NRRPT EXAM
NRRPT Prep Applied Radiation Protection
Exam Questions With Correct Answers &
Rationale
Question Number: 699 Applied Radiation Protection
For calculating dose to an organ from internal sources, the "specific effective energy" of a radionuclide is
BEST described as:
A) the energy given off by the radionuclide per unit of radionuclide activity.
B) the energy absorbed per unit mass of the organ per unit of radionuclide activity.
C) the energy absorbed per unit mass of the organ per disintegration of the radionuclide.
D) the energy given off by the radionuclide per disintegration of the radionuclide.
E) the energy transferred to the organ per unit of radionuclide activity. - ✔✔✔ - The correct answer is: C
The "SEE" is used in the Medical Internal Radiation Dosimetry (MIRD) dose modeling technique.
Question Number: 700 Applied Radiation Protection
What is the BEST method of disposal of dog carcasses which have been treated with a radionuclide with
a 78-hour half life?
A) Wait 3.25 days and prepare for shipment to a disposal facility or incinerate.
B) Wait 1.625 days and bury.
C) Wait 3.25 days and bury.
D) Wait 32.5 days and prepare for shipment to a disposal facility or incinerate.
E) Wait 32.5 days and bury. - ✔✔✔ - The correct answer is: D
It is common for radioactive materials licenses to allow the disposal of radioactive materials after ten
half-lives as "clean" materials. In this case, the waste is still biohazardous, so proper burial or
incineration is indicated.
Question Number: 701 Applied Radiation Protection
The major radiological health concern associated with burial of low level solid radioactive waste is:
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, NRRPT EXAM
A) external radiation at the surface of the burial site.
B) contamination of potable water supplies.
C) airborne radioactivity resulting from contaminated soil.
D) release of volatile radioactive daughter products.
E) contamination of vegetables grown in soil at the site. - ✔✔✔ - The correct answer is: BThe critical
exposure pathway for near-surface disposal of radioactive materials is through drinking water. Most of
the regulations surrounding the burial of radioactive materials, such as waste classification and
stabilization requirements, are designed to prevent contamination of potable (drinkable) water.
Question Number: 702 Applied Radiation Protection
An adequate Radiation Safety Program is the ultimate responsibility of:
A) the owner of the licensed facility.
B) the operator of the source of radiation.
C) the Radiation Safety Officer.
D) the line supervisor.
E) the radiation worker. - ✔✔✔ - The correct answer is: A
The radioactive materials license is issued to the owner of the facility. It is the licensee who is
responsible for all aspects of compliance with the license, including the implementation of a radiation
safety program. It is the duty of the RSO to administer the program.
Question Number: 703 Applied Radiation Protection
An x-ray machine is operated in a closed room for several minutes. After the machine is turned off, how
long should the operator wait before entering the room?
A) He may enter immediately.
B) 10 seconds
C) 30 seconds
D) 1 minute
E) 1 hour - ✔✔✔ - The correct answer is: A
When the current to the x-ray tube is turned off, the production of electrons stops. The principle behind
x-ray production in the tube is bremsstrahlung of these electrons with the target material. When the
electron production stops, so does the x-ray production. There is, of course, no radioactive material in
an x-ray machine.
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, NRRPT EXAM
Question Number: 704 Applied Radiation Protection
The exposure rate of the turbine floor of a boiling water reactor plant could be expected to be
decreased to less than 1% at least after shutdown?
A) five minutes
B) one hour
C) twenty-four hours
D) thirty-six hours
E) forty-eight hours - ✔✔✔ - The correct answer is: A
A good thumb rule for decay is that after seven half-lives, activity is less than 1% of original activity (it is
actually 1/(2)7, or 1/128). Since the nuclide of concern on the turbine floor of a BWR is N-16 (T 1/2 = 7.1
sec; 6.1,7.1 MeV gamma's), it would take only 49.7 seconds to decay to less than 1%. N-16 is produced
from the (n,p) reaction on O-16 in the reactor coolant.
Question Number: 705 Applied Radiation Protection
The goal and future requirement regarding high level liquid waste is:
A) transformation by irradiation to shorter lived, less toxic materials.
B) verification and deep ground burial.
C) use as a heat source.
D) disposal into geological formations.
