ENGR302I

Radiation

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

Atom Bomb

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

Consequences of Nuclear Wars…

Shock Effects Thermal Effects Radiation Effects

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.

Internet Resources Radiation and Health Physics(

www.sph.umich.edu/group/eih/UMSCHPS/Sources.htm)

Nuclear Regulatory Commission(www.nrc.gov)