Test wiedzy na operatora reaktora PWR
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.
1. For water flowing through a venturi, there is a proportional relationship between flow rate and differential pressure. For steam flowing through a venturi, the relationship must be modified to account for changes in ___ as the steam flows through the venturi.
2. An operator attempts to close a fully-open upright manual gate valve to isolate a pump in a cooling water system that has been cooled down for maintenance. However, the operator is unable to rotate the handwheel in the close direction. Which one of the following could cause this condition?
A hydraulic lock has developed under the valve disk.
A hydraulic lock has developed in the valve bonnet between the valve disk and the packing gland.
The two halves of the valve disk have expanded and are jammed against the valve seats.
The valve disk has jammed against its backseat by the difference in the thermal contraction of the stem and the bonnet.
3. Which one of the following describes the function and use of the backseat on a manual valve?
Removes pressure from the packing/stuffing box and is typically used to isolate the stuffing box for valve repacking.
Removes pressure from the packing/stuffing box and is typically used when needed to isolate packing leakage.
Acts as a backup in case the primary seat leaks and is typically used during system isolation for personnel protection.
Acts as a backup in case the primary seat leaks and is typically used when needed to prevent the primary seat from leaking excessively.
4. Refer to the drawing of a water supply pump with two suction sources (see figure below). All motor-operated valves (MOVs) are currently closed. Which one of the following MOV interlocks will permit the pump to take a suction on either the building sump or the water storage tank, while preventing the two sources from being cross-connected?
Neither MOV-1 nor MOV-2 can be opened unless MOV-3 is fully closed.
None of the MOVs can be opened unless at least one MOV remains fully closed.
None of the MOVs can be opened unless at least two MOVs remain fully closed.
Neither MOV-1 nor MOV-2 can be opened unless the other source MOV is fully closed.
5. Refer to the simplified drawing of a control rod position detector (see figure below). Coils of wire connected to an AC power supply are being used to monitor the position of a control rod in a reactor. The coils are mounted in a column outside the reactor vessel head such that the steel control rod drive shaft passes upward through the coils as the control rod is withdrawn. Currently, the top of a control rod drive shaft is located between coils A and B as shown. The control rod is to be withdrawn until the top of the control rod drive shaft is located just below coil C. Compared to the initial coil output currents, after the control rod is withdrawn the output current of coil A will be __________; and the output current of coil B will be __________.
the same; higher
the same; lower
6. An air-operated isolation valve requires 2 400 pounds-force applied to the top of the actuator diaphragm to open. The actuator diaphragm has a surface area of 60 square inches and the valve stem travels 2 inches from fully open to fully closed. If control air pressure to the valve actuator begins to increase from 0 psig, which one of the following is the approximate air pressure required to open the valve?
7. Refer to the valve controller logic diagram (see figure below). Which one of the following combinations of inputs will result in the valve receiving an OPEN signal?
1 - On, 2 - Off, 3 - Off, 4 - On
1 - Off, 2 - On, 3 - On, 4 - Off
1 - On, 2 - Off, 3 - On, 4 - Off
1 - Off, 2 - On, 3 - Off, 4 - On
8. An outside water storage tank is equipped with submerged heaters. The heaters energize at minimum power when water temperature decreases to 48°F. If water temperature continues to decrease, heater power will increase directly with the temperature deviation from 48°F until maximum power is reached at 40°F. On cold days, the tank water temperature is usually maintained at about 44°F with the heaters energized at half power. Which one of the following types of control is used in the heater control circuit to produce these characteristics?
Proportional plus integral only
Proportional plus derivative only
Proportional plus integral plus derivative
9. Refer to the drawing of a flow control valve (see figure below) that is located in the drain line from a water storage tank. The flow control valve is positioned by a level controller that can maintain a stable tank water level anywhere between 10 percent above and 10 percent below the controller setpoint. The level controller receives input from a direct-acting level detector. Which one of the following describes the characteristics of the tank level controller?
Direct-acting with proportional only control.
Direct-acting with proportional plus integral control.
Reverse-acting with proportional only control.
Reverse-acting with proportional plus integral control.
10. A centrifugal pump is operating normally in an open system with all valves fully open. If the pump discharge valve is throttled to 50 percent, pump suction pressure will __________; and pump discharge pressure will __________.
