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Electromagnetic Radiation Radar, radio, and TV
(transparent) Microwave (Rotation of
molecule) Visible, UV (Vibration, absorbed
by skin) X-ray and gamma-ray
(Ionization, nearly transparent, but highly energetic)
Ionizing Radiation Ionizing radiations are:
X-ray Alpha particles (helium nuclei) Beta rays (electrons) Gamma rays Neutrons and Protons
Effects on humans are: Damage DNA Interference with normal cells
Half-Life
Half Lives Uranium-235 0.7 billion years Plutonium-239 24,360 years Cesium-137 30 years Strontium-90 28.8 years Iodine-131 8.04 days
DecayofRatePercentageT
702/1
•N/N0=1/1,000 10 half-lives
•N/N0=1/1,000,000 20 half-lives
•N/N0=1/1,000,000,000 30 half-lives
Biological Half-life Radioactive material within a living cell:
Radioactive decay Normal biological decay
Isotope iodine-125 Non-biological half-life 60 days Biological half-life 38 days
Isotope carbon-14 Half-life 5000 years (essentially constant
during one’s life time. Carbon-dating
Units of Radiation Source
Becquerel, Curie
Absorbed rad (radiation adsorbed dose)
Human Biological Damage rem (roentgen equivalent man) For x-ray and gamma-ray 1 rem=1 rad
Nuclear Waste Depositories Permanent subterranean Entombment under the sea Nuclear transmutation Storage under polar caps Other less serious proposals
Permanent Storage Storage sites must be
Geographically stable with no flowing ground water for tens of thousands of years
100 sites are designated as “temporary” storage sites Permanent site (2010)– Yucca Mountain (Nevada –
Near a young volcano and active fault line), Carlsbad (New Mexico - Oozing brine could cause steel brines to corrode)
Transporting nuclear wastes to these facilities is also a problem
NIMBY Syndrome Listen to NPR’s All Things Considered 2/22/02
NPR 2/5/02
Hydrogen Bombs Isotopes of hydrogen and deuterium
are fused to produce helium No limits to the explosive power
US tested one with the explosive power of 68,000,000 tons of TNT
Consequences are horrifically unclear Nuclear Winter, Worldwide famine
Weapon Design Conventional vs. Nuclear Bombs The A-Bomb
Critical mass Dirty Bombs Depleted Uranium
The H-Bomb (thermonuclear) Neutron Bombs Thermonuclear Bunker Busters
1-Megaton Blast
Distance from Ground zero 1 mile
Over-pressure: 43 psi Winds: 1700 mph Many Humans Killed
2 miles Over-pressure: 17 psi Winds: 400 mph Humans battered to death; lung hemorrhage; eardrums ruptured; Heavy
machinery damaged
5 miles Over-pressure: 4psi Winds: 130 mph Bones fractured; All trees down; Buildings flattened
20 miles Over-pressure: Below 1 psi Winds: Below 35 mph Many broken windows
Effects Short term (somatic, massive , direct)
Fast growing cells are most susceptible to ionizing radiation
Bone marrow cells (making blood cells) Ovaries, testes, lenses of the eyes Cancer cells grow faster than normal cells so they
are treated with radiation Effects are
Reddening of the skin, drop in the white blood cells, nausea, vomiting, hair loss, bleeding, and death
Long term (chronic, low dose, indirect) Chromosome (DNA) damage - cancer
Nuclear Arm Treaties
Listen to NPR’s all thing Considered 2/22/02
Listen to NPR’s all thing Considered 5/13/02
Sources of Exposure Non-ionizing radiation
Natural UV from the sun
Man-made UV from tanning machines
Ionizing radiation Natural
High frequency UV Intercontinental flights (cosmic rays) Soil and rocks Radon (radioactive decay of uranium in soil)
Man-Made Dental and chest x-rays Nuclear Medicine (Cobalt-60) Nuclear reactors
Nuclear Agency US Department of Energy (DoE)
Nuclear Weapons Research Licensing the nuclear reactors Nuclear Waste
US Environmental Protection Agency (EPA) Set exposure limits and standards Cleanup of contaminated areas
US Nuclear Regulatory Commission (NRC) Source material (uranium and thorium) Enriched material (enriched uranium,, plutonium) Dose limits for radiation medicine Implementing EPA Standards
UN International Atomic Energy Commission (IAEC) Verify through inspection that States comply with their commitments
under the Non-Proliferation Treaty. Nuclear Technology Transfer Assist members in the planning peaceful nuclear programs
Public Exposure Background 100 mrem Medical 50 mrem Radon 200 mrem Nuclear reactors 10 mrem
Total 360 mrem
Ref: Nuclear Regulatory Commission
How much radiation do you receive?
To a good approximation you can estimate the amount of radiation you receive every year from various sources. Here is how to estimate:1.Where do you live? _________ Elevation* (meters) _______Cosmic radiation Sea level 28 mrem Elevation X 0.015Terrestrial If you live within 10 km of a nuclear or coal power plant, add 0.3 _______2.What is your house made of?Brick or concrete (add 70), wood (add 30) _______3.Ground radiation (US average) 26 mremRadon (Water, food, and air (US average) 28 mremWatching TV 1 mrem4.How many miles are you flying every year?Number of miles ______ x .001 _______5.How is your health?Number of chest x-ray _____ x 40 _______Number of dental x-ray _____ x 5 ________Number of mammogram _____ x 30 _______ Others (chemotherapy) _______
TOTAL _______
Exposure Limit (EPA/NRC)
125 mrems every three months (500 mrems per year) Higher for nuclear reactor
personnel (5000 mrem per year)
American Guinea pigs In 1986, The Between 1940 and 1970, the US
Government conducted radiation experiments on 695 human subjects without their knowledge.
In 1994, Energy secretary Hazel O’Leary declassified millions of pages of documents. As a result
Congress approved Radiation Exposure Compensation Act ($50,000 for residence who lived downwind from certain nuclear tests and later developed cancer)
$75000 for soldiers who developed cancer after participating in above ground nuclear war tests
$150,000,000 for residents of Martial Islands who became ill after 1940s-1950s tests
Regulation (Continued) 1980 – Low-Level Radioactive Waste Policy Act
“Encourages” neighboring states to cooperate on reaching agreement on waste disposal in their “compact” and choose appropriate sites for disposal.
1985 – Nuclear Waste Policy Act Disposal of high-level nuclear waste is at the hands of Federal
Government, while authorizing states and Native American tribes to participate n the selection of appropriate permanent repository site.