Radiation Concepts

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Presentation Transcript


Ionizing Radiation Alpha Particle Neutron Particle Beta Particle Radioactive Atom Gamma Ray (X Ray)


Radioactive Material - any material containing atoms that emit radiation. Gamma Ray Gamma Ray


Radioactive Contamination - is radioactive material in an unwanted place.


Ionizing Radiation - radiation with enough energy to remove an electron from its atom.


Characteristics • +2 charge • 2 protons • 2 neutrons • Large mass Range • Very short range • 1" -2" in air Shielding • Paper • Outer layer of skin Hazards • Internal Sources • Plutonium • Uranium • Radium • Thorium • Americium a a a a a


Characteristics • -1 charge • Small mass Range • Short range • About 10' in air Shielding • Plastic safety glasses • Thin metal Hazards • Skin and eyes • Can be internal Sources • Radioisotopes • Activation Products • Sealed sources


Characteristics • No charge • No mass • Similar to x-rays Range • Long range • About 1100' in air Hazards • External (whole body) • Can be internal Sources • X-ray machines • Electron microscopes • Sealed sources • Accelerators • Nuclear reactors • Radioisotopes Shielding • Lead • Steel • Concrete Paper Plastic Lead


Characteristics • No charge • Found in nucleus Range • Extended range Shielding • Water • Plastic Hazards • External (whole body) Sources • Fission • Reactor operation • Sealed sources • Accelerators Paper Lead Water


roentgen (R) • measures exposure (ionization) of air by X-rays & gamma-rays rad (radiation absorbed dose) • measures energy deposited in any material by any type of ionizing radiation rem (Roentgen Equivalent to Man) • estimates biological damage or health risk due to absorption of ionizing radiation • unit of dose equivalent


Measure the number of nuclear transformations (disintegrations) which occur in a certain time period Curie (abbreviated, Ci) = 37,000,000,000 disintegrations per second (dps) = 2,200,000,000,000 disintegrations per minute (dpm) Radioactive contamination measures an amount of activity over a unit of surface area. e.g. 5000 dpm/100 cm2 2


Prefix Symbol Translation Numerical Value Scientific Notation Tera T 1 trillion 1,000,000,000,000 1012 Giga G 1 billion 1,000,000,000 109 Mega M 1 million 1,000,000 106 Kilo k 1 thousand 1,000 103 Milli m 1 thousandth 1/1,000 10-3 Micro m 1 millionth 1/1,000,000 10-6 Nano n 1 billionth 1/1,000,000,000 10-9 Pico p 1 trillionth 1/1,000,000,000,000 10-12


Nuclear plant - 1000 megawatts (MW) electric power 1 kilogram (kg) weighs 2.2 pounds Chest X-Ray dose = 5 millirem (mrem) Biochemist might use a 10 microCurie (mCi) source 10 nCi/100 cm2 = low level radioactive contamination Natural radium content of soil = 1 picoCi/gram (pCi/g)


millirem - is the basic unit of radiation dose equivalent. It measures biological risk in humans. Abbreviation: mrem 1000 mrem = 1 rem


Acute radiation dose refers to persons who receive large amounts of radiation over a short period of time.


Chronic radiation dose refers to persons who receive small amounts of radiation over a long period of time.


There is a slight risk that cancer may be caused by chronic radiation doses. This risk level is very small compared to the natural occurrence rate of cancer. Chronic radiation dose refers to persons who receive small amounts of radiation over a long period of time.


The previous statements assume a Linear, No-Threshold (LNT) response to radiation. There is a growing body of scientific evidence that this assumption is incorrect, and that low levels of radiation exposure are not harmful. There is also evidence that low levels of radiation exposure can have a beneficial (i.e., hormesis) effect.


Inhalation • Breathing • Smoking Wound or Cut Absorption Ingestion • Eating • Drinking • Chewing


• Radiation effects on cell chromosomes: Somatic Effects observed in the exposed individual Heritable (Genetic) Effects observed in future generations of exposed individual

RW I: 



Heritable effects have been observed in laboratory animals.

RW I: 

RW I • Smoking 1.4 cigarettes (lung cancer) • Eating 40 tablespoons of peanut butter • Eating 100 charcoal broiled steaks • 2 days in New York City (air pollution) • Driving 40 miles in a car (accident) • Flying 2500 miles in a jet (accident) • Canoeing for 6 miles • Receiving 10 mrem radiation dose (cancer)


Days of Average Life Expectancy Lost Due to Various Causes 3500 2250 1600 1100 777 365 227 207 60 10 6 Being an unmarried male Smoking (1 pack/day) Being an unmarried female Being a coal miner 25% overweight Alcohol abuse (U.S. average) Being a construction worker Driving a motor vehicle All industries Radiation: 100 mrem/yr x 70 years Coffee


Time Distance Shielding

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