King Fahd University of Petroleum and Minerals
PHYS 353-062
Radiation and Health Physics
Final Exam (Open Book)
Name:
1. Which of the following nuclei has the largest binding energy per nucleon?
a. He-4
b. C-12
c. O-16
d. Fe-56
e. Pb-208
2. What is the Q-value for the emission of a 4.602 MeV alpha particle from Ra-226?
a. 4.60 MeV
b. 4.62 MeV
c. 4.64 keV
d. 4.66 keV
e. 4.68 MeV
3. In an elastic collision between a 2.0 MeV neutron and a room temperature hydrogen
atom, what is the maximum energy that can be transferred to the hydrogen atom?
a. 0.25 MeV
b. 0.50 MeV
c. 0.75 MeV
d. 0.95 MeV
e. 1.00 MeV
4. A wood sample from an old vase has a C-14 specific activity of 10 dis/min per gram.
If samples from a nearby growing tree yield 15 dis/min per gram, what is the age of
the vase?
a. 2300 years
b. 3400 years
c. 4800 years
d. 5000 years
e. 5700 years
5. Sr-90 (T1/2 = 27.7 y) decays by beta emission into Y-90 (T1/2 = 64.2 hours), which
then decays by beta emission into Zr-90. What is the mean, or average, life of a Y-90
atom?
a. 31.1 h
b. 44.5 h
c. 77.04 h
d. 92.6 h
e. 128.4 h
6. In tissue, fast neutrons lose 80% to 95% of their energy by interacting with
a. Hydrogen
b. Carbon
c. Nitrogen
d. Oxygen
e. Calcium
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7. What is the specific activity of Y-90?
a. 5.42  1015 Bq/kg
b. 7.22  1016 Bq/kg
c. 2.01  1019 Bq/kg
d. 7.22  1019 Bq/kg
e. 6.49  1021 Bq/kg
8. Starting with a pure Sr-90 sample at time t = 0, a researcher finds the Y-90 activity is
3.4 mCi at t = 72.0 h. What was the activity of the Sr-90 at t = 0?
a. 1.84 mCi
b. 3.40 mCi
c. 3.47 mCi
d. 6.29 mCi
e. 7.39 mCi
9. Which of the following radionuclides has the smallest specific activity? The
radionuclide’s half-life is in parenthesis.
a. Al-28 (2.2 min)
b. I-131 (8.1 d)
c. Mn-54 (313 d)
d. Cs-137 (30 y)
e. Ra-226 (1600 y)
10. Which of the following radionuclides emits the highest energy beta particle?
a. C-14
b. P-32
c. Co-60
d. Y-90
e. Cs-137
11. An investigator receives Co-60 (5.27 y half-life) for use in a research study.
Unfortunately, the Co-60 is contaminated with Cs-137 (30.0 y half-life). The initial
Co-60 activity is 400 times the initial Cs-137 activity. How long after the initial assay
will the Cs-137 activity be 0.02 times the Co-60 activity?
a. 13 y
b. 16 y
c. 19 y
d. 27 y
e. 34 y
12. The energy released by one atom of U-238 in its decay to Pb-206 would raise the
temperature of 1 liter of water at ambient temperature by approximately
a. 2  1011 oC
b. 2  1012 oC
c. 2  109 oC
d. 2  1013 oC
e. 2  108 oC
13. What is the maximum range of the beta particles emitted by tritium in water?
a. 2 m
b. 4 m
c. 6 m
d. 8 m
e. 10 m
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14. What fraction of the energy of 1.0-MeV photon is lost if it scatters through an angle
of 90o?
a. 0.338
b. 0.662
c. 0.204
d. 0.796
e. 0.500
15. A radionuclide emits only beta radiation with a maximum energy of 2.0 MeV. What is
the ratio of shielding thicknesses of polyethylene required to shield a 10-Ci source
versus a 1.0 Ci-source of this radionuclide?
a. 1/100
b. 1/10
c. 1
d. 10
e. 100
16. You have lead and polyethylene shielding materials. In shielding a pure 2.5 MeV beta
emitter, how would you arrange the available materials to minimize worker exposure?