E) disposal into salt formations. - ✔✔✔ - The correct answer is: B
High level waste, which includes spent reactor fuel and liquid wastes from the solvent extraction
process, requires stabilization and disposal in deep ground geologic repositories. Although vitrification
technology and deep ground burial are practiced in other industrialized nations, the U.S. lags behind in
implementing these methods.
Question Number: 706 Applied Radiation Protection
Below about 0.2 MeV, the most predominant photon interaction in lead of significance in health physics
is which of the following?
A) Pair production
B) Compton screening
C) Photoelectric effect
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, NRRPT EXAM
D) Rayleigh scattering
E) Thompson scattering - ✔✔✔ - The correct answer is: C
Photoelectric effect predominates below 200 keV, Compton effect between 200 keV and 5 MeV, and
Pair production above 5 MeV.
Question Number: 707 Applied Radiation Protection
A Pu-Be source should be stored:
A) in a secured area and surrounded with sufficient lead shielding to reduce the exposure rate to
permissible levels.
B) in a properly posted and secured area and surrounded with sufficient hydrogenous shielding to
reduce the dose equivalent rate to permissible levels.
C) in a safe.
D) in a locked room posted with "Caution: High Radiation Area" signs.
E) in a locked room posted with "Caution: Neutron Radiation Hazard". - ✔✔✔ - The correct answer is: B
Pu-Be is a neutron producing source, so it must be shielded with hydrogenous material. Since Pu is
special nuclear material as defined by the NRC, it must also be secured under 10 CFR Part 70.
Question Number: 708
Applied Radiation Protection
How many centimeters of lead were required for a shield if seven half-value layers were used to shield a
beam of gamma photons? (attenuation coefficient for lead = 0.4559 per centimeter)
A) 1.52 cm
B) 10.6 cm
C) 13.2 cm
D) 15.2 cm
E) 30.4 cm - ✔✔✔ - The correct answer is: B
Since the attenuation coefficient (µ) would be equal to .693/HVL Then:
1 HVL
= .693/µ
= .693/(.4559/cm)
= 1.52 cm
4|P A G E
NRRPT Prep Applied Radiation Protection
Exam Questions With Correct Answers &
Rationale
Question Number: 699 Applied Radiation Protection
For calculating dose to an organ from internal sources, the "specific effective energy" of a radionuclide is
BEST described as:
A) the energy given off by the radionuclide per unit of radionuclide activity.
B) the energy absorbed per unit mass of the organ per unit of radionuclide activity.
C) the energy absorbed per unit mass of the organ per disintegration of the radionuclide.
D) the energy given off by the radionuclide per disintegration of the radionuclide.
E) the energy transferred to the organ per unit of radionuclide activity. - ✔✔✔ - The correct answer is: C
The "SEE" is used in the Medical Internal Radiation Dosimetry (MIRD) dose modeling technique.
Question Number: 700 Applied Radiation Protection
What is the BEST method of disposal of dog carcasses which have been treated with a radionuclide with
a 78-hour half life?
A) Wait 3.25 days and prepare for shipment to a disposal facility or incinerate.
B) Wait 1.625 days and bury.
C) Wait 3.25 days and bury.
D) Wait 32.5 days and prepare for shipment to a disposal facility or incinerate.
E) Wait 32.5 days and bury. - ✔✔✔ - The correct answer is: D
It is common for radioactive materials licenses to allow the disposal of radioactive materials after ten
half-lives as "clean" materials. In this case, the waste is still biohazardous, so proper burial or
incineration is indicated.
Question Number: 701 Applied Radiation Protection
The major radiological health concern associated with burial of low level solid radioactive waste is:
1|P A G E
, NRRPT EXAM
A) external radiation at the surface of the burial site.
B) contamination of potable water supplies.
C) airborne radioactivity resulting from contaminated soil.
D) release of volatile radioactive daughter products.
E) contamination of vegetables grown in soil at the site. - ✔✔✔ - The correct answer is: BThe critical
exposure pathway for near-surface disposal of radioactive materials is through drinking water. Most of
the regulations surrounding the burial of radioactive materials, such as waste classification and
stabilization requirements, are designed to prevent contamination of potable (drinkable) water.
