Sensors and Detectors Flashcards
Density input is normally used in steam flow instruments to convert __________ into __________.
A. mass flow rate; volumetric flow rate
B. volumetric flow rate; mass flow rate
C. mass flow rate; differential pressure
D. differential pressure; volumetric flow rate
volumetric flow rate; mass flow rate
If the steam pressure input to a density-compensated steam flow instrument fails high, the associated
flow rate indication will…
A. decrease, because the density input has decreased.
B. increase, because the density input has decreased.
C. decrease, because the density input has increased.
D. increase, because the density input has increased.
increase, because the density input has increased.
The density compensating input to a steam flow instrument is used to convert volumetric flow rate
into…
A. velocity flow rate.
B. gallons per minute.
C. mass flow rate.
D. differential flow rate.
mass flow rate.
If the steam pressure input to a density-compensated steam flow instrument fails low, the indicated
flow rate will…
A. increase, because the density input has increased.
B. decrease, because the density input has increased.
C. increase, because the density input has decreased.
D. decrease, because the density input has decreased.
decrease, because the density input has decreased.
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
__________.
A. volumetric flow rate; mass flow rate
B. steam pressure; mass flow rate
C. steam velocity; volumetric flow rate
D. differential pressure; volumetric flow rate
volumetric flow rate; mass flow rate
A main steam flow rate differential pressure detector was properly calibrated to produce a main steam
flow rate indication of 500,000 lbm/hr with the following initial input conditions:
Detector high pressure input = 1,000 psia
Detector low pressure input = 950 psia
The current detector input conditions are as follows:
Detector high pressure input = 985 psia
Detector low pressure input = 935 psia
Assume that the detector and associated circuitry do not have steam density compensation. Also,
assume that the main steam quality and volumetric flow rate do not change.
The current main steam flow rate indication is __________ 500,000 lbm/hr; and the current main
steam flow rate is __________ 500,000 lbm/hr.
A. equal to; greater than
B. less than; greater than
C. equal to; less than
D. greater than; less than
equal to; less than
A nuclear power plant is initially operating with the following main steam parameter values:
Main steam pressure = 1,000 psia
Main steam flow rate = 500,000 lbm/hr
Main steam pressure decreases and stabilizes at 950 psia.
Assume 100 percent quality saturated steam and that main steam volumetric flow rate is the same
before and after the pressure change.
Which one of the following is the approximate mass flow rate of main steam after the pressure
change?
A. 528,000 lbm/hr
B. 500,000 lbm/hr
C. 472,000 lbm/hr
D. 444,000 lbm/hr
472,000 lbm/hr
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.
A. velocity
B. enthalpy
C. internal energy
D. specific volume
specific volume
A nuclear power plant is operating at 100 percent power with constant steam generator water levels.
Only main feedwater is entering the steam generators and only main steam is leaving the steam
generators. Both the main feedwater mass flow rate and the main steam mass flow rate instruments
use venturi flow sensing elements.
For the above conditions, the indication that most accurately reflects the mass flow rate through a
steam generator will typically be the mass flow rate indication for…
A. main feedwater, because condensation can adversely affect the characteristics of a steam flow
venturi.
B. main feedwater, because steam generator pressure changes affect the specific volume of steam
more than water.
C. main steam, because the enthalpy of high quality steam flowing through a venturi is constant,
unlike the enthalpy of water.
D. main steam, because a given mass flow rate of steam through a venturi develops a larger pressure
change than the same mass flow rate of water.
main feedwater, because steam generator pressure changes affect the specific volume of steam
more than water.
The most probable cause for fluctuating indication from a liquid flow rate differential pressure
detector is…
A. gas or steam being trapped in the liquid.
B. unequal temperature gradients in the liquid.
C. vortexing of the liquid passing through the flow device.
D. the valve on the high pressure sensing line being partially closed.
gas or steam being trapped in the liquid.
A properly calibrated differential pressure-type water flow detector is located several feet below a
horizontal pipe containing the detector’s sensing element. The detector was removed for inspection
and then reconnected to the sensing element with its low-pressure sensing line filled with air and its
high-pressure sensing line filled with water.
When the water system is operating, indicated flow rate will be…
A. zero.
B. equal to actual flow rate.
C. lower than actual flow rate.
D. higher than actual flow rate.
higher than actual flow rate.
How will flow rate indication be affected if the equalizing valve for the associated differential pressure
detector is fully opened?
A. Increase temporarily, and then return to the initial value.
B. Decrease temporarily, and then return to the initial value.
C. Increase to the maximum value.
D. Decrease to the minimum value.
Decrease to the minimum value.
A differential pressure flow detector is connected to a calibrated orifice in a cooling water system.
Which one of the following will cause indicated volumetric flow rate to be lower than actual
volumetric flow rate?
A. System pressure decreases.
B. The orifice erodes over time.
C. Debris becomes lodged in the orifice.
D. A leak develops in the low pressure sensing line.
The orifice erodes over time.
Flow rate is being measured using a differential pressure flow detector and a calibrated orifice. If
actual flow rate remains constant, which one of the following will cause indicated flow rate to be
higher than actual flow rate?
A. The flow detector equalizing valve is inadvertently opened.
B. A leak develops in the high pressure sensing line.
C. Debris becomes lodged in the orifice.
D. The orifice erodes over time.
Debris becomes lodged in the orifice.
Refer to the drawing of a pipe elbow used for flow measurement in a cooling water system (see figure
below).
A differential pressure (D/P) flow detector is connected to instrument lines A and B.
If instrument line A develops a leak, indicated flow rate will __________ due to a __________
measured D/P.
A. increase; larger
B. increase; smaller
C. decrease; larger
D. decrease; smaller
decrease; smaller
If the orifice in a differential pressure (D/P) flow sensor erodes such that the orifice opening becomes
larger, indicated flow rate will __________ due to a __________ D/P across the orifice. (Assume
actual flow rate remains the same.)
A. increase; larger
B. increase; smaller
C. decrease; larger
D. decrease; smaller
decrease; smaller
Refer to the drawing of a horizontal pipe elbow (top view) in an operating water system (see figure
below).
Three separate differential pressure flow detectors are connected to taps A, B, C, and D as follows:
Detector
Taps
X A and D
Y B and D
Z C and D
Assuming zero head loss in this section of pipe, how will the detectors be affected if tap D ruptures?
A. All detectors will fail low.
B. All detectors will fail high.
C. Two detectors will fail low and one will fail high.
D. Two detectors will fail high and one will fail low.
All detectors will fail low.
Refer to the drawing of a pipe elbow used for flow measurement in a cooling water system (see figure
below).
A differential pressure (D/P) flow detector is connected to instrument lines A and B.
If instrument line B develops a leak, indicated flow rate will __________ due to a __________
measured D/P.
A. increase; larger
B. increase; smaller
C. decrease; larger
D. decrease; smaller
increase; larger
An orifice is being used in an operating cooling water system to measure flow rate. Which one of the
following will cause the differential pressure sensed across the orifice to decrease?
A. System pressure decreases.
B. System flow rate decreases.
C. Debris becomes lodged in the orifice.
D. A leak develops in the low pressure sensing line.
System flow rate decreases.
Refer to the drawing of a horizontal pipe elbow (top view) in an operating water system (see figure
below). Three separate bellows differential pressure flow detectors are connected to taps A, B, C, and
D as follows:
Detector
Taps
X A and D
Y B and D
Z C and D
Assume that water is incompressible and there is no head loss in this section of pipe. How will the
detectors be affected if system flow rate remains the same while system pressure increases from 1000
psig to 1200 psig?
A. All detectors will indicate higher flow.
B. Only two detectors will indicate higher flow.
C. Only one detector will indicate higher flow.
D. Detector indication will not change.
Detector indication will not change.
Refer to the drawing of a horizontal pipe elbow (top view) in an operating water system (see figure
below).
Three separate bellows-type differential pressure flow detectors are connected to taps A, B, C, and D
as follows:
Detector
Taps
X A and D
Y B and D
Z C and D
Assuming zero head loss in this section of pipe, how will the detectors be affected if tap B experiences
a significant leak? (Assume water system pressure does not change.)
A. All detectors will fail low.
B. All detectors will fail high.
C. Only one detector will fail, and it will fail low.
D. Only one detector will fail, and it will fail high.
Only one detector will fail, and it will fail high.
A steam flow measuring instrument uses density compensation and square root compensation to
convert the differential pressure across a flow element to flow rate in lbm/hr.
The purpose of square root compensation in this flow measuring instrument is to convert __________
into __________.
A. volumetric flow rate; mass flow rate
B. volumetric flow rate; differential pressure
C. differential pressure; mass flow rate
D. differential pressure; volumetric flow rate
differential pressure; volumetric flow rate
Flow detectors (such as an orifice, flow nozzle, and venturi tube) measure flow rate using the principle
that the flow rate of a liquid is…
A. directly proportional to the differential pressure (D/P) squared.
B. inversely proportional to the D/P squared.
C. directly proportional to the square root of the D/P.
D. inversely proportional to the square root of the D/P.
directly proportional to the square root of the D/P.
A cooling water system is operating at steady-state conditions indicating 900 gpm with 60 psid across
the flow transmitter venturi. If cooling water flow rate is increased to 1,800 gpm, differential
pressure across the flow transmitter venturi will be approximately…
A. 85 psid.
B. 120 psid.
C. 175 psid.
D. 240 psid.
240 psid.
The flow rate of water passing through a venturi can be determined by measuring the…
A. differential pressure of the water as it passes through the venturi.
B. change in the velocity of the water as it passes through the venturi.
C. linear displacement of a metering plug installed in the throat of the venturi.
D. rotation rate of a paddle wheel-type device installed in the throat of the venturi.
differential pressure of the water as it passes through the venturi.
A cooling water system is operating at a steady-state flow rate of 700 gpm with 60 psid across the flow
transmitter venturi. If cooling water flow rate is increased to 1,000 gpm, differential pressure across
the flow transmitter venturi will be…
A. 85.7 psid.
B. 122.4 psid.
C. 171.4 psid.
D. 244.8 psid.
122.4 psid.
Refer to the drawing of a venturi flow element (see figure below) with direction of water flow
indicated by the arrow.
Where should the high pressure tap of a differential pressure flow detector be connected?
A. Point A
B. Point B
C. Point C
D. Point D
Point A
A differential pressure (D/P) detector is being used with a venturi to measure main steam flow rate.
With a steam flow rate of 5 x 10^6 lbm/hr, the measured D/P is 40 psid.
If steam flow changes such that the current D/P is 30 psid, what is the approximate current steam flow
rate? (Assume that main steam pressure at the inlet of the venturi remains constant.)
A. 2.1 x 10^6 lbm/hr
B. 3.5 x 10^6 lbm/hr
C. 3.7 x 10^6 lbm/hr
D. 4.3 x 10^6 lbm/hr
4.3 x 10^6 lbm/hr
Which one of the following flow measuring elements produces the largest unrecoverable head loss
when used in an operating fluid system?
A. Venturi
B. Flow nozzle
C. Pipe elbow
D. Orifice
Orifice
Refer to the drawing of a venturi flow element in an operating cooling water system (see figure
below).
At what point does the lowest pressure occur?
A. Point A
B. Point B
C. Point C
D. Point D
Point B
Refer to the drawing of a venturi flow element in an operating cooling water system (see figure
below).
A differential pressure detector measuring flow rate through the venturi will produce the highest flow
rate indication if its high-pressure tap is connected at point _____; and its low-pressure tap is
connected at point _____.
A. A; B
B. A; D
C. B; C
D. B; D
A; B
A cooling water system is operating at a steady-state flow rate of 500 gpm with 60 psid across the
associated venturi flow element. If cooling water flow rate increases to 1,000 gpm, the differential
pressure sensed by the venturi flow element will be approximately…
A. 85 psid.
B. 120 psid.
C. 240 psid.
D. 480 psid.
240 psid.
