifier. A negative rate trip is not generated.What occurs when Channel N41 decreases below 10% power (assuming no operator action)? A. The turbine trip/reactor trip interlock is unblocked.B. A reactor trip occurs from automatic unblocking of the PR High Flux Trip (Low Setpoint).C. High voltage to the SR detectors remains blocked.D. The pressurizer high water level reactor trip is unblocked.

Back 21

C

Front 22

Assume that the following conditions exist during an accident:* Fuel is intact* Time after reactor trip is 2 hours* All control rods are fully inserted* RCPs are tripped and RVLIS is not available* RCS boron concentration is greater than Cold Shutdown concentration* Count rate on both SR channels is about 10 E4 cps and significantly oscillatingWhich statement is consistent with the conditions given? A. The fuel is partially uncovered and water level in the downcomer is far below the top of the fuel.B. Voiding is confined to the upper interior regions of the core where the heat flux is highest.C. The reactor vessel downcomer is filled with a subcooled liquid.D. The void fraction of reactor coolant vessel coolant is less than 10% voided.

Back 22

A

Front 23

WHICH of the following statements is correct concerning the Nuclear Instrumentation System? A. One of two IR detectors below 1.0E-10 amps will automatically re-energize the SR detectorsB. Two of two IR detectors above 1.0E-10 amps will automatically de-energize the SR detectorsC. One of two IR detectors above 1.0E-10 amps will automatically de-energize the SR detectorsD. Two of two IR detectors below 1.0E-10 amps will automatically re-energize the SR detectors

Back 23

D

Front 24

The Reactor is at 100% power. The lower detector in PR channel N-43 failed four days ago. Channel N-43 was removed from service, and its associated protection bistables were tripped. Now, PR channel N-41 gradually fails (low) due to a failure in its level amplifier. A negative rate trip is NOT generated. Which one of the following statements is correct at the time channel N-41 decreases below 10% power, assuming no operator action? A. The Turbine trip/Reactor trip interlock is automatically blockedB. A Reactor trip occurs due to automatic unblocking of the PR High Flux Trip (low setpoint)C. The Pressurizer high water level Reactor trip is automatically blockedD. High voltage to the SR detectors remains blocked

Back 24

D

Front 25

The reactor is critical at 1.0 x 10-8 amps. A fault causes the loss of 118 VAC protection bus NN01. This condition will result in which of the following? A. A Reactor trip on SR High Flux due to the de-energization of permissive P-6B. No Reactor trip due to the de-energization of IR channel N35C. A Reactor trip due to the de-energization of PR channel N41D. A Reactor trip due to the de-energization of IR channel N35

Back 25

D

Front 26

One excore nuclear instrumentation system channel qualified to withstand a post-accident containment environment is: A. Intermediate Range N36B. Source / wide range N61C. Source Range N31D. Power Range N41

Back 26

B

Front 27

What is the purpose of the Gamma-metrics instrumentation system? A. Provides an environmentally and seismically qualified means to monitor the reactor after an accident.B. Provides a high flux at shutdown alarm for evacuation of the containment during refueling.C. Can be used as an alternate to one failed power range channel in performance of Technical Specification required QPTR.D. Can be substituted for one channel of source range instrumentation during startup.

Back 27

A

Front 28

The following readings are noted on the power range and intermediate NIS channels.N-35 = 5x10E-6 ampsN-36 = 1x10E-5 ampsN-41 = 8.5%N-42 = 9.0%N-43 = 8.4%N-44 = 9.0%Which one of the following describes the problem indicated by these readings? A. N-42 and N-44 reading high for these conditions.B. N-41 and N-43 reading low for these conditions.C. N-35 reading low for existing conditions.D. N-36 reading high for existing conditions.

Back 28

C

Front 29

The plant is operating at 100% power when Intermediate Range channel N36 fails low. Assume the reactor does not trip.What action, if any, is required for this failure? A. Trip the inoperable channel within the next six hours.B. No action is necessary.C. Place the Level Trip Switch on the IR drawer in bypass position.D. Manually trip the reactor the PR Low Flux trip should have unblocked.

