Test wiedzy na operatora reaktora BWR

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Test składa się z 50 pytań jednokrotnego wyboru, aby zaliczyć test należy uzyskać przynajmniej 80% poprawnych pytań (40). Test jest zgodny z wymaganiami stawianymi przez amerykański dozór jądrowy, Operator Licensing Examination Standards for Power Reactors, NUREG-1021, Rev. 11.
Test w języku angielskim.

Powodzenia,
Rafał

1. Refer to the drawing of an open system with subcooled water flowing through valves A, B, C and D (see figure below). All valves are initially 50 percent open. The inlet pressure to valve A is constant at 60 psia. The initial steady-state inlet and outlet pressures for valve B are as follows: I) Inlet pressure = 50 psia II) Outlet pressure = 35 psia. After a single valve operation, the current steady-state inlet and outlet pressures for valve B are as follows: I) Inlet pressure = 48 psia II) Outlet pressure = 36 psia. Which one of the following valve operations could be responsible for the difference between the initial and current steady-state inlet and outlet pressures for valve B? *

1 point

Valve A was opened more.

Valve B was closed more.

Valve C was closed more.

Valve D was opened more.

2. Refer to the drawing of four air-operated valves (see figure below). Note: The valve actuators may be shown with or without air pressure applied.Which valves are currently shown in their failed (i.e., no air pressure applied to the actuator) positions? *

1 point

A and B

B and C

C and D

D and A

3. A typical check valve is designed to... *

1 point

permit flow in only one direction.

prevent system overpressure.

isolate system components.

perform automatic pump venting.

4. A steam flow measuring instrument uses density compensation and square root extraction to convert the differential pressure across the flow element to flow rate in lbm/hr. The purpose of density compensation in this flow measuring instrument is to convert __________ into __________. *

1 point

volumetric flow rate; mass flow rate

steam pressure; mass flow rate

steam velocity; volumetric flow rate

differential pressure; volumetric flow rate

5. Refer to the drawing of a reactor vessel differential pressure (D/P) level detection system that was calibrated at 1,000 psia (see figure below). A reactor vessel cooldown has resulted in a decrease in reactor vessel pressure from 1,000 psia to 500 psia over several hours. Without density compensation of the level instrumentation, at the end of the cooldown, reactor vessel level indication would indicate __________ than actual level because the density of the water in the __________ has changed significantly. (Assume the reference leg does not flash to steam.) *

1 point

higher; reactor vessel

higher; reference leg

lower; reactor vessel

lower; reference leg

6. Refer to the simplified drawing of a control rod position detector circuit (see figure below). A magnet on the control rod extension (or drive) shaft sequentially closes individual reed switches mounted vertically adjacent to the control rod drive housing. A constant +5 DC volts is supplied to the input of the resistor network at resistor R1. A control rod is initially fully inserted such that all reed switch contacts are open; then the rod is withdrawn until reed switch contact S1 is closed. Compared to the initial circuit currents, the current through resistor R5 after the rod withdrawal will be __________; and the output current of the resistor network to the amplifier will be __________. *

1 point

lower; higher

lower; lower

higher; higher

higher; lower

7. Following a loss-of-coolant accident, a reactor scram resulted. The source range monitors (SRMs) were inserted and are currently positioned in a voided region of the core. If the SRMs are subsequently repositioned to a water-filled region of the core, the indicated count rate will __________; primarily due to a __________ in the water-filled region of the core. *

1 point

decrease, smaller fast neutron flux

decrease, smaller thermal neutron flux

increase, larger fast neutron flux

increase, larger thermal neutron flux

8. A vertical safety valve with a 3-inch diameter disk has a spring applying 1000 lbf to the top of the valve disk in opposition to system pressure. Which one of the following is the approximate system pressure at which the safety valve will begin to open? *

1 point

35 psig

141 psig

444 psig

111 psig

9. A main steam system uses a combination of safety and relief valves for overpressure protection. Which one of the following describes a major design consideration for installing both types of valves in the same system? *

1 point

The safety valves are installed to prevent chattering of the relief valves during normal power operation.

The safety valves are installed to prevent unnecessary opening of the relief valves during a steam pressure transient.

The relief valves are installed to prevent chattering of the safety valves during normal power operation.

The relief valves are installed to prevent unnecessary opening of the safety valves during a steam pressure transient.