Refer to the drawing of a convergent-divergent venturi (see figure below). Subcooled water is
flowing through the venturi, and the pipe diameters at P1 and P2 are equal.
Compared to the conditions at the inlet of the venturi (P1), the pressure at the outlet of the venturi (P2)
is __________; and the water velocity at the outlet of the venturi is __________.
A. the same; the same
B. the same; slightly lower
C. slightly lower; the same
D. slightly lower; slightly lower
slightly lower; the same
Water is flowing through a venturi flow element. At the throat of the venturi, the __________ water
pressure and the __________ water velocity occurs.
A. highest; highest
B. lowest; lowest
C. lowest; highest
D. highest; lowest
lowest; highest
Water is flowing through each of the following devices. Which one of the devices will produce an
outlet pressure that is greater than the inlet pressure?
A. Convergent nozzle
B. Divergent nozzle
C. Orifice
D. Flow restrictor
Divergent nozzle
Refer to the drawing of a pipe elbow (top view) in an operating water system (see figure below).
At which one of the following pairs of connection points will the greatest differential pressure be
sensed? (Assume a constant pipe diameter and zero head loss in this section of pipe.)
A. Points A and B
B. Points B and C
C. Points C and D
D. Points D and A
Points B and C
A venturi is being used to measure the flow rate in a cooling water system. As the water flows from
the throat to the discharge of the venturi, water pressure will __________; and volumetric flow rate
will __________.
A. increase; remain the same
B. increase; increase
C. decrease; remain the same
D. decrease; decrease
increase; remain the same
A cooling water system is operating at a steady-state flow rate of 700 gpm with 60 psid across the
associated venturi flow element. If cooling water flow rate increases to 900 gpm, the differential
pressure sensed by the venturi flow element will be approximately…
A. 68 psid.
B. 77 psid.
C. 99 psid.
D. 127 psid.
99 psid.
A main steam flow rate measuring instrument uses a steam pressure input to produce main steam mass
flow rate indication. Assuming steam volumetric flow rate does not change, a steam pressure
decrease will cause indicated steam mass flow rate to…
A. increase, because the density of the steam has increased.
B. decrease, because the density of the steam has decreased.
C. remain the same, because steam pressure does not affect the mass flow rate of steam.
D. remain the same, because the steam pressure input compensates for changes in steam pressure.
decrease, because the density of the steam has decreased.
A differential pressure detector is being used with an orifice plate to measure water flow rate through a
pipe. When the flow detector was last calibrated, the following parameters were observed:
Upstream Pressure = 125 psig
Downstream Pressure = 116 psig
Actual Flow Rate = 100 gpm
Indicated Flow Rate = 100 gpm
Significant erosion of the orifice has occurred since the calibration such that actual flow rate through
the orifice has increased to 120 gpm while the upstream and downstream pressures have changed to
110 psig and 106 psig respectively.
What is the approximate flow rate that is currently indicated?
A. 44 gpm
B. 67 gpm
C. 81 gpm
D. 120 gpm
67 gpm
A cooling water system is operating at steady-state conditions at 900 gpm with 64 psid across the flow
transmitter venturi. Cooling water flow rate changes such that venturi differential pressure decreases
to 36 psid.
Which one of the following is the new system flow rate?
A. 506 gpm
B. 576 gpm
C. 675 gpm
D. 745 gpm
675 gpm
A differential pressure detector is being used with an orifice plate to measure water flow rate through a
pipe. When the flow detector was last calibrated, the following parameters were observed:
Upstream Pressure = 135 psig
Downstream Pressure = 120 psig
Actual Flow Rate = 100 gpm
Indicated Flow Rate = 100 gpm
Significant erosion of the orifice hole has occurred since the last calibration, such that actual flow rate
through the orifice has increased to 120 gpm while the upstream and downstream pressures have
changed to 124 psig and 109 psig respectively.
What is the currently indicated flow rate?
A. 44 gpm
B. 67 gpm
C. 100 gpm
D. 120 gpm
100 gpm
A cooling water system uses a horizontal venturi with a differential pressure flow detector to provide
flow rate indication. Water enters and leaves the venturi at 70°F, 120 psig, and 20 ft/sec. Water
velocity at the throat of the venturi is 45 ft/sec. Assume water is incompressible and the venturi
experiences no unrecoverable head loss.
What is the approximate pressure of the water at the throat of the venturi?
A. 109 psig
B. 98 psig
C. 86 psig
D. 71 psig
109 psig
A cooling water system is operating at steady-state conditions. A calibrated system flow meter
indicates 600 gpm with 50 psid across the flow element.
If cooling water flow rate increases to 900 gpm, the differential pressure sensed by the flow element
will be approximately…
A. 63 psid.
B. 75 psid.
C. 97 psid.
D. 112 psid.
112 psid.
The following is the current calibration data for an orifice plate that is being used for water flow rate
measurement:
Upstream Pressure = 135 psig
Downstream Pressure = 120 psig
Flow Rate = 100 gpm
During a surveillance, the following pressures are observed across the orifice plate:
Upstream Pressure = 124 psig
Downstream Pressure = 117 psig
What is the approximate water flow rate through the orifice plate?
A. 47 gpm
B. 57 gpm
C. 68 gpm
D. 78 gpm
68 gpm
Refer to the drawing of a differential pressure manometer (see figure below).
The manometer is filled with water and installed across an orifice in a ventilation duct to determine the
rate of air flow. The manometer is currently indicating a water level difference of 16 inches at an air
flow rate of 300 ft^3
/min.
Which one of the following will be the approximate rate of air flow when the manometer indicates a
water level difference of 4 inches?
A. 75 ft^3
/min.
B. 125 ft^3
/min.
C. 150 ft^3
/min.
D. 175 ft^3
/min.
150 ft^3
/min.
A differential pressure detector is being used with an orifice plate to measure water flow rate through a
pipe. When the flow instrument was last calibrated, the following parameters were observed:
Upstream Pressure = 125 psig Actual Flow Rate = 100 gpm
Downstream Pressure = 116 psig Indicated Flow Rate= 100 gpm
Since the calibration, debris has collected in the orifice such that the actual flow rate through the
orifice has decreased to 80 gpm while the upstream and downstream pressures have changed to 135
psig and 110 psig, respectively.
What is the approximate flow rate that is currently indicated by the flow instrument?
A. 125 gpm
B. 133 gpm
C. 156 gpm
D. 167 gpm
167 gpm
Refer to the drawing of a differential pressure manometer (see figure below).
The manometer is filled with water and installed across an orifice in a ventilation duct to determine the
rate of air flow. The manometer is currently indicating a water level difference of 8 inches at an air
flow rate of 300 cubic feet per minute (ft^3
/min).
Which one of the following will be the approximate air flow rate when the manometer indicates a
water level difference of 4 inches?
A. 75 ft^3
/min
B. 150 ft^3
/min
C. 188 ft^3
/min
D. 212 ft^3
/min
212 ft^3
/min
A cooling water system uses a horizontal venturi with a differential pressure flow detector to provide
flow rate indication. Water enters and leaves the venturi at 70°F, 100 psig, and 24 ft/sec. Water
velocity at the throat of the venturi is 50 ft/sec. Assume water is incompressible and the venturi
experiences no unrecoverable head loss.
What is the approximate pressure of the water at the throat of the venturi?
A. 98 psig
B. 94 psig
C. 87 psig
D. 74 psig
87 psig
Refer to the drawing of a frictionless venturi flow element (see figure below). Subcooled water is
flowing through the venturi with the following initial conditions:
Flow rate = 500 gpm
Tap A pressure = 40 psia
Tap B pressure = 36 psia
Flow rate increases to 1,000 gpm, which results in a tap A pressure of 68 psia. What is the new
pressure at tap B?
A. 60 psia
B. 52 psia
C. 44 psia
D. 32 psia
52 psia
Refer to the drawing of a frictionless venturi flow element (see figure below). Subcooled water is
flowing through the venturi with the following initial conditions:
Flow rate = 500 gpm
Tap A pressure = 40 psia
Tap B pressure = 36 psia
When flow rate is increased to 750 gpm, the pressure at tap A increases to 68 psia. What is the new
pressure at tap B?
A. 66 psia
B. 62 psia
C. 59 psia
D. 52 psia
59 psia
Refer to the drawing of a frictionless venturi flow element (see figure below). Subcooled water is
flowing through the venturi with the following initial conditions:
Flow rate = 500 gpm
Tap A pressure = 48 psia
Tap B pressure = 44 psia
When flow rate is increased to 900 gpm, the pressure at tap A increases to 62 psia. What is the new
pressure at tap B?
A. 46 psia
B. 49 psia
C. 55 psia
D. 60 psia
49 psia
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detector (see figure
below).
The associated level instrument was calibrated with the water storage tank at 100°F. If mass in the
tank remains constant and the water temperature increases to 120°F, the indicated level will…
A. remain the same although actual level increases.
B. increase but remain less than actual level.
C. decrease in direct proportion to the temperature rise.
D. increase in direct proportion to the temperature rise.
remain the same although actual level increases.
Refer to the drawing of a pressurizer differential pressure (D/P) level detection system (see figure
below). The pressurizer level instrument was calibrated while the plant was in a cold shutdown
condition.
When the plant is returned to normal operating conditions, pressurizer level will indicate __________
than actual level because a given pressurizer level at normal operating conditions produces a
__________ D/P compared to cold shutdown conditions.
A. higher; smaller
B. higher; larger
C. lower; smaller
D. lower; larger
lower; larger
Refer to the drawing of a water storage tank with a differential pressure level detector that was recently
calibrated at a tank water temperature of 80°F (see figure below).
If the mass of the water in the tank remains the same while the tank water temperature is raised from
80°F to 150°F, the indicated level will…
A. remain equal to actual level.
B. increase, due to the expansion of the water.
C. remain the same.
D. decrease, due to the expansion of the water.
remain the same.
Refer to the drawing of a water storage tank with two tank differential pressure (D/P) level indicators
(see figure below).
Two D/P level indicators are installed on a large water storage tank. Indicator 1 was calibrated at
100°F water temperature and indicator 2 was calibrated at 200°F water temperature.
Assuming both indicators are on scale, which indicator will indicate the higher level?
A. Indicator 1 at all water temperatures
B. Indicator 2 at all water temperatures
C. Indicator 1 below 150°F, indicator 2 above 150°F
D. Indicator 2 below 150°F, indicator 1 above 150°F
Indicator 2 at all water temperatures
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below).
The level detector is being used in a level control system that was calibrated to maintain tank level at
80 percent when the tank water temperature was 100°F. If tank water temperature gradually
increases and stabilizes at 150°F, the level control system will cause actual tank level to…
A. remain stable at 80 percent.
B. increase and stabilize above 80 percent.
C. oscillate and then stabilize at 80 percent.
D. decrease and stabilize below 80 percent.
increase and stabilize above 80 percent.
Refer to the drawing of a water storage tank with two tank differential pressure (D/P) level indicators
(see figure below).
Two D/P level indicators are installed on a large water storage tank. Indicator 1 was calibrated at
100°F water temperature and indicator 2 was calibrated at 200°F water temperature.
Assuming both indicators are on scale, which indicator will indicate the lower level?
A. Indicator 1 at all water temperatures
B. Indicator 2 at all water temperatures
C. Indicator 1 below 150°F, indicator 2 above 150°F
D. Indicator 2 below 150°F, indicator 1 above 150°F
Indicator 1 at all water temperatures
Refer to the drawing of a water storage tank with two differential pressure (D/P) level indicators (see
figure below).
Two D/P level indicators are installed on a large water storage tank. Indicator No. 1 was calibrated at
200°F water temperature and indicator No. 2 was calibrated at 100°F water temperature.
Assuming both indicators are on scale, which indicator will indicate the lower level?