Back 29

C

Front 30

With thermal power output held constant, Tavg is decreased 50F. A calorimetric is performed to adjust NIs.What affect, if any, does lower Tavg have on power range detectors? A. More thermal neutrons leaking out cause PR detectors to indicate higher than calorimetric.B. Fewer neutrons leaking out cause PR detectors to indicate lower than calorimetric.C. Tavg has no effect on PR detectors; NIs indicate the same as the calorimetric.D. More neutrons leaking out would cause PR detectors to indicate higher than calorimetric.

Back 30

B

Front 31

A reactor trip from 100% power occurred 27 minutes ago.Should Source Range detectors be energized? A. Yes, at a negative 1/3 dpm startup rate, sufficient time has elapsed to reach 1E-10 amps in the intermediate range.B. No, at a negative 1/3 dpm startup rate it takes 33 minutes to reach 1E-10 amps in the intermediate range.C. No, the source ranges must be reset manually below P-6.D. Yes, the source ranges automatically energize when P-10 clears.

Back 31

A

Front 32

The plant is at 100% power. Power Range Channel N41 has failed high and all required actions of OFN SB-008 are complete when PZR Pressure Channel PT-456 fails low.What reactor trip logic is satisfied as a result? A. OPdeltaT Reactor TripB. PZR High Pressure Reactor TripC. OTdeltaT Reactor TripD. PZR Low Pressure Reactor Trip

Back 32

C

Front 33

What reactor trip CANNOT be blocked by an interlock or permissive? A. Pressurizer High LevelB. Pressurizer Low PressureC. Power Range Hi Neutron Flux RateD. Turbine Trip

Back 33

C

Front 34

What signal is generated when control power fuses on a power range drawer are pulled? A. Over temperature deltaT reactor trip.B. Overpower deltaT reactor trip.C. Power range high flux reactor trip.D. Power less than 10%, permissive P-10.

Back 34

C

Front 35

Assume the following conditions exist during an accident:* Fuel is intact* Time after reactor trip is one hour* All control rods are fully inserted* RCS boron concentration is greater than the Cold Shutdown concentration* Reactor coolant void fraction i

Back 35

C

Front 36

The following conditions are present:* Unit tripped from 100% power* RCS pressure rapidly dropped to below 1000 psig* SI actuated and started injecting* Containment pressure rapidly increased* Steam Generator pressures and levels are at normal post trip

Back 36

B

Front 37

During voiding in the core, why would the Source Range instrumentation output signal increase? A. The escaping neutrons and gammas increase noise in the detector output cable.B. Water in the downcomer decreases, exposing the detector to gammas. These gammas are of sufficient energy to cause the detector output to resemble that for thermal neutrons.C. The water in the downcomer has reduced the cooling seen by the detectors and the elevated temperatures have increased the gas ionization of the detector.D. Water in the downcomer decreases, exposing the detector to neutrons escaping from the voided core.

Back 37

D

Front 38

The following plant conditions exist:* Reactor is tripped* RCPs are tripped* Steam Generator Levels are decreasing* RCS temperature is constantThe subcooling monitor indicates and has always indicated a subcooled primary. RVLIS shows and has always shown a full vessel. Source Range output now starts to increase. Why? A. This is a normal post-trip response for these detectors.B. Voids are forming in the core.C. A sudden temperature change has affected the detectors.D. The reactor is experiencing a restart.

Back 38

D

Front 39

Following a reactor trip, the unit stabilizes in the source range and all RCPs are stopped.Later, you notice the source range counts increasing. What two parameters, if any, can be compared to determine if this is a restart event and why? A. Source Range channels and Intermediate Range channels. Increasing counts in the source range with no increasing in the intermediate range indicates a restart event.B. RVLIS and Subcooling monitor. If the RVLIS indicates full and there is adequate subcooling, then this could be a restart event.C. RVLIS and Steam Generator water level. If the RVLIS is indicating full an steam generator water level is in the narrow range, this could be a restart event.D. Nothing needed to compare. It is very common for source range counts to increase when neutrons become the dominate neutron contributor following shutdown.

