NRRPT Prep Detection and Measurement
Study Guide Exam Latest 2026/2027
Updated Verified Questions and Solutions
A+ Pass Guaranteed
Question Number: 399 Detection and Measurement
In NTE (nuclear track emulsion) film, the tracks are caused by:
A) alpha particles.
B) beta particles.
C) gamma photons.
D) recoil neutrons.
E) recoil protons.
- ANS - The correct answer is: E
In this fast neutron responsive dosimeter, recoil protons from elastic
scattering with hydrogen atoms in the film create short "tracks" of
ionization as stable silver atoms are created. These tracks are counted
either by eye or mechanically and equated to total neutron dose
equivalent.
Question Number: 400 Detection and Measurement
,The sensitivity of photographic film to photons is energy dependent
primarily because of:
A) varying conditions of temperature and humidity during exposure.
B) strong photoelectric absorption by the silver bromide in the emulsion.
C) varying energies of the Compton-scattered photons.
D) pair production.
E) build-up.
- ANS - The correct answer is: B
Film is considered to be "energy dependent" since it is most efficient for
photon detection when interaction is by photoelectric effect. As we know,
photoelectric effect predominates only below 200 keV. This is one reason
that filters are used in film badges.
Question Number: 401 Detection and Measurement
What is the effective half-life in the human body for Cobalt-60, if the
biological half-life is eight days?
A) 0.125 days
B) 1.52 days
C) 7.97 days
D) 45.8 days
E) 1.52 years
- ANS - The correct answer is: C
,A good thumb rule for calculating effective half-life is that if the isotope
has a half-life greater than 100 days, the effective half-life (Teff) is only a
bit less than the biological half-life. The effective half-life is never greater
than the biological half-life. The equation to calculate Teff is as follows:
Teff = Tb * Tr / Tb + Tr Where:
Tb = biological half-life
Tr = radiological (physical) half-life
Question Number: 402 Detection and Measurement
If the DAC for Rn-222 is 3.0 x 10 -8 µCi /ml, the working level is: A) 9.0 x
10-8 µCi /ml
B) 9.0 x 10-9 µCi /ml
C) 3.0 x 10-9 µCi /ml
D) 6.0 x 10-7 µCi /ml
E) 6.0 x 10-8 µCi /ml
- ANS - The correct answer is: A
According to 10 CFR Part 20 Appendix B, the DAC for Rn-222 is 1/3 of the
working level.
Question Number: 403 Detection and Measurement
An individual who receives 40 DAC-hours will receive a committed
effective dose equivalent of:
, A) 10 millirem
B) 40 millirem
C) 80 millirem
D) 100 millirem
E) 1250 millirem
- ANS - The correct answer is: D
Assuming the DAC is based upon the sALI, one DAC-hour is equal to a
CEDE of 2.5 mrem. Therefore:
40 DAC-hrs * 2.5 mrem/DAC-hr = 100 mrem
Question Number: 404 Detection and Measurement
The full width at half maximum peak energy for a Cesium-137 photopeak
using a GeLi detector is 3 keV. The photopeak energy is 0.662 MeV. The
percent resolution of the detection system for this energy is:
A) 0.22%
B) 0.45%
C) 4.53%
D) 22.0%
E) 45.3%
- ANS - The correct answer is: B
Study Guide Exam Latest 2026/2027
Updated Verified Questions and Solutions
A+ Pass Guaranteed
Question Number: 399 Detection and Measurement
In NTE (nuclear track emulsion) film, the tracks are caused by:
A) alpha particles.
B) beta particles.
C) gamma photons.
D) recoil neutrons.
E) recoil protons.
- ANS - The correct answer is: E
In this fast neutron responsive dosimeter, recoil protons from elastic
scattering with hydrogen atoms in the film create short "tracks" of
ionization as stable silver atoms are created. These tracks are counted
either by eye or mechanically and equated to total neutron dose
equivalent.
Question Number: 400 Detection and Measurement
,The sensitivity of photographic film to photons is energy dependent
primarily because of:
A) varying conditions of temperature and humidity during exposure.
B) strong photoelectric absorption by the silver bromide in the emulsion.
C) varying energies of the Compton-scattered photons.
D) pair production.
E) build-up.
- ANS - The correct answer is: B
Film is considered to be "energy dependent" since it is most efficient for
photon detection when interaction is by photoelectric effect. As we know,
photoelectric effect predominates only below 200 keV. This is one reason
that filters are used in film badges.
Question Number: 401 Detection and Measurement
What is the effective half-life in the human body for Cobalt-60, if the
biological half-life is eight days?
A) 0.125 days
B) 1.52 days
C) 7.97 days
D) 45.8 days
E) 1.52 years
- ANS - The correct answer is: C
,A good thumb rule for calculating effective half-life is that if the isotope
has a half-life greater than 100 days, the effective half-life (Teff) is only a
bit less than the biological half-life. The effective half-life is never greater
than the biological half-life. The equation to calculate Teff is as follows:
Teff = Tb * Tr / Tb + Tr Where:
Tb = biological half-life
Tr = radiological (physical) half-life
Question Number: 402 Detection and Measurement
If the DAC for Rn-222 is 3.0 x 10 -8 µCi /ml, the working level is: A) 9.0 x
10-8 µCi /ml
B) 9.0 x 10-9 µCi /ml
C) 3.0 x 10-9 µCi /ml
D) 6.0 x 10-7 µCi /ml
E) 6.0 x 10-8 µCi /ml
- ANS - The correct answer is: A
According to 10 CFR Part 20 Appendix B, the DAC for Rn-222 is 1/3 of the
working level.
Question Number: 403 Detection and Measurement
An individual who receives 40 DAC-hours will receive a committed
effective dose equivalent of:
, A) 10 millirem
B) 40 millirem
C) 80 millirem
D) 100 millirem
E) 1250 millirem
- ANS - The correct answer is: D
Assuming the DAC is based upon the sALI, one DAC-hour is equal to a
CEDE of 2.5 mrem. Therefore:
40 DAC-hrs * 2.5 mrem/DAC-hr = 100 mrem
Question Number: 404 Detection and Measurement
The full width at half maximum peak energy for a Cesium-137 photopeak
using a GeLi detector is 3 keV. The photopeak energy is 0.662 MeV. The
percent resolution of the detection system for this energy is:
A) 0.22%
B) 0.45%
C) 4.53%
D) 22.0%
E) 45.3%
- ANS - The correct answer is: B