11. Centrifugal pumps A and B are identical except that pump A uses a single-suction impeller while pump B uses a double-suction impeller. If both pumps are pumping water at the same inlet temperature, inlet pressure, and flow rate, single-suction pump A typically will have the __________ impeller axial thrust and the __________ required net positive suction head.
12. Refer to the drawing of an operating cooling water system (see figure below). The pump is unable to achieve its rated volumetric flow rate due to cavitation. Which one of the following will enable the pump to achieve a higher volumetric flow rate before cavitation occurs?
Decrease the service water flow rate.
Operate the system at a lower pressure.
Remove the existing pump motor and install a motor with a higher horsepower rating.
Move the surge tank connection closer to the suction of the pump.
13. A nuclear power plant is operating at steady-state 80 percent power when a reactor coolant pump (RCP) shaft seizes. Which one of the following indications would not accompany the seized shaft?
Reactor coolant system pressure transient.
Decreased flow rate in the associated reactor coolant loop.
Decreased flow rate in the remaining reactor coolant loop(s).
Increased current to the affected RCP with possible breaker trip.
14. A large AC motor has a maximum ambient temperature rating of 40°C. Which one of the following will occur if the motor is continuously operated at rated load with an ambient temperature of 50°C?
Accelerated embrittlement of the motor windings, leading to an open circuit within the motor windings.
Accelerated embrittlement of the motor windings, leading to a short circuit within the motor windings.
Accelerated breakdown of the motor winding insulation, leading to an open circuit within the motor windings.
Accelerated breakdown of the motor winding insulation, leading to a short circuit within the motor windings.
15. A main generator that is connected to an infinite power grid has the following indications: 500 MW; 300 MVAR (out);2,800 amps. If main generator field current is reduced slightly, amps will __________; and MW will __________.
decrease; remain the same
increase; remain the same
16. If the speed of a centrifugal pump is increased to double pump flow rate, pump motor current will...
increase two-fold (double).
17. Which one of the following describes the relationship between the current drawn by an AC induction motor and the amount of heat generated in the motor windings?
Heat generation is directly proportional to the current.
Heat generation is proportional to the cube of the current.
Heat generation is proportional to the square of the current.
Heat generation is proportional to the square root of the current.
18. Which one of the following statements describes the use of high-voltage disconnect switches?
Their use should be limited to normal load current interruption.
They may be used to isolate transformers in an unloaded network.
They trip open like circuit breakers, but must be manually closed.
They must be closed with caution when under load because of possible arcing.
19. A fission chamber neutron monitoring instrument is operating in the proportional region. If a complete loss of fission chamber gas pressure occurs, the instrument indication will fail...
20. A Geiger-Mueller detector with a a "pancake" probe is being used to monitor workers leaving a radiologically controlled area for contamination. The probe is sensitive to alpha, beta, and gamma radiation. The background count rate is 20 cpm. As one worker’s shoe is scanned the count rate increases to 1,000 cpm. Given the following separate actions: 1) When a sheet of paper is placed between the probe and the shoe, the count rate decreases to 600 cpm. 2) When a sheet of aluminum foil is placed between the probe and the shoe, the count rate decreases to 600 cpm. Which one of the following lists the type(s) of radiation being emitted by the contamination?
Alpha and gamma
Beta and gamma
21. A fission chamber detector is initially operating in the proportional region to measure neutron flux in the source range. If the voltage applied to the detector is changed so that the detector now operates in the ion chamber region, the detector will produce __________ pulses; and will experience a __________ positive space charge effect.
22. During a refueling outage, the fuel assemblies were reconfigured to reduce the radial power peak at the center of the core while maintaining the same rated thermal power. Excore power range detectors were calibrated at 50 percent power just prior to the outage. How will indicated reactor power compare to actual reactor power when the nuclear power plant is stabilized at 50 percent power following the outage?
Indicated reactor power will be higher than actual reactor power due to increased core neutron leakage.
Indicated reactor power will be higher than actual reactor power due to decreased core neutron leakage.
Indicated reactor power will be lower than actual reactor power due to decreased core neutron leakage.
Indicated reactor power will be lower than actual reactor power due to increased core neutron leakage.
23. A critical reactor will become prompt critical when the reactivity is equal to the...
effective delayed neutron fraction.
effective decay constant.
worth of the most reactive rod.