A. Indicator 1 at all water temperatures.
B. Indicator 2 at all water temperatures.
C. Indicator 1 below 150°F, indicator 2 above 150°F.
D. Indicator 2 below 150°F, indicator 1 above 150°F.
Indicator 2 at all water temperatures.
Refer to the drawing of a water storage tank with two differential pressure (D/P) level indicators (see
figure below).
Indicator 1 was calibrated at 120°F and indicator 2 was calibrated at 180°F. If tank water temperature
is currently 150°F, then indicator…
A. 1 will read greater than indicator 2, and greater than actual level.
B. 1 will read greater than indicator 2, and less than actual level.
C. 2 will read greater than indicator 1, and greater than actual level.
D. 2 will read greater than indicator 1, and less than actual level.
2 will read greater than indicator 1, and greater than actual level.
Refer to the drawing of a water storage tank with two differential pressure (D/P) level indicators (see
figure below).
Indicator 1 was calibrated at 180°F and indicator 2 was calibrated at 120°F. If tank water temperature
is 150°F, then indicator…
A. 1 will read greater than indicator 2, and greater than actual water level.
B. 1 will read greater than indicator 2, and less than actual water level.
C. 2 will read greater than indicator 1, and greater than actual water level.
D. 2 will read greater than indicator 1, and less than actual water level.
1 will read greater than indicator 2, and greater than actual water level.
Refer to the drawing of a steam generator differential pressure (D/P) level detection system that was
calibrated at normal operating conditions (see figure below).
A reactor coolant system cooldown has decreased steam generator pressures from 900 psia to 400 psia.
Without density compensation of the level instrumentation, at the end of the cooldown the steam
generator level indication will be __________ than actual level because the density of the water in the
__________ has changed significantly.
A. higher; reference leg
B. higher; steam generator
C. lower; reference leg
D. lower; steam generator
higher; steam generator
Refer to the drawing of a steam generator (SG) differential pressure (D/P) level detection system (see
figure below) that was calibrated at the current SG pressure of 400 psia.
A reactor coolant system heatup has resulted in an increase in SG pressure from 400 psia to 900 psia
over 4 hours. The ambient air temperature surrounding the SG has remained constant.
Without density compensation of the level instrumentation, at the end of the heatup SG level
indication would indicate __________ than actual level because the density of the water in the
__________ has changed significantly.
A. higher; steam generator
B. higher; reference leg
C. lower; steam generator
D. lower; reference leg
lower; steam generator
A reactor is currently shut down with the reactor coolant system at 140°F and 150 psig. Pressurizer
level is being monitored using a differential pressure detector with a wet reference leg. The
pressurizer level instrument was calibrated at normal plant operating conditions.
The pressurizer level instrument currently indicates __________ than actual pressurizer level because,
compared to the calibration conditions, there has been a significant change in the density of the fluid in
the __________.
A. lower; reference leg
B. lower; pressurizer
C. higher; reference leg
D. higher; pressurizer
higher; pressurizer
Refer to the drawing of a pressurizer and differential pressure (D/P) level detection system that was
recently calibrated at normal operating conditions (see figure below). Assume that the associated
pressurizer level instrument does not use density compensation.
With the nuclear power plant shut down at reduced reactor coolant system temperature and pressure,
the pressurizer level instrument will indicate __________ than actual water level because the D/P
currently sensed by the D/P detector is __________ than the D/P for the same pressurizer water level
at normal operating conditions.
A. lower; smaller
B. lower; larger
C. higher; smaller
D. higher; larger
higher; smaller
Refer to the drawing of a pressurizer differential pressure (D/P) level detection system (see figure
below).
The associated pressurizer level instrument was recently calibrated with the nuclear power plant at
normal operating conditions. Assume that the level instrument does not use density compensation.
If the plant is currently shut down at reduced reactor coolant system temperature and pressure,
pressurizer water level will currently indicate __________ than actual water level because, for a given
pressurizer water level, the D/P sensed by the D/P detector is currently __________.
A. higher; smaller
B. higher; larger
C. lower; smaller
D. lower; larger
higher; smaller
Refer to the drawing of a differential pressure (D/P) level detection system for a pressurizer at normal
operating temperature and pressure (see figure below).
A nuclear power plant uses several differential pressure detectors like the one below to provide
multiple channels of pressurizer water level indication. A hot channel was calibrated when the
pressurizer was at normal operating temperature. A cold channel was calibrated when the pressurizer
was at 160°F.
How will the level indications on the two channels compare when the pressurizer is at normal
operating temperature?
A. The cold channel will indicate higher than the hot channel, due to the difference in reference leg
water density at the two calibration temperatures.
B. The cold channel will indicate lower than the hot channel, due to the difference in reference leg
water density at the two calibration temperatures.
C. The cold channel will indicate higher than the hot channel, due to the difference in pressurizer
water density at the two calibration temperatures.
D. The cold channel will indicate lower than the hot channel, due to the difference in pressurizer
water density at the two calibration temperatures.
The cold channel will indicate lower than the hot channel, due to the difference in pressurizer
water density at the two calibration temperatures.
Refer to the drawing of a pressurizer differential pressure (D/P) level detection system (see figure
below).
With the pressurizer containing saturated water and steam at 2,250 psia, pressurizer level indication is
20 feet. Assume that reference leg level and temperature do not change. Also, ignore the effect of
steam density changes on level indication.
With no change in actual pressurizer level, what will level indication be at 600 psia (saturated)?
A. 14.9 feet
B. 18.3 feet
C. 22.4 feet
D. 26.8 feet
26.8 feet
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below).
If the differential pressure detector equalizing valve is opened, level indication will:
A. decrease and stabilize below actual level.
B. increase and stabilize above actual level.
C. oscillate above and below actual level.
D. remain constant at the current level.
increase and stabilize above actual level.
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detector (see figure
below).
The level detector is being used in a level control system that is calibrated to maintain tank level at 75
percent at the current water temperature of 90°F. If water temperature gradually increases and
stabilizes at 120°F, the level control system will cause actual tank level to…
A. remain at 75 percent.
B. increase and stabilize above 75 percent.
C. oscillate around 75 percent.
D. decrease and stabilize below 75 percent.
increase and stabilize above 75 percent.
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below).
The D/P sensed by the detector varies in the __________ direction as the temperature of the water in
the tank if the __________ of the tank water is constant. (Assume reference leg and tank water
temperatures are initially the same.)
A. same; level
B. inverse; level
C. same; mass
D. inverse; mass
same; level
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detector (see figure
below).
The level detector is being used in a level control system that is calibrated to maintain tank level at 75
percent at the current water temperature of 120°F. If water temperature gradually decreases and
stabilizes at 90°F, actual tank level will…
A. remain at 75 percent.
B. increase and stabilize above 75 percent.
C. oscillate around 75 percent.
D. decrease and stabilize below 75 percent.
decrease and stabilize below 75 percent.
A cooling water system is cooling a lube oil heat exchanger. Cooling water system surge tank level is
being measured using a differential pressure level detector that has been calibrated at the current water
temperature in the tank. A leak in the heat exchanger results in lube oil collecting in the surge tank.
Assuming that the temperature of the contents in the surge tank does not change, indicated tank level
will be __________ than actual tank level because lube oil is __________ than water.
A. higher; more dense
B. higher; less dense
C. lower; more dense
D. lower; less dense
lower; less dense
Many steam generator water level instruments are designed with a condensing chamber in the
reference leg. The purpose of the condensing chamber is to…
A. maintain a constant water level in the reference leg during normal operations.
B. provide reference leg compensation for the steam generator pressure exerted on the variable leg.
C. prevent reference leg flashing during a rapid depressurization of the steam generator.
D. ensure the reference leg temperature remains close to the temperature of the variable leg.
maintain a constant water level in the reference leg during normal operations.
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below).
Assume the initial temperature of the reference leg and the water in the tank is 100°F, and that
reference leg temperature does not change.
If the temperature of the water in the tank increases by 20°F, the D/P sensed by the detector will
__________ as long as the water __________ is maintained constant.
A. increase; level
B. decrease; level
C. increase; mass
D. decrease; mass
increase; level
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below). Assume that the initial temperature of the reference leg and the water in the tank
are the same, and that reference leg temperature and level do not change.
The level detector is being used in a level control system (not shown) that is calibrated to maintain tank
level at 75 percent at the current tank water temperature (70°F) and pressure (5 psig).
If the tank water temperature remains constant, but the tank pressure is increased by 10 psig, the level
control system will cause actual tank level to…
A. remain at 75 percent.
B. increase and stabilize above 75 percent.
C. oscillate around 75 percent.
D. decrease and stabilize below 75 percent.
remain at 75 percent.
The downcomer region of a steam generator contains 40 feet of saturated water at 536°F. A steam
generator water level detector has a pressure tap located at the bottom of the downcomer region.
Approximately how much of the total pressure at the pressure tap is caused by the downcomer water?
A. 0.6 psi
B. 13.0 psi
C. 27.7 psi
D. 156.0 psi
13.0 psi
Refer to the drawing of a differential pressure (D/P) level detection system (see figure below) for a
pressurizer at normal operating temperature and pressure. The level detector has just been calibrated.
The high pressure side of the detector is connected to the __________; and if the equalizing valve is
opened, the indicated pressurizer level will be __________ than the actual level.
A. condensing pot; lower
B. condensing pot; higher
C. pressurizer; lower
D. pressurizer; higher
condensing pot; higher
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below).
The D/P level detector was just calibrated and returned to operation with the following conditions:
* The reference leg contains 20 feet of water at 70°F.
* The tank contains 18 feet of water at 70°F.
* Tank level indication is 18 feet.
Assume the actual tank water level and the temperature of the water in the tank and reference leg do
not change. Which one of the following will be the new tank level indication if the reference leg
water level decreases to 18 feet?
A. 22 feet
B. 20 feet
C. 18 feet
D. 2 feet
20 feet
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below).
The water storage tank is 40 feet tall. The level detection system is calibrated to provide a level
indication of 30 feet when the tank and reference leg levels are equal.
If the tank is completely filled with water, the tank level will indicate…
A. less than 30 feet.
B. 30 feet.
C. greater than 30 feet, but less than 40 feet.
D. 40 feet.
30 feet
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below).
Assume that the initial temperature of the reference leg and the water in the tank is 100°F, and that
reference leg temperature does not change.
If the temperature of the water in the tank increases by 20°F, the D/P sensed by the detector will
__________ if the __________ of the water in the tank is constant.
A. decrease; level
B. decrease; mass
C. remain the same; level
D. remain the same; mass
remain the same; mass
Refer to the drawing of a vented water storage tank with a differential pressure (D/P) level detection
system (see figure below). The water in the tank and reference leg is at the same temperature.
The tank level indicator was just calibrated to indicate 0 percent when the tank is empty and 100
percent when the water level reaches the upper tap. The indicator’s display range is 0 percent to 120
percent. The initial water level is as indicated in the figure.
If the tank water level slowly increases and stabilizes just below the top of the tank, the level indication
will increase until…
A. the water level stabilizes, at which time the level indication will stabilize at 100 percent.
B. the water level stabilizes, at which time the level indication will stabilize at a value greater than
100 percent.
C. the water level reaches the upper tap, at which time the level indication will remain at 100 percent
as the water level continues to increase.
D. the water level reaches the upper tap, at which time the level indication will continue to increase as
the water level continues to increase.
the water level reaches the upper tap, at which time the level indication will remain at 100 percent
as the water level continues to increase.
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below). The level detector has just been calibrated.
How will the indicated level be affected if condensation partially fills the normally-dry reference leg?
A. Indicated level will not be affected.
B. Indicated level will be lower than actual level.
C. Indicated level will be higher than actual level.
D. Indicated level may be higher or lower than actual level depending on the pressure in the upper
volume of the tank.