List the materials as a function of distance from the radiation source, and determine
the optimum shielding configuration.
a. Lead only
b. Polyethylene only
c. Lead followed by polyethylene
d. Polyethylene followed by lead
e. Lead, polyethylene, and lead
17. The average number of ion pairs produced by 100-keV beta particle that stops in air is
approximately
a. 300
b. 30
c. 30,000
d. 3,000
e. 300,000
18. For photon energies between 100 keV to 2.5 MeV, the dominant contribution to the
mass absorption coefficient in tissue is
a. The photoelectric effect
b. Compton scattering
c. Pair production
d. Rayleigh scattering
e. Coulomb scattering
19. At 20 MeV, the dominant photon interaction(s) with tissue is (are)
a. The photoelectric effect
b. Compton scattering
c. Pair production
d. About equal contributions from the photoelectric effect and Compton
scattering
e. About equal contributions from Compton scattering and pair production
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20. A sievert is defined to be
a. 1 J/kg
b. 1 C/kg
c. 1.0  106 erg/kg
d. 100 R
e. 100 rad
21. The Roentgen is defined for
a. Photon energy deposition in tissue for energies less than 3 MeV
b. Photon energy deposition in air for energies less than 3 MeV
c. Photon energy deposition in tissue for energies less than 6 MeV
d. Photon energy deposition in air for energies less than 6 MeV
e. Photon energy deposition in air for all energies
22. A gray is an absorbed dose that is equivalent to
a. 100 rem
b. 1000 erg/g
c. 100 J/kg
d. 10 J/kg
e. 1 J/kg
23. The gray is applicable to
a. Only gamma rays
b. Only gamma rays and charged particles
c. All types of ionizing radiation excluding exotic particles with energies greater
than 1000 GeV
d. All types of ionizing radiation excluding Auger electrons
e. All types of ionizing radiation
24. A Becquerel is equivalent to
a. 1 pCi
b. 1 nCi
c. 1 Ci
d. 1 disintegration/second
e. 3.7 disintegrations/second
25. The rad is defined as the deposition of
a. 100 erg/g of bone
b. 100 erg/g of tissue
c. 100 erg/g of air
d. 100 erg/g in water
e. 100 erg/g in any material
26. Which of the following dosimetric quantities accounts for whole body exposure?
a. Exposure
b. Absorbed dose
c. Kerma
d. Effective dose
e. Committed dose equivalent
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27. Kerma describes energy deposition by charged particles released by
a. Directly ionizing radiations such as protons and electrons
b. Indirectly ionizing radiations such as photons and neutrons
c. All radiation types
d. Directly ionizing radiations such as protons and electrons for energies less
than 3 MeV
e. Indirectly ionizing radiations such as photons and neutrons for energies less
than 3 MeV
28. One Becquerel is equal to
a. 2.7  1011 Ci
b. 2.7  1010 Ci
c. 3.7  1010 Ci
d. 1.0  1010 Ci
e. 1.0  109 Ci
29. 1.0 R of X-ray radiation in the energy range of 0.1-3.0 MeV produces how many rads
in air?
a. 0.78 rad
b. 0.87 rad
c. 0.93 rad
d. 0.95 rad
e. 1.00 rad
30. 1.0 R of X-ray radiation in the energy range of 0.1-3.0 MeV produces how many rads
in muscle tissue?
a. 0.78 rad
b. 0.87 rad
c. 0.93 rad
d. 0.95 rad
e. 1.00 rad
31. Residential ionization type smoke detectors use what type of isotope?
a. Ra-226
b. Th-232
c. U-238
d. Pu-239
e. Am-241
32. The specific gamma-ray emission rate for Cs-137 in units of R h1 Ci1 m2 is
approximately
a. 1.3
b. 0.12
c. 0.30
d. 0.50
e. 0.67
33. How many alpha particles are emitted by a nucleus of an atom of U-238 that
sequentially decays to Pb-206?
a. 2
b. 4
c. 6
d. 8
e. 10
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34. A worker receives a lung dose of 12 mGy from alpha radiation from an internally
deposited radionuclide and a 40 mGy uniform, whole body dose from external gamma
radiation. What is the equivalent dose to the lung?
a. 100 mSv
b. 160 mSv
c. 220 mSv
d. 280 mSv
e. 1040 mSv
35. ICRP Publication 60 established what annual limit(s) for effective dose?
a. 20 mSv/year averaged over 5-year periods with the effective dose in any year
not greater than 50 mSv
b. 50 mSv organ dose with the exception of the lens of the eye which is limited
to 15 mSv
c. 25 mSv
d. 100 mSv organ dose
e. 100 mSv
36. ICRP Publication 60 establishes what average annual limit for effective dose for
public exposure? The average is to be calculated over a 5-year period.
a. 0.1 mSv
b. 0.5 mSv
c. 1.0 mSv
d. 2.0 mSv
e. 5.0 mSv
37. A 2.0-Ci source of Co-60 is located 2.0 m from you. What is the exposure rate at your
location?