10. Refer to the drawing of a cooling water system in which both centrifugal pumps A and B are operating (see figure below). An operator stops pump B, but the pump B check valve fails to close. In comparison to normal operation with only pump A running, operation with the failed pump B check valve will result in pump A flow rate being __________ than normal; and heat exchanger flow rate being __________ than normal. *

1 point

higher; higher

higher; lower

lower; higher

lower; lower

11. Two common types of check valves used in nuclear power plants are... *

1 point

globe and gate.

ball and plug.

swing and lift.

needle and angle.

12. What happens to the pressure and velocity of water as it passes through a venturi? *

1 point

Pressure remains constant, but the velocity increases as the diameter of the venturi decreases.

Pressure increases, but the velocity decreases as the diameter of the venturi decreases.

Pressure decreases, but the velocity remains constant as the diameter of the venturi increases.

Pressure increases, but the velocity decreases as the diameter of the venturi increases.

13. Refer to the drawing of a reactor vessel (RV) differential pressure (D/P) level detection system (see figure below) that was recently calibrated at normal operating conditions. With the reactor shut down, RV pressure was inadvertently decreased from 1000 psig to 500 psig in 5 minutes due to operator error. RV pressure was stabilized at 500 psig, but during the pressure decrease a small amount of water in the condensing chamber flashed to steam. Assume the reference leg water remained subcooled, except for the small amount of water that flashed to steam in the condensing chamber. As a result of the small loss of condensing chamber water, RV level will indicate __________ than actual level; and as the condensing chamber refills, indicated level will __________. *

1 point

higher; decrease and stabilize above the actual level

higher; decrease and stabilize below the actual level

lower; increase and stabilize above the actual level

lower; increase and stabilize below the actual level

14. Gamma radiation contributes to the output of a fission chamber mainly by interacting with the... *

1 point

detector gas.

detector leads.

center electrode.

U-235 coating on the detector walls.

15. Fission chamber detectors are used to monitor reactor power/neutron level in a shutdown reactor as well as a reactor operating at rated power (and all power levels in between). At what power level(s) is it necessary to compensate the output of the fission chamber detectors for gamma interactions with the detectors and why? *

1 point

At all power levels, because gamma interactions produce larger detector pulses than neutron interactions.

At all power levels, because gamma interactions produce smaller detector pulses than neutron interactions.

Only when shutdown or at low power levels, because gamma flux is not proportional to reactor power at low power levels.

Only when operating at high power levels, because gamma flux is not proportional to reactor power at high power levels.

16. Which one of the following lists the two types of gas-filled radiation detectors whose outputs will be least affected by a small variation (±10 volts) in the voltage applied to the detectors? (Assume the applied voltage remains within normal range.) *

1 point

Limited proportional and Geiger-Mueller

Ion chamber and proportional

Proportional and limited proportional

Geiger-Mueller and ion chamber

17. The difference between the setpoint in an automatic controller and the steady-state value of the controlled parameter is called... *

1 point

offset.

gain.

deadband.

feedback.

18. Refer to the drawing of a water storage tank with a level control system (see figure below). The tank water level is being automatically controlled at 50 percent by a proportional-integral (PI) controller that positions the drain valve. Tank water level is currently stable with 500 gpm entering the tank and the drain valve is 50 percent open. Tank inlet flow rate suddenly increases to 700 gpm and remains constant. When tank water level stabilizes, level will be __________; and the drain valve position will be __________. *

1 point

higher than 50 percent; more open

higher than 50 percent; the same

50 percent; more open

50 percent; the same

19. Refer to the drawing of a lube oil temperature control system (see figure below). The temperature control valve is currently 50 percent open.If the cooling water inlet temperature decreases, the temperature controller will position the temperature control valve more __________, causing cooling water differential temperature through the heat exchanger to __________. *

1 point

closed; increase

closed; decrease

open; increase

open; decrease

20. Which one of the following changes in nuclear power plant status will bring the reactor recirculation system closer to the condition in which the recirculation pump will cavitate? *

1 point

During a plant shutdown, recirculation pump suction temperature decreases while reactor pressure remains constant.

Recirculation pump speed increases.

Reactor water level increases.

During reactor power operations, extraction steam to one of the high pressure feedwater heaters isolates.

21. Refer to the drawing of a cooling water system and the associated pump/system operating curves (see figure below). Pumps A and B are identical single-speed centrifugal pumps and initially only pump A is operating. Pump B is then started. After the system stabilizes, system flow rate will be...

1 point

the same as the initial flow rate.

less than twice the initial flow rate.

twice the initial flow rate.

more than twice the initial flow rate.

