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Radiation
“Life on earth has developed with an ever
present background of radiation. It is not
something new, invented by the wit of man:
Radiation has always been there.”
- Eric J. Hall Professor of Radiology, Columbia University
Definition of Radiation
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Radiation is a type of energy given up by
unstable isotopes.
An isotope is an atom with a different
number of neutrons than normal.
Discovery of Radiation
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Dec. 22, 1895 - Wilhelm Conrad Roentgen
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March 1896 – Anoine Henri Becquerel
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Photographic Plates stored in a drawer with Uranium
crystals.
Feb. 17, 1898 – Marie & Pierre Curie
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X-Rays of his wife’s hand.
Introduced the term “radio-active”
1911 – Ernest Rutherford
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Radioactive elements experience “decay” over time.
Electromagnetic Spectrum
Types of Radiation
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α - Alpha Particles are stopped by paper.
β - Beta Particles are stopped by
aluminum foil.
Γ - Gamma Rays are stopped by lead,
steel, & concrete.
Protons are stopped by the atmosphere.
Neutrons are slowed down and eventually
stopped by water & concrete.
Shielding Radiation
Detecting Radiation
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We can NOT use our senses to detect
radiation.
We CAN us Geiger Counters & film to
detect radiation.
For our protection, we label radioactive
substances with the radiation symbol…
Measuring Radiation
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The amount of radiation affecting people is
measured in units known as millirems.
Most people are exposed to less than 360
millirems per year.
Common Sources of Radiation
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68% background radiation (from the
environment)
31% medical treatments/procedures
<1% fallout, nuclear industry, etc.
Effects of Exposure
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Cell Damage & Death
Cancer
Radiation Cataracts
Radiation Sickness
Acute Death
Levels of Exposure
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Occupational Limit of 5,000 millirems.
Increased Cancer Risk at 10,000 millirems.
Radiation Sickness is Possible at over 50,000
millirems of exposure
Hair loss, severe blood changes, and
possible death within 2-6 weeks with over
200,000 millirems of exposure.
Half of the patients die within 30 days with
exposure over 450,000 millirems.
Uses of Radiation
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Medicine
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Science
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Absolute Age
Industry
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X-rays
Cancer Treatment
Diagnose Diseases
Kills Germs
Result of the use of Nuclear Energy
Agriculture
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Fertilizers
Insect Control
Food Preservation
Radiation Contradictions
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Radiation is a two edged sword: its
usefulness in both medicine and
anthropological and archaeological studies is
undisputed, yet the same materials can be
used for destruction.
Human curiosity drove inquiring scientists to
harness the power of the atom. Now
humankind must accept the responsibility for
the appropriate and beneficial uses of this
very powerful tool.
Radioactive Materials
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Americium – 241: Smoke Detectors
Californium – 252: Inspect Luggage
Cesium – 137: Cancer Treatment
Cobalt – 60: Sterilize Surgical Instruments
Krypton - 85: Appliance Indicator Lights
Promethium – 147: Electric Blanket Thermostats
Thorium – 229: Fluorescent Lights
Uranium – 234: Dental Fixtures
Uranium – 235: Fuel for Nuclear Power Plants
Do Cell Phones Cause Cancer?
Nuclear Energy
Fission vs. Fusion
Nuclear Energy
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Nuclear energy comes from
the nucleus of atoms.
There are two types of
nuclear energy, fusion &
fission.
Fusion is nuclear energy
that comes from joining
atoms.
Fission is nuclear energy
that comes from splitting
atoms.
Currently the only nuclear
energy that we use to make
electricity is fission.
Nuclear Fission
Nuclear Fusion
The Manhattan Project
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Top Secret project undertaken during World
War II by American Scientists
Example of uncontrolled nuclear energy in
the form of nuclear fission.
The first test bomb was exploded on July 16,
1945 near Alamogordo, New Mexico
Little Boy & Fat Man
Hiroshima
Destruction
Affect on People
Nagasaki
Thermonuclear Weapons