Indicated level will be lower than actual level.
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detector (see figure
below).
The level instrument has just been calibrated to read actual tank water level. If the reference leg
subsequently experiences high ambient temperature, indicated level will…
A. equal the actual level.
B. read less than the actual level.
C. read greater than the actual level.
D. drift above and below the actual level.
read greater than the actual level.
Refer to the drawing of a water storage tank with two differential pressure (D/P) level indicators (see
figure below).
Indicator 1 was calibrated at 200°F and indicator 2 was calibrated at 100°F. If tank water temperature
is 150°F, then…
A. indicator 1 will read greater than indicator 2.
B. indicator 2 will read greater than indicator 1.
C. indicators 1 and 2 will read the same.
D. both indicators will be inaccurate, but it is impossible to predict which indicator will read greater.
indicator 1 will read greater than indicator 2.
Refer to the drawing of two water storage tanks with four differential pressure (D/P) level detectors
(see figure below).
The tanks are identical with equal water levels and both are pressurized to 20 psig. All detectors were
calibrated at the current water temperature and 70°F external (ambient) temperature.
Which detectors will provide the most accurate level indication following an increase in external
(ambient) temperature from 70°F to 100°F? (Assume tank contents temperatures and external
pressure do not change.)
A. 1 and 3
B. 2 and 4
C. 1 and 4
D. 2 and 3
2 and 4
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below).
A calibrated D/P level detector is being used to measure level in a vented tank inside the auxiliary
building. If building pressure increases with no change in temperature, the associated level indication
will…
A. decrease, then increase and stabilize at the actual level.
B. decrease and stabilize below the actual level.
C. increase and stabilize above the actual level.
D. remain at the actual level.
remain at the actual level.
Refer to the drawing of a pressurizer differential pressure (D/P) level detection system (see figure
below).
The pressurizer level instrument was calibrated while the plant was at normal operating conditions.
With the plant in cold shutdown conditions, the pressurizer level D/P instrument will indicate
__________ than actual level because the D/P sensed by the detector at cold shutdown conditions will
be __________ than at normal operating conditions for the same level.
A. lower; greater
B. lower; smaller
C. higher; greater
D. higher; smaller
higher; smaller
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detector (see figure
below).
The associated level instrument was calibrated with the water storage tank at 120°F. If the mass in
the tank remains constant and the water temperature decreases to 100°F, the indicated level will…
A. remain the same although actual level decreases.
B. remain the same although actual level increases.
C. increase in direct proportion to the temperature decrease.
D. decrease in direct proportion to the temperature decrease.
remain the same although actual level decreases.
Refer to the drawing of a pressurizer level detection system (see figure below). The differential
pressure (D/P) detector was calibrated while the plant was at normal operating conditions.
With the plant initially at normal operating conditions, a pressurizer steam space leak occurred.
Pressurizer pressure decreased by 300 psia, and the ambient air temperature surrounding the reference
leg increased by 80°F, where these parameters stabilized.
If the actual pressurizer water level is 60 percent, the reduced pressurizer pressure will tend to make
the indicated pressurizer level read __________ than actual level; and the increased reference leg
temperature will tend to make the indicated pressurizer level read __________ than actual level.
A. higher; higher
B. higher; lower
C. lower; higher
D. lower; lower
higher; higher
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below).
The level instrument has just been calibrated to indicate actual tank water level. Assume that tank
water temperature and level remain constant. If the reference leg temperature increases by 20°F,
indicated tank water level will…
A. be unpredictable.
B. equal the actual level.
C. be less than the actual level.
D. be greater than the actual level.
equal the actual level.
The level indication for a wet reference leg differential pressure (D/P) level instrument will fail low as
a result of…
A. a break on the reference leg.
B. a rupture of the diaphragm in the D/P cell.
C. the reference leg flashing to steam.
D. a break on the variable leg.
a break on the variable leg.
Refer to the drawing of a steam generator differential pressure (D/P) level detection system (see figure
below).
The D/P detector was calibrated at the current conditions. Which one of the following will cause the
level instrument to indicate lower than actual level? (Assume actual level remains the same.)
A. The variable leg ruptures.
B. The equalizing valve is opened.
C. The reference leg temperature increases.
D. The D/P detector diaphragm ruptures.
The variable leg ruptures.
Refer to the drawing of a water storage tank with a differential pressure (D/P) level detection system
(see figure below).
Tank water level indication will be lower than actual level when reference leg temperature is
__________ than calibration conditions; or when there is a break in the __________ leg of the D/P
detector.
A. less; reference
B. less; variable
C. greater; reference
D. greater; variable
less; variable
Refer to the drawing of a steam generator (SG) differential pressure (D/P) level detection system (see
figure below) that was recently calibrated at normal operating conditions.
With the reactor shut down, SG pressure was inadvertently decreased from 900 psig to 700 psig in 5
minutes due to operator error. SG pressure was stabilized at 700 psig, but during the pressure
decrease a small amount of water in the condensing pot flashed to steam. Assume the reference leg
water remained subcooled, except for the small amount of water that flashed to steam in the
condensing pot.
As a result of the small loss of condensing pot water, SG level will indicate __________ than actual
level; and as the condensing pot refills, indicated level will __________.
A. higher; decrease and stabilize above the actual level
B. higher; decrease and stabilize below the actual level
C. lower; increase and stabilize above the actual level
D. lower; increase and stabilize below the actual level
higher; decrease and stabilize above the actual level
Refer to the drawing of a steam generator (SG) differential pressure (D/P) level detection system (see
figure below).
Which one of the following events will result in a SG level indication that is greater than actual level?
A. The SG pressure increases by 50 psia.
B. The variable leg breaks and completely drains.
C. A portion of the reference leg water flashes to steam.
D. The temperature surrounding the SG and reference leg decreases by 30°F.
A portion of the reference leg water flashes to steam.
Refer to the drawing of a steam generator (SG) differential pressure (D/P) level detection system (see
figure below).
The SG is at normal operating temperature and pressure with accurate level indication. Which one of
the following events will result in a SG level indication that is greater than actual level?
A. The external pressure surrounding the D/P detector increases by 2 psi.
B. SG pressure increases by 50 psi with no change in actual water level.
C. Actual SG level increases by 6 inches.
D. The temperature of the reference leg increases by 20°F.
The temperature of the reference leg increases by 20°F.
Refer to the drawing of a steam generator (SG) differential pressure (D/P) level detection system (see
figure below).
The SG is supplying steam at normal operating temperature and pressure and the level instrumentation
has just been calibrated. Which one of the following events will result in a SG level indication that is
less than the actual SG level?
A. SG pressure increases by 50 psi.
B. Actual SG water level decreases by 6 inches.
C. The external pressure surrounding the D/P detector decreases by 2 psi.
D. The temperature surrounding the reference leg increases by 20°F.
SG pressure increases by 50 psi.
Refer to the drawing of a steam generator (SG) differential pressure (D/P) level detection system (see
figure below).
The SG is at normal operating temperature and pressure with accurate level indication. Which one of
the following events will result in a SG level indication that is lower than actual level?
A. Actual SG level decreases by 6 inches.
B. The temperature surrounding the reference leg decreases by 20°F.
C. The external pressure surrounding the D/P detector decreases by 2 psi.
D. SG pressure decreases by 50 psi with no change in actual water level.
The temperature surrounding the reference leg decreases by 20°F.
Refer to the drawing of a pressurizer differential pressure (D/P) level detection system (see figure
below).
A reactor is shutdown with the reactor coolant system being maintained at 100 psia. The pressurizer
level detector has just been calibrated. Suddenly a rupture in the condensing pot of the level detector
results in a rapid drop of the condensing pot pressure to atmospheric pressure.
Given the following current conditions:
* The condensing pot is at atmospheric pressure.
* Pressurizer pressure is 98 psia and slowly decreasing.
* Bulk reference leg temperature is 120°F.
* Actual pressurizer level has not changed significantly.
Which one of the following describes the current pressurizer level indication from the detector?
A. Off scale low, because the bulk of the water in the reference leg has flashed to steam.
B. Off scale high, because the bulk of the water in the reference leg has flashed to steam.
C. Off scale low, because the static pressure on the reference leg is much less than the static pressure
in the pressurizer.
D. Off scale high, because the static pressure on the reference leg is much less than the static pressure
in the pressurizer.
Off scale high, because the static pressure on the reference leg is much less than the static pressure
in the pressurizer.
Semiconductor strain gages are often used in transmitters for…
A. reactor coolant pressure instruments.
B. reactor coolant temperature instruments.
C. control rod position instruments.
D. steam generator level instruments.
reactor coolant pressure instruments
If the pressure sensed by a bourdon tube increases, the curvature of the detector will __________
because the greater force is being applied to the __________ curve of the detector.
A. increase; outer
B. increase; inner
C. decrease; outer
D. decrease; inner
decrease; outer
In a diaphragm type pressure detector, pressure is measured using the __________ of the diaphragm.
A. rotational movement
B. axial deflection
C. change in circumference
D. change in diameter
axial deflection
A centrifugal pump is taking suction from the bottom of a vented cylindrical storage tank that contains
100,000 gallons of water at 60°F. A pressure gauge at the inlet to the pump indicates 40 psig. Over
the next several days, storage tank temperature increases to 90°F with no change in tank water level
and no change in head loss in the pump suction line.
Which one of the following is the current pressure at the inlet to the pump?
A. 31.2 psig
B. 34.6 psig
C. 37.4 psig
D. 39.8 psig
39.8 psig
A simple bellows pressure detector is connected to a cooling water system. The detector is located in
the reactor containment and has its low pressure side vented to the containment atmosphere. Current
system pressure indication is 100 psig.
If a main steam line break raises containment pressure by 40 psig, the system pressure indication will:
(Disregard any temperature effect on the pressure detector.)
A. increase by 40 psig.
B. increase by the square root of 40 psig.
C. decrease by 40 psig.
D. decrease by the square root of 40 psig.
decrease by 40 psig.
A cooling water system bourdon tube pressure detector is located inside a sealed building and system
pressure currently indicates 50 psig. A building ambient temperature increase of 20°F will cause a
__________ change in indicated system pressure; a building pressure increase of 20 psig will cause a
__________ change in indicated system pressure.
A. significant; significant
B. negligible; significant
C. significant; negligible
D. negligible; negligible
negligible; significant
A bellows pressure transmitter with its low-pressure side vented to containment atmosphere is being
used to measure reactor coolant system (RCS) pressure. A decrease in the associated pressure
indication could be caused by either a containment pressure __________ or an RCS pressure
__________.
A. decrease; decrease
B. increase; increase
C. decrease; increase
D. increase; decrease
increase; decrease
Cooling water system pressure is being monitored by a simple diaphragm pressure detector with its
low pressure side vented to the containment. If a main steamline rupture raises containment pressure
by 20 psi, cooling water system pressure indication will: (Disregard any temperature effect on the
detector.)
A. increase by 20 psi.
B. decrease by 20 psi.
C. increase by the square root of 20 psi.
D. decrease by the square root of 20 psi.
decrease by 20 psi.
The pressure within a cooling water system is 100 psig, as indicated by a bourdon tube pressure
detector. The cooling water system and the detector are located inside a reactor containment
building. The pressure detector case is vented to the containment building, which is currently at
atmospheric pressure.
If a steam line rupture raises the containment building pressure by 20 psi, the cooling water system
pressure indication will… (Disregard any temperature effect on the detector.)
A. decrease to 80 psig.
B. decrease by an undefined amount.
C. increase to 120 psig.
D. increase by an undefined amount.
decrease to 80 psig.
A cooling water system pressure detector uses a bourdon tube as the sensing element. Which one of
the following explains how the indicated system pressure will be affected if a local steam leak raises
the temperature of the bourdon tube by 50°F? (Assume the cooling water system pressure does not
change.)