Clear selection

22. Which one of the following will provide the first motor protection against electrical damage caused by gradual bearing degradation? *

1 point

Thermal overload device

Overcurrent trip relay

Underfrequency relay

Undervoltage device

23. Which one of the following types of neutrons has an average neutron generation lifetime of 12.5 seconds? *

1 point

Prompt

Delayed

Fast

Thermal

24. Which one of the following conditions describes a reactor that is exactly critical? *

1 point

Keff = 0; ΔK/K = 0

Keff = 0; ΔK/K = 1

Keff = 1; ΔK/K = 0

Keff = 1; ΔK/K = 1

25. Which one of the following defines K-excess? *

1 point

Keff - 1

Keff + 1

(Keff - 1)/Keff

(1-Keff)/Keff

26. The shutdown margin (SDM) upon full insertion of all control rods following a reactor scram from full power is __________ the SDM immediately prior to the scram. *

1 point

less than

equal to

greater than

independent of

27. One hour ago, a reactor scrammed from steady-state 100 percent power due to an instrument malfunction. All systems operated normally. Given the following absolute values of reactivities added since the scram, assign a (+) or (–) as appropriate and choose the current value of core reactivity. I) Xenon = ( ) 1,0 %ΔK/K II) Fuel temperature = ( ) 2,0 %ΔK/K III) Control rods = ( ) 14,0 %ΔK/K IV) Voids = ( ) 3,0 %ΔK/K *

1 point

-8,0 %ΔK/K

-14,0 %ΔK/K

-20,0 %ΔK/K

-10,0 %ΔK/K

28. If reactor power changes from 10^-(5) percent to 10^(-6) percent in 5 minutes, the average reactor period is:

1 point

negative 80 seconds.

positive 80 seconds.

negative 130 seconds.

positive 130 seconds.

Clear selection

29. Reactor power was increased from 20 percent to 30 percent in one hour using only control rod withdrawal. Which one of the following describes the response of void fraction during the power increase? *

1 point

Void fraction initially decreases, then increases back to the original value.

Void fraction initially increases, then decreases back to the original value.

Void fraction decreases and stabilizes below the original value.

Void fraction increases and stabilizes above the original value.

30. Initially, a nuclear power plant is operating at steady-state 100 percent power and 100 percent core flow rate. Then, reactor power is reduced to 90 percent by inserting control rods. (Assume that recirculation pump speed and valve positions do not change.) What is the effect of the power reduction on core flow rate? *

1 point

Core flow rate will increase, due to a decrease in recirculation ratio.

Core flow rate will increase, due to a decrease in two-phase flow resistance.

Core flow rate will decrease, due to an increase in recirculation ratio.

Core flow rate will decrease, due to an increase in two-phase flow resistance.

31. Reactors A and B are identical and have operated at 100 percent power for six months when a reactor scram occurs simultaneously on both reactors. All control rods fully insert, except for one reactor B control rod that remains fully withdrawn. Which reactor, if any, will have the longer reactor period five minutes after the scram, and why? *

1 point

Reactor A, due to the greater shutdown reactivity.

Reactor B, due to the smaller shutdown reactivity.

Both reactors will have the same reactor period because both reactors will be stable at a power level low in the source range.

Both reactors will have the same reactor period because only the longest-lived delayed neutron precursors will be releasing fission neutrons.

32. Which one of the following increases in void fraction would produce the greatest amount of negative reactivity? *

1 point

From 5 percent to 10 percent near the beginning of a fuel cycle.

From 5 percent to 10 percent near the end of a fuel cycle.

From 40 percent to 45 percent near the beginning of a fuel cycle.

From 40 percent to 45 percent near the end of a fuel cycle.

33. Reactors A and B are identical except that reactor A has an effective delayed neutron fraction of 0,007 and reactor B has an effective delayed neutron fraction of 0,006. Initially, both reactors are critical at 1,0*10^(-8) percent power when +0,1 %ΔK/K is simultaneously added to both reactors. Five minutes after the reactivity additions, reactor _____ will be at the higher power level; and reactor _____ will have the shorter period. *

1 point

A; A

A; B

B; A

B; B

34. A reactor startup is in progress following a one-month shutdown. Upon reaching criticality, the operator establishes a positive 80-second period and stops control rod motion.After an additional five minutes, reactor power will be __________; and reactor period will be __________. (Assume reactor power remains below the point of adding heat.) *

1 point

constant; constant

constant; increasing

increasing; constant

increasing; increasing

35. A reactor startup is being performed by adding equal amounts of positive reactivity and waiting for neutron population to stabilize. As the reactor approaches criticality, the numerical change in stable neutron population resulting from each reactivity addition will __________; and the time required for the neutron population to stabilize after each reactivity addition will __________. *