Back 39

B

Front 40

Which of the following describes the response of excore nuclear instrumentation due to void formation in the reactor vessel and core region? A. The predominant effect on excore instrumentation indication response during homogeneous voiding conditions is the resulting change in Keff, which is more important than the change in downcomer fluid density.B. The net effect on E, r, Lf, Lth, due to void formation is an increase in Keff and corresponding nuclear instrumentation indication.C. Void formation and subsequent reduction in moderator hydrogen nuclei concentration causes the mean free path for neutron scattering to decrease, lowering excore nuclear instrumentation indication.D. Void formation in the core reduces source neutron production available for subcritical multiplication and interaction with the excore nuclear instrumentation following the post trip -1/3 DPM decay time.

Back 40

D

Front 41

The following plant conditions exist:* Reactor tripped / Safety Injection Actuated* S/G levels are constant at normal post trip valuesWhich indications would confirm that reduced shutdown margin is the cause of an abnormally high response on the Source Range instruments following a reactor trip. A. RVLIS Forced Flow Range indicates about 20%, and subcooling margin is negative.B. RVLIS Forced Flow Range indicates about 65% when all RCPs are running.C. RVLIS Natural Circulation Range indicates about 100% when no RCP is running.D. RVLIS Natural Circulation Range indicates about 40%, and the boron concentration in a hot leg coolant sample is 400 ppm.

Back 41

C

Front 42

The plant is in MODE 2 preparing to roll the main turbine.What is a direct result of a loss of Vital AC Instrument Bus NN02? A. Intermediate Range High Flux Reactor Trip.B. Idle Component Cooling Water Pump Start.C. Charging Pump Suction Swaps to the RWST.D. Source Range Hi Flux Reactor Trip.

Back 42

A

Front 43

Early in a restart from a long refueling outage, the reactor operator notices an unexpected increase in source range NI count rate? Which of the following is a likely cause for this increase? A. Divert valve is in the VCT position and the deminerlizer is saturatedB. Divert valve is in the VCT position and deminerlizer is not saturatedC. Demineralizer just placed in service has been saturated D. Letdown temperature has significantly increased

Back 43

B

Front 44

The reactor is at critical at 1.0 E-8 amps and stable. Inverter NN11 output breaker trips open causing a loss of 120 VAC (Instrument Bus NN01).For this condition, what reactor trip signal is generated first? A. PZR High Pressure.B. IR Channel Bistable Trip.C. PZR Low Pressure.D. S/G Lo-Lo Level.

Back 44

B

Front 45

The unit is at 100% power when NI41 fails. All required actions have been performed. I & C requests authorization to perform an ACOT on PRZR Press Channel 456.What action is required prior to performing the ACOT? A. No action is required since the instruments in question affect the same bistable.B. Trip the bistable TB 421C to comply with this associated action requirement.C. No action is required since the instruments in question are not related.D. Bypass NI41 in order to prevent an inadvertent reactor trip.

Back 45

D

Front 46

At 100% power NI44 failed high. All NI44 bistables are tripped. If PRZR Pressure Channel 456 failed low, what would the plant response be? A. The reactor would trip on 2/4 OT delta T.B. All heaters turn off.C. PORV Block Valves would close.D. The reactor would trip on 2/4 OP delta T.

Back 46

A

Front 47

What set of auctioneered inputs goes to the Subcooling Margin Monitors? A. Low WR RCS or NR PZR pressure and high temperature.B. Low WR RCS pressure and low temperature.C. High WR RCS pressure and high temperature.D. High WR RCS or NR PZR pressure and low temperature.

Back 47

A

Front 48

When would RVLIS indication be most affected? A. When adverse CTMT conditions exist.B. When accumulators inject into the vessel.C. When a break in the vessel head occurs.D. When a PORV is stuck full open.

Back 48

C