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1 Module 1 Introduction to Radiation. 2 Introduction to Radiation Terminal Objective: DEFINE the...

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1 Module 1 Introduction to Radiation
Transcript

1

Module 1

Introduction to Radiation

2

Introduction to Radiation

Terminal Objective:

DEFINE the fundamentals of radiation, radioactive material, ionization, ionizing radiation, and contamination.

3

Enabling Objectives

• LIST the three basic components of an atom.

• DESCRIBE the differences between ionizing radiation and non-ionizing radiation.

• DEFINE radioactivity.

4

Enabling Objectives

• STATE the four basic types of ionizing radiation.

• DESCRIBE the shielding materials and biological hazards for each of the four types of ionizing radiation.

• LIST the three techniques for minimizing exposure to radiation and radioactive material (ALARA).

5

Radiation Basics Video

QuickTime™ and aCinepak decompressor

are needed to see this picture.

6

• Protons

• Neutrons

• Electrons

Parts of an Atom

10

Stable and Unstable Atoms

• An atom with too many or too few neutrons contains excess energy and is not stable.

• Unstable atoms give off excess energy (radiation).

• Unstable atoms are radioactive.

11

Ionization

Removing electrons from atoms or molecules

Radiation

12

Ionizing Radiation

Excess energy (from unstable atoms), capable of removing electrons from an atom

Radiation

13

Non-Ionizing Radiation

Non-ionizing Ionizing

14

Radioactivity

Radioactivity is the process of

unstable (radioactive) atoms trying

to become stable by emitting

ionizing energy.

15

Radioactive Material

Radioactive Material Material containing unstable (radioactive) atoms

Radioactive Contamination

Radioactive material in an unwanted place

16

“Radiological” vs. “Nuclear”

“Radiological” deals with radiation or material that emits radiation.

Example Radiological WMD: “Dirty Bomb”

“Nuclear” refers to processes that involve splitting a nucleus (fission) or combining nuclei of atoms (fusion).

Example Nuclear WMD: atomic bomb

17

Measuring Radiation

Radiation Dose

• Radiation energy absorbed by the human body

• Dose is measured in units of rem.

• A millirem (mrem) is one thousandth of a rem.

18

Measuring Radiation

Radiation Dose Rate

• Radiation energy received over a period of time

• Radiation dose rate is dose per time

• mrem per hour = mrem/hr “strength” of radiation at a location

19

Types of Ionizing Radiation

QuickTime™ and aCinepak decompressor

are needed to see this picture.

20

Types of Ionizing Radiation

• Alpha radiation

• Beta radiation

• Gamma rays/X-rays

• Neutron radiation

Some radioactive materials may emit more than one kind of radiation

21

Alpha Radiation

• Range:

1 to 2 inches

• Shielding:

Paper, Cloth,

Dead Layer of Skin

22

Biological Hazard • Not an external radiation hazard• Easily stopped by the dead layer

of skin • Internal hazard – If material is

inside the body, then the alpha radiation reaches live cells.

Alpha Radiation (continued)

23

Sources

• Uranium (nuclear power plant fuel and nuclear weapons)

• Plutonium (nuclear weapons)

• Americium (smoke detectors)

• Thorium (high-temperature metals)

Alpha Radiation (continued)

24

Beta Radiation

• Range:

about 10 feet

• Shielding:

Thick Clothing, ¼ Inch Aluminum, ¼ Inch Plastic

25

Biological Hazard• External hazard to skin and eyes• Internal hazard if the material that

emits the beta radiation is inside the body. Then beta radiation can deposit energy in a small area of body tissue.

Beta Radiation (continued)

26

Sources • Used nuclear reactor fuel • Nuclear weapons fallout (strontium)• Some industrial radioactive sources such

as cesium• Tritium in glow-in-the-dark EXIT signs,

watch dials, and night-sights on firearms• Radioactive nickel in chemical agent

detectors

Beta Radiation (continued)

27

Gamma Rays/X-Rays

• Range:

Hundreds of feet

• Shielding:

Inch of Lead, 3 Inches of Steel, 6 inches Concrete, 1 foot of Dirt

28

Biological Hazard

• Gamma rays and X-rays easily penetrate body tissues, outside or inside of the body.

• Whole body (internal and external) hazard

 

Gamma Rays/X-Rays (continued)

29

Sources • Uranium, plutonium, radioactive cobalt,

and cesium• Industrial radiation sources • Medical sources, cancer treatment

machines• Many beta-emitters also emit gamma

radiation.• Potassium in soil, bananas, and potassium

chloride (salt substitute)

Gamma Rays/X-Rays (continued)

30

Neutron Radiation

• Range:

Hundreds of feet

• Shielding:

10 Inches of Plastic, 1 foot of Concrete, 3 feet of Dirt, 3 feet of Water

31

Biological Hazard

• Whole body hazard (external and internal neutrons are a whole body hazard).

• Neutrons penetrate body tissues.

• Neutrons cause damage whether the material is inside or outside of the body.

Neutron Radiation (continued)

32

Sources

• Nuclear reactions inside nuclear reactor while reactor is operating

• Burst of radiation from exploding nuclear weapon

• Plutonium, industrial sources, moisture gauges with californium or mixture of americium and beryllium

Neutron Radiation (continued)

33

Comparison of Ionizing Radiation

Aluminum Lead ConcreteAluminum Lead ConcreteAluminum Lead Concrete

Alpha Radiation

Gamma RaysStopped by a few inches of lead or six inches of concrete

Neutrons

OrganicTissue

Radiation Source

Stopped by a sheet of paper or dead layer of skin

Stopped by a foot concrete or water

Beta Radiation

Stopped by thick layers of clothing or by a quarter inch of aluminum or plastic

3 InchesLead

1 footConcrete

¼ InchAluminum

34

Particle Size Comparison

Speck of Dust Atom Alpha Particle

Earth City Ping Pong Ball

35

Alpha, Beta, and Neutron “Particles”

Rifle Cartridge Bullet

Radioactive atom Alpha, Beta or Neutron “Particles”

36

Comparison of Radiation and Contaminants

• Radiation is energy.

• Radioactive contaminants are materials that emit radiation.

• Radioactive contaminants are radioactive atoms that get onto something unwanted or are in an uncontrolled place.

• Radioactive atoms cannot be neutralized to make them non-radioactive.

37

Exposure vs. Contamination

External Exposure External Contamination

38

Internal Contamination and Internal Exposure

Radioactive material inside the body

Both contaminatedand exposed

39

ALARA

• AAs

• LLow

• AAs

• RReasonably

• AAchievable

40

ALARA Video

QuickTime™ and aCinepak decompressor

are needed to see this picture.

41

ALARA

Minimize time

Maximize distance

Use shielding

42

Review

• What’s the difference if I get exposed or What’s the difference if I get exposed or if I get contaminated?if I get contaminated?

• How do I protect myself from alpha, How do I protect myself from alpha, beta, gamma, or neutron radiation?beta, gamma, or neutron radiation?

• How can I practice the principles of How can I practice the principles of ALARA in this situation?ALARA in this situation?

• What’s the difference if I get exposed or What’s the difference if I get exposed or if I get contaminated?if I get contaminated?

• How do I protect myself from alpha, How do I protect myself from alpha, beta, gamma, or neutron radiation?beta, gamma, or neutron radiation?

• How can I practice the principles of How can I practice the principles of ALARA in this situation?ALARA in this situation?

43


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