A. Indicated pressure will decrease because the bourdon tube will become more flexible.
B. Indicated pressure will increase because the bourdon tube will become more flexible.
C. Indicated pressure will decrease because the bourdon tube internal pressure will increase.
D. Indicated pressure will increase because the bourdon tube internal pressure will increase.
Indicated pressure will increase because the bourdon tube will become more flexible.
A cooling water system pressure detector uses a bourdon tube as the sensing element. Which one of
the following explains how the indicated system pressure will be affected if the temperature of the
bourdon tube decreases by 30°F? (Assume the cooling water system pressure does not change.)
A. Indicated pressure will decrease because the bourdon tube will become less flexible.
B. Indicated pressure will increase because the bourdon tube will become less flexible.
C. Indicated pressure will decrease because the bourdon tube internal pressure will decrease.
D. Indicated pressure will increase because the bourdon tube internal pressure will decrease.
Indicated pressure will decrease because the bourdon tube will become less flexible.
A bourdon-tube pressure detector was indicating 50 percent of scale when it was suddenly exposed to
a high pressure transient that caused permanent strain to the bourdon tube. The detector remained
intact and actual pressure was restored to its original value.
During the pressure transient, the affected pressure indication initially went off scale high. After the
original pressure was restored, the indication was…
A. unpredictable.
B. less than 50 percent of scale.
C. 50 percent of scale.
D. greater than 50 percent of scale.
greater than 50 percent of scale.
Refer to the drawing of a bellows-type differential pressure (D/P) detector (see figure below).
The spring in this detector (shown in a compressed state) has weakened from long-term use. If the
actual D/P is constant, how will indicated D/P respond as the spring weakens?
A. Increase, because the spring will expand more
B. Decrease, because the spring will expand more
C. Increase, because the spring will compress more
D. Decrease, because the spring will compress more
Increase, because the spring will compress more
If a bourdon tube pressure detector is over-ranged sufficiently to permanently distort the bourdon tube,
subsequent pressure measurement will be inaccurate because the __________ of the detector tube will
be inaccurate.
A. distance moved by the tip
B. change in the length
C. expansion of the cross-sectional area
D. change in the volume
distance moved by the tip
A properly calibrated 0 to 100 psia diaphragm pressure detector is connected to a pressurized system;
the low pressure side of the detector is vented to the atmosphere. The detector is currently producing
a system pressure indication of 75 psia.
If the detector diaphragm ruptures, indicated pressure will be approximately…
A. 0 psia.
B. 15 psia.
C. 60 psia.
D. 90 psia.
15 psia.
Refer to the drawing of a bellows-type pressure detector (see figure below).
A bellows-type pressure detector with its low-pressure side vented to containment atmosphere is being
used to measure reactor vessel pressure.
A decrease in the associated pressure indication will be
caused by either a containment pressure __________ or a __________.
A. increase; ruptured bellows
B. increase; broken spring
C. decrease; ruptured bellows
D. decrease; broken spring
increase; ruptured bellows
A resistance temperature detector operates on the principle that the change in the electrical resistance
of…
A. two dissimilar metals is directly proportional to the temperature change measured at their junction.
B. two dissimilar metals is inversely proportional to the temperature change measured at their
junction.
C. a metal is directly proportional to its change in temperature.
D. a metal is inversely proportional to its change in temperature.
a metal is directly proportional to its change in temperature.
A resistance temperature detector operates on the principle that the change in the electrical resistance
of a metal is __________ proportional to the change in __________.
A. inversely; metal temperature
B. inversely; metal temperature squared
C. directly; metal temperature
D. directly; metal temperature squared
directly; metal temperature
In a comparison between a thermocouple and a resistance temperature detector, the thermocouple
generally…
A. measures temperature less accurately.
B. is less affected by ambient temperature changes.
C. has a lower usable temperature range.
D. responds more slowly to a temperature change.
measures temperature less accurately.
If the reference junction temperature of a thermocouple remains constant, the output voltage of the
thermocouple is __________ proportional to the __________.
A. directly; measuring junction temperature
B. directly; square root of the measuring junction temperature
C. inversely; measuring junction temperature
D. inversely; square root of the measuring junction temperature
directly; measuring junction temperature
Refer to the drawing of a simple thermocouple circuit (see figure below).
A thermocouple temperature indication is initially 350°F. A small steam leak raises reference (cold)
junction temperature by 20°F, while the measuring junction temperature remains constant. Without
temperature compensation for the reference junction, the new temperature indication will be…
A. 310°F.
B. 330°F.
C. 370°F.
D. 390°F.
330°F.
A thermocouple operates on the principle that a measurable voltage will be produced when two…
A. similar metals form two junctions at the same temperature.
B. similar metals form two junctions at different temperatures.
C. dissimilar metals form two junctions at the same temperature.
D. dissimilar metals form two junctions at different temperatures.
dissimilar metals form two junctions at different temperatures.
Refer to the drawing of a simple thermocouple circuit (see figure below).
A thermocouple temperature indication is initially 390°F. A small steam leak raises reference (cold)
junction temperature by 20°F, while the measuring junction temperature remains constant. Without
temperature compensation for the reference junction, the new temperature indication will be…
A. 370°F.
B. 390°F.
C. 400°F.
D. 410°F.
370°F
In contrast to a thermocouple, a resistance temperature detector…
A. is used in high temperature applications.
B. does not require an external power supply for temperature indication.
C. uses a single type of metal or alloy in the sensing element.
D. is commonly placed in direct contact with the monitored substance.
uses a single type of metal or alloy in the sensing element.
Refer to the drawing of a simple thermocouple circuit (see figure below).
A thermocouple temperature indication is initially 150°F. A small steam leak raises both the
measuring (hot) junction and reference (cold) junction temperatures by 20°F. Without temperature
compensation for the reference junction, the new temperature indication will be…
A. 130°F.
B. 150°F.
C. 170°F.
D. 190°F.
150°F
Refer to the drawing of a simple thermocouple circuit (see figure below).
Circuit temperature indication is initially 350°F. The reference (cold) junction temperature decreases
by 10°F, while the measuring junction temperature remains constant. Without temperature
compensation for the reference junction, the new temperature indication will be…
A. 340°F.
B. 350°F.
C. 360°F.
D. 370°F.
360°F
What is the purpose of the reference junction panel that is provided with many thermocouple circuits?
A. Ensures that thermocouple output is amplified sufficiently for use by temperature indication
devices.
B. Ensures that temperature changes away from the thermocouple measuring junction do not affect
thermocouple temperature indication.
C. Ensures that electrical noise in the thermocouple extension wires does not affect thermocouple
temperature indication.
D. Ensures that different lengths of thermocouple extension wires do not affect thermocouple
temperature indication.
Ensures that temperature changes away from the thermocouple measuring junction do not affect
thermocouple temperature indication.
Unlike a resistance temperature detector, a typical thermocouple…
A. uses a single type of metal in the sensing element
B. requires a temperature-controlled reference junction.
C. can provide temperature input to a valve controller in a cooling water system.
D. requires an external power supply to provide indication of temperature.
requires a temperature-controlled reference junction.
Refer to the drawing of a simple thermocouple circuit (see figure below).
A thermocouple temperature indication is initially 410°F with the reference (cold) junction at 125°F.
An ambient temperature decrease lowers the reference junction temperature to 110°F, while the
measuring junction temperature remains constant. Without temperature compensation for the
reference junction, the new thermocouple temperature indication will be…
A. 380°F.
B. 395°F.
C. 410°F.
D. 425°F.
425°F
Refer to the drawing of a simple thermocouple circuit (see figure below).
Given that the temperatures at the measuring and reference junctions remain constant, if a ventilation
system malfunction causes the temperature of the temperature indication panel to increase by 10°F,
indicated temperature will…
A. not be affected.
B. increase by 10°F.
C. decrease by 10°F.
D. change in an unpredictable manner.
not be affected.
Refer to the drawing of a simple thermocouple circuit (see figure below).
The measuring and reference junctions are located inside the reactor containment building while the
instrument is located in a remote location outside the containment building. Thermocouple
temperature indication is initially 500°F.
An ambient temperature decrease outside the containment building lowers the temperature of the
instrument by 10°F, while the measuring and reference junction temperatures remain constant.
Thermocouple temperature indication at the lower ambient temperature will be…
A. 490°F.
B. 500°F.
C. 510°F.
D. unpredictable.
500°F
Refer to the drawing of a simple chromel-alumel thermocouple circuit (see figure below).
What is the effect on the thermocouple reference junctions if the chromel and alumel extension wires
from the thermocouple connection head to the reference junction panel are replaced with copper
wires?
A. There will no longer be any reference junctions.
B. The reference junctions will be located in the temperature instrument.
C. The reference junctions will still be located in the reference junction panel.
D. The reference junctions will be located in the thermocouple connection head.
The reference junctions will be located in the thermocouple connection head.
Which one of the following is a characteristic of a resistance temperature detector but not a
thermocouple?
A. Sensing element is made from a single metal or alloy.
B. Requires a reference junction for accurate temperature measurement.
C. Extension leads made from relatively expensive metals or alloys are required for accurate
temperature measurement.
D. Temperature measurement relies on a sensor material property that varies directly with the change
in the measured temperature.
Sensing element is made from a single metal or alloy.
Refer to the drawing of a simple chromel-alumel thermocouple circuit (see figure below).
What is the effect on the thermocouple reference junctions if the copper extension wires from the
reference junction panel to the temperature instrument are replaced with alumel (top) and chromel
(bottom) extension wires?
A. The reference junctions will be located in the thermocouple connection head.
B. The reference junctions will still be located in the reference junction panel.
C. The reference junctions will be located in the temperature instrument.
D. There will no longer be any reference junctions.
The reference junctions will be located in the temperature instrument.
Refer to the drawing of a simple chromel-alumel thermocouple circuit (see figure below).
The thermocouple, thermocouple connection head, and reference junction panel are located inside a
reactor building (RB) while the temperature instrument is located outside the RB. Thermocouple
temperature indication is initially 440°F.
A steam leak inside the RB increases the temperatures of the thermocouple connection head and
reference junction panel by 40°F, while the temperature at the measuring tip is unchanged. What is
the resulting temperature indication?
A. 400°F
B. 440°F
C. 480°F
D. 520°F
400°F
A simple two-wire resistance temperature detector (RTD) is being used to measure the temperature of
a water system. Copper extension wires run from the RTD to a temperature instrument 40 feet away.
If the temperature of the extension wires decreases, the electrical resistance of the extension wires will
__________; and the temperature indication will __________ unless temperature compensation is
provided.
A. increase; increase
B. increase; decrease
C. decrease; increase
D. decrease; decrease
decrease; decrease
Refer to the drawing of a simple thermocouple circuit (see figure below).
The measuring junction temperature is currently 300°F while the reference junction temperature is
being held constant at 120°F. The thermocouple circuit is capable of indicating 32°F to 600°F and
has just been calibrated at the current conditions.
If the measuring junction temperature decreases and stabilizes at 90°F, what temperature will be
indicated?
A. 32°F
B. 60°F
C. 90°F
D. 120°F
90°F
For proper operation of a thermocouple circuit, the reference junction temperature…
A. must be less than the measuring junction temperature.
B. must be greater than the measuring junction temperature.
C. may be less than, greater than, or equal to the measuring junction temperature.
D. may be less than or greater than, but not equal to, the measuring junction temperature.
may be less than, greater than, or equal to the measuring junction temperature.
A simple two-wire resistance temperature detector (RTD) is being used to measure the temperature in
a water system. Copper extension wires run from the RTD to a temperature measuring instrument 40
feet away. If the temperature of the extension wires increases, the electrical resistance of the
extension wires will __________; and the temperature indication will __________ unless temperature
compensation is provided.
