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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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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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Ionizing Radiation
Excess energy (from unstable atoms), capable of removing electrons from an atom
Radiation
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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 Contamination
Radioactive 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
• 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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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 Radiation
Stopped by thick layers of clothing or by a quarter inch of aluminum or plastic
3 InchesLead
1 footConcrete
¼ InchAluminum
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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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Internal Contamination and Internal Exposure
Radioactive material inside the body
Both contaminatedand exposed
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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?
• 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?