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Radiation Safety RSO > RSO > Flashcards

RSO Flashcards

1
Q

What is the atomic number of an atom?

A

The total number of protons in the atom.

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2
Q

What is the mass number of an atom?

A

The total number of protons and neutrons in the atom.

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3
Q

What is a stable vs unstable atom?

A

In a stable atom, the nuclear forces are strong enough to hold the nucleus together indefinitely.

In an unstable atom, the nuclear forces are not strong enough to hold the nucleus together indefinitely. They are radioactive.

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4
Q

What is radioactive decay?

A

The process of an atom emitting radiation.

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5
Q

What is alpha radiation?

A

A particle ejected from an atom during radioactive decay.
It is made from 2 protons and 2 neutrons without any electrons.

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6
Q

List features of alpha radiation.

A
  • Highly ionizing
  • Short travel (7cm in air)
  • Blocked by paper/dead skin layer
  • Only produced by heavy radionucleotides (more than 82 protons)
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7
Q

What is a beta particle?

A

Either a positron or an electron.
Produced from a proton changing into a neutron or neutron into a proton.

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8
Q

List features of beta particles.

A

-Limited travel, more than alpha (~2m in air)
- Can penetrate ~0.2cm into skin
- blocked by thin plastic
- Can create x-rays (bremsstrahlung)

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9
Q

What is bremsstrahlung?

A

When an electron interacts with an atom, it may be attracted to the nucleus. If the electron gets close enough to the nucleus, then it will slow and lose energy. This energy may be converted into an x-ray photon.
More likely with atoms with higher proton numbers.

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10
Q

How does an atom create gamma radiation?

A

Atoms may have excess energy (be excited) after alpha or beta release. This energy can be released in the form of a gamma photon.

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11
Q

What is a neutral atom?

A

An atom that has no electrical charge. There are an equal number of protons and electrons.

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12
Q

How many neutrons does Cs137 have?
Cs has an atomic number of 55.

A

137 - 55 = 82 neutrons.

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13
Q

Name three types of radiation emitted by naturally occurring radioactive nucleotides.

A

Alpha particles, beta particles, gamma rays.

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14
Q

What happens to the atomic mass and atomic number

A
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15
Q

What happens to the atomic mass and atomic number when an atom releases a negative beta particle?

A

Mass remains essentially unchanged (minimal decrease)
Atomic number increases by 1.

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16
Q

What happens to the atomic mass and atomic number when an atom releases a positive beta particle?

A

Mass remains essentially unchanged (minimal decrease)
Atomic number decreases by 1.

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17
Q

What happens to the atomic mass and atomic number when an atom releases an alpha particle?

A

Mass decreases by 4.
Atomic number decreases by 2.

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18
Q

What happens to the atomic mass and atomic number when an atom releases a gamma ray?

A

No change in atomic mass or number.

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19
Q

When does a nuclear energy worker require a licensed dosimetry provider?

A

5 mSv or higher.

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20
Q

What obligations do pregnant/breastfeeding nuclear energy workers have?

A

Must inform the licensee in writing when they choose to do so.

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21
Q

What obligations do pregnant/breastfeeding nuclear energy licensee have?

A

Must ensure that pregnant workers receive less than 4 mSv for the remainder of the pregnancy after informing.

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22
Q

Under what conditions must a licensee post warning signs at the boundaries and points of access to an area?

A

When there is a substance quantity greater than 100 times the exemption quantity.
and
There is a possibility that a person will be exposed to an effective dose rate greater than 25milliSv/hr.

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23
Q

How many hours are in an average work year?

A

2000hrs (40hrs/wk for 50wks)

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24
Q

How does an ionization chamber distinguish between alpha and beta radiation when making a measurement?

A

Alpha radiation causes a stronger electrical signal than beta, so they can be differentiated by the height of the pulse signal.

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25
Q

How can a Geiger-muller counter be used to measure beta radiation in a mixed gamma/beta radiation field?