A. increase; increase
B. increase; decrease
C. decrease; increase
D. decrease; decrease
increase; increase
Refer to the drawing of a simple chromel-alumel thermocouple circuit (see figure below).
The thermocouple, thermocouple connection head, and reference junction panel are located inside a
reactor building (RB), while the temperature instrument is located outside the RB. Initially, the
temperature instrument indicates 440°F.
A steam leak outside the RB increases the temperature of the temperature instrument from 80°F to
120°F, while the temperatures at the thermocouple, thermocouple connection head, and reference
junction panel remain unchanged. Assuming the temperature instrument remains operable, what is
the resulting temperature indication?
A. 400°F
B. 440°F
C. 480°F
D. 560°F
440°F
Refer to the drawing of a simple chromel-alumel thermocouple circuit (see figure below). Initially,
the temperature instrument indicates 350°F.
A steam leak inside the reactor building (RB) increases the temperature of the thermocouple
connection head, reference junction panel, and extension wires inside the RB from 120°F to 160°F.
The temperature at the location measured by the thermocouple remains the same.
What is the resulting temperature indication?
A. 310°F
B. 350°F
C. 390°F
D. 430°F
310°F
An open circuit in a thermocouple detector causes the affected temperature indication to fail…
A. high.
B. low.
C. to reference junction temperature.
D. as is.
to reference junction temperature.
A resistance temperature detector (RTD) is used in a balanced bridge circuit to indicate temperature.
If the RTD develops an open circuit (bridge circuit remains intact), temperature indication will fail…
A. high.
B. low.
C. as is.
D. to midscale.
high
If shorting occurs within a resistance temperature detector, the associated indication will fail…
A. low.
B. high.
C. as is.
D. to midscale.
low
Refer to the drawing of a simple thermocouple circuit (see figure below) that is calibrated for a
reference junction temperature of 90°F.
Thermocouple temperature indication is currently 150°F. Indicator range is from 0°F to 2000°F.
Which one of the following temperature indications will result if one of the thermocouple extension
wires becomes dislodged from its terminal in the reference junction panel?
A. 0°F
B. 60°F
C. 90°F
D. 2000°F
90°F
Because of a thermocouple temperature display failure, the millivolt output of a thermocouple circuit
is being converted to a temperature value using conversion tables. The tables are based on a
thermocouple reference junction temperature of 32°F. The actual reference junction is located in a
panel that is maintained at 120°F. Room temperature surrounding the panel is 80°F.
What adjustment must be made to the temperature value taken from the conversion tables to calculate
the actual temperature at the measuring tip of the thermocouple?
A. Add 48°F.
B. Subtract 48°F.
C. Add 88°F.
D. Subtract 88°F.
Add 88°F.
A resistance temperature detector (RTD) and a thermocouple (TC) are commonly used sensors for
temperature measurement. If a temperature display fails, which of the sensors, if any, has a property
that can be measured manually and converted to a temperature value with the aid of conversion tables.
A. TC only.
B. RTD only.
C. Both TC and RTD.
D. Neither TC nor RTD.
Both TC and RTD.
Because of a thermocouple temperature display failure, the millivolt output of a thermocouple circuit
is being converted to a temperature value using conversion tables. The tables are based on a
thermocouple reference junction temperature of 32°F. The actual reference junction is located in a
panel that is currently at 80°F.
The temperature value taken from the conversion tables is 120°F.
What adjustment must be made to the temperature value taken from the conversion tables to calculate
the actual temperature at the measuring tip of the thermocouple?
A. Add 48°F.
B. Subtract 48°F.
C. Add 88°F.
D. Subtract 88°F.
Add 48°F.
Because of a thermocouple temperature display failure, the millivolt output of a thermocouple circuit
is being converted to a temperature value using conversion tables. The tables are based on a
thermocouple reference junction temperature of 32°F. The actual reference junction is located in a
panel that is maintained at 96°F. Room temperature surrounding the panel is 72°F.
What adjustment must be made to the temperature value taken from the conversion tables to calculate
the actual temperature at the measuring tip of the thermocouple?
A. Add 64°F.
B. Subtract 64°F.
C. Add 40°F.
D. Subtract 40°F.
Add 64°F.
What type of sensor is most commonly used to provide remote position indication of a valve that is
normally either fully open or fully closed?
A. Limit switch
B. Reed switch
C. Servo transmitter
D. Linear variable differential transformer
Limit switch
Refer to the drawing of a simple chromel-alumel thermocouple circuit (see figure below).
Given the following:
* The temperature instrument currently indicates 370°F.
* The reference junction temperature is constant at 120°F.
* The temperature instrument is capable of indicating 32°F to 1,000°F and has just been
calibrated.
Which one of the following temperature indications will result if the chromel lead becomes
disconnected from its terminal in the thermocouple connection head?
A. 32°F
B. 120°F
C. 250°F
D. 1,000°F
120°F
Which one of the following devices is commonly used to provide remote indication of valve position
on an analog meter in units of “percent of full open”?
A. Limit switch
B. Reed switch
C. Linear variable differential transformer
D. Resistance temperature detector
Linear variable differential transformer
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 __________.
A. higher; higher
B. higher; lower
C. the same; higher
D. the same; lower
the same; lower
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 __________.
A. lower; higher
B. lower; lower
C. higher; higher
D. higher; lower
lower; higher
A reactor is shut down at 100 cps in the source range when a loss of coolant accident occurs.
Assuming the source neutron production rate remains constant, how and why will excore source range
detector outputs change as homogeneous core voiding increases from 20 percent to 40 percent?
A. Increases, because more neutron leakage is occurring.
B. Decreases, because less neutron leakage is occurring.
C. Increases, because Keff is increasing.
D. Decreases, because Keff is decreasing.
Increases, because more neutron leakage is occurring.
Reed switches are being used in an electrical measuring circuit to monitor the position of a control rod
in a reactor. The reed switches are mounted in a column above the reactor vessel such that the control
rod drive shaft passes by the reed switches as the control rod is withdrawn.
Which one of the following describes the action that causes the electrical output of the measuring
circuit to change as the control rod is withdrawn?
A. An AC coil on the control rod drive shaft induces a voltage into each reed switch as the drive shaft
passes by.
B. A metal tab on the control rod drive shaft mechanically closes each reed switch as the drive shaft
passes by.
C. The primary and secondary coils of each reed switch attain maximum magnetic coupling as the
drive shaft passes by.
D. A permanent magnet on the control rod drive shaft attracts the movable contact arm of each reed
switch as the drive shaft passes by.
A permanent magnet on the control rod drive shaft attracts the movable contact arm of each reed
switch as the drive shaft passes by.
Given the following conditions:
* The reactor is shut down.
* The reactor coolant system is at normal operating pressure and temperature.
* The BF3 source range detectors are properly positioned outside the reactor vessel and adjacent
to the lower portion of the core.
* All BF3 source range detectors are indicating approximately 100 cps.
* A sudden loss of coolant accident occurs that causes uniform bulk boiling throughout the
reactor vessel and core.
Assuming that the source neutron flux level remains constant, how and why will source range detector
outputs change as the uniform core voiding increases from 0 percent to 50 percent?
A. Increase, because the detectors will experience a higher rate of neutron interactions due to the axial
power distribution shifting toward the lower portion of the core.
B. Increase, because the detectors will experience a higher rate of neutron interactions due to
increasing neutron leakage from the core.
C. Decrease, because the detectors will experience a lower rate of neutron interactions due to a
decreasing shutdown neutron flux level.
D. Decrease, because the detectors will experience a lower rate of gamma interactions due to
decreasing reactor coolant attenuation.
Increase, because the detectors will experience a higher rate of neutron interactions due to
increasing neutron leakage from the core.
Scintillation detectors convert radiation energy into light by a process known as…
A. gas amplification.
B. space charge effect.
C. luminescence.
D. photoionization.
luminescence
A BF3 proportional counter is being used to measure neutron level during a reactor startup. Which
one of the following describes the method used to ensure that neutron indication is not affected by
gamma reactions in the detector?
A. Two counters are used: one sensitive to neutron and gamma and the other sensitive to gamma only.
The outputs are electrically opposed to cancel the gamma-induced currents.
B. The BF3 proportional counter measures neutron flux of such high intensity that the gamma signal
is insignificant compared to the neutron signal.
C. In a proportional counter, gamma-induced pulses are of insufficient duration to generate a
significant output. Only neutron pulses have sufficient duration to be counted by the detector
instrumentation.
D. In a proportional counter, neutron-induced pulses are significantly larger than gamma pulses.
The detector instrumentation filters out the smaller gamma pulses.
In a proportional counter, neutron-induced pulses are significantly larger than gamma pulses.
The detector instrumentation filters out the smaller gamma pulses.
Most of the electrons collected in a fission chamber are released as a result of ionizations caused
directly by…
A. fission fragments.
B. fission gammas.
C. fission betas.
D. fissionable materials.
fission fragments.
Which one of the following describes the reason for the high sensitivity of a Geiger-Mueller tube
radiation detector?
A. Changes in applied detector voltage have little effect on detector output.
B. Geiger-Mueller tubes are thinner than other radiation detector types.
C. Any incident radiation event causing primary ionization results in ionization of the entire detector
gas volume.
D. Geiger-Mueller tubes are operated at relatively low detector voltages, allowing detection of low
energy radiation.
Any incident radiation event causing primary ionization results in ionization of the entire detector
gas volume.
A gas-filled radiation detector operating in the ion chamber region is exposed to a constant gamma
radiation field. If the detector’s applied voltage is increased, but kept within the ion chamber region,
the detector’s output will…
A. increase, because the production rate of secondary ions will increase.
B. increase, because the recombination rate of primary ions will decrease.
C. remain the same, because the detector is already producing its maximum output.
D. remain the same, because the detector’s operation is unaffected by the change in applied voltage.
remain the same, because the detector’s operation is unaffected by the change in applied voltage.
Which one of the following materials is typically installed inside an ion chamber detector that is used
for reactor power indication?
A. Polyethylene
B. Boron-10
C. Uranium-238
D. Rhodium-103
Boron-10
In a gas-filled radiation detector operating in the proportional region, essentially __________ of the
ions caused by incident radiation are collected; and the number of ions collected from secondary
ionizations is __________ the applied voltage.
A. all; independent of
B. none; related to
C. all; related to
D. none; independent of
all; related to
Which one of the following features is typically used to enhance thermal neutron detection in a
gas-filled detector?
A. Encapsulate the detector in polyethylene.
B. Encapsulate the detector in boron-10.
C. Line the inside of the detector with polyethylene.
D. Line the inside of the detector with boron-10.
Line the inside of the detector with boron-10.
Which one of the following is a characteristic of Geiger-Mueller tube radiation detectors?
A. They can discriminate between neutron and gamma radiation.
B. They can discriminate between gammas of differing energies in the MeV range.
C. They provide an output that is inversely proportional to the applied voltage within the
Geiger-Mueller region.
D. They undergo maximum gas amplification whenever an ion is formed in the tube.
They undergo maximum gas amplification whenever an ion is formed in the tube.
Which one of the following describes why a BF3 proportional counter can be used in the source range
to measure neutron radiation in a radiation field that also contains gamma radiation?
A. Neutrons directly ionize the BF3 gas, producing larger pulses than gammas.
B. Neutrons interacting with the BF3 gas result in the release of alpha particles, which produce larger
pulses than gammas.
C. Neutrons are captured by boron-10 and produce additional neutrons that completely ionize the fill
gas in the detector.
D. The gamma radiation field is insignificant when compared to the neutron field.
Neutrons interacting with the BF3 gas result in the release of alpha particles, which produce larger
pulses than gammas.
Which one of the following types of radiation will produce the greatest number of ions while passing
through one centimeter of air? (Assume the same initial kinetic energy for each type of radiation.)
A. Alpha
B. Beta
C. Gamma
D. Neutron
Alpha
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.)