a. 0.65 R/h
b. 1.30 R/h
c. 2.60 R/h
d. 3.20 R/h
e. 4.00 R/h
38. Nuclides A and B have gamma-ray emission constants A and B, respectively. At
what distance r will the exposure rates from 2.0 Ci point sources of these nuclides be
equal?
a. rA  rB
b. rA  A / B 
1/ 2
rB
c. rA  B / A  rB
d. rA  A / B rB
e. rA  B / A rB
39. The average energy of a beta-ray spectrum is what fraction of its maximum energy?
a. 1 / 6
b. 1 / 5
c. 1 / 4
d. 1 / 3
e. 1 / 2
1/ 2
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40. The gamma-ray dose buildup factor is a function of
a. Only the energy of the gamma-ray emitted by the source
b. Only the atomic number of the shielding material
c. Only the number of mean free paths traversed directly through the shield
d. Only the energy of the gamma ray emitted by the source and the atomic
number of the shielding material
e. The energy of the gamma ray emitted by the source, the atomic number of the
shielding material, and the number of mean free paths traversed directly
through the shield
41. For 1 MeV neutrons, the half-value thickness for concrete is about
a. 1 cm
b. 3 cm
c. 5 cm
d. 7 cm
e. 9 cm
42. Which of the following expressions involving the buildup factor (B), shield thickness
(X), and the attenuation factor () define the transmission factor (T)?
a. T  (1  X )
b. T  (1 / B)e  X
c. T  Be  X
d. T  (1 / B) ln( X )
e. T  B for photons and T  (1  X ) for charged particles
43. For S-35 the radiological half-life is 87.1 days, and the biological half-life in the male
gonad is 623 days. What is the effective half-life of S-35 on these conditions?
a. 38.2 d
b. 76.4 d
c. 152.8 d
d. 536 d
e. 710 d
44. The ICRP 30 relationship between the derived air concentration (DAC) and the
annual limit on intake (ALI) is
a. DAC = (ALI/2000) Bq/m3
b. DAC = (ALI/2000) Ci/cm3
c. DAC = (ALI/2500) Bq/m3
d. DAC = (ALI/2500) Ci.cm3
e. DAC = (ALI/1000) Bq/m3
45. According to ICRP 60, the occupational dose limit for a declared pregnant worker is
a. An equivalent dose of 1 mSv to the abdomen or an intake < 1/20 ALI
b. An equivalent dose of 1 mSv to the abdomen or an intake < 1/40 ALI
c. An equivalent dose of 2 mSv to the abdomen or an intake < 1/20 ALI
d. An equivalent dose of 2 mSv to the abdomen or an intake < 1/10 ALI
e. An equivalent dose of 2 mSv to the abdomen or an intake < 1/40 ALI
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46. A worker receives a whole-body count rate after inhaling dust loaded with Co-60. The
whole-body count indicates 3000 nCi of Co-60 are present. If the inhalation ALI for
Co-60 is 200 Ci for the compound inhaled, what is the committed effective dose
equivalent that results from the intake. Assume that ICRP 26 is used at your facility.
a. 0.012 rem
b. 0.025 rem
c. 0.075 rem
d. 25 rem
e. 30 rem
47. You are asked to construct a thermal neutron shield, and sheets of lead and cadmium
are available. Which material(s) would be used?
a. Cadmium only
b. Lead only
c. Cadmium closest to the source followed by lead
d. Lead closest to the source followed by cadmium
e. Does not matter as long as at least two relaxation lengths of material is used
48. An essential element of the application of maximum permissible exposure levels to
occupational radiation protection is the ALARA (as low as reasonably achievable)
philosophy. These maximum permissible levels are
a. Acceptable and personnel may be exposed those levels
b. Not to be considered as acceptable, but represent levels that should not be
exceeded
c. Absolute and should rarely be changed
d. Normally established to be 50% of the legal requirements
e. Dependent of the worker’s lifetime exposure
49. The maximum allowable equivalent dose on the surface and at 1 m of a yellow II
package is respectively
a. 5 mSv/h, 1 mSv/h
b. 0.5 mSv/h, 0.01 mSv/h
c. 0.5 mSv/h, 1 mSv/h
d. 5 mSv/h, 0.01 mSv/h
e. 0.05 mSv/h, 0.001 mSv/h
50. If the transport index (TI) for a package is 3, this means that
a. The dose rate at the surface of the package is 3 mSv/h
b. The dose rate at 1m from the surface of the package is 30 Sv/h
c. The dose rate at the surface of the package is 30 Sv/h
d. The dose rate at 1 m from the surface of the package is 3 mSv/h
e. None of the above
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