24. A reactor is operating at 75 percent power with the following conditions: 1) Power defect = -0.0157 Δ/K/K 2) Shutdown margin = 0,0241 Δ/K/K 3) Effective delayed neutron fraction = 0,0058 4) Effective prompt neutron fraction = 0,9942. How much positive reactivity must be added to make the reactor prompt critical?
25. During a reactor coolant system cooldown, positive reactivity is added to the core if the moderator temperature coefficient is negative. This is partially due to...
a decreasing thermal utilization factor.
an increasing thermal utilization factor.
a decreasing resonance escape probability.
an increasing resonance escape probability.
26. Why does the fuel temperature coefficient becomes less negative at higher fuel temperatures?
As reactor power increases, the rate of increase in the fuel temperature diminishes.
Neutrons penetrate deeper into the fuel, resulting in an increase in the fast fission factor.
The amount of self-shielding increases, resulting in less neutron absorption by the inner fuel.
The amount of Doppler broadening per degree change in fuel temperature diminishes.
27. A reactor has been shut down for three weeks with all control rods fully inserted. If a single control rod is fully withdrawn from the core, neutron flux level will… (Assume the reactor remains subcritical.)
increase and stabilize above the original level.
increase, then decrease and stabilize at the original level.
increase, then decrease and stabilize above the original level.
remain the same during and after the withdrawal.
28. Reactor power is increased from 50 percent to 60 percent in one hour. What is the most significant contributor to the initial change in xenon-135 reactivity?
Production of xenon-135 directly from fission.
Production of xenon-135 from iodine-135 decay.
Loss of xenon-135 due to absorption of neutrons.
Loss of xenon-135 due to decay to cesium-135.
29. A nuclear power plant was operating with the following initial steady-state conditions: A) Power level = 80 percent B) Reactor coolant boron concentration = 630 ppm C) Average reactor coolant temperature = 582°F. After a normal load decrease, the current steady-state conditions are as follows: A) Power level = 50 percent B) Reactor coolant boron concentration = 650 ppm c) Average reactor coolant temperature = 572°F. Given the following values, how much reactivity was added by control rod movement during the load decrease? (Assume fission product poison reactivity does not change.) 1) Total power coefficient = -1,5*10^(-2) %ΔK/K/% 2) Moderator temperature coefficient = -2,0*10^(-2) %ΔK/K/°F 3) Differential boron worth = -1,5*10^(-2) %ΔK/K/ppm
30. A reactor was operating at 50 percent power for one week when power was ramped to 100 percent. Which one of the following describes the equilibrium xenon-135 concentration at 100 percent power?
Twice the 50 percent power concentration.
Less than twice the 50 percent power concentration.
More than twice the 50 percent power concentration.
Remains the same, because it is independent of power.
31. Reactors A and B are operating at steady-state 100 percent power with equilibrium xenon-135. The reactors are identical except that reactor A is operating near the end of a fuel cycle (EOC) and reactor B is operating near the beginning of a fuel cycle (BOC). Which reactor has the greater concentration of xenon-135, and why?
Reactor A (EOC), due to the smaller 100 percent power thermal neutron flux.
Reactor A (EOC), due to the larger 100 percent power thermal neutron flux.
Reactor B (BOC), due to the smaller 100 percent power thermal neutron flux.
Reactor B (BOC), due to the larger 100 percent power thermal neutron flux.
32. A reactor was operating for several months at 100 percent power when a reactor trip occurred. Which one of the following is primarily responsible for the startup rate value 2 minutes after the trip?
The Keff in the core.
The rate of source neutron production in the core.
The effective delayed neutron fraction in the core.
The decay rates of the delayed neutron precursors in the core.
33. With Keff equal to 0,982, how much positive reactivity is required to make the reactor critical? (Round answer to the nearest 0,01 %ΔK/K.)
34. Which one of the following is the reason that delayed neutrons are so effective at controlling the rate of reactor power changes?
Delayed neutrons make up a large fraction of the fission neutrons compared to prompt neutrons.
Delayed neutrons have a long mean generation time compared to prompt neutrons.
Delayed neutrons produce a large amount of fast fission compared to prompt neutrons.
Delayed neutrons are born with high kinetic energy compared to prompt neutrons.
35. Integral rod worth is the...
change in reactivity per unit change in control rod position.
rod worth associated with the most reactive control rod.
change in worth of a control rod per unit change in reactor power.
reactivity added by moving a control rod from one position to another position.