A. Limited proportional and Geiger-Mueller
B. Ion chamber and proportional
C. Proportional and limited proportional
D. Geiger-Mueller and ion chamber
Geiger-Mueller and ion chamber
Which one of the following describes a characteristic of a Geiger-Mueller radiation detector?
A. Radiation types can be identified by pulse height and duration.
B. Specific radionuclides can be identified with the use of gamma spectrometry.
C. Small variations in applied voltage will result in large changes in detector output.
D. Any type of radiation that ionizes the detector gas will produce the same magnitude detector output
pulse.
Any type of radiation that ionizes the detector gas will produce the same magnitude detector output
pulse.
A Geiger-Mueller radiation detector is located in a radiation field consisting of beta, gamma, and fast
neutron radiation. Assuming each type of radiation enters the detector gas chamber and ionizes the
detector gas, which one of the following describes the resulting detector pulse sizes?
A. Beta radiation will produce a larger pulse size than either gamma or fast neutron radiation.
B. Gamma radiation will produce a larger pulse size than either beta or fast neutron radiation.
C. Fast neutron radiation will produce a larger pulse size than either beta or gamma radiation.
D. Beta, gamma, and fast neutron radiation will produce pulse sizes that are equal in magnitude.
Beta, gamma, and fast neutron radiation will produce pulse sizes that are equal in magnitude.
A gas-filled radiation detector operating in the proportional region is exposed to a constant gamma
radiation field. If the detector’s applied voltage is increased but maintained within the proportional
region, the rate of ion collection will…
A. increase, because more secondary ionizations are occurring in the detector.
B. increase, because fewer primary ions are recombining with electrons prior to reaching the
electrodes.
C. stay approximately the same, because the ion chamber is operating at saturated conditions.
D. stay approximately the same, because all of the primary ions were already being collected at the
lower voltage.
increase, because more secondary ionizations are occurring in the detector.
What is the function of the positive electrode in an ion chamber?
A. Produce ions when exposed to a radiation field.
B. Release electrons to combine with positive ions.
C. Perform gas quenching to maximize detector sensitivity.
D. Collect the electrons released during gas ionization.
Collect the electrons released during gas ionization.
Just prior to a plant outage, the power range nuclear instruments (using excore detectors) were
calibrated at 50 percent reactor power. During the outage, 25 percent of the fuel assemblies were
shuffled to reduce the power being produced at the center of the core. No fuel assemblies were
replaced.
Immediately after the outage, when the reactor is stabilized at 50 percent, indicated reactor power will
be __________ than actual power because neutron leakage from the core has __________.
A. higher; increased
B. higher; decreased
C. lower; increased
D. lower; decreased
higher; increased
A gas-filled radiation detector operating in the ion chamber is exposed to a constant gamma radiation
field. If the applied voltage is increased but maintained within the ion chamber region, the rate of ion
collection will…
A. increase, because more secondary ionizations are occurring in the detector.
B. stay approximately the same, because all of the primary ions were already being collected at the
lower voltage.
C. increase, because fewer primary ions are recombining in the detector prior to reaching the
electrodes.
D. stay approximately the same, because the ion chamber is operating at saturated conditions.
stay approximately the same, because all of the primary ions were already being collected at the
lower voltage.
What is the effect on a gas-filled neutron detector operating in the proportional region if the detector
voltage is increased such that the detector operates closer to the high end of the proportional region?
A. Neutron-induced pulses will become so large that gamma pulse discrimination is no longer
needed, yielding a more accurate neutron count rate.
B. The positive space charge effect will increase and prevent collection of both gamma- and
neutron-induced pulses, yielding a less accurate neutron count rate.
C. A high rate of incident gamma radiation will result in the combination of multiple small
gamma-induced pulses into larger pulses. The larger combined pulses will be counted as
neutron-induced pulses, yielding a less accurate neutron count rate.
D. Detection of any single ionizing event will result in ionizing nearly the entire detector gas volume.
The resulting large pulses will prevent the detector from differentiating between radiation types,
yielding a less accurate neutron count rate.
A high rate of incident gamma radiation will result in the combination of multiple small
gamma-induced pulses into larger pulses. The larger combined pulses will be counted as
neutron-induced pulses, yielding a less accurate neutron count rate.
A gas-filled radiation detector operating in the proportional region is exposed to a constant gamma
radiation field. If the applied voltage is decreased but maintained within the proportional region, the
rate of ion collection will…
A. stay approximately the same, because all primary ions are collected as long as detector voltage
remains in the proportional region.
B. stay approximately the same, because the detector is still operating at saturated conditions.
C. decrease, because a decreased space charge around the positive electrode reduces gas
amplification.
D. decrease, because fewer secondary ionizations are occurring in the detector.
decrease, because fewer secondary ionizations are occurring in the detector.
A gas-filled radiation detector operating in the ion chamber region is exposed to a constant gamma
radiation field. If the applied voltage is decreased but maintained within the ion chamber region, the
rate of ion collection will…
A. stay approximately the same, because all of the primary ions continue to be collected and
essentially no secondary ionizations are occurring.
B. stay approximately the same, because detector operation in the ionization chamber region is
characterized by complete ionization of the detector gas.
C. decrease, because fewer primary ionizations are occurring in the detector as detector voltage
decreases.
D. decrease, because fewer secondary ionizations are occurring in the detector as detector voltage
decreases.
stay approximately the same, because all of the primary ions continue to be collected and
essentially no secondary ionizations are occurring.
A nuclear power plant startup is in progress immediately following a reactor refueling outage. The
external nuclear instrumentation (NI) was calibrated at 50 percent power just prior to the refueling
outage and has not been readjusted.
If actual reactor power level is increased to 50 percent and stabilized, NI power level will indicate
__________ than actual reactor power level because, when compared to pre-outage 50 percent power
level operation, __________.
A. higher; the total core fission rate has increased
B. lower; the total core fission rate has decreased
C. higher; the fission rate in the outer portion of the core has increased
D. lower; the fission rate in the outer portion of the core has decreased
lower; the fission rate in the outer portion of the core has decreased
Which one of the following describes the reason for the high sensitivity of a gas-filled radiation
detector operating in the Geiger-Mueller region?
A. Any radiation-induced ionization results in a large detector output pulse.
B. Geiger-Mueller detectors are longer than other types of radiation detectors, resulting in greater
detector surface area.
C. The detector output is inversely proportional to the applied voltage within the Geiger-Mueller
region.
D. High detector voltage allows differentiation between the various radiation types.
Any radiation-induced ionization results in a large detector output pulse.
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?
A. Indicated reactor power will be higher than actual reactor power due to increased core neutron
leakage.
B. Indicated reactor power will be higher than actual reactor power due to decreased core neutron
leakage.
C. Indicated reactor power will be lower than actual reactor power due to decreased core neutron
leakage.
D. Indicated reactor power will be lower than actual reactor power due to increased core neutron
leakage.
Indicated reactor power will be higher than actual reactor power due to increased core neutron
leakage.
Which one of the following statements describes the operation of a gas-filled radiation detector
operating in the proportional region?
A. The number of ions collected from both primary and secondary ionizations is independent of the
applied voltage.
B. Essentially all of the ions from primary ionizations are collected; the number of ions collected
from secondary ionizations is independent of the applied voltage.
C. The number of ions collected from both primary and secondary ionizations varies directly with the
applied voltage on a logarithmic scale.
D. Essentially all of the ions from primary ionizations are collected; the number of ions collected
from secondary ionizations varies directly with the applied voltage on a logarithmic scale.
Essentially all of the ions from primary ionizations are collected; the number of ions collected
from secondary ionizations varies directly with the applied voltage on a logarithmic scale.
A boron trifluoride (BF3) detector (proportional counter) is normally used to monitor only source
range core neutron level. How will the detector and source range count rate indication be affected if
normal detector high voltage is inadvertently applied during reactor operation in the power range?
A. The BF3 gas will become completely ionized and source range indication will stabilize at a
constant low value.
B. The BF3 gas will become completely ionized and source range indication will stabilize at a
constant high value.
C. The detector electrodes will become exposed to an extremely high neutron flux and cause a false
high reading on the source range indication.
D. The detector electrodes will become exposed to an extremely high gamma flux and cause a false
high reading on the source range indication.
The BF3 gas will become completely ionized and source range indication will stabilize at a
constant low value.
A beta particle and an alpha particle enter and cause ionization in a gas-filled radiation detector
operating in the Geiger-Mueller region. Which one of the following accurately compares the
amplitude of the detector pulses caused by each type of radiation?
A. The beta particle pulse will be larger in amplitude.
B. The alpha particle pulse will be larger in amplitude.
C. The pulses will be the same for both types of radiation.
D. Cannot be determined without particle kinetic energy information.
The pulses will be the same for both types of radiation.
A nuclear power plant has been shut down for one month. A portable gas-filled radiation detector is
needed to monitor shutdown reactor core neutron level from a location outside the reactor vessel.
The detector must be able to distinguish between ionizations caused by gamma and neutron radiation.
Which region(s) of the gas-filled detector characteristic curve is/are acceptable for operation of the
detector?
A. Geiger-Mueller, Ion Chamber, and Proportional regions are all acceptable.
B. Proportional region is acceptable, and Ion Chamber region also may be usable.
C. Ion Chamber region is acceptable, and Geiger-Mueller region also may be usable.
D. Geiger-Mueller region is acceptable, and Proportional region also may be usable.
Proportional region is acceptable, and Ion Chamber region also may be usable.
Quench gases are added to gas-filled radiation detectors that operate in the __________ region; the
quench gases prevent a single ionization event from causing __________ in the detector gas volume.
A. ion chamber; multiple discharges
B. ion chamber; secondary ionizations
C. Geiger-Mueller; multiple discharges
D. Geiger-Mueller; secondary ionizations
Geiger-Mueller; multiple discharges
Which one of the following contains the pair of radiation detector types that are the most sensitive to
low-energy beta and/or gamma radiation?
A. Geiger-Mueller and scintillation
B. Geiger-Mueller and ion chamber
C. Ion chamber and scintillation
D. Ion chamber and proportional
Geiger-Mueller and scintillation
A beta particle and an alpha particle with equal kinetic energies cause ionization in a gas-filled
radiation detector. The detector is operating in the ion chamber region of the gas ionization curve.
Which one of the following describes the amplitudes of the detector pulses caused by each type of
radiation?
A. The beta particle pulse will be larger in amplitude.
B. The alpha particle pulse will be larger in amplitude.
C. The amplitudes of both pulses will be approximately equal for all detector voltages in the ion
chamber region.
D. The amplitudes of both pulses will be approximately equal for all detector voltages in the ion
chamber region, as well as all detector voltages outside the ion chamber region.
The alpha particle pulse will be larger in amplitude.
Which one of the following types of radiation detectors is generally not used for measuring a
high-intensity beta and gamma radiation field because of a relatively long detector recovery time, or
dead time, following each ionization event?
A. Geiger-Mueller
B. Ion chamber
C. Proportional
D. Scintillation
Geiger-Mueller
A proportional detector with pulse height discrimination circuitry is being used in a constant field of
neutron and gamma radiation to provide source range neutron count rate indication. Assume that the
pulse height discrimination setpoint does not change.
If the detector voltage is increased but maintained within the proportional region, count rate indication
will increase because…
A. a single neutron- or gamma-induced ionizing event will result in multiple pulses inside the
detector.
B. the ratio of the number of neutron-induced pulses to gamma-induced pulses inside the detector will
increase.
C. the positive space charge effect will increase and promote the collection of both gamma- and
neutron-induced pulses.
D. all detector pulses will increase in amplitude and previously uncounted gamma pulses will be
added to the total count rate.
all detector pulses will increase in amplitude and previously uncounted gamma pulses will be
added to the total count rate.
Which one of the following types of radiation detectors uses a gas volume for radiation detection and
will typically produce the weakest output signal if all of the detectors are placed in the same gamma
radiation field?