1 point

increase; remain the same

increase; increase

remain the same; remain the same

remain the same; increase

36. A reactor startup is in progress with a current Keff of 0,95 and a stable source range count rate of 120 cps. Which one of the following stable count rates will occur when Keff becomes 0,98? *

1 point

210 cps

245 cps

300 cps

375 cps

37. Refer to the drawing of two water storage tanks with four differential pressure (D/P) level detectors (see figure below). The tanks are identical and are being maintained at 2 psig overpressure, 60°F, and the same constant water level. The tanks are located within a sealed containment structure that is being maintained at standard atmospheric pressure. All level detectors have been calibrated and are producing the same level indication.If a ventilation malfunction causes the containment structure pressure to decrease to 13 psia, which detectors will produce the highest level indications? *

1 point

1 and 2

3 and 4

1 and 4

2 and 3

38. For which of the following ideal processes, if any, is the steam inlet enthalpy equal to the steam outlet enthalpy? (Assume horizontal fluid flow in each process.) (A) Dry saturated steam flowing through a pressure reducing valve. (B) Dry saturated steam flowing through a fixed convergent nozzle. *

1 point

(A) only

(B) only

Both (A) and (B)

Neither (A) nor (B)

39. Refer to the drawing of a simple Rankine cycle shown on a Temperature-Entropy (T-S) diagram (see figure below). The starting point for the numbers on the diagram was chosen at random.Note: A simple Rankine cycle does not include condensate/feedwater heating, turbine exhaust moisture removal, or steam reheat.The sequence of numbers that represents the total heat added in the reactor vessel is __________; and the sequence of numbers that represents the total heat rejected in the main condenser is __________. *

1 point

2 → 3 → 4; 1 → 2

3 → 4 → 5; 1 → 2

2 → 3 → 4; 5 → 1

3 → 4 → 5; 5 → 1

40. Refer to the drawing of a lube oil heat exchanger (see figure below). The lube oil heat exchanger is in operation when the cooling water flow rate is increased to twice its former value. Which one of the following will increase as a result? *

1 point

Lube oil outlet temperature

Cooling water outlet temperature

Lube oil differential temperature

Cooling water differential temperature

41. Refer to the drawing of a pool boiling curve (see figure below). In which region(s) of the curve does a reactor normally operate to transfer heat from the fuel cladding to the coolant at 100 percent power? *

1 point

Regions II and III

Region II only

Regions I and II

Region I only

42. Refer to the drawing of a hypothetical fuel bundle coolant channel (see figure below). For the hypothetical fuel bundle coolant channel shown below, at what point along its length does transition boiling begin? *

1 point

43. Refer to the drawing of a core recirculation jet pump (see figure below). During normal operation, the lowest pressure will exist at point _____; and the highest velocity will occur at point _____. *

1 point

3; 3

3; 4

4; 3

4; 4

44. The radial peaking factor for a fuel bundle is expressed mathematically as... *

1 point

core average bundle power / individual bundle power

peak nodal power / core average nodal power

core average nodal power / peak nodal power

individual bundle power / core average bundle power

45. A BWR core consists of 30 000 fuel rods. Each fuel rod has an active length of 12 feet. The core is producing 1 800 MW of thermal power. If the total peaking factor for a node is 1,6, what is the maximum local linear power density being produced in the node? *

1 point

4.0 kW/ft

6.0 kW/ft

8.0 kW/ft

10.0 kW/ft

46. The ratio of the highest fuel pin heat flux in a node to the average fuel pin heat flux in the same node is called the __________ peaking factor. *

1 point

local

radial

axial

total

47. Which one of the following is the most probable location for superheated steam in a boiling water reactor steam cycle that uses moisture-separator reheaters? *

1 point

The outlet of the high pressure turbine.

The inlet of the low pressure turbines.

The inlet of the high pressure turbine.

The outlet of the low pressure turbines.

48. What effect will occur if heat is removed from water that is in a subcooled condition? *

1 point

The enthalpy of the water will decrease.

The temperature of the water will increase.

The quality of the water will increase.

The density of the water will decrease.

49. A nuclear power plant is operating at 80 percent power with 5°F of condensate depression in the main condenser. If the condensate depression decreases to 2°F, the steam cycle thermal efficiency will __________; and the condensate pumps will operate __________ cavitation. *

1 point

increase; closer to

increase; farther from

decrease; closer to

decrease; farther from

50. In a reactor operating at 100 percent power, reactor pressure suddenly increases. Which one of the following is the most limiting thermal limit for this situation? *

1 point

Linear heat generation rate.

Average planar linear heat generation rate.

Critical power ratio.

Preconditioning interim operating management recommendations.

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