36. Which one of the following indicates that a reactor has achieved criticality during a normal reactor startup?
Constant positive startup rate during rod withdrawal.
Increasing positive startup rate during rod withdrawal.
Increasing positive startup rate with no rod motion.
Constant positive startup rate with no rod motion.
37. 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.
Both (A) and (B)
Neither (A) nor (B)
38. Which one of the following describes the temperature of a saturated liquid?
At the boiling point.
Below the boiling point.
Above the boiling point.
Unrelated to the boiling point.
39. Departure from nucleate boiling should not be allowed to occur in the core because...
as steam bubbles begin to blanket the fuel rod, the radiative heat transfer decreases.
as steam bubbles in the coolant form and then collapse, water hammer occurs.
as steam bubbles begin to blanket the fuel rod, its temperature rises sharply.
as steam bubbles form in the coolant, voids-induced reactivity changes cause undesirable power changes.
40. Subcooled water enters a fuel assembly in a reactor operating at power. As the water flows upward through the fuel assembly, the water begins to boil and exits the fuel assembly as a saturated steam-water mixture.If fuel assembly power is unchanged and system pressure is increased such that all of the water remains subcooled, the average fuel temperature in the fuel assembly would be __________ because boiling is a __________ efficient method of heat transfer.
41. A reactor is currently producing 200 MW of core thermal power. Reactor coolant pumps are adding an additional 10 MW of thermal power to the reactor coolant system. The core is rated at 1 330 MW. Which one of the following is the current core thermal power output in percent?
42. Refer to the drawing of a venturi in a steam line (see figure below). The venturi inlet and outlet pipe diameters at P1 and P2 are equal. Currently, steam is flowing through the venturi, reaching sonic velocity in the throat of the venturi. If the steam inlet pressure (P1) remains constant while the downstream pressure (P2) decreases, the mass flow rate of the steam will __________; and the velocity of the steam at the venturi outlet will __________.
increase; remain the same
remain the same; increase
remain the same; remain the same
43. Operating two pumps in parallel instead of operating a single pump will result in a...
large increase in pump head and a small increase in pump flow rate.
small increase in pump head and a small increase in pump flow rate.
small increase in pump head and a large increase in pump flow rate.
large increase in pump head and a large increase in pump flow rate.
44. Which one of the following explains why condensate subcooling is necessary in a nuclear power plant steam cycle?
To provide a better condenser vacuum.
To maximize overall steam cycle thermal efficiency.
To provide net positive suction head for the condensate pumps.
To minimize turbine blade and condenser tube erosion by entrained moisture.
45. Condensate depression is the process of...
removing condensate from turbine exhaust steam.
spraying condensate into turbine exhaust steam.
heating turbine exhaust steam above its saturation temperature.
cooling turbine exhaust steam below its saturation temperature.
46. Any vapor having a temperature above saturation temperature is a...
dry saturated vapor.
wet saturated vapor.
47. A nuclear power plant is shut down with the pressurizer in a saturated condition as follows: 1) Pressurizer liquid temperature = 588°F 2) Pressurizer vapor temperature = 588°F 3) Pressurizer pressure = 1 410 psia. Pressurizer heaters are energized to raise pressurizer pressure to 1 450 psia. When pressurizer pressure stabilizes at 1 450 psia, liquid temperature will be __________ and vapor temperature will be __________.
the same; the same
the same; higher
higher; the same
48. Refer to the drawing of a water-filled manometer (see figure below). The manometer is installed across an orifice in a ventilation duct to determine the direction of airflow. With the manometer conditions as shown, the pressure at P1 is __________ than P2; and the direction of airflow is __________.
less; right to left
less; left to right
greater; right to left
greater; left to right
49. How does critical heat flux (CHF) vary with core height during normal full power operation?
CHF increases from the bottom to the top of the core.
CHF decreases from the bottom to the core midplane, then increases from the midplane to the top of the core.
CHF decreases from the bottom to the top of the core.
CHF increases from the bottom to the core midplane, then decreases from the midplane to the top of the core.
50. A reactor is operating at steady-state 80 percent power with all control rods fully withdrawn and in manual control. Compared to a 50 percent insertion of one control rod, a 50 percent insertion of a group (or bank) of control rods will cause a __________ increase in the maximum axial peaking factor and a __________ increase in the maximum radial peaking factor. (Assume reactor power remains constant.)
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