A. Geiger-Mueller
B. Ion chamber
C. Proportional counter
D. Scintillation
Ion chamber
Which one of the following types of radiation detectors is typically the least accurate in determining
the dose rate to a human body from an unspecified source of radiation?
A. Geiger-Mueller
B. Ion chamber
C. Proportional counter
D. Scintillation
Geiger-Mueller
A fission chamber neutron detector is located in a constant neutron radiation field and is initially
operating in the proportional region. If the voltage applied to the detector is changed such that the
detector operates in the ion chamber region, the rate of neutron interactions in the detector will
__________; and the amplitude of each neutron-induced detector pulse will __________.
A. increase; increase
B. decrease; decrease
C. remain the same; increase
D. remain the same; decrease
remain the same; decrease
Which one of the following describes the positive space charge effect associated with a gas-filled
radiation detector?
A. Multiple detector pulses result from a single ionization event because positive ions form a cloud
around the negative electrode, which increases the electric field strength, thereby initiating
secondary ionizations.
B. Multiple detector pulses result from a single ionization event because positive ions form a cloud
around the positive electrode, which increases the electric field strength, thereby initiating
secondary ionizations.
C. The pulse amplitude resulting from an ionization event is reduced because positive ions form a
cloud around the negative electrode, which reduces the electric field strength, thereby limiting
secondary ionizations.
D. The pulse amplitude resulting from an ionization event is reduced because positive ions form a
cloud around the positive electrode, which reduces the electric field strength, thereby limiting
secondary ionizations.
The pulse amplitude resulting from an ionization event is reduced because positive ions form a
cloud around the positive electrode, which reduces the electric field strength, thereby limiting
secondary ionizations.
In which usable region(s) of the gas-filled detector ionization curve is the pulse height resulting from
the detection of a 1 MeV beta particle the same as a 5 MeV alpha particle?
A. Geiger-Mueller only.
B. Geiger-Mueller and Ionization Chamber.
C. Proportional only.
D. Proportional and Ionization Chamber.
Geiger-Mueller only.
Which one of the following personal radiation monitoring devices can be charged with DC voltage to
“zero” the device prior to use?
A. Film badge
B. Alarming dosimeter
C. Thermoluminescent dosimeter
D. Self-reading pocket dosimeter
Self-reading pocket dosimeter
A Geiger-Mueller detector with a pancake probe (often called a frisker) is being used to monitor
personnel leaving a radiologically controlled area. The probe is equipped with a mica window.
Two individuals have radioactive skin contamination—one individual with only alpha emitters, and
the other with only beta emitters. Both types of radiation are being emitted at the same rate. The
same percentage of each type of radiation enters the probe’s detection chamber and causes ionization.
Which one of the following describes the detector’s count rate response to the alpha and beta
radiation?
A. The count rate will be higher for the alpha radiation.
B. The count rate will be higher for the beta radiation.
C. The count rate will be the same for both types of radiation.
D. Cannot be determined without knowing the energy levels of the radiation.
The count rate will be the same for both types of radiation.
Just prior to a plant outage, the power range nuclear instruments (using excore detectors) were
calibrated at 50 percent reactor power. During the outage, 40 fuel assemblies from the center of the
core were exchanged with 40 higher enriched fuel assemblies from the outer portions of the core. No
other fuel assemblies were affected.
Immediately after the outage, when the reactor is stabilized at 50 percent power, indicated reactor
power will be __________ than actual reactor power because neutron leakage from the core has
__________.
A. lower; decreased
B. lower; increased
C. higher; decreased
D. higher; increased
lower; decreased
A proportional detector with pulse height discrimination circuitry is being used in a constant field of
neutron and gamma radiation to provide source range neutron count rate indication. Assume the
pulse height discrimination threshold does not change.
If the detector voltage is decreased significantly, but maintained within the proportional region, the
detector count rate indication will __________; and the detector will become __________ susceptible
to the positive space charge effect.
A. decrease; less
B. decrease; more
C. remain the same; less
D. remain the same: more
decrease; less
A gas-filled radiation detector that operates in the Geiger-Mueller region of the gas ionization curve is
being used in a constant radiation field. If the detector’s operating voltage is increased by 50 volts
while remaining in the Geiger-Mueller region, the detector’s count rate indication will __________;
and the ability of the detector to detect gamma radiation will __________.
A. increase; improve
B. increase; remain the same
C. remain the same; improve
D. remain the same; remain the same
remain the same; remain the same
A proportional detector with pulse height discrimination circuitry is being used in a constant field of
neutron and gamma radiation to provide source range neutron count rate indication. Assume the
pulse height discrimination value does not change.
If the detector voltage is increased significantly, but maintained within the proportional region, the
detector count rate indication will __________; and the detector will become __________ susceptible
to the positive space charge effect.
A. increase; less
B. increase; more
C. remain the same; less
D. remain the same: more
increase; more
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.
A. larger; larger
B. larger; smaller
C. smaller; larger
D. smaller; smaller
smaller; smaller
A gas-filled radiation detector is operating in the proportional region with a count rate indication of
1.0 x 10^5 cpm in a constant radiation field. The detector does not have pulse height discrimination
circuitry.
If the detector’s operating voltage is increased by 20 percent while remaining in the proportional
region, the total number of ions resulting from a single ionization within the detector will __________;
and the detector count rate indication will __________.
A. increase; increase
B. increase; remain the same
C. remain the same; increase
D. remain the same; remain the same
increase; remain the same
Radiation interacting with a gas-filled radiation detector produces primary ion pairs. A primary ion
pair consists of an electron and the ion formed by its removal. If the detector voltage is high enough,
a primary ion pair can produce secondary ion pairs.
When secondary ion pairs are formed, they are typically caused by interactions between the primary
__________ and the __________ in the detector.
A. ion; gas
B. ion; electrodes
C. electron; gas
D. electron; electrodes
electron; gas
A typical gamma ray (1 to 2 MeV) normally produces a free electron in a gas-filled radiation detector
by…
A. transferring energy to a nucleus, which recoils and leaves behind a free electron.
B. transferring energy to a bound electron, which recoils and becomes a free electron.
C. entering the electrostatic field of a nucleus, where it transforms into a proton and a free electron.
D. entering the electrostatic field of a bound electron, where it transforms into a positron and a free
electron.
transferring energy to a bound electron, which recoils and becomes a free electron.
A typical alpha particle produces free electrons in a gas-filled radiation detector primarily by…
A. colliding with gas nuclei.
B. colliding with bound electrons.
C. electrostatic attraction of gas nuclei.
D. electrostatic attraction of bound electrons.
electrostatic attraction of bound electrons.
Which one of the following describes a characteristic of a self-reading pocket dosimeter (SRPD)?
A. The output of an SRPD is a dose rate in mR/hr.
B. SRPDs are primarily sensitive to beta radiation.
C. SRPD readings must be considered inaccurate when they are dropped.
D. SRPDs hold their charge indefinitely when removed from a radiation field.
SRPD readings must be considered inaccurate when they are dropped.
Which one of the following types of radiation is the major contributor to the dose indication on a
self-reading pocket dosimeter (SRPD)?
A. Alpha
B. Beta
C. Gamma
D. Neutron
Gamma
Which one of the following describes a characteristic of a self-reading pocket dosimeter?
A. Provides dose rate indication in mR/hr.
B. More sensitive to gamma radiation than beta radiation.
C. Contains crystals that luminesce when exposed to ionizing radiation.
D. Can be stored as an accurate record of lifetime radiation exposure.
More sensitive to gamma radiation than beta radiation.
A nuclear plant worker normally wears a thermoluminescent dosimeter (TLD) or similar device for
measuring radiation exposure. When a self-reading pocket dosimeter (SRPD) is also required, where
will the SRPD be worn and why?
A. Below the waist near the TLD to measure radiation from the same source(s).
B. Below the waist away from the TLD to measure radiation from different sources.
C. Above the waist near the TLD to measure radiation from the same source(s).
D. Above the waist away from the TLD to measure radiation from different sources.
Above the waist near the TLD to measure radiation from the same source(s).
A Geiger-Mueller detector with a pancake probe (often called a frisker) is being used to monitor
workers leaving a radiologically controlled area for contamination. The probe is equipped with a
mica window. The background detector count rate is 20 cpm.
As one worker’s shoe is scanned, the count rate increases to 200 cpm. When a sheet of paper is
placed between the probe and the shoe, the count rate decreases to 60 cpm. Which one of the
following is indicated by the decrease in the count rate?
A. The contamination contains beta particles.
B. The contamination contains alpha particles.
C. The contamination does not contain beta particles.
D. The contamination does not contain alpha particles.
The contamination contains alpha particles.
A Geiger Mueller detector with a pancake probe (sometimes called a frisker) is being used to monitor
for skin contamination. During frisking, the probe is more likely to detect contamination if the probe
is held __________ than one-half inch from the skin; and is moved __________ than two inches per
second.
A. farther; faster
B. farther; slower
C. closer; faster
D. closer; slower
closer; slower
A nuclear plant worker normally wears a thermoluminescent dosimeter (TLD) or similar device for
measuring whole body radiation exposure. When a self-reading pocket dosimeter (SRPD) is also
required for whole body monitoring, where will the SRPD be worn and why?
A. Near the TLD to add exposure to the TLD measurement.
B. Near the TLD to measure radiation affecting the same part of the body.
C. Away from the TLD to add exposure to the TLD measurement.
D. Away from the TLD to measure radiation affecting a different part of the body.
Near the TLD to measure radiation affecting the same part of the body.
A Geiger-Mueller detector with 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:
* When a sheet of paper is placed between the probe and the shoe, the count rate decreases to 600
cpm.
* 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?
A. Beta only
B. Alpha only
C. Beta and gamma
D. Alpha and gamma
Alpha and gamma
A Geiger-Mueller detector with 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:
* When a sheet of paper is placed between the probe and the shoe, the count rate decreases to 400
cpm.
* When a sheet of aluminum foil is placed between the probe and the shoe, the count rate
decreases to 20 cpm.
The results of the above actions indicate that the radiation from the shoe contamination consists of…
A. beta only.
B. alpha and beta only.
C. beta and gamma only.
D. alpha, beta, and gamma.
alpha and beta only.
Which one of the following describes the ion collection that occurs in a proportional counter, such as a
BF3 detector?
A. A fraction of the ions created by primary ionizations are collected. No secondary ionizations take
place.
B. Virtually all of the ions created by primary ionizations are collected. No secondary ionizations
take place.
C. Virtually all of the ions created by primary ionizations along with a fraction of the ions created by
secondary ionizations are collected.
D. Virtually all of the ions created by primary and secondary ionizations are collected.
Virtually all of the ions created by primary and secondary ionizations are collected.
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…
A. upscale.
B. downscale.
C. as is.
D. to midscale.
downscale
During reactor power operation, a reactor coolant sample is taken and analyzed. Which one of the
following lists three radionuclides that are all indicative of a fuel cladding failure if detected in
elevated concentrations in the reactor coolant sample?
A. Lithium-6, cobalt-60, and argon-41
B. Iodine-131, cesium-138, and strontium-89
C. Nitrogen-16, xenon-135, and manganese-56
D. Hydrogen-2, hydrogen-3, and oxygen-18
Iodine-131, cesium-138, and strontium-89
During power operation, a reactor coolant sample is taken and analyzed. Which one of the following
lists three nuclides that are all indicative of a possible fuel cladding failure if found to be at elevated
concentrations in the reactor coolant sample?
A. Oxygen-18, iron-59, and zirconium-95
B. Cobalt-60, iodine-131, and xenon-135
C. Krypton-85, strontium-90, and cesium-136
D. Hydrogen-2, hydrogen-3, and nitrogen-16
Krypton-85, strontium-90, and cesium-136