A

Beta can be measured indirectly by using a probe with a beta shield.
Measure with the shield open (beta & gamma), and then closed (gamma only). Then subtract.

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26
Q

How does a scintillation detector measure radiation?

A

A scintillator reacts to a photon and luminates.
The light connects witha photocathode to produce an electron.
The election travels down a photomultiplier tube which multiplies the election charge by many magnitudes.
An anode at the end of the photomultiplier tube reads the charge.

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27
Q

What is the meaning of dead time for a Geiger-Müller detector?

A

The potential electric field is being re-established. No radiation detection can take place during this time.

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28
Q

Explain what geometric efficiency and intrinsic efficiency are for a radiation detector.

A

Geometric efficiency is the % of radiation that gets from source into detector

Intrinsic efficiency is the % of radiation entering the detector that is measured (a & b close to 100%) (x & g often pass through detector)

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29
Q

How is background radiation dealt with when making radiation measurements?

A

Shield to reduce background or measure background levels and subtract from readings.

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30
Q

What is a TLD?

A

Thermoluminescent Dosimeter

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31
Q

What is an OSL?

A

Optically stimulated luminescent dosimeter

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32
Q

Describe the difference in the mechanism of luminescence in a TLD and luminescence in an OSL.

A

Both methods have crystals that react to radiation and trap the resulting energy within (excited electrons are trapped).
TLD releases the trapped energy in the form of light when exposed to heat (measurement cannot be repeated).
OSL releases trapped energy in the form of light when exposed to laser (measurements can be repeated, OSL more precise than TLD, OSL have a larger range of measurement).

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33
Q

What are the advantages of TLD/OSL dosimetry?

A
  • Wide dose measurement range
  • Stores information for a long time
  • Less energy dependent than film
  • Inexpensive
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34
Q

Why would electronic dosimeters be used?

A

Necessary as an alarm/early warning system in some high risk situations.

For internal responsibility system to monitor ongoing radiation exposures (not as a replacement for TLD/OSL in Canada)

Might be used for guests in low risk situations.

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35
Q

What should you do if one of your workers lose their dosimeter or suspect it has been contaminated?

A

Stop worker from radiation work.

Inform CNSC.

Assign new dossimeter.

If there is a risk of the worker exceeding action levels, then discuss with CNSC when able to return to work.

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36
Q

Convert 1000mR/hr into SI units

A

100r = 1Gy
100mR = 1mGy
1000mR = 10mGy

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37
Q

How does gamma radiation dose from a point source change from 1m distance to 2m, 3m, and 4m?

A

2m = 1/4
3m = 1/9
4m = 1/16

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38
Q

A vial of I-131 contains 40MBq. What is the activity 40d later if the half life is 8d?

A

1.25MBq

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39
Q

What is an ion?

A

A charged particle.

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40
Q

How much time before the disposal of records must the CNSC be notified?

A

90d

41
Q

What is the CNSC?

A

The Canadian Nuclear Safety Commission

42
Q

What is an effective shield for alpha particles?

A

Paper, plastic, dead skin layer, lead.

43
Q

What is an effective shield for beta particles?

A

Plastic or glass

44
Q

If an atom absorbs a neutron, what happens to the atomic and mass numbers?

A

The atomic number remains the same.
The mass number increases by 1.

45
Q

What distinguishes gamma rays, UV light, visible light, and radio waves from each other?

A

Photon energy / wavelength

46
Q

Why do neutrons interact more easily with the nucleus of an atom than alpha or beta particles?

A

Neutrons have no charge. alpha and beta particles have charges that effect the way they move.

47
Q

What is a radioactive nucleotide?

A

An unstable nucleus.

48
Q

Why is concrete more appropriate as a neutron shield than lead?

A

Concrete has a high water content - lots of H atoms.
Low atomic mass molecules provide a more elastic scattering when interacting with neutrons - therefore they absorb more of the energy than molecules with a higher atomic mass.