Question Number: 702 Applied Radiation Protection
An adequate Radiation Safety Program is the ultimate responsibility of:
A) the owner of the licensed facility.
B) the operator of the source of radiation.
C) the Radiation Safety Officer.
D) the line supervisor.
E) the radiation worker. - ✔✔✔ - The correct answer is: A
The radioactive materials license is issued to the owner of the facility. It is the licensee who is
responsible for all aspects of compliance with the license, including the implementation of a radiation
safety program. It is the duty of the RSO to administer the program.
Question Number: 703 Applied Radiation Protection
An x-ray machine is operated in a closed room for several minutes. After the machine is turned off, how
long should the operator wait before entering the room?
A) He may enter immediately.
B) 10 seconds
C) 30 seconds
D) 1 minute
E) 1 hour - ✔✔✔ - The correct answer is: A
When the current to the x-ray tube is turned off, the production of electrons stops. The principle behind
x-ray production in the tube is bremsstrahlung of these electrons with the target material. When the
electron production stops, so does the x-ray production. There is, of course, no radioactive material in
an x-ray machine.
2|P A G E
, NRRPT EXAM
Question Number: 704 Applied Radiation Protection
The exposure rate of the turbine floor of a boiling water reactor plant could be expected to be
decreased to less than 1% at least after shutdown?
A) five minutes
B) one hour
C) twenty-four hours
D) thirty-six hours
E) forty-eight hours - ✔✔✔ - The correct answer is: A
A good thumb rule for decay is that after seven half-lives, activity is less than 1% of original activity (it is
actually 1/(2)7, or 1/128). Since the nuclide of concern on the turbine floor of a BWR is N-16 (T 1/2 = 7.1
sec; 6.1,7.1 MeV gamma's), it would take only 49.7 seconds to decay to less than 1%. N-16 is produced
from the (n,p) reaction on O-16 in the reactor coolant.
Question Number: 705 Applied Radiation Protection
The goal and future requirement regarding high level liquid waste is:
A) transformation by irradiation to shorter lived, less toxic materials.
B) verification and deep ground burial.
C) use as a heat source.
D) disposal into geological formations.
E) disposal into salt formations. - ✔✔✔ - The correct answer is: B
High level waste, which includes spent reactor fuel and liquid wastes from the solvent extraction
process, requires stabilization and disposal in deep ground geologic repositories. Although vitrification
technology and deep ground burial are practiced in other industrialized nations, the U.S. lags behind in
implementing these methods.
Question Number: 706 Applied Radiation Protection
Below about 0.2 MeV, the most predominant photon interaction in lead of significance in health physics
is which of the following?
A) Pair production
B) Compton screening
C) Photoelectric effect
3|P A G E
, NRRPT EXAM
D) Rayleigh scattering
E) Thompson scattering - ✔✔✔ - The correct answer is: C
Photoelectric effect predominates below 200 keV, Compton effect between 200 keV and 5 MeV, and
Pair production above 5 MeV.
Question Number: 707 Applied Radiation Protection
A Pu-Be source should be stored:
A) in a secured area and surrounded with sufficient lead shielding to reduce the exposure rate to
permissible levels.
B) in a properly posted and secured area and surrounded with sufficient hydrogenous shielding to
reduce the dose equivalent rate to permissible levels.
C) in a safe.
D) in a locked room posted with "Caution: High Radiation Area" signs.
E) in a locked room posted with "Caution: Neutron Radiation Hazard". - ✔✔✔ - The correct answer is: B
Pu-Be is a neutron producing source, so it must be shielded with hydrogenous material. Since Pu is
special nuclear material as defined by the NRC, it must also be secured under 10 CFR Part 70.
Question Number: 708
Applied Radiation Protection
How many centimeters of lead were required for a shield if seven half-value layers were used to shield a
beam of gamma photons? (attenuation coefficient for lead = 0.4559 per centimeter)
A) 1.52 cm
B) 10.6 cm
C) 13.2 cm
D) 15.2 cm
E) 30.4 cm - ✔✔✔ - The correct answer is: B
Since the attenuation coefficient (µ) would be equal to .693/HVL Then:
1 HVL
= .693/µ
= .693/(.4559/cm)
= 1.52 cm
4|P A G E
