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Module 1

Introduction to Radiation

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Introduction to Radiation

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

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Enabling Objectives

• LIST the three basic components of an atom.

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

• DEFINE radioactivity.

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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).

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Why should we be interested?

• Knowledge is good• Natural plutonium incident Eastern Wa.• The dreaded what if• Federal Govt. thinks it’s a good idea

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Radiation Basics Video

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• Protons

• Neutrons

• Electrons

Parts of an Atom

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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.

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Ionization

Removing electrons from atoms or molecules

Radiation

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Ionizing Radiation

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

Radiation

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Non-Ionizing Radiation

Non-ionizing Ionizing

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Radioactivity

Radioactivity is the process of unstable (radioactive) atoms trying to become stable by emitting ionizing energy.

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Radioactive Material

Radioactive Material Material containing unstable (radioactive) atoms

Radioactive ContaminationRadioactive material in an unwanted place

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“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

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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.

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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

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Types of Ionizing Radiation

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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

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Alpha Radiation

• Range:1 to 2 inches

• Shielding:Paper, Cloth,Dead Layer of Skin

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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)

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Sources• Uranium (nuclear power plant fuel

and nuclear weapons)• Plutonium (nuclear weapons)• Americium (smoke detectors)• Thorium (high-temperature

metals)

Alpha Radiation (continued)

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Beta Radiation

• Range:about 10 feet

• Shielding:Thick Clothing, ¼ Inch Aluminum, ¼ Inch Plastic

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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)

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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)

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Gamma Rays/X-Rays

• Range:Hundreds of feet

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

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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)

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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)

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Neutron Radiation

• Range:Hundreds of feet

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

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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)

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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)

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

3 InchesLead

1 footConcrete

¼ InchAluminum

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Particle Size Comparison

Speck of Dust Atom Alpha Particle

Earth City Ping Pong Ball

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Alpha, Beta, and Neutron “Particles”

Rifle Cartridge Bullet

Radioactive atom Alpha, Beta or Neutron “Particles”

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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.

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Exposure vs. Contamination

External Exposure External Contamination

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Internal Contamination and Internal Exposure

Radioactive material inside the body

Both contaminatedand exposed

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ALARA

• AAs

• LLow

• AAs

• RReasonably

• AAchievable

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ALARA Video

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ALARA

Minimize time

Maximize distance

Use shielding

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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?

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