49
Q

What type of nuclear radiation has the shortest range in air?

A

alpha radiation.

50
Q

If Ra-226 releases an alpha particle, what is the mass number of the resulting atom?

A

222

51
Q

How long must a nuclear licensee retain records?

A

Unless otherwise specified in the regulation, until 1 year after the license expires.

52
Q

What is the best shielding for use with beta radiation at short range?

A

plastic or glass.

53
Q

Why is 1mGy of alpha more damaging than 1 mGy of beta?

A

Alpha has a higher linear energy transfer

Alpha radiation is more ionizing.

54
Q

What are the rules of thumb with regards to half life reductions?

A

7 half lives reduces to 1%
10 half lives reduces to 0.1%

55
Q

What is the difference between absorbed, equivalent, and effective dose?

A

Absorbed dose is the amount of radiation that is absorbed.

Equivalent dose factors in the type of radiation and how ionizing it is.

Effective dose factors in the sensitivity of the tissue.

56
Q

What is 1 Gy?

A

1 Gray is 1J/kg

57
Q

What makes a good gamma radiation shield?

A

Lead, or other high density material. Greater molecular weight increases the changes that the photon will be obstructed.

58
Q

If an average worker is in an area of 1microSv/hr. What is their annual dose?

A

1 * 2000 = 2000mcSv

(assuming 40hrs/d, 50wks/yr)

59
Q

At what dosage of radiation to the whole body do we see changes to blood cell lines?

A

250mSv

60
Q

What is the major effect to embryos that receive radiation very early in pregnancy?

A

Death

61
Q

Why don’t alpha and beta follow the inverse square law?

A

Alpha and beta particles cannot travel infinite distances and so they reduce at a more rapid rate.

62
Q

How can an ionization chamber or proportional counter distinguish between different types of radiation?

A

By electronically discriminating between signal strengths.

63
Q

Which type of external radiation dosimeters are available from licensed dosimetry service providers for ascertaining legal doses?

A

TLD and OSL dosimeters.

Thermoluminescent Dosimeters

Optical-Stimulated Luminescent dosimeters

64
Q

When is a nuclear energy worker required to wear a dosimeter?

A

When there is a reasonable probability that they will be exposed to 5mSv or more radiation

65
Q

What does the term “energy compensated” mean in a Geiger-meier counter?

A

The counter reduces the response to low energy photons to smooth out the energy curve and enable the counter to read a wider range of energy.

66
Q

What international organisation publishes recommendations for radiation dose limits?

A

ICRP
International Commission on Radiological Protection

67
Q

List three types of Geiger-meier counter probes.

A

Pancake
Side window
End window

68
Q

What level of training must be given to workers that work in the vicinity of radiation sources but do not work directly with the sources and should not receive a significant dose?

A

Basic awareness training.

69
Q

How often must survey equipment be calibrated?

A

Every 12 months.

70
Q

What determines if someone is a nuclear energy worker?

A

Any worker that may receive a radiation dose of 1mSv or more.

71
Q

What is necessary of a survey instrument probe used to measure alpha radiation?

A

A thin window

72
Q

Why are scintillation detectors more efficient than gas-filled detectors at detecting gamma radiation?

A

Solid or liquid scintillation detectors have a denser detector material allowing for more gamma interactions to occur.

73
Q

Can a Geiger-muller counter be used to distinguish between different types of radiation?

A

Yes, by comparing different readings using shielding materials.

74
Q

When must a radiation warning sign be posted at an entrance to an area?

A

When there is a radiation source greater than 100 times the exemption quantity
or
When there is a dose rate of 25mcSv or greater in an area.

75
Q

What are the two primary components of a scintillation detector?

A

The scintillator and the photomultiplier tube.

76
Q

How to you calculate the effective half life, when given the biological and physical half life of a nuclear substance?

A

(biological half life * physical half life) / (biological half life * physical half life)

77
Q

Who determines what type of package is acceptable for the transportation of a nuclear substance?

A

IAEA
International Atomic Energy Agency

78
Q

What is special form nuclear material with respect to transportation?

A

A nuclear material in a sealed container that has been examined and certified by CNSC.

79
Q

What information must be written on shipping packages for nuclear material?

A

The UN number and matching proper description.

Radiation category label if appropriate including TI when appropriate

80
Q

What is a transportation index?

A

A measurement of radiation from a package.

Measure radiation at 1m from the package in mSv/hr & multiply by 100.

Round value up to 1 decimal place (with 0.05 being 0)

81
Q

What is category assignment for the transportation of nuclear material?

A

After packaging, the TI and the package surface radiation levels are used to put the package into category 1, 2, or 3. (1 being lowest, 3 highest)

82
Q

Who needs to know when you are shipping nuclear material?

A

The consignor must notify the consignee of shipment and timing to ensure a trained person is available to receive.

If the material is high risk, then authorities must also be notified in advance.

83
Q

What is exclusive use shipping of nuclear material?

A

If the TI (transportation index is 10 or greater, then it must be shipped exclusively. It is the only package shipped and is sent directly to destination.

84
Q

What should be done if a radiation source is found to be leaking?

A

Stop using source
Prevent spread of contamination
Report to CNSC

85
Q

How are long-lived and short-lived radioactive waste disposed of?

A

Long lived (>90d) send to

86
Q

When are licenses not required for nuclear material?

A

If the total amount of material is below the exemption quantity.
or
The amount of material within a nuclear device is less than 10 times the exemption quantity.

87
Q

How many protons are in Hydrogen?
Deuterium?
Tritium?

A

All three contain 1 proton.
Deuterium is a H isotope with 1 neutron.
Tritium is a H isotope with 2 neutrons.

88
Q

What types of facilities require a Class 1 licence?

A

Nuclear reactors, particle accelerators greater than 50 MeV.

89
Q

What types of facilities require a Class 2 licence?

A

Particle accelerators less than 50MeV.
Teletherapy.

90
Q

When there is an incident, how soon must a report be sent to the CNSC?

A

21d.

91
Q

What is an exception quantity in regards to nuclear material?

A

An exemption quantity is a measured nuclear activity of a substance listed in Schedule 1 of the Nuclear Substances and Radiation Devices regulations.

Licenses are not needed if substances are below the exception quantity. The value is also referenced in other areas of the regulations.

92
Q

When must leak tests for nuclear material be performed?

A
  • Material in radiation devices, every 12 months.
  • Material in storage, every 24 months.
  • Material not in storage or a radiation device, every 6 months.
  • Immediately when an event may have resulted in damage.
93
Q

How long must nuclear leak test results be kept for?

A

3 years.

94
Q

When a nuclear leak test is performed, at what dose must action be taken and what action is required?

A

If a leak of 200Bq or more is detected:
- Discontinue use of the source/shield/device
- Take action to limit the spread of radiation/contamination
- Immediately notify the CNRC

95
Q

What is the main federal body that is responsible for nuclear safety in Canada?

A

The CNSC
Canadian Nuclear Safety Commission

96
Q

What is a becquerel?

A

A Bq is the SI unit for measuring radiation.
1Bq is the activity of one nucleus decay per second.

97
Q

What is the measurement curie?

A

Curie (Ci) is an older unit of measuring radiation that was replaced by the becquerel.

1Ci = 37*10(9) Bq

98
Q

What is a sealed source in the context of nuclear material?

A

A sealed source is a radioactive material that is permanently sealed in a capsule or bonded and in a solid form.
The capsule is designed to prevent release of radioactive material under normal activity/conditions.

99
Q

What does it mean to be classified as a nuclear energy worker?

A
  • A nuclear energy worker is any worker that may be exposed to more than 1mSv in a year.
  • NEWs must be trained and informed about potential health risks.
  • They must be consulted and give written informed consent accepting the classification.

Radiation Safety RSO (1